Dopamine Reviews: 2002
(395 References)
(2002). "Drugs to treat autonomic dysfunction in Parkinson's disease." Mov Disord 17 Suppl 4: S103-11.
(2002). "DA agonists -- non-ergot derivatives: ropinirole: management of Parkinson's disease." Mov Disord 17 Suppl 4: S98-102.
(2002). "DA agonists -- non-ergot derivatives: pramipexole: management of Parkinson's disease." Mov Disord 17 Suppl 4: S93-7.
(2002). "DA agonists -- non-ergot derivatives: piribedil: management of Parkinson's disease." Mov Disord 17 Suppl 4: S90-2.
(2002). "DA agonists -- non-ergot derivatives: apomorphine: management of Parkinson's disease." Mov Disord 17 Suppl 4: S83-9.
(2002). "DA agonists -- ergot derivatives: pergolide: management of Parkinson's disease." Mov Disord 17 Suppl 4: S79-82.
(2002). "DA agonists -- ergot derivatives: lisuride: management of Parkinson's disease." Mov Disord 17 Suppl 4: S74-8.
(2002). "DA agonists -- ergot derivatives: dihydroergocryptine (DHEC): management of Parkinson's disease." Mov Disord 17 Suppl 4: S72-3.
(2002). "DA agonists -- ergot derivatives: cabergoline: management of Parkinson's disease." Mov Disord 17 Suppl 4: S68-71.
(2002). "DA agonists -- ergot derivatives: bromocriptine: management of Parkinson's disease." Mov Disord 17 Suppl 4: S53-67.
(2002). "Aripiprazole. Abilitat, OPC 14597." Drugs R D 3(1): 25-7.
Adachi, N. (2002). "[Cerebral ischemia and histamine]." Nippon Yakurigaku Zasshi 120(4): 215-21.
Cerebral ischemia induces excess release of glutamate and an increase in the intracellular Ca2+ concentration, which provoke catastrophic enzymatic processes leading to irreversible neuronal injury. Histamine plays the role of neurotransmitter in the central nervous system, and histaminergic fibers are widely distributed in the brain. In cerebral ischemia, release of histamine from nerve endings has been shown to be enhanced by facilitation of its activity. An inhibition of the histaminergic activity in ischemia aggravates the histologic outcome. In contrast, intracerebroventricular administration of histamine improves the aggravation, whereas blockade of histamine H2 receptors aggravates ischemic injury. Furthermore, H2 blockade enhances ischemic release of glutamate and dopamine. These findings suggest that central histamine provides beneficial effects against ischemic neuronal damage by suppressing release of excitatory neurotransmitters. However, histaminergic H2 action facilitates the permeability of the blood-brain barrier and shows deleterious effects on cerebral edema.
Adibhatla, R. M., J. F. Hatcher, et al. (2002). "Citicoline: neuroprotective mechanisms in cerebral ischemia." J Neurochem 80(1): 12-23.
Cytidine-5'-diphosphocholine (citicoline or CDP-choline), an intermediate in the biosynthesis of phosphatidylcholine (PtdCho), has shown beneficial effects in a number of CNS injury models and pathological conditions of the brain. Citicoline improved the outcome in several phase-III clinical trials of stroke, but provided inconclusive results in recent clinical trials. The therapeutic action of citicoline is thought to be caused by stimulation of PtdCho synthesis in the injured brain, although the experimental evidence for this is limited. This review attempts to shed some light on the properties of citicoline that are responsible for its effectiveness. Our studies in transient cerebral ischemia suggest that citicoline might enhance reconstruction (synthesis) of PtdCho and sphingomyelin, but could act by inhibiting the destructive processes (activation of phospholipases). Citicoline neuroprotection may include: (i) preserving cardiolipin (an exclusive inner mitochondrial membrane component) and sphingomyelin; (ii) preserving the arachidonic acid content of PtdCho and phosphatidylethanolamine; (iii) partially restoring PtdCho levels; (iv) stimulating glutathione synthesis and glutathione reductase activity; (v) attenuating lipid peroxidation; and (vi) restoring Na(+)/K(+)-ATPase activity. These observed effects of citicoline could be explained by the attenuation of phospholipase A(2) activation. Based on these findings, a singular unifying mechanism has been hypothesized. Citicoline also provides choline for synthesis of neurotransmitter acetylcholine, stimulation of tyrosine hydroxylase activity and dopamine release.
Akaike, A., H. Katsuki, et al. (2002). "[Role of nitric oxide in survival and death of neurons]." Nippon Yakurigaku Zasshi 119(1): 15-20.
The prominent pathological feature of the brain in Parkinson's disease is selective degeneration of dopaminergic neurons in the substantia nigra of the midbrain. Glutamate and nitric oxide (NO) are the major effectors of the radical stress that may induce selective loss of dopaminergic neurons. It has been postulated that neurotoxicity induced by glutamate and NO in dopaminergic neurons is regulated by certain endogenous factors. We have reported that estradiol protects dopaminergic neurons against NO-mediated glutamate neurotoxicity by reducing intracellular reactive oxygen species (ROS) levels. We further searched for a candidate for neuroprotective substances with unique structure. From the ether extract of fetal calf serum (FCS), we isolated a novel substance possessing protective activity against neurotoxicity induced by glutamate NO. The compound was a sulfur-containing diterpenoid and showed hydroxyl radical scavenging activity. We further analyzed the change of resistance to excitotoxicity in midbrain dopaminergic neurons in co-culture with the striatum by using a slice culture technique. The results suggested that the generation of NO is involved in NMDA cytotoxicity on dopaminergic neurons and that increased activity of SOD in co-culture renders dopaminergic neurons resistant to NMDA cytotoxicity by preventing peroxynitrite formation. Those findings suggest that regulation of intracellular ROS levels plays a critical role in protecting neurons against NO-mediated radical stress in neurodegenerative disorders.
Albert, U., C. Bergesio, et al. (2002). "Management of treatment resistant obsessive-compulsive disorder. Algorithms for pharmacotherapy." Panminerva Med 44(2): 83-91.
Treatment resistant OCD subjects, defined as those patients who undergo an adequate trial of SRI (clomipramine or SSRI) and do not respond or show unsatisfactory results, account for 40-50% of all patients. Once the appropriateness of the trial has been assessed, several options exist for the clinicians. If clomipramine or citalopram have been used, an appropriate strategy consists in giving the same drug intravenously. Double-blind studies exist on the efficacy of clomipramine IV, while data are missing for citalopram. Another option that should be considered first, although data are scarce, is the addition of a cognitive behavioral therapy, when available, in the forms of exposure and response prevention. When such options are not suitable or available, augmentation of the ongoing SRI with another compound represents the preferable strategy. Double-blind, placebo-controlled studies have shown the efficacy of adding pindolol (7.5 mg/d), risperidone (2 mg/d) and olanzapine (5-10 mg/d). Other agents have been proposed, but data emerging from double-blind studies were negative or contradictory. Another option available is switching from CMI to SSRI, or vice versa, or from SSRI to SSRI. Data regarding such treatment strategy, however, are highly preliminary, based on a couple of open label reports and on studies performed in treatment resistant depression. An unresolved question is whether augmentation should be preferred to switching. No data exist in OCD; a practical approach would suggest augmentation first, considering that response should be obtained faster than by switching compound. When all the available and effective strategies prove uneffective, clinicians should consider switching the patient to other compounds in monotherapy, such as venlafaxine, sumatriptan, inositol, although research is strongly needed before conclusions on the efficacy of such compounds can be drawn.
Allam, M. F., M. J. Campbell, et al. (2002). "[Parkinson's disease and smoking: coherence and plausibility]." Rev Neurol 34(7): 686-9.
INTRODUCTION. Many studies have shown that smoking is lower in patients with Parkinson s disease. However, in other investigations this was not observed. The various studies involved showed wide variation with regard to methodology, criteria for diagnosis and periods of observation and hence it is difficult to compare them. DEVELOPMENT. The first studies published were designed to examine the effects of smoking in general and information was obtained regarding the possible disorders related to tobacco smoking according to the records of mortality, which may contain errors due to selective mortality and mistaken diagnosis. Most of the studies of cases and controls included prevalent cases which accepted the study, mainly hospital cases. Also it is probable that the prevalent cases of Parkinson s disease do not smoke because of their disorders of movement. CONCLUSIONS. Many researchers have found important information about the pathophysiology of Parkinson s disease and its association with smoking. However, the hypothesis regarding the association between smoking and low risk of Parkinson s disease are various and independent, apart from the hypothesis of a truly biological mechanisms. Since the subject is still controversial, systematic reviews together with epidemiological and experimental studies are necessary.
Amano, T., H. Matsubayashi, et al. (2002). "[Alteration of neuronal activities following repeated administration of stimulants]." Nihon Arukoru Yakubutsu Igakkai Zasshi 37(1): 31-40.
It has been well-known that abuse of psychostimulants such as amphetamine and methamphetamine (MAP) induces behavioral sensitization (reverse tolerance) to MAP, resulting in psychotic effects such as hallucinatory-delusional state. Animals treated with MAP repeatedly also show the behavioral sensitization to MAP. This paper focuses on the pathogenesis and mechanism underlying sensitization to MAP after repeated treatment with MAP. MAP is known to release dopamine (DA), noradrenalin (NA) and serotonin (5-HT), and bind with the same sites on DA-, NA- and 5-HT-transporters as do these monoamines, thereby inhibiting re-uptake of these substances. As a result, these monoamines accumulate in the synaptic areas unnerved by the monoamine systems. An increase in the monoamines also occurs in the dendritic areas of DA, NA and 5-HT cells probably by a mechanism similar to those in the presynaptic terminals of monoamines. Releases and syntheses of DA, NA and 5-HT are inhibited by the monoamine per se via their autoreceptors such as D2, alpha 2 and 5-HT1A receptors, respectively. It is noteworthy that repeated MAP treatment results in the reduction of DA transporters, and such a decrease in transporters has been also found in MAP abusers by PET studies, suggesting a decrease in DA transporters is related with the appearance of reverse tolerance. Repeated MAP administration induces immediate early gene such as c-fos, c-jun and arc, and the increase in arc is inhibited by D1 and NMDA antagonists, suggesting an important role of such genes in inducing reverse tolerance. In electrophysiological studies using anesthetized rats treated with MAP repeatedly, hyposensitivities and hypersensitivities to DA and MAP have been found in nucleus accumbens receiving dopaminergic input from ventral tegmental area, 24-30 h and 5 days after the final administration of MAP, respectively, although the sensitivities recovered to the normal level 10 days after the treatment. The hypersensitivities were probably mediated via D1/D2 receptors. Thus, the hypersensitivities of nucleus accumbens neurons to DA and MAP are actually completed after repeated treatment of MAP. Therefore, it is of great interest to elucidate the molecular mechanism responsible for the DA receptor hypersensitivity.
Ament, P. W., N. Jamshed, et al. (2002). "Linezolid: its role in the treatment of gram-positive, drug-resistant bacterial infections." Am Fam Physician 65(4): 663-70.
While the choices available for the management of gram-positive, drug-resistant bacterial infections are becoming limited, antimicrobial resistance is becoming increasingly problematic because of the widespread overuse of antibiotics. Linezolid is a synthetic antibiotic belonging to a new class of antimicrobials called the oxazolidinones. Linezolid disrupts bacterial growth by inhibiting the initiation process of protein synthesis--a mechanism of action that is unique to this class of drugs. It is well absorbed with high bioavailability that allows conversion to oral therapy as soon as the patient is clinically stable. It has been approved for certain gram-positive infections including certain drug-resistant enterococcus, staphylococcus, and pneumococcus strains. It is generally well tolerated, with myelosuppression being the most serious adverse effect. As a nonselective inhibitor of monoamine oxidase, caution is recommended when used with adrenergic or serotonergic agents (e.g., tyramine, dopamine, pseudoephedrine, and selective serotonin reuptake inhibitors). Judicious use of this medication should help physicians treat patients with multidrug-resistant infections.
Anastasiadis, A. G., M. A. Ghafar, et al. (2002). "Economic aspects of medical erectile dysfunction therapies." Expert Opin Pharmacother 3(3): 257-63.
The introduction of safe and effective oral therapies has changed the significance of erectile dysfunction (ED) forever. Seldom has a new drug changed the landscape of pharmacotherapy in so many ways as sildenafil (Viagra, Pfizer). This article highlights the various oral, intracavernosal and intraurethral therapies currently available for ED and evaluates the socio-economic impact of each method.
Andersson, K. E. and P. Hedlund (2002). "Pharmacologic perspective on the physiology of the lower urinary tract." Urology 60(5 Suppl 1): 13-20; discussion 20-1.
Myogenic activity, distention of the detrusor, and signals from the urothelium may initiate voiding. In the bladder, afferent nerves have been identified not only in the detrusor, but also suburothelially, where they form a plexus that lies immediately beneath the epithelial lining. Extracellular adenosine triphosphate (ATP) has been found to mediate excitation of small-diameter sensory neurons via P2X3 receptors, and it has been shown that bladder distention causes release of ATP from the urothelium. In turn, ATP can activate P2X3 receptors on suburothelial afferent nerve terminals to evoke a neural discharge. However, most probably, not only ATP but also a cascade of inhibitory and stimulatory transmitters and mediators are involved in the transduction mechanisms underlying the activation of afferent fibers during bladder filling. These mechanisms may be targets for future drugs. The central nervous control of micturition involves many transmitter systems, which may be suitable targets for pharmacologic intervention. gamma-Aminobutyric acid, dopamine, enkephalin, serotonin, and noradrenaline receptors and mechanisms are known to influence micturition, and potentially, drugs that affect these systems could be developed for clinical use. However, a selective action on the lower urinary tract may be difficult to obtain. Most drugs currently used for treatment of detrusor overactivity have a peripheral site of action, mainly the efferent (cholinergic) neurotransmission and/or the detrusor muscle itself. In the normal bladder, muscarinic receptor stimulation produces the main part of detrusor contraction, but evidence is accumulating that in disease states, such as neurogenic bladders, outflow obstruction, idiopathic detrusor instability, and interstitial cystitis, as well as in the aging bladder, a noncholinergic activation via purinergic receptors may occur. If this component of activation is responsible not only for part of the bladder contractions, but also for the symptoms of the overactive bladder, it should be considered an important target for therapeutic interventions.
Andersson, K. E. (2002). "Treatment of the overactive bladder: possible central nervous system drug targets." Urology 59(5 Suppl 1): 18-24.
The well-known side effects of antimuscarinic drugs have focused interest on other modalities of treatment of the overactive bladder. To effectively control bladder activity, identification of suitable targets for pharmacologic intervention is necessary. Such targets may be found in the central nervous system (CNS) or peripherally. Several CNS transmitters may modulate voiding, but few drugs with a defined CNS site of action have been developed for treatment of voiding disorders. Drugs affecting gamma-aminobutyric acid, opioid, serotonin, noradrenaline, dopamine, or glutamatergic receptors and mechanisms are known to influence micturition, and potentially such drugs could be developed for clinical use. However, a selective action on the lower urinary tract may be difficult to obtain.
Andersson, K. E. and P. Hedlund (2002). "New directions for erectile dysfunction therapies." Int J Impot Res 14 Suppl 1: S82-92.
Research in the field of erectile function and dysfunction has continued to expand rapidly. Based on the information available, some directions for future erectile dysfunction therapies can be identified. The first direction is improvement of current therapeutic principles. A second generation of orally active phosphodiesterase (PDE) inhibitors is being introduced, and further developments within this field can be expected. The recent introduction of apomorphine has opened the way for new dopamine receptor agonists. The second direction is combinations of existing therapeutic principles. Combinations of apomorphine and sildenafil and apomorphine and alpha(1)-adrenoceptor (AR) antagonists, for example, seem attractive and may have a therapeutic potential in patients not responding satisfactorily to single-drug treatment. Nitrosylated alpha(1)-AR antagonists, combining nitric oxide donation and alpha(1)- or alpha(2)-AR antagonism, are currently being evaluated. The third direction is new targets within the central nervous system. Melanocortin receptor agonists have shown promise not only in animal models, but also in preliminary studies in humans. Other possible targets, such as growth hormone-releasing peptide receptors, are being explored. The fourth direction is new peripheral targets. Rho-kinase antagonism and non-nitric oxide-mediated stimulation of soluble guanylyl cyclase have been suggested as possible new principles for drug development. The fourth direction is gene therapy. Progress has been made in intracavernosal somatic gene therapy and will probably continue. Still, problems remain, and advantages over conventional pharmacological therapies have to be demonstrated. The final direction is prevention strategies. Strategies to prevent cavernosal degeneration and/or to restore cavernosal function will be one of the most exciting challenges for future research.
Andreoli, S. P. (2002). "Acute renal failure." Curr Opin Pediatr 14(2): 183-8.
Acute renal failure is characterized by an increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to appropriately regulate fluid and electrolyte homeostasis. There are many different causes of acute renal failure in children, including prerenal disease, intrinsic renal failure, which includes ischemic hypoxic insults, and obstructive uropathy. This review will focus on hypoxic/ischemic acute renal failure, the most common causes of hospital acquired acute renal failure in children. This review will briefly discuss the epidemiology and incidence of acute renal failure in pediatric patients and review new insights into the pathogenesis of acute renal failure. including hemodynamic alterations induced by alterations in nitric oxide and endothelin metabolism, the role of the inflammatory response, and alteration in polarity in the acute renal failure. The therapy of acute renal failure has changed substantially during the past few years. Controlled trials (in adults) to test the efficacy of "renal dose" dopamine have shown that it is ineffective, and hemofiltration has become increasingly popular as a choice of therapy for acute renal failure.
Ankli, A., M. Heinrich, et al. (2002). "Yucatec Mayan medicinal plants: evaluation based on indigenous uses." J Ethnopharmacol 79(1): 43-52.
As part of an ethnopharmacological field study 48 medicinal plants were evaluated using several biological assays with the goal to obtain information on the pharmacological effects of these plants, which may be of direct relevance to the indigenous uses. Three species used to treat gastrointestinal disorders showed remarkable activity against Helicobacter pylori. One of them showed activity against Giardia duodenalis. Cytotoxic effects against KB cells were found for six species. In the group of plants used for dermatological conditions several species were active against gram-positive bacteria and Candida albicans. Two plant species of this group were found to be active in an Nuclear Factor-kappaB (NF-kappaB) assay measuring inhibition of this pro-inflammatory transcription factor. A species of the Solanaceae, applied in cases of pain and fever, showed a weak activity against Plasmodium falciparum. One species traditionally used for diabetes exhibited antihyperglycemic activity. None of the six species from the group of 'women's medicine' showed relevant affinity to the D(2) dopamine receptor. Based on this evaluation, plants with strong activities should be further investigated phytochemically and pharmacologically to identify active fractions and compounds.
Anokhina, I. P. and T. V. Proskuriakova (2002). "[Involvement of the neuropeptide cholecystokinin in the mechanisms of regulation of emotions and craving]." Vestn Ross Akad Med Nauk(6): 36-40.
The paper presents an idea on the organization and functions of the cholecystokinin (CCK) system. Particular emphasis is laid on the modulating influence of CCK on dopamine neuromediation in the mesolymbic structures of the brain, which are linked with the regulation of emotions and craving. Experimental and clinical studies have indicated that CCK and its preparations arrest the major manifestation of the withdrawal syndrome, including pathological craving for alcohol, and anxiety. In the post-withdrawal period, these drugs also effectively suppress alcohol craving. The designed new tetrapeptide, a CCK analogue, selectively inhibits anxiety in animals with this emotional disorder, which is followed by normalization of dopamine exchange and GABA-system functions. It is concluded that by interacting with the dopamine-system, CCK takes a direct part in the regulation of emotions and craving.
Arenas, E. (2002). "Stem cells in the treatment of Parkinson's disease." Brain Res Bull 57(6): 795-808.
Stem cells have been suggested as candidate therapeutic tools for neurodegenerative disorders, given their ability to give rise to the appropriate cell types after grafting in vivo. In this review I summarize some of the evidence currently available concerning two approaches for the treatment of Parkinson's disease: (1) The generation of dopaminergic neurons from embryonic stem cells, multipotent stem cells, and neuronal progenitor cells for cell replacement therapy. (2) The engineering of multipotent stem cells to release glial cell-line derived neurotrophic factor, a potent neurotrophic factor for dopaminergic neurons, in a neuroprotective and neuroregenerative approach to the treatment of Parkinson's disease.
Arsland, D. (2002). "[Dementia with Lewy bodies]." Tidsskr Nor Laegeforen 122(5): 525-9.
BACKGROUND: Some 10%-15% of patients with dementia are diagnosed as dementia with Lewy bodies (DLB), a disorder characterised by the presence of Lewy bodies in the brainstem and cortex. MATERIAL AND METHODS: Review of pathology, clinical symptoms, pharmacological and nonpharmacological treatment, based on the literature and on personal experience. RESULTS: Neurochemical findings are marked cortical reduction of acetylcholine and nigrostriatal dopamine deficiency. Key features of the clinical syndrome are dementia, fluctuating consciousness, visual hallucinations and parkinsonism. There are pathological and clinical overlaps between DLB and Alzheimer's disease on the one hand, and between DLB and Parkinson's disease on the other; the relationship between these diseases awaits further elucidation. Clinical consensus criteria for DLB have been published and shown to have high sensitivity and specificity. Fluctuating consciousness may be difficult to detect, but diagnostic instruments exist that may help in the evaluation. Drug treatment of DLB is difficult. Cholinesterase inhibitors have been shown to improve cognition and psychiatric symptoms. Atypical antipsychotics may improve psychosis, but some patients develop severe sensitivity reactions. The effect of antiparkinson agents is unknown.
Assal, F. and J. L. Cummings (2002). "Neuropsychiatric symptoms in the dementias." Curr Opin Neurol 15(4): 445-50.
PURPOSE OF REVIEW: Neuropsychiatric, or non-cognitive symptoms are increasingly recognized as manifestations of dementias. RECENT FINDINGS: In Alzheimer's disease, recent advances have included the identification of behavioral profiles, differentiation of apathy and depression, characterization of risk factors for psychosis and its links to agitation and aggression, and an analysis of depressive symptoms in the absence of major depression. Functional neuroimaging data mainly supported the role of the anterior cingulate in apathy. The orbitofrontal and anterior cingulate tangle burden were associated with agitation, and increased orbitofrontal and mid-temporal muscarinic M2 receptors with psychosis and hallucinations. Selected genetic polymorphisms of dopamine and serotonin receptors or transporters were linked with aggression, hallucinations or psychosis. When compared with other dementias, individuals with frontotemporal dementia disclosed, as expected, different behaviors and particularly aberrant social behavior. The frequency of delusions and visual hallucinations was increased in Parkinson's disease, Parkinson's disease with dementia, and dementia with Lewy bodies, suggesting common mechanisms such as Lewy body pathology and cholinergic deficiency. The latter was supported by an improvement of these symptoms by cholinesterase inhibitors. SUMMARY: Future research directions include both clinical and basic neuroscience investigations. The detection of early neuropsychiatric symptoms might be a marker for dementia, and the possible existence of a mild neuropsychiatric impairment syndrome should be explored. More longitudinal studies with pathological confirmation will facilitate correlations with neuropsychiatric symptoms. Functional neuroimaging and behavioral neurogenetics will permit in-vivo correlations and consequently help patient management and care.
Aubin, H. J. (2002). "Tolerability and safety of sustained-release bupropion in the management of smoking cessation." Drugs 62 Suppl 2: 45-52.
Sustained-release bupropion (bupropion SR) was first launched in the US in 1997 as an aid to smoking cessation and has since been launched in many other countries. Adverse events associated with the use of bupropion SR at the recommended dosage of 150mg twice daily in clinical trials most commonly included insomnia, headache, dry mouth, nausea and anxiety; insomnia and anxiety are also recognised as symptoms of nicotine withdrawal. Only insomnia and dry mouth occurred significantly more frequently with bupropion SR than with placebo. Relative to placebo, no significant changes in mean values for heart rate, blood pressure or routine laboratory parameters have been reported in smokers using bupropion SR alone in clinical trials. When bupropion SR was compared with a nicotine transdermal patch in a clinical trial, insomnia predominated in the bupropion SR group, while dream abnormalities were more common in smokers using the nicotine patch. Bupropion SR and the nicotine transdermal patch in combination can be used safely (with appropriate monitoring) as an aid to smoking cessation. Infrequent but clinically important adverse reactions to bupropion SR include seizures and hypersensitivity reactions: in controlled clinical trials of bupropion SR (300 mg/day), where smokers were carefully screened for risk factors for seizure, the incidence of both seizures and severe hypersensitivity reactions was approximately 0.1% for each event. In order to avoid a risk of seizure of greater than 0.1%, smokers should be screened for predisposing risk factors and adhere to the manufacturer's dosage recommendations (maximum daily dose of 300mg). Thus, bupropion SR is generally well tolerated, as seen by the low discontinuation rate due to an adverse event in clinical trials (6 to 12%). The most common adverse events (insomnia and dry mouth) are generally transient and often resolve quickly without therapeutic intervention; they can be managed if necessary by a reduction in bupropion dose.
Baghdadli, A., V. Gonnier, et al. (2002). "[Review of psychopharmacological treatments in adolescents and adults with autistic disorders]." Encephale 28(3 Pt 1): 248-54.
Autism is an early developmental disorder. It leads to severe and durable disturbances. Given this problem, no treatment can be excluded a priori. Thus, many approaches are used to deal with autistic disorders. In France, pharmacological treatments are, for instance, largely and mostly used in adults. In the USA, these treatments concern 50% of persons with autism of any age. Nevertheless, they are rarely based on controlled studies. At the present, however, prescriptions and expected effects appear to be hard to localize. Furthermore, only few controlled studies validate their use. Aim - We offer a review of studies about medical treatments used in adolescents and adults with autism. They are classified in 3 categories: the first (category I) includes drugs used for their neurochemical effects focusing on autistic signs. The second (category II) covers drugs used for treatment of behavioural disorders frequently associated with autism. The third (category III) corresponds to a wide range of drugs or vitamins for wich only few case studies exist reporting irregular positive effects. The main hypothesis of this review is that autism involves a dysfunction of the neuromediation systems. This hypothesis opens new perspectives in the research of medical treatments in autism by focusing on molecules, which are supposed to have an effect on neuromediation systems. Method - Our review is based on studies, which have been published during the past twenty years. For many studies, data are limited to adolescents and adults. So we expanded our review to data available in children. The data bases that we have used are medline and psyclit. Keywords have been chosen according to: pharmacological considerations (psychotropic, psychoactive drugs, psychopharmacology) and clinical symptoms (autism, automutilations, aggressive behavior, and hyperactivity). Hypothesis of a dysfunction in the neuromediation systems in autism - Many studies exist about biochemical abnormalities in autism. As in schizophrenia and mental retardation, dysfunctions of the neuromediation systems are considered to be etiological factors. In 30% of people with autism the most regular dysfunction is the increase of serotonine. This led to the serotoninergic hypothesis in autism and to the use of active drugs in the serotonine system. However, the presence of other neurometabolic abnormalities also motivates the use of drugs, supposed to be active in other neuromediation systems. Pharmacological treatments in autism - Category I section sign 1 Active drugs in the dopamine system. Haloperidol (Dopamine antagonist): The effects of this molecule have been broadly studied in autism. Results indicate high efficiency in some symptoms of autism (lack in social behaviour, stereotypical behaviour) and in behavioural impairments that may be associated with autism (aggressive behaviour, hyperactivity). Its side effects, particulary the risk of late dyskinesy, make atypical antipsychotics preferable because of their lower risks. Risperidone (Dopamine and serotonine antagonist): Among several studies only few have been controlled. They indicate that Risperidone has positive effects on the behaviour and is quite well tolerated. section sign 2 Active drugs in the serotonine system. Clomipramine: after promising results, the medium-term efficiency has decreased and severe side effects have limited its use. Fluvoxamine, Fluoxetine, Sertraline (Specific serotonine drugs): Their efficiency has been mainly tested through open studies and their results are contrasted. In some cases, social behaviours have improved and aggressiveness and stereotyped behaviours have decreased. Fenfluramine: At present, this drug is removed from the market. Yet, some studies have suggested that it improves behavioural disturbances as well as performances in autism. section sign 3 Active drugs in the opiate system. Naltrexone: Several controlled studies have indicated an improvement in social and aggressive behaviours. Nevertheless, these studies have used small size sample and have not been replicated. Category II. This category correspond to drugs supposed to be active on neurochemical disturbances found in autism but their target symptoms are not autism specific signs as defined by the ICD 10. Buspirone: This serotonine agonist may have a good impact on emotional disorders and sleeping confusions. Methylphenidate: Most of the current studies about this noradrenergic drug concern children. The results are variable. Paradoxical effects may exist in children with severe mental retardation. Propanolol: Some isolated studies habe reported its efficiency on behavioural disturbances. Clonidine: This adrenergic drug treats efficiently some cases of aggressive behaviour and hyperactivity. Category III. This category contains a wide range of drugs, vitamins or method used in autism after sporadic observations of their positive effects. Secretine: An important improvement has been reported in isolated cases. However, controlled studies in children do not confirm these results. Vitamines B6, B12 and Magnesium: An improvement in socialization and in behavioural disorders have been reported in some cases, but these results are not yet confirmed. Lithium, Carbamazepine, Valproate: Results of some case studies have found it to be efficient in cyclic disorders. Gluten and casein free diet: An improvement of social behaviour have been reported by some parents after these diets. No controlled study has validated this observation. Conclusion - There is no consensus on the use of psychopharmacological treatments in autism. Although there exist many clinical observations, only few controlled studies have validated the efficiency and safety of these treatments. At the present time and until having sufficient studies, drugs are generally limited to severe disorders, for which usual psycho-educational approaches are insufficient.
Balachandran, K. P., D. Stewart, et al. (2002). "Chronic pericardial constriction linked to the antiparkinsonian dopamine agonist pergolide." Postgrad Med J 78(915): 49-50.
Constrictive pericarditis is present when a fibrotic, thickened, and adherent pericardium restricts diastolic filling of the heart. Several drugs can cause pericarditis, which can lead to chronic pericardial constriction. A case of constrictive pericarditis in a patient receiving the antiparkinsonian drug pergolide is reported.
Balfour, D. J. (2002). "The neurobiology of tobacco dependence: a commentary." Respiration 69(1): 7-11.
This commentary summarises the evidence that nicotine has the pharmacological properties of a psychostimulant drug of dependence. Behaviourally it serves as a reinforcer in self-administration experiments. Within the brain, acute nicotine stimulates the release of dopamine (DA) in the shell of the nucleus accumbens whereas repeated nicotine results in selective sensitization of its effects on DA overflow in the accumbal core. These effects are thought to play a central role in the acquisition of responding for nicotine and the development of associations between delivery of the drug and cues that predict its delivery. These responses, therefore, are thought to be pivotal to its ability to cause dependence. The commentary also emphasises the evidence that cigarette smoke provides a vehicle for nicotine that maximises its addictive potential since it delivers nicotine directly into the lungs and, within 10-15 s, to the brain. For habitual cigarette smokers, this process is repeated frequently and regularly and in the context of many other sensory cues within the smoke that potentially provide additional conditioned reinforcers. This, it is argued, explains the strong addiction that many smokers develop to tobacco smoke. Smoking cessation is also associated with the expression of an abstinence syndrome that can, largely, be attributed to nicotine withdrawal and is also likely to contribute to the maintenance of the habit. The commentary closes with a brief review of the pharmacological mechanisms that may contribute to the efficacy of nicotine replacement therapy and Zyban (bupropion) as aids to smoking cessation.
Balthazart, J., M. Baillien, et al. (2002). "Interactions between aromatase (estrogen synthase) and dopamine in the control of male sexual behavior in quail." Comp Biochem Physiol B Biochem Mol Biol 132(1): 37-55.
In male quail, like in other vertebrates including rodents, testosterone acting especially through its estrogenic metabolites is necessary for the activation of male sexual behavior. Also, the administration of dopamine agonists and antagonists profoundly influences male sexual behavior. How the steroid-sensitive neural network and dopamine interact physiologically, remains largely unknown. It is often implicitly assumed that testosterone or its metabolite estradiol, stimulates male sexual behavior via the modification of dopaminergic transmission. We have now identified in quail two possible ways in which dopamine could potentially affect sexual behavior by modulating the aromatization of testosterone into an estrogen. One is a long-acting mechanism that presumably involves the modification of dopaminergic transmission followed by the alteration of the genomic expression of aromatase. The other is a more rapid mechanism that does not appear to be dopamine receptor-mediated and may involve a direct interaction of dopamine with aromatase (possibly via substrate competition). We review here the experimental data supporting the existence of these controls of aromatase activity by dopamine and discuss the possible contribution of these controls to the activation of male sexual behavior.
Bandmann, O. and N. W. Wood (2002). "Dopa-responsive dystonia -- the story so far." Neuropediatrics 33(1): 1-5.
Dopa-responsive dystonia (DRD) is an eminently treatable condition and its recognition is therefore of crucial importance. In classical cases, the disease manifests in early childhood with walking problems due to dystonia of the lower limbs. The dystonia is frequently accompanied by "parkinsonian" features such as reduced facial expression or slowing of fine finger movements. Biochemically, the disorder is typically characterized by low levels of the neurotransmitter metabolite homovanillic acid and reduced levels of neopterin and tetrahydrobiopterin (BH4) in the cerebrospinal fluid. This is due to heterozygote mutations of the GTP cyclohydrolase I gene, which is the rate-limiting enzyme in the synthesis of BH4. BH4 is an essential co-factor for tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of dopamine. Reduced levels of BH4 lead to the dopamine-deficit syndrome DRD because of reduced TH activity. Other genes implicated in the pathogenesis of this disorder are the TH gene itself and the parkin gene. This article summarizes all relevant aspects of DRD including recent advances in the genetics of this disorder and the widening phenotype. Particular emphasis is given to clinically relevant aspects such as diagnostic difficulties and atypical presentations in infancy and early childhood.
Barrington, K. and L. P. Brion (2002). "Dopamine versus no treatment to prevent renal dysfunction in indomethacin-treated preterm newborn infants." Cochrane Database Syst Rev(3): CD003213.
BACKGROUND: Indomethacin therapy for closure of patent ductus arteriosus frequently causes oliguria, and occasionally more serious renal dysfunction. Low dose dopamine has been suggested as a means for preventing this side effect. OBJECTIVES: Primary objective: To determine whether dopamine therapy may prevent indomethacin-mediated deterioration in renal function in the preterm newborn infant without serious adverse effects. Secondary objective: To assess the effects of dopamine on the above variables in two subgroups: (1) patients given indomethacin as prophylaxis of intraventricular hemorrhage, and (2) patients given indomethacin as treatment of patent ductus arteriosus SEARCH STRATEGY: Standard methods of the Cochrane Neonatal Review Group (CNRG) were used. We searched MEDLINE (1966-2001) using PubMed as the search engine, EMBASE (1974-2001) and the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library (Issue 3, 2001). In addition we contacted the principal investigators if necessary to ascertain the required information. SELECTION CRITERIA: Randomized or quasi-randomized studies of the effects of dopamine on urine output, glomerular filtration rate, fluid balance or incidence of renal failure, in preterm newborn infants receiving indomethacin. The comparison group should have received no dopamine. DATA COLLECTION AND ANALYSIS: We used the standard methods of the Cochrane Collaboration and those of the CNRG. The primary outcomes of interest were: mortality before discharge; intraventricular hemorrhage, grade three or four; cystic periventricular leukomalacia; renal failure (either oliguria, defined as a urine output less than 1 ml/kg/hour or an elevation in creatinine by more than 40 micromoles/L); failure to close the ductus arteriosus; need for surgical PDA ligation. For categorical outcomes, we calculated typical estimates for relative risk and risk difference. For continuous outcomes the weighted mean difference (WMD) was calculated. Fixed effect models were assumed for meta-analysis. MAIN RESULTS: Three studies were found (total number randomized patients, 75) which fulfilled the entry criteria for this review. All were single center trials which enrolled NICU patients receiving indomethacin for symptomatic patent ductus arteriosus. There are no (or only partial) results for effects of dopamine on several of the primary outcomes, including death before discharge, serious intraventricular hemorrhage, cystic periventricular leukomalacia, or renal failure. There has been inadequate investigation of the effects of dopamine on cerebral perfusion or cardiac output, or GI complications, or endocrine toxicity. Dopamine improved urine output [WMD 0.68 ml/kg/hour (95% CI 0.22, 1.44)], but there was no evidence of effect on serum creatinine (WMD 2.04 micromoles/liter, CI -17.90, 21.97) or the incidence of oliguria (urine output < 1 ml/kg/hour) (RR 0.73, CI 0.35, 1.54). There was no evidence of effect of dopamine on the frequency of failure to close the ductus arteriosus (RR 1.11, CI 0.56, 2.19). REVIEWER'S CONCLUSIONS: There is no evidence from randomized trials to support the use of dopamine to prevent renal dysfunction in indomethacin-treated preterm infants.
Becker, G., M. Kocher, et al. (2002). "Radiation therapy in the multimodal treatment approach of pituitary adenoma." Strahlenther Onkol 178(4): 173-86.
BACKGROUND: Pituitary tumors are relatively uncommon, comprising 10-12% of all intracranial tumors. The treatment consisting of surgery, radiotherapy and drug therapy or a combination of these modalities is aimed at the control of tumor cell proliferation and--in endocrine active tumors--the reduction of hormone secretion. However, the slow proliferation characteristics of pituitary tumors necessitate long-term studies for the evaluation of the treatment results. In the last decade there has been continuous improvement in surgical procedures, radiotherapy techniques and drug generation. In this paper, literature will be reviewed to assess the role of modern radiotherapy and radiosurgery in the management of pituitary adenomas. MATERIAL AND METHODS: Nowadays, magnetic resonance imaging for the definition of the target volume and a real three-dimensional (3-D) treatment planning with field conformation and the possibility for non-coplanar irradiation has to be recommended. Most groups irradiate these benign tumors with single doses of 1.8-2.0 Gy up to a total dose of 45 Gy or 50.4 Gy in extensive parasellar adenomas. Adenomas are mostly small, well circumscribed lesions, and have, therefore, attracted the use of stereotactically guided high-precision irradiation techniques which allow extreme focussing and provide steep dose gradients with selective treatment of the target and optimal protection of the surrounding brain tissue. RESULTS: Radiation therapy controls tumor growth in 80-98% of patients with non-secreting adenomas and 67-89% for endocrine active tumors. Reviewing the recent literature including endocrine active and non-secreting adenomas, irradiated postoperatively or in case of recurrence the 5-, 10- and 15-year local control rates amount 92%, 89% and 79%. In cases of microprolactinoma primary therapy consists of dopamine agonists. Irradiation should be preferred in patients with macroprolactinomas, when drug therapy and/or surgery failed or for patients medically unsuitable for surgery. Reduction and control of prolactin secretion can be achieved in 44-70% of patients. After radiotherapy in acromegaly patients somatomedin-C and growth hormone concentrations decrease to normal levels in 70-90%, with a decrease rate of 10-30% per year. Hypercortisolism is controlled in 50-83% of adults and 80% of children with Cushing's disease, generally in less than 9 months. Hypopituitarism is the most common side effect of pituitary irradiation with an incidence of 13-56%. Long-term overall risk for brain necrosis in a total of 1,388 analyzed patients was estimated to be 0.2%. Other side effects are rare too, and do also depend on the damage produced by tumor itself or preceding surgery. They include deterioration of vision in 1.7% of all cases, vascular changes in 6.3%, neuropsychological disorders such as dementia in 0.7% and secondary malignancies in 0.8%, if single doses of 2.0 Gy and total doses of 50 Gy are not exceeded. CONCLUSION: Conventional radiation therapy of pituitary adenoma is highly effective. It is recommended after subtotal resection of primary tumors such as macroadenomas, after gross total resection from endocrine active adenomas with postsurgical hormone secretion and for recurrent tumors. Radiosurgery seems to be a possible treatment alternative in experienced centers, and only in patients with adenomas smaller than 25-30 mm with a minimum distance of 2-3 mm to the chiasm.
Beckers, A., H. Valdes-Socin, et al. (2002). "[Differential diagnosis and medical treatment in Cushing's disease]." Neurochirurgie 48(2-3 Pt 2): 163-72.
Cushing's disease remains a difficult diagnosis in spite of new technical procedures such as pituitary MRI, selective bilateral petrosal or cavernous sampling, (111)In pentreotide scan and 18 Flurodeoxyglucose pituitary PET scan. In this article, we review biological diagnostic procedures of Cushing's disease and corticotroph adenomas. According to our experience and the literature, we summarize the approach in medical treatment of Cushing's disease.
Ben-Shachar, D. (2002). "Mitochondrial dysfunction in schizophrenia: a possible linkage to dopamine." J Neurochem 83(6): 1241-51.
Mitochondria are not only the principal source of high energy intermediates, but play an important role in intracellular calcium buffering, are main producers of reactive oxygen species, and are the source of pro- and antiapoptotic key factors. Moreover, the mitochondria are of a ubiquitous nature and the respiratory chain has a dual genetic basis, i.e. the mitochondrial and the nuclear DNAs. Thus mitochondrial impairment could provide an explanation for the tremendous heterogeneity of clinical and pathological manifestations in schizophrenia. This article reviews several independent lines of evidence that suggest an involvement of mitochondrial dysfunction in schizophrenia. Among them are altered cerebral energy metabolism, mitochondrial hypoplasia, dysfunction of the oxidative phosphorylation system and altered mitochondrial related gene expression. In addition, the interaction between dopamine, a predominant etiological factor in schizophrenia, and mitochondrial respiration is considered as a possible mechanism underlying the hyper- and hypo-activity cycling in schizophrenia. Understanding the role of mitochondria in schizophrenia may encourage novel treatment approaches, the identification of candidate genes and new insights into the pathophysiology and etiology of the disorder.
Bergman, H. and G. Deuschl (2002). "Pathophysiology of Parkinson's disease: from clinical neurology to basic neuroscience and back." Mov Disord 17 Suppl 3: S28-40.
Parkinson's disease (PD) is characterized by motor and nonmotor (cognitive and limbic) deficits. The motor signs of PD include hypokinetic signs such as akinesia/bradykinesia, rigidity and loss of normal postural reflexes, and hyperkinetic signs such as tremor. Dopamine depletion in the striatum is the hallmark of PD and of its animal models, still the pathophysiology of the parkinsonian symptoms and especially of parkinsonian tremor are under debate. The most extreme hypotheses argue about peripheral versus central nervous system origin, intrinsic cellular oscillator versus network oscillators, and basal ganglia-based pathophysiology versus cerebellar-thalamic based pathophysiology. Recent studies support the view that parkinsonian symptoms are most likely due to abnormal synchronous oscillating neuronal activity within the basal ganglia. Peripheral factors do only play a minor role for the generation, maintenance, and modulation of PD tremor and other signs. The most likely candidates producing these neuronal oscillations are the weakly coupled neural networks of the basal ganglia-thalamo-cortical loops. However, the present evidence supports the view that the basal ganglia loops are influenced by other neuronal structures and systems and that the tuning of these loops by cerebello-thalamic mechanisms and by other modulator neurotransmitter systems entrain the abnormal synchronized oscillations. Neurosurgical procedures, such as lesions or high-frequency stimulation of different parts of the loop, might resume the normal unsynchronized activity of the basal ganglia circuitry, and, therefore, ameliorate the clinical symptoms of Parkinson's disease.
Betarbet, R., T. B. Sherer, et al. (2002). "Animal models of Parkinson's disease." Bioessays 24(4): 308-18.
Animal models are important tools in experimental medical science to better understand pathogenesis of human diseases. Once developed, these models can be exploited to test therapeutic approaches for treating functional disturbances observed in the disease of interest. On the basis of experimental and clinical findings, Parkinson's disease (PD) was the first neurological disease to be modeled and, subsequently, to be treated by neurotransmitter replacement therapy. Agents that selectively disrupt or destroy catecholaminergic systems, such as reserpine, methamphetamine, 6-hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine have been used to develop PD models. Recently, it has been found that agricultural chemicals, such as rotenone and paraquat, when administered systemically, can reproduce specific features of PD in rodents, apparently via oxidative damage. Transgenic animals that over-express alpha-synuclein are used to study the role of this protein in dopaminergic degeneration. This review critically discusses animal models of PD and compares them with characteristics of the human disease.
Beyer, C., T. Ivanova, et al. (2002). "Cell type-specificity of nonclassical estrogen signaling in the developing midbrain." J Steroid Biochem Mol Biol 81(4-5): 319-25.
Estrogens have widespread biological functions in the CNS involving the coordination of developmental processes, the regulation of cell physiology, and the control of neuroendocrine systems. In the midbrain, estrogens promote the survival, maturation, and function of neurons and, in particular, of dopamine cells. Aside from classical signaling through nuclear estrogen receptors, we have provided evidence that cellular transmission of estrogen effects in the midbrain comprises a complex intracellular signaling scenario. The major conclusion drawn from our studies is that estrogens interact with yet unidentified membrane receptor complexes which stimulate the phospholipase C and induce the formation of inosite-tri-phosphate (IP(3)). This causes a rapid and transitory rise in intracellular free calcium. The modulation of calcium homeostasis is the primary nonclassical physiological response to estrogens in all cell types. Surprisingly, a different secondary downstream signaling cascade seems to be activated in each estrogen-responsive cell population, i.e. phosphatidylinositol-3 kinase (PI3-kinase) in GABAergic and cAMP/ protein kinase A (PKA) in dopaminergic neurons, mitogen-activated protein kinase (MAP-kinase) in astrocytes. The precise biological role of estrogens for the different cell types is still fragmentary. We assume that estrogens positively influence intracellular signaling mechanisms which are important for cell differentiation and survival. It remains to be elucidated what determines the cell type-specificity of these estrogen responses.
Biglan, K. M. and R. G. Holloway (2002). "A review of pramipexole and its clinical utility in Parkinson's disease." Expert Opin Pharmacother 3(2): 197-210.
Parkinson's disease (PD) is a common neurodegenerative disorder characterised by selective loss of dopaminergic neurones in the substantia nigra and resulting in progressive disability. Therapy has focused on replacing depleted dopamine (DA) via supplementation with levodopa or DA agonists. Pramipexole (Mirapex), Pharmacia Corp.) has recently been approved for the treatment of PD. Evidence from preclinical studies and clinical trials have proven the effectiveness of this agent in ameliorating the symptoms of PD. There is also non-human evidence that pramipexole may be neuroprotective and could therefore possibly slow disease progression; however, this has yet to be proven in humans. The use of pramipexole may be limited by its side effect profile compared to standard therapies and its relatively higher cost compared to levodopa. Despite these concerns, pramipexole does have a role in the treatment of PD in all stages of the illness and may arguably be the treatment of choice in early disease. In addition to its use in PD, pramipexole has shown some utility in the treatment of restless legs syndrome (RLS), depression and schizophrenia.
Bjorklund, L. M. and O. Isacson (2002). "Regulation of dopamine cell type and transmitter function in fetal and stem cell transplantation for Parkinson's disease." Prog Brain Res 138: 411-20.
Blain, I., P. Slama, et al. (2002). "Copper-containing monooxygenases: enzymatic and biomimetic studies of the O-atom transfer catalysis." J Biotechnol 90(2): 95-112.
This review reports our recent studies or the mechanism of O-atom transfer to a benzylic C-H bond promoted by Dopamine beta-Hydroxylase (DBH) and its biomimetic models. We demonstrate that it is possible to carry out parallel and comparative studies on this enzyme (DBH) and its biomimetic models with the same substrate: 2-aminoindane (3). It was chosen because its two stereogenic centers, both in benzylic positions, make it very powerful for studying the stereochemistry of an O-atom transfer reaction. DBH-catalyzed hydroxylation of 3 produced exclusively 14% of trans-(1S,2S)-2-amino-1-indanol (4) (93% ee). Studies with stereospecifically deuterium-labeled 2-aminoindanes (1R,2S)-3b and (1S,2S)-3a showed that the formation of 4 was the rcsult of an overall process with retention of configuration where an O-atom is stereospecifically inserted in the trans pro-S position of the substrate. With copper(I) and (II) complexes of IndPY2 ligands we studied the reaction with dioxygen and observed an O-atom transfer to a benzylic C-H bond which was performed in the same manner as that of DBH. With the deuterium-labeled cis-2-d-IndPY2 ligand, we demonstrated that the reaction occurs by a stereospecific process with retention of configuration. In both cases (enzymatic vs. biomimetic) the O-atom transfers occur in a two-step process involving radical intermediates.
Blankenberg, F. G. and H. W. Strauss (2002). "Nuclear medicine applications in molecular imaging." J Magn Reson Imaging 16(4): 352-61.
With the emergence of the new field of molecular imaging, there is an increasing demand for development of sensitive and safe novel imaging agents that can be rapidly translated from small animal models into patients. Nuclear medicine and positron emission tomography (PET) techniques have the ability to detect and serially monitor a variety of biologic and pathophysiologic processes, usually with tracer quantities of radiolabeled peptides, drugs, and other molecules at doses free of pharmacologic side effects, unlike the current generation of intravenous agents required for magnetic resonance (MR) and computed tomography (CT) scanning. In this article, we will review a representative sampling of the wide array of radiopharmaceuticals developed specifically for nuclear medicine radionuclide imaging that have been approved for clinical use, and those in pre-clinical trials. We will also review the existing strategies used to select the appropriate biologic markers and targets for radionuclide labeling that have been employed in the development of novel radiotracers and the imaging of small animals with new microSPECT (single photon emission computed tomography) technologies.
Blount, P. J., C. D. Nguyen, et al. (2002). "Clinical use of cholinomimetic agents: a review." J Head Trauma Rehabil 17(4): 314-21.
BACKGROUND: There are many agents in clinical use that manipulate central nervous system levels of epinephrine, dopamine, and serotonin. However, development of pharmacological options to manipulate central acetylcholine systems has lagged behind because of poor penetration of the blood-brain barrier and significant peripheral nervous system side effects. Newer agents have demonstrated some efficacy in the management of behavioral and cognitive side effects in Alzheimer's disease, and preliminary data in traumatic brain injury suggest acetylcholine esterase inhibitors may play a significant role in the treatment of this patient population as well. CONCLUSIONS: In this article, the basic neuroanatomy and pharmacology of the central acetylcholine system are reviewed, along with agents currently available for clinical use.
Bonuccelli, U., A. Colzi, et al. (2002). "Pergolide in the treatment of patients with early and advanced Parkinson's disease." Clin Neuropharmacol 25(1): 1-10.
Introduced on the market in 1989, pergolide, a D1/D2 dopamine receptor agonist, is still widely prescribed for the treatment of patients with early and advanced Parkinson's disease (PD). Initially, pergolide was introduced as an adjunct therapy to levodopa treatment in patients exhibiting fluctuating motor responses and dyskinesias. Results of recent randomized controlled clinical trials in de novo patients with PD show that pergolide is able to improve parkinsonian symptoms when used as monotherapy. Moreover, preliminary results of a long-term monotherapy study in early PD suggest that pergolide is as effective as levodopa, and that a significant delay in the time of the onset of levodopa-induced motor complications can be obtained. A number of randomized studies have shown that pergolide is more effective than bromocriptine as adjunct therapy to levodopa in patients with advanced PD; the greater benefit found with pergolide could be ascribed to its action on both D1 and D2 dopamine receptors. However, controlled comparative studies with new dopamine agonists, such as ropinirole, cabergoline, and pramipexole, have not been performed yet. Interestingly, few open studies in patients with complicated PD have shown that high doses of pergolide (> 6 mg/d) are able to improve motor fluctuations and dyskinesias through a dramatic reduction of levodopa dosage. The side-effect profile of pergolide is similar to that of other dopamine agonists, and complications such as sleep attack and serosal fibrosis have been rarely reported.
Boraud, T., E. Bezard, et al. (2002). "From single extracellular unit recording in experimental and human Parkinsonism to the development of a functional concept of the role played by the basal ganglia in motor control." Prog Neurobiol 66(4): 265-83.
Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects the whole basal ganglia (BG). Various techniques have been used to study BG physiology and pathophysiology. Among these, extracellular single unit recording remains of particular importance. An impressive number of studies of BG electrophysiological activity have been carried out, both in non-human and in human primates, but the data collected show many omissions and disparities. BG activity has been well defined in the physiological situation, but remains far from clear in the Parkinsonian and virtually unexplored in the dopamine (DA)-replacement situation. This paper provides a brief synopsis of (i) recording techniques and (ii) BG electrophysiological activity in normal, Parkinsonian, and dopamine-replacement situations. We have restricted the data used to those obtained in BG structures of human and non-human primates. Only single unit recordings have been reported and four electrophysiological characteristics retained: mean firing frequency, firing pattern, periodic oscillation, and response to both passive and active movement. We have attempted to summarize (i) the commonly accepted characteristics of each BG structure in the three situations, (ii) discrepancies that exist, and (iii) missing elements. Then, the main successive theories aimed to explain the role played by BG in motor control are presented and discussed in the light of the most recently obtained results using the latest technological advances.
Borsini, F., K. Evans, et al. (2002). "Pharmacology of flibanserin." CNS Drug Rev 8(2): 117-42.
Flibanserin has preferential affinity for serotonin 5-HT(1A), dopamine D(4k), and serotonin 5-HT(2A) receptors. In vitro and in microiontophoresis, flibanserin behaves as a 5-HT(1A) agonist, a very weak partial agonist on dopamine D(4) receptors, and a 5-HT(2A) antagonist. In vivo flibanserin binds equally to 5-HT(1A) and 5-HT(2A) receptors. However, under higher levels of brain 5-HT (i.e., under stress), flibanserin may occupy 5-HT(2A) receptors in higher proportion than 5-HT(1A) receptors. The effects of flibanserin on adenylyl cyclase are different from those of buspirone and 8-OH-DPAT, two other purported 5-HT(1A) receptor agonists. Flibanserin reduces neuronal firing rate in cells of the dorsal raphe, hippocampus, and cortex with the CA1 region being the most sensitive in the brain. Flibanserin-induced reduction in firing rate in the cortex seems to be mediated through stimulation of postsynaptic 5-HT(1A) receptors, whereas the reduction of the number of active cells seems to be mediated through dopamine D(4) receptor stimulation. Flibanserin quickly desensitizes somatic 5-HT autoreceptors in the dorsal raphe and enhances tonic activation of postsynaptic 5-HT(1A) receptors in the CA3 region. Flibanserin preferentially reduces synthesis and extracellular levels of 5-HT in the cortex, where it enhances extracellular levels of NE and DA. Flibanserin displays antidepressant-like activity in most animal models sensitive to antidepressants. Such activity, however, seems qualitatively different from that exerted by other antidepressants. Flibanserin seems to act via direct or indirect stimulation of 5-HT(1A), DA, and opioid receptors in those animal models. Flibanserin does not display consistent effects in animal models of anxiety and seems to exert potential antipsychotic effects. Flibanserin may induce some sedation but does not induce observable toxic effects at pharmacologically relevant doses.
Bourin, M., D. J. David, et al. (2002). "[Mechanism of action of antidepressants and therapeutic perspectives]." Therapie 57(4): 385-96.
Depression is an incapacitating disease which needs appropriate treatment. This article reviews the pharmacology of antidepressant drugs and the future perspectives of treating mood disorders such as depression. The foremost theory for explaining the biological basis of depression has been the monoamine hypothesis. Depression is due to a deficiency in one or other biogenic monoamines (serotonin, 5-HT; noradrenaline, NA; dopamine, DA). Antidepressant drugs are therefore classified according to their ability to improve monoaminergic transmission. Since this first theory, other explanations based on abnormal function of monoamine receptors or associated with impaired signalling pathways have been suggested. Notable progress has been accomplished in the treatment of major depressive disorders with new compounds recently discovered (selective serotonin reuptake inhibitors: SSRI; serotonin noradrenaline reuptake inhibitors: SNRI). Behavioural, electrophysiological and microdialysis studies have shown that serotonin (5-HT) receptors, mainly 5-HT1A, 5-HT1B and 5-HT2C sub-types, exert a key role in modulating antidepressant activity. Indirect activation of neurotransmitter receptors by antidepressants may also lead, via increases in endogenous levels of serotonin in synapses in specific brain regions, to activation of various G proteins coupled to a receptor, signal of transduction, transcription factors and neurotrophic factors such as brain-derived neurotrophic factor (BDNF). Thus, depression may be considered as a transduction mechanism anomaly. This hypothesis needs to be clarified by molecular biology. Although antidepressants have improved the therapeutic potential compared to tricyclics (TCA) in terms of reduced side effects, a number of problems still occur with these drugs. Clinical effects are not always observed until after this time has elapsed (4-6 weeks) and a substantial proportion of depressed patients show only partial or no response to antidepressants. Knowledge of the existence of links between neurotransmitter systems and the discovery of the most specific target, 5-HT receptors, should lead to improvements in antidepressant therapy. Developing drugs using innovative mechanisms such as directly acting on 5-HT receptors (5-HT1A agonists or 5-HT2 antagonists), would appear to be useful in the treatment of depression. The use of antidepressants in anxiety disorders such as obsessional compulsive disorders and even generalised anxiety, highlights the distinction between antidepressants and classic anxiolytics such as benzodiazepines, or even buspirone.
Bradberry, C. W. (2002). "Dynamics of extracellular dopamine in the acute and chronic actions of cocaine." Neuroscientist 8(4): 315-22.
Cocaine amplifies dopaminergic neurotransmission via blockade of presynaptic neuronal uptake. This action is believed to be a crucial component of cocaine's ability to exert its reinforcing effects. This review will provide a brief overview of extracellular dopamine dynamics associated with cocaine. The acute effects of cocaine reviewed include comparison of intravenous and intraperitoneal routes of administration to better understand how fast and slow routes (e.g., crack and intranasal) differ in their pharmacokinetics and neurochemical effects and how those differences relate to differences in abuse potential. Changes in the acute effects of cocaine within a session have been examined in neurochemical studies of acute tolerance to self-administered cocaine in rhesus monkeys, and the potential impact of that tolerance to patterns of use is discussed. Between-session sensitization of the dopaminergic response to cocaine is reviewed, and data indicating this also occurs in primates have been obtained in self-administering rhesus monkeys, demonstrating neurochemical sensitization in a primate species. The important question of whether cocaine-associated environmental cues elicit conditioned increases in dopamine release has also been examined in the rhesus monkey, with results indicating that, unlike rats, nonhuman primates do not show conditioned increases in dopamine release.
Braus, D. F. (2002). "[Temporal perception and organisation, neuronal synchronisation and schizophrenia]." Fortschr Neurol Psychiatr 70(11): 591-600.
Basic perceptual or motor skills involving the central nervous system as well as the subjective present require the orderly temporal organization of internal and external information. Current research in schizophrenia increasingly centers on the accompanying neurocognitive deficits with frequent reports of altered temporal processes. There has been, however, less explicit research on the basic phenomenon of temporal order. Using concrete operationalized neuropsychological procedures the present study addressed the question whether chronic schizophrenic patients (28 medicated as well as 7 unmedicated) differ in their ability to correctly judge the temporal order of visual or acoustic stimuli when compared with a healthy control group (n = 26). Within this context we found a significant impairment in basal temporal perception among patients. Moderating variables such as medication, attention deficits or the effects of motivation as an essential explanatory factor for this finding could be excluded by statistical analysis. Instead, our findings point to a fundamental disturbance in the temporal coordination of neuronal network functions in association with schizophrenic psychoses. Within this context neurophysiological, neurochemical, neuroanatomical and neuropsychological overlapping of schizophrenia and temporal perception are being presented along with a discussion of the hypothesis that disturbances in neuronal synchronization and in timing processes at different levels are of essence and a possible underlying substrate in the schizophrenic spectrum.
Braver, T. S. and D. M. Barch (2002). "A theory of cognitive control, aging cognition, and neuromodulation." Neurosci Biobehav Rev 26(7): 809-17.
A theory is described which links cognitive changes observed in normal aging to an underlying decline in the function of the dopamine (DA) system projection to prefrontal cortex (PFC). The theory postulates that this neural mechanism is integral to the representation, maintenance and updating of context information, and as such impacts cognitive control across a wide range of cognitive domains, including working memory, attention, and inhibition. Behavioral and brain imaging data in support of the theory are discussed, which demonstrate selective impairments in context processing among healthy older adults associated with abnormal PFC activation. These findings highlight the utility of a computational approach to cognitive aging. Current directions for further refinement and validation of the model are outlined.
Breese, G. R., D. J. Knapp, et al. (2002). "Integrative role for serotonergic and glutamatergic receptor mechanisms in the action of NMDA antagonists: potential relationships to antipsychotic drug actions on NMDA antagonist responsiveness." Neurosci Biobehav Rev 26(4): 441-55.
NMDA receptor antagonists worsen symptoms in schizophrenia and induce schizophrenic-like symptoms in normal individuals. In animals, NMDA antagonist-induced behavioral responses include increased activity, head weaving, deficits in paired pulse inhibition and social interaction, and increased forced swim immobility. Repeated exposure to NMDA antagonists in animals results in behavioral sensitization-a phenomenon accentuated in rats with dopaminergic neurons lesioned during development. In keeping with an involvement of serotonin and glutamate release in NMDA antagonist action, selected behaviors induced by NMDA antagonists are minimized by 5-HT(2A) receptor antagonists and mGLU2 receptor agonists. These observations provide promising new approaches for treating acute NMDA antagonist-induced psychosis. Further, acute atypical antipsychotic drugs also minimize NMDA antagonist actions to a greater degree than typical antipsychotics. However, because knowledge concerning acute versus chronic effectiveness of various antipsychotic drugs against NMDA antagonist neuropathology is limited, future studies to define more fully the basis of their differences in efficacy after chronic treatment could provide an understanding of their actions on neural mechanisms responsible for the core pathogenesis of schizophrenia.
Bullock, R. and S. Libretto (2002). "Risperidone in the treatment of psychoses in the elderly: a case report series." Eur Psychiatry 17(2): 96-103.
Risperidone is one of the newer atypical antipsychotic agents, which combines potent serotonin and dopamine receptor antagonism. It shows efficacy against the positive and negative symptoms of schizophrenic psychoses and other psychotic conditions, and has a low propensity to cause extrapyramidal side effects. The aim of these case reports in elderly patients is to provide the benefit of personal experience with risperidone to the body of published literature and to demonstrate the types of patients that may benefit from treatment. These cases were compiled retrospectively from data collected on referral and during routine hospital appointments. This series covers four main areas of concern when treating the elderly: low-maintenance dosing minimising the likelihood of adverse events; successful treatment of patients previously uncontrolled and experiencing side effects with other antipsychotics; the possibility of intermittent rather than continuous treatment; and the benefits to patients, carers and the health services. At low doses, risperidone is an effective and well-tolerated treatment for psychoses in elderly patients that improves the quality of life for both patients and their caregivers.
Burckhardt, G., F. Di Sole, et al. (2002). "The Na+/H+ exchanger gene family." J Nephrol 15 Suppl 5: S3-21.
Na+/H+ exchangers (NHEs) extrude protons from, and take up sodium ions into cells. Six isoforms, NHE-1 - NHE-6, have been cloned. NHE proteins are composed of an N-terminal domain, which most likely crosses the cell membrane 12 times and constitutes the cation exchange machinery, and a C-terminal tail, which modulates the exchanger by interacting with protein kinases and regulatory factors. The "house-keeping" NHE-1 is located at the basolateral membrane of most renal tubule cells; NHE-2 is located apically in selected nephron segments. As suggested from data with NHE-1 and NHE-2 deficient mice, both isoforms play a minor role in renal salt and water handling. NHE-3 is located at the apical membrane of proximal tubule and thick ascending limb cells, is involved in Na+ absorption, and is responsible for the majority of bicarbonate absorption. NHE-3 is modulated by the NHE regulating factor, which interacts with further proteins, protein kinases, and the cytoskeleton. Downregulation of NHE-3 by parathyroid hormone, dopamine, and by an increase in blood pressure leads to saluresis/diuresis. The failure of dopamine to downregulate NHE-3 may cause hypertension through renal salt and water retention. NHE-3 knockouts are hypotonic and can not survive on low salt diet. In chronic acidosis, NHE-3 is upregulated possibly through increased local endothelin production. NHE4 has been found mostly in renal medulla. The precise function of this isoform, which is activated by hypertonicity and can perform K+/H+ exchange, is not clear. The segmental location and function of NHE-5 and NHE-6 in the kidney are unknown at present.
Bymaster, F. P. and C. C. Felder (2002). "Role of the cholinergic muscarinic system in bipolar disorder and related mechanism of action of antipsychotic agents." Mol Psychiatry 7 Suppl 1: S57-63.
The evidence for the involvement of cholinergic muscarinic receptors in mania and depression is reviewed. Small pilot trials with cholinesterase inhibitors and muscarinic agonists suggest that stimulation of muscarinic receptors may produce an antimanic effect, possibly by activation of muscarinic M(4) receptors. It is concluded that it is not likely that currently used mood stabilizers, such as lithium, valproic acid and carbamazepine, work directly through muscarinic receptor mechanisms. Furthermore, the evidence indicates that antipsychotic agents used for mania are working through the common mechanism of antagonism of dopamine D(2) receptors, and interactions with muscarinic receptors do not play a key role. Finally, it is hypothesized that olanzapine has robust antimanic activity, due to blockade of dopamine D(2) receptors and antagonism of other monoaminergic receptors. Olanzapine may normalize mood due to antidepressant-like activities, such as 5-HT(2A) receptor antagonism and increasing cortical norepinephrine and dopamine.
Cabib, S., S. Puglisi-Allegra, et al. (2002). "The contribution of comparative studies in inbred strains of mice to the understanding of the hyperactive phenotype." Behav Brain Res 130(1-2): 103-9.
Attention-deficit hyperactivity disorder (ADHD) is a highly prevalent childhood psychiatric disorder characterized by impaired attention, excessive motor activity and impulsivity. Converging evidence, suggests a primary role of disturbances in brain dopamine (DA) transmission and a role of genetic factors in its pathology. Inbred provide a well-defined and stable genotype for analysis. C57BL/6 (C57) and DBA/2 (DBA) mice are amongst the most studied inbred strains in the behavioral pharmacology of DA, and they differ in several parameters of the DA system that relate directly to behavioral differences. These strains also exhibit several qualitatively different behavior patterns that rely on separate DA networks (e.g. mesoaccumbens vs. nigrostriatal) and on different modes of inheritance. C57 mice are good learners in most tasks also involving associative learning but are totally unable to learn active avoidance although being very active. Moreover, C57 mice show greater novelty-induced locomotor activity than DBA, which is modulated strongly by DA neurons in the ventral tegmental area (VTA) region. Pharmacological studies also indicate a facilitated mesoaccumbens DA transmission in C57 mice when compared to DBAs. Increased density of D2 autoreceptors located on VTA neurons, and lower D2 postsynaptic receptors in the NAS were observed in DBA relative to C57. Activation of D2 autoreceptors inhibits impluse flow, synthesis, and release rates of DA neurons. As would be predicted from their higher D2 autoreceptor: DBA compared to C57 mice show reduced DA synthesis and release within the mesoaccumbens DA system when challenged with DA direct agonists. However, DBA mice are by fare more susceptible than C57s to stress-induced enhanced mesoaccumbens DA release and in stressful situation, they show sustained active behavioral responses whilst C57 adopt extremely passive responses (behavioral despair). Finally, chronic or repeated stress promote opposite adaptation of VTA DA autoreceptors in the two strains and render the hypoactive DBAs as active as the C57 mice. These results indicate that a complex interaction between genetic and environmental factors controls, mesoaccumbens DA functioning and hyperactive phenotype.
Caley, C. F. and C. K. Cooper (2002). "Ziprasidone: the fifth atypical antipsychotic." Ann Pharmacother 36(5): 839-51.
OBJECTIVE: To review the pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of ziprasidone as a treatment for schizophrenia. DATA SOURCES: Information was selected from a MEDLINE search (July 2000-October 2001) of English-language medical literature using ziprasidone as the search term. Manual searches of pertinent journal article references, request for medical information from Pfizer, and access of the Web site of the Food and Drug Administration were also performed. STUDY SELECTION: All available published information regarding the pertinent characteristics of ziprasidone were considered for selection. DATA EXTRACTION: Pharmacology and pharmacokinetic studies were selected to provide a comprehensive description of these characteristics. Clinical investigations were evaluated for design, sample size, diagnosis, duration, and outcome. Data from all investigations were selected by 1 author and reviewed by both authors. DATA SYNTHESIS: Ziprasidone is a benzisothiazolyl piperazine-type atypical antipsychotic that shares the serotonin(2A)/dopamine(2) (5-HT(2A)/D(2)) profile of the available atypical antipsychotics. Ziprasidone has demonstrated in vitro activity as a 5-HT(1A) receptor agonist and as a very weak inhibitor of serotonin and norepinephrine reuptake. These data do not support ziprasidone as being a clinically meaningful inhibitor of serotonin/norepinephrine reuptake. Oral bioavailability of ziprasidone taken with food is approximately 60%, half-life is approximately 6-7 hours, and protein binding is extensive at >99%. Twelve metabolites have been identified, yet only 4 of these are considered to be primary metabolites. Metabolism of ziprasidone by aldehyde oxidase produces its only metabolite with potential pharmacologic activity; CYP3A4 also contributes to the metabolism of ziprasidone. Clinical studies support ziprasidone as efficacious for the treatment of patients with acute exacerbations of schizophrenia or schizoaffective disorder. Daily doses permitted in these clinical trials ranged from 40 to 160 mg, but only doses between 120 and 160 mg/d have been superior to placebo. Future research efforts should be directed toward refractory schizophrenia, cognitive impairment in schizophrenia, affective and anxiety symptoms associated with schizoaffective disorder, and bipolar disorder. Adverse effect characteristics of ziprasidone commonly include headache, nausea, and somnolence; infrequent effects include extrapyramidal symptoms and weight gain. Ziprasidone has been reported to cause an average QTc prolongation of approximately 20 msec; there have only been 2 patients (0.06%) reported by the manufacturer to have a measured QTc interval >500 msec. CONCLUSIONS: Ziprasidone is a safe and efficacious atypical antipsychotic for the acute management of schizophrenia. Efficacy data and most safety data for ziprasidone support its use as a first-line treatment for schizophrenia; however, its potential effects on ventricular repolarization relegate it to second-line status in patients with comorbid cardiovascular risks.
Candito, M., E. Billaud, et al. (2002). "[Biochemical diagnosis of pheochromocytoma and neuroblastomas]." Ann Biol Clin (Paris) 60(1): 15-36.
Pheochromocytoma and neuroblastoma are distinct tumours, but their biological diagnosis is based on secretion increase of one or several catecholamines. Assays have to be very sensible and specific for an early diagnosis. 24 hours urinary catecholamines and metabolites are currently measured, but technical improvements permit plasma metanephrine assay, an excellent indicator of pheochromocytoma. HPLC coupled to electrochemical detection represents the most efficient methodology. After a review of urinary and plasma assay methods, the authors show usual values of catecholamines, metanephrines, HVA and VMA, according to ages, and give examples of results encountered in classical or not tumours and in falsely positive cases. Urinary metanephrine assay is the most sensible and specific in biological diagnosis of pheochromocytoma, while catecholamines and VMA assays lack of sensibility. Results have to be given by 24 hours and by creatinine ratio. Metanephrine assay can be performed also in plasma and exhibits the same interest. However, in urine as in plasma, in case of renal failure, results cannot be interpreted. Neuroblastoma biological diagnosis is based classically on HVA, VMA, and dopamine assays, nowadays only in 24 hours urine (or in urinary micturition for screening), and results are also expressed as creatinine ratio. But even if several assays are advisable, 5% of the neuroblastoma cases do not produce increased catecholamine values. In some cases, metanephrine assay could be of interest. After the age of 12 months, clinical expression of neuroblastoma is dramatic in 70% of cases. So, a biological screening has been experimented in several countries including France. A French translation of the consensus conference report (1998) is appended, which shows the complexity of neuroblastoma screening. Now, there is no evidence that early tumour detection by screening lessens the mortality rate, but a weak benefit is not excluded.
Cantello, R., R. Tarletti, et al. (2002). "Transcranial magnetic stimulation and Parkinson's disease." Brain Res Brain Res Rev 38(3): 309-27.
While motor cortical areas are the main targets of the integrative activity of basal ganglia, their main output consists of the corticospinal system. Transcranial magnetic stimulation (TMS), a relatively new method to investigate corticospinal physiology, has been widely used to assess possible changes secondary to Parkinson's disease (PD). The use of single- and paired-pulse TMS, two varieties of the original technique, disclosed multiple functional alterations of the corticospinal pathway. For instance, when the latter was tested at 'rest', or in response to somesthetic afferents, it showed excess excitability or reduced inhibition. In turn, during production of a voluntary output, its activation was defective, or inadequately modulated. One major mechanism may be a dysfunction of the interneurons mediating the level of excitation within cortical area 4. For instance, there is a shortening of the so-termed 'central silent period', which is a complex, TMS-induced, inhibitory phenomenon possibly mediated by activation of GABA(B) receptors. The so-called 'short-interval intracortical inhibition', which is possibly mediated by GABA(A) receptors, is also diminished. Levodopa restores these and other TMS alterations, thus demonstrating that cortical area 4 is sensitive to dopamine modulation. Overall, TMS has provided substantial new pathophysiological insights, which point to a central role of the primary motor cortex in the movement disorder typical of PD. Repetitive (r-)TMS, another form of TMS, has been studied as a treatment for PD motor signs. Although some reports are favorable, others are not, and have raised the problem of appropriate control experiments. Although extremely interesting, the potential therapeutic role of r-TMS in PD needs further evaluation.
Capuano, B., I. T. Crosby, et al. (2002). "Schizophrenia: genesis, receptorology and current therapeutics." Curr Med Chem 9(5): 521-48.
Schizophrenia is a debilitating mental disease affecting approximately 1% of the population worldwide. Since the discovery of the first modern treatment for schizophrenia, chlorpromazine, in 1952 there have been many new structures investigated, only a small fraction of which have resulted in clinically useful drugs. Of these, haloperidol may be regarded as the drug for first line treatment. Since then, clozapine has emerged as the benchmark therapeutic ameliorating positive and negative symptoms and devoid of movement disorders, with its greatest feature being improvement of treatment-resistant patients. However, a major, potential lethal side-effect of clozapine is the induction of agranulocytosis, a blood disorder with unknown mechanism that results in lowered white-blood cell counts and consequent susceptibility to infections. In the 50 years of antipsychotic drug development, several novel theories have evolved that focus on receptor sub-types (serotonin 5-HTsub>2A, dopamine D(2) and D(4)) and the degree to which they need to be selectively attenuated by the drugs. Also of significance is the location of these receptors in the brain in relation to the disease state, the myriad of side-effects associated with antipsychotics and physicochemical properties of antipsychotic molecules relative to models of the drugs and the GPCR receptors involved. The techniques for investigation have shown increasing sophistication and refinement over this period, involving cloned receptors and PET scanning for determination of receptor location, density and binding, and rate constants at receptors. Knowledge of receptor structure, although in its infancy since no membrane bound CNS-receptor has yet been crystallized, is likely to benefit substantially with advances in computer-aided modelling. Overall, these new techniques have resulted in a number of novel antipsychotics such as risperidone, sertindole, olanzapine, seroquel, zotepine and ziprasidone, whose design, synthesis and testing has benefited enormously from the accumulated knowledge base of the past 50 years. In this review, we will provide a comprehensive update of the theories of action and clinical profiles of the latest drugs listed. The following appraisal of the literature will provide the practising medicinal chemist interested in this critical area of research with sufficient insight and understanding, to embark on productive investigations into the design and development of new therapeutic agents devoid of clinically limiting side-effects.
Carlsson, A. (2002). "Treatment of Parkinson's with L-DOPA. The early discovery phase, and a comment on current problems." J Neural Transm 109(5-6): 777-87.
Carr, K. D. (2002). "Augmentation of drug reward by chronic food restriction: behavioral evidence and underlying mechanisms." Physiol Behav 76(3): 353-64.
Chronic food restriction and maintenance of low body weight have long been known to increase the self-administration and motor-activating effects of abused drugs. Using a lateral hypothalamic self-stimulation (LHSS) rate-frequency method, it is shown that chronic food restriction augments the rewarding (i.e., threshold lowering) effect of diverse drugs of abuse. Further, the effect is attributed to increased sensitivity of a neural substrate, rather than a change in drug bioavailability or pharmacokinetics, because it is preserved when drugs are injected directly into the lateral cerebral ventricle (intracerebroventricularly). The food restriction regimen that augments drug reward also increases the induction of c-fos, by intracerebroventricular amphetamine, in limbic forebrain dopamine (DA) terminal areas. The possibility of increased DA receptor function is suggested by findings that rewarding and motor-activating effects of direct DA receptor agonists are augmented by food restriction, and the augmented behavioral effects of amphetamine are reversed by an otherwise subthreshold dose of D-1 antagonist. Initial studies of DA receptor-mediated signal transduction, that are focused on the D-2 receptor, suggest increased functional coupling between receptor and G-protein (i.e., quinpirole-stimulated [(35)S]GTPgammaS binding) in dorsal striatum. Unlike behavioral sensitization induced by intermittent stress or psychostimulant treatment, which persist indefinitely following induction, the augmenting effect of food restriction abates within 1 week of restored ad libitum feeding and weight gain. The possible involvement of endocrine hormones and/or 'feeding-related' neuropeptides, whose levels change dynamically with depletion and repletion of adipose stores, is therefore under investigation. Initial tests have been limited to acute treatments aimed at attenuating the effects of hypoinsulinemia, hypoleptinemia and elevated corticosterone levels in food-restricted rats. None of these treatments has attenuated the behavioral effect of food restriction. While a melanocortin receptor agonist has been found to enhance drug reward, melanocortin receptors do not seem to mediate the augmenting effect of food restriction. Continuing investigations of endocrine adiposity signals, 'feeding-related' neuropeptides and dopaminergic signal transduction may further elucidate the way in which drugs of abuse exploit mechanisms that mediate survival-related behavior, and help explain the high comorbidity of drug abuse and eating disorders.
Castellanos, F. X. and R. Tannock (2002). "Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes." Nat Rev Neurosci 3(8): 617-28.
Cavalieri, E. L., E. G. Rogan, et al. (2002). "Initiation of cancer and other diseases by catechol ortho-quinones: a unifying mechanism." Cell Mol Life Sci 59(4): 665-81.
Exposure to estrogens is a risk factor for breast and other human cancers. Initiation of breast, prostate and other cancers has been hypothesized to result from reaction of specific estrogen metabolites, catechol estrogen-3,4-quinones, with DNA to form depurinating adducts at the N-7 of guanine and N-3 of adenine by 1,4-Michael addition. The catechol of the carcinogenic synthetic estrogen hexestrol, a hydrogenated derivative of diethylstilbestrol, is metabolized to its quinone, which reacts with DNA to form depurinating adducts at the N-7 of guanine and N-3 of adenine. The catecholamine dopamine and the metabolite catechol (1,2-dihydroxybenzene) of the leukemogen benzene can also be oxidized to their quinones, which react with DNA to form predominantly analogous depurinating adducts. Apurinic sites formed by depurinating adducts are converted into tumor-initiating mutations by error-prone repair. These mutations could initiate cancer by estrogens and benzene, and Parkinson's disease by the neurotransmitter dopamine. These data suggest a unifying molecular mechanism of initiation for many cancers and neurodegenerative diseases and lay the groundwork for designing strategies to assess risk and prevent these diseases.
Chaudhuri, K. R., S. Pal, et al. (2002). "'Sleep attacks' or 'unintended sleep episodes' occur with dopamine agonists: is this a class effect?" Drug Saf 25(7): 473-83.
Controversial reports of sudden onset 'sleep attacks' resulting in road traffic accidents have recently been reported in patients with Parkinson's disease (PD) taking the non-ergot dopamine D(2 )/D(3) receptor agonists pramipexole and ropinirole. These reports have generated considerable debate as the concept of 'sleep attacks' is disputed amongst sleep specialists and most believe that isolated 'sleep attacks' not preceded by warning on the background of chronic sleepiness or 'unintended sleepiness' do not exist. A series of case reports suggested that this phenomenon may not be exclusive to the non-ergot dopamine agonists such as pramipexole or ropinirole and indeed may occur with most dopaminergic agents. Recent evidence suggest that a 'sleepiness' or 'hypoactivity' reaction to dopaminergic therapy may be related to underlying dopamine deficiency of PD rather than a drug effect. In this report we provide the evidence for the phenomenon being a class effect attributable to all dopamine agonists currently employed in the management of PD. Controversy surrounding excessive daytime sleepiness (EDS) in PD and the use of the Epworth Sleepiness Scale (ESS) in relation to PD is also discussed. In spite of variable reports, EDS is recognised to be common in PD and is likely to be related to both the disease process and drug therapy. Studies using multiple sleep latency tests have also reported differing results in PD although a recent study indicated that a subset of 'sleepy' patients with PD may experience pathological somnolence with resultant detrimental consequence on daytime and cognitive functions. We recommend that the issue of 'sleepiness' or 'sleep attacks' in PD should be routinely checked in all patients with PD and indirectly assessed by using either the ESS or the recently introduced Parkinson's Disease Sleep Scale. Those with reported 'sleep attacks' or 'unintended sleep episodes' and excessive daytime sleepiness while taking dopamine agonists or dopaminergic agents such as levodopa should have a review of their medication, should not be driving a car on their own and some may merit formal sleep architecture studies. The latter may identify sleep disorders such as secondary narcolepsy which may benefit from the use of a wakefulness promoting agent.
Citver, A. S., A. M. Shields, et al. (2002). "Indirect modulation of dopamine D2 receptors as potential pharmacotherapy for schizophrenia: III. Retinoids." J Clin Pharm Ther 27(3): 161-8.