gamma-Aminobutyric acid (Gaba) and the dopamine hypothesis of schizophrenia

Chemical profiling, anticonvulsant and anxiolytic effects of the smoke constituents isolated from Leonotis leonurus (L.) R.Br

ETHNOPHARMACOLOGICAL RELEVANCE

The use of medicinal plants for central nervous system (CNS)-related ailments, such as epilepsy and anxiety, is prevalent in South Africa. Plants from the Lamiaceae family are commonly used for their therapeutic benefits. Leonotis leonurus (L.) R.Br. has been reported in ethnobotanical literature to have anticonvulsant and anxiolytic effects through the inhalation of pyrolysis products obtained by combustion of the aerial parts.

AIM AND OBJECTIVES

To explore the chemical profiles and CNS activity of the smoke extract and isolated constituents of L. leonurus in zebrafish larvae, through anticonvulsive and anxiolytic activity assays.

MATERIALS AND METHODS

The smoke extract of L. leonurus was obtained through the combustion of the aerial parts of the plant using a custom-built smoke recovery apparatus. The chemical profile of the smoke constituents was determined using Ultra-Performance Liquid Chromatography coupled with Mass Spectrometry (UPLC-MS). Targeted compounds were subjected to preparative High-Performance Liquid Chromatography for separation before structure elucidation using Nuclear Magnetic Resonance (NMR). The maximum tolerated concentrations, as well as the anxiolytic activity of the smoke extract were determined in five days post fertilisation zebrafish larvae. Reverse-thigmotaxis and locomotor activity of larvae in the light/dark transition assay were used to determine anxiolytic activity. Zebrafish larvae at six days post fertilisation (dpf) were subjected to several concentrations of the smoke constituents of L. leonurus. The baseline locomotor activity of the larvae was tracked for 30 min, prior to addition of pentylenetetrazole (PTZ) to induce seizure-like behaviour in the larvae, after which the locomotor activity of the larvae was once again tracked for an additional 30 min.

RESULTS

The UPLC-MS profiles of the smoke extract revealed the presence of two main compounds, leoleorin A and leoleorin B, which were targeted and isolated. Upon subjection to NMR spectroscopy for structure elucidation, the compounds were confirmed to be labdane diterpenoids. Both leoleorin A and leoleorin B, and the smoke extract displayed suppression of the PTZ induced seizure-like behaviour in zebrafish larvae. Under light and dark conditions, the smoke extract and compounds displayed potential anxiolytic activity at different concentrations.

CONCLUSION

Our results suggest that the smoke constituents of L. leonurus may exert anticonvulsant and anxiolytic effects which align with the traditional indications and the mode of administration.

Benzodiazepines and Mood Stabilizers in Schizophrenia Patients Treated with Oral versus Long-Acting Injectable Antipsychotics-An Observational Study

Schizophrenia is a chronic, invalidating, and polymorphic disease, characterized by relapses and remission periods. The main treatment option in schizophrenia are antipsychotics, administered as an oral or as a long-acting injectable (LAI) formulation. Although international guidelines rarely recommend it, mood stabilizers (MS) and/or benzodiazepines (BZD) are frequently prescribed as adjunctive therapy in schizophrenia patients for various reasons. This is an observational, cross-sectional study including stabilized schizophrenia patients. A total of 315 patients were enrolled. Of these, 77 patients (24.44%) were stabilized on LAIs and 238 (75.56%) patients on oral antipsychotics (OAP). Eighty-four patients (26.66%) had concomitant treatment with MS and 119 patients (37.77%) had concomitant benzodiazepine treatment. No statistical significance was observed in MS or BZD use between LAIs and OAPs. In total, 136 patients (43.17%) were stabilized on antipsychotic monotherapy. Our study shows that the long-term use of benzodiazepines and mood stabilizers remains elevated among stabilized schizophrenia patients, regardless of the antipsychotic formulation (oral or LAI). Patients receiving second-generation LAI antipsychotics (SGA-LAI) seem to be more likely to be stabilized on monotherapy compared to those receiving oral antipsychotics. Further randomized controlled trials are necessary in order to clarify the benefits of the current drug polypharmacy trends.

A Rarity Among the Rare: Psychiatric Manifestations in a Young Woman With Stiff-Person Syndrome

Stiff-person syndrome (SPS) is a rare progressive neurologic disease associated with autoantibodies against glutamic acid decarboxylase, an intracellular enzyme involved in the production of gamma-aminobutyric acid. 

We present a case involving a 35-year-old Haitian female who was placed under the Baker Act in the emergency department for suicidal behavior and acute psychosis. She has a history of SPS with a positive glutamic acid decarboxylase (GAD) antibody, a condition most commonly found in females between 20 and 50 years of age. The condition was managed by an outpatient neurologist using diazepam, baclofen, and monthly intravenous immunoglobulin treatments. She also has an extensive history of organic neurological conditions, including traumatic brain injury at 18 years old and COVID-19-related anoxic encephalitis that occurred in December 2020. Both psychiatric and neurological physical exams were completed. They revealed a cerebellar tremor, bilateral ptosis, poor eye contact, decreased concentration, poor insight, depressed mood, flat affect, poor judgement, delusional thoughts and a disorganized thought process with tangential speech. CT and MRI imaging of the brain showed no acute intracranial abnormalities. A quantitative titer of the GAD antibody was completed and shown to be elevated >250IU/mL. Depakote 500mg twice daily and risperidone 3mg twice daily were prescribed. The patient had progressive improvement of psychosis including delusional thoughts over the following five days and was able to be discharged with instructions to follow-up with outpatient neurology. 

Efficacy of lurasidone in the treatment of agitation: A post hoc analysis of five short-term studies in acutely ill patients with schizophrenia

OBJECTIVE

This post hoc analysis evaluated the effect of lurasidone on agitation in acutely ill patients with schizophrenia.

METHOD

Patient-level data were pooled from five 6-week, randomized, double-blind, placebo-controlled studies of fixed-dose, once-daily, oral lurasidone (40, 80, 120, or 160 mg/d). Agitation was assessed with the Positive and Negative Syndrome Scale-Excited Component (PANSS-EC) score, utilizing a mixed model for repeated measurement analysis.

RESULTS

In patients with higher levels of agitation at baseline (PANSS-EC score≥14; n=773), lurasidone was associated with significantly greater improvement in least-squares (LS) mean PANSS-EC scores versus placebo at Day 3/4 (-1.6 vs -1.0; p<0.05), Day 7 (-2.3 vs -1.6; p<0.05), and at Week 6 endpoint (-5.5 vs -3.8; p<0.001; effect size=0.43). In patients with lower agitation at baseline (PANSS-EC score<14; n=754), LS mean PANSS-EC score change was significantly greater for lurasidone compared with placebo at Day 7 (-0.8 vs -0.1; p<0. 01) through Week 6 endpoint (-1.9 vs -0.9; p<0.001; effect size=0.31). Higher doses of lurasidone were notably more effective than lower doses in patients with more severe agitation at study baseline.

CONCLUSION

In this pooled analysis of 5 short-term studies, lurasidone provided early and sustained reduction in agitation, assessed using the PANSS-EC score, in patients with an acute exacerbation of schizophrenia. Higher doses of lurasidone were particularly effective in patients with more severe agitation at study baseline. Overall, these results suggest that lurasidone may be a useful treatment option for patients exhibiting agitation associated with acute psychotic symptoms of schizophrenia. ClinicalTrials.gov Identifiers: NCT00088634 (Study D1050196); NCT00549718 (Study D1050229), NCT00615433 (Study D1050231); NCT00790192 (Study D1050233). Study D1050006 was completed prior to the requirement to register trials.

Metabotropic glutamate receptors as targets for new antipsychotic drugs: Historical perspective and critical comparative assessment

In this review, we aim to present, discuss and clarify our current understanding regarding the prediction of possible antipsychotic effects of metabotropic glutamate (mGlu) receptor ligands. The number of preclinical trials clearly indicates, that this group of compounds constitutes an excellent alternative to presently used antipsychotic therapy, being effective not only to positive, but also negative and cognitive symptoms of schizophrenia. Although the results of clinical trials that were performed for the group of mGlu2/3 agonists were not so enthusiastic as in animal studies, they still showed that mGlu ligands do not induced variety of side effects typical for presently used antipsychotics, and were generally well tolerated. The lack of satisfactory effectiveness towards schizophrenia symptoms of mGlu2/3 activators in humans could be a result of variety of uncontrolled factors and unidentified biomarkers different for each schizophrenia patient, that should be taken into consideration in the future set of clinical trials. The subject is still open for further research, and the novel classes of mGlu5 or mGlu2/3 agonists/PAMs were recently introduced, including the large group of compounds from the third group of mGlu receptors, especially of mGlu4 subtype. Finally, more precise treatment based on simultaneous administration of minimal doses of the ligands for two or more receptors, seems to be promising in the context of symptoms-specific schizophrenia treatment.

William T. Carpenter Jr: 35 years of clinical trials

William T. Carpenter Jr has had a major impact on the design and conduct of clinical trials in schizophrenia. His contributions range from the decisive evaluation of the efficacy of hemodialysis to the development of novel approaches to evaluate new treatments for cognitive impairments and negative symptoms. He has developed innovative dosage reduction strategies. He has led efforts to focus drug development on those illness components that are not responsive to antipsychotic treatment. He has emphasized throughout his career the use of translational science to provide the conceptual framework for clinical trial interventions. This article reviews highlights of his many contributions, with an emphasis on 3 areas: (1) dosage reduction studies; (2) the use of the domains of psychopathology to identify drug development targets; and (3) the use of translational science to guide new drug development.

Modeling interneuron dysfunction in schizophrenia

Schizophrenia is a debilitating neurodevelopmental disorder affecting approximately 1% of the population and imposing a significant burden on society. One of the most replicated and well-established postmortem findings is a deficit in the expression of the gene encoding the 67-kDa isoform of glutamic acid decarboxylase (GAD67), the primary GABA-producing enzyme in the brain. GAD67 is expressed in various classes of interneurons, with vastly different morphological, molecular, and physiological properties. Importantly, GABA system deficits in schizophrenia encompass multiple interneuronal subtypes, raising several important questions. First, do different classes of interneurons regulate different aspects of behavior? Second, can we model cell-type-specific GABAergic deficits in mice, and will the rodent findings translate to human physiology? Finally, will this knowledge open the door to knowledge-based approaches to treat schizophrenia?

Modulation of ion channels in clinical psychopharmacology: adults and younger people

This review focuses on the use of Na(+), Ca(2+) and Cl(-) channel modulators in psychiatric disease. Drugs that modulate ion channels have been used in psychiatry for more than a century, and in this review we critically evaluate clinical research that reports the therapeutic effects of drugs acting on GABA(A), voltage-gated Na(+) and voltage-gated Ca(2+) channels in pediatric and adult patients. As in other fields, the evidence underpinning the use of medicines in younger people is far less robust than for adults. In addition, we discuss some current developments and highlight clinical disorders in which current molecules could be further tested. Notable success stories, such as benzodiazepines (in sleep and anxiety disorders) and antiepileptics (in bipolar disorder), have been the result of serendipitous discoveries or refinements of serendipitous discoveries, as in all other major treatments in psychiatry. Genomic, high-throughput screening and molecular pharmacology discoveries may, however, guide further developments in the future. This could include increased research in promising targets that have been perceived as commercially risky, such as selective α-subunit GABA(A) receptors.

The GABA B receptor agonist CGP44532 and the positive modulator GS39783 reverse some behavioural changes related to positive syndromes of psychosis in mice

BACKGROUND AND PURPOSE

An important role of GABAergic neurotransmission in schizophrenia was proposed a long time ago, but there is limited data to support this hypothesis. In the present study we decided to investigate GABA(B) receptor ligands in animal models predictive for the antipsychotic activity of drugs. The GABA(B) receptor antagonists CGP51176 and CGP36742, agonist CGP44532 and positive allosteric modulator GS39783 were studied.

EXPERIMENTAL APPROACH

The effects of all ligands were investigated in MK-801- and amphetamine-induced hyperactivity tests. The anti-hallucinogenic-like effect of the compounds was screened in the model of head twitches induced by (±)1-(2.5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Furthermore, the effect of GS39783 and CGP44532 on DOI-induced frequency of spontaneous excitatory postsynaptic currents (EPSCs) in slices from mouse brain frontal cortices was investigated. The anti-cataleptic properties of the compounds were also assessed.

KEY RESULTS

The GABA(B) receptor activators CGP44532 and GS39783 exhibited antipsychotic-like effects both in the MK-801- and amphetamine-induced hyperactivity tests, as well as in the head-twitch model in mice. Such effects were not observed for the GABA(B) receptor antagonists. DOI-induced increased frequency of spontaneous EPSCs was also decreased by the compounds. Moreover, CGP44532 and GS39783 inhibited haloperidol-induced catalepsy and EPSCs.

CONCLUSION AND IMPLICATIONS

These data suggest that selective GABA(B) receptor activators may be useful in the treatment of psychosis.

Schizophrenia, "Just the Facts" 6. Moving ahead with the schizophrenia concept: from the elephant to the mouse

The current construct of schizophrenia as a unitary disease is far from satisfactory, and is in need of reconceptualization. The first five papers in our "facts" series reviewed what is known about schizophrenia to date, and a limited number of key facts appear to stand out. Schizophrenia is characterized by persistent cognitive deficits, positive and negative symptoms typically beginning in youth, substantive heritability, and brain structural, functional and neurochemical alterations including dopaminergic dysregulation. Several pathophysiological models have been proposed with differing interpretations of the illness, like the fabled six blind Indian men groping different parts of an elephant coming up with different conclusions. However, accumulating knowledge is integrating the several extant models of schizophrenia etiopathogenesis into unifying constructs; we discuss an example, involving a neurodevelopmental imbalance in excitatory/inhibitory neural systems leading to impaired neural plasticity. This imbalance, which may be proximal to clinical manifestations, could result from a variety of genetic, epigenetic and environmental causes, as well as pathophysiological processes such as inflammation and oxidative stress. Such efforts to "connect the dots" (and visualizing the elephant) are still limited by the substantial clinical, pathological, and etiological heterogeneity of schizophrenia and its blurred boundaries with several other psychiatric disorders leading to a "fuzzy cluster" of overlapping syndromes, thereby reducing the content, discriminant and predictive validity of a unitary construct of this illness. The way ahead involves several key directions: a) choosing valid phenotype definitions increasingly derived from translational neuroscience; b) addressing clinical heterogeneity by a cross-diagnostic dimensional and a staging approach to psychopathology; c) addressing pathophysiological heterogeneity by elucidating independent families of "extended" intermediate phenotypes and pathophysiological processes (e.g. altered excitatory/inhibitory, salience or executive circuitries, oxidative stress systems) that traverse structural, functional, neurochemical and molecular domains; d) resolving etiologic heterogeneity by mapping genomic and environmental factors and their interactions to syndromal and specific pathophysiological signatures; e) separating causal factors from consequences and compensatory phenomena; and f) formulating or reformulating hypotheses that can be refuted/tested, perhaps in the mouse or other experimental models. These steps will likely lead to the current entity of schizophrenia being usefully deconstructed and reconfigured into phenotypically overlapping, but etiopathologically unique and empirically testable component entities (similar to mental retardation, epilepsy or cancer syndromes). The mouse may be the way to rescue the trapped elephant!

The effects of lorazepam on extrastriatal dopamine D(2/3)-receptors-A double-blind randomized placebo-controlled PET study

Lorazepam is a widely used anxiolytic drug of the benzodiazepine class. The clinical actions of benzodiazepines are thought to be mediated via specific allosteric benzodiazepine binding sites and enhancement of GABAergic neurotransmission in the brain. However, the indirect effects of benzodiazepines on other neurotransmitter systems have not been extensively studied. Previous experimental evidence suggests that benzodiazepines inhibit striatal dopamine release by enhancing the GABAergic inhibitory effect on dopamine neurons whereas very little is known about cortical or thalamic gamma-amino-butyric (GABA)-dopamine interactions during benzodiazepine administration. We explored the effects of lorazepam (a single 2.5 mg dose) on cortical and thalamic D(2/3) receptor binding using Positron-Emission Tomography (PET) and the high-affinity D(2/3)-receptor ligand [(11)C]FLB 457 in 12 healthy male volunteers. We used a randomized, double-blind and placebo-controlled study design. Dopamine D(2)/D(3) receptor binding potential was measured with the reference tissue method in several extrastriatal D(2)-receptor areas including frontal, parietal, temporal cortices and thalamus. The main subjective effect of lorazepam was sedation. Lorazepam induced a statistically significant decrease of D(2)/D(3) receptor BP(ND) in medial temporal and dorsolateral prefrontal cortex (DLPFC) that was also confirmed by a voxel-level analysis. The sedative effect of lorazepam was associated with a decrease in D(2)/D(3) receptor BP(ND) in the DLPFC. In conclusion, lorazepam decreased [(11)C]FLB 457 binding in frontal and temporal cortex, suggesting that cortical GABA-dopamine interaction may be involved in the central actions of lorazepam in healthy volunteers. The correlation between lorazepam-induced sedation and D(2)/D(3) receptor binding potential (BP) change further supports this hypothesis.

GABA(A) receptors and their associated proteins: implications in the etiology and treatment of schizophrenia and related disorders

Gamma-aminobutyric acid type A (GABA(A)) receptors play an important role in mediating fast synaptic inhibition in the brain. They are ubiquitously expressed in the CNS and also represent a major site of action for clinically relevant drugs. Recent technological advances have greatly clarified the molecular and cellular roles played by distinct GABA(A) receptor subunit classes and isoforms in normal brain function. At the same time, postmortem and genetic studies have linked neuropsychiatric disorders including schizophrenia and bipolar disorder with GABAergic neurotransmission and various specific GABA(A) receptor subunits, while evidence implicating GABA(A)R-associated proteins is beginning to emerge. In this review we discuss the mounting genetic, molecular, and cellular evidence pointing toward a role for GABA(A) receptor heterogeneity in both schizophrenia etiology and therapeutic development. Finally, we speculate on the relationship between schizophrenia-related disorders and selected GABA(A) receptor associated proteins, key regulators of GABA(A) receptor trafficking, targeting, clustering, and anchoring that often carry out these functions in a subtype-specific manner.

In vivo detection of gray and white matter differences in GABA concentration in the human brain

A novel selective multiple quantum filtering-based chemical shift imaging method was developed for acquiring GABA images in the human brain at 3 T. This method allows a concomitant acquisition of an interleaved total creatine image with the same spatial resolution. Using T(1)-based image segmentation and a nonlinear least square regression analysis of GABA-to-total creatine concentration ratios in frontal and parietal lobes of healthy adult volunteers as a function of the tissue gray matter fraction, the mean GABA concentration in gray and white matter was determined to be 1.30+/-0.36 micromol/g and 0.16+/-0.16 micromol/g (mean+/-SD, n=13), respectively. It is expected that this method will become a useful tool for studying GABAergic function in the human brain in vivo.

Are Autistic and Catatonic Regression Related? A Few Working Hypotheses Involving Gaba, Purkinje Cell Survival, Neurogenesis, and ECT

Autistic regression seems to occur in about a quarter of children with autism. Its cause is unknown. Late-onset autistic regression, that is, after 2 years of age, shares some features with catatonic regression. A working hypothesis is developed that some children with autistic regression suffer from early-onset catatonic regression. This hypothesis cannot be answered from current data and is difficult to address in clinical studies in the absence of definite markers of autistic and catatonic regression. Treatment implications are theoretical and involve the potential use of anticatatonic treatments for autistic regression. Focus is on electroconvulsive therapy (ECT)--an established but controversial treatment that is viewed by many, but not all, as the most effective treatment for severe, life-threatening catatonic regression. Clinical trials of ECT in early- or late-onset autistic regression in children have not been done yet. The effects of electroconvulsive seizures--the experimental analogue of ECT--should also be tested in gamma-aminobutyric acid-ergic animal models of autistic regression, autism, catatonia, and other neurodevelopmental disorders. Purkinje cell survival and neurogenesis are putative outcome measures in these models.

Pharmacological management of acute agitation

Acute agitation occurs in a variety of medical and psychiatric conditions, and when severe can result in behavioural dyscontrol. Rapid tranquillisation is the assertive use of medication to calm severely agitated patients quickly, decrease dangerous behaviour and allow treatment of the underlying condition. Intramuscular injections of typical antipsychotics and benzodiazepines, given alone or in combination, have been the treatment of choice over the past few decades. Haloperidol and lorazepam are the most widely used agents for acute agitation, are effective in a wide diagnostic arena and can be used in medically compromised patients. Haloperidol can cause significant extrapyramidal symptoms, and has rarely been associated with cardiac arrhythmia and sudden death. Lorazepam can cause ataxia, sedation and has additive effects with other CNS depressant drugs.Recently, two fast-acting preparations of atypical antipsychotics, intramuscular ziprasidone and intramuscular olanzapine, have been developed for treatment of acute agitation. Intramuscular ziprasidone has shown significant calming effects emerging 30 minutes after administration for acutely agitated patients with schizophrenia and other nonspecific psychotic conditions. Intramuscular ziprasidone is well tolerated and has gained widespread use in psychiatric emergency services since its introduction in 2002. In comparison with other atypical antipsychotics, ziprasidone has a relatively greater propensity to increase the corrected QT (QTc) interval and, therefore, should not be used in patients with known QTc interval-associated conditions. Intramuscular olanzapine has shown faster onset of action, greater efficacy and fewer adverse effects than haloperidol or lorazepam in the treatment of acute agitation associated with schizophrenia, schizoaffective disorder, bipolar mania and dementia. Intramuscular olanzapine has been shown to have distinct calming versus nonspecific sedative effects. The recent reports of adverse events (including eight fatalities) associated with intramuscular olanzapine underscores the need to follow strict prescribing guidelines and avoid simultaneous use with other CNS depressants. Both intramuscular ziprasidone and intramuscular olanzapine have shown ease of transition to same-agent oral therapy once the episode of acute agitation has diminished. No randomised, controlled studies have examined either agent in patients with severe agitation, drug-induced states or significant medical comorbidity. Current clinical experience and one naturalistic study with intramuscular ziprasidone suggest that it is efficacious and can be safely used in such populations. These intramuscular atypical antipsychotics may represent a historical advance in the treatment of acute agitation.

Role of neuroactive steroid allopregnanolone in antipsychotic-like action of olanzapine in rodents

Olanzapine increases brain allopregnanolone (ALLO) levels sufficiently to modulate neuronal activity by allosterically regulating GABAA receptors. Recently, we reported the antipsychotic-like profile of ALLO in rodents. The present study examined the hypothesis that olanzapine-induced elevation of endogenous neurosteroid ALLO is vital for its neuroleptic-like action. The conditioned avoidance response (CAR) and apomorphine-induced climbing behavioral paradigms were used in rodents. Administration of ALLO (1 microg, intracerebroventricular (i.c.v.)) or neurosteroidogenic agents such as the mitochondrial diazepam binding inhibitor receptor agonist, FGIN 1-27 (0.5 microg, i.c.v.) or the ALLO precursor, progesterone (10 mg/kg, i.p.) significantly potentiated olanzapine-induced blockade of CAR and apomorphine-induced climbing. In contrast, these agents failed to alter the antipsychotic-like effect of risperidone and haloperidol. On the other hand, inhibition of the endogenous biosynthesis of neurosteroids by the 3beta-hydroxysteroid dehydrogenase inhibitor, trilostane (30 mg/kg, i.p.), the 3alpha-hydroxysteroid oxidoreductase inhibitor, indomethacin (5 mg/kg, i.p.), or the GABAA receptor antagonist bicuculline (1 mg/kg, i.p.) and dehydroepiandrosterone sulfate (DHEAS) (1 mg/kg, i.p.) blocked the effect of olanzapine, but not of risperidone and haloperidol. Socially isolated animals, known to exhibit decreased brain ALLO and GABAA receptor functions, displayed a shortening in the muscimol-induced loss of righting reflex and an increased susceptibility to apomorphine-induced climbing. Administration of olanzapine, but not of haloperidol and risperidone, normalized the duration of muscimol-elicited loss of righting reflex. Although all three antipsychotics proved capable of antagonizing the apomorphine-induced climbing, a dose almost five times higher of olanzapine was required in socially isolated animals. The data obtained suggest that enhancement of the GABAergic tone plays a key role in the antipsychotic-like effect exerted by olanzapine in rodents, likely as a consequence of augmented levels of neuroactive steroids, in particular ALLO, in the brain. The present findings provide the first specific behavioral evidence in support of the hypothesis that neuroactive steroid ALLO- mediated GABAergic modulation is essential for the antipsychotic-like action of olanzapine.

Cataleptic effect of neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one in mice: modulation by serotonergic agents

The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) induced catalepsy in mice is modified by dopaminergic, adenosinergic and GABAergic agents. In light of serotonergic agents being implicated in antipsychotic-induced catalepsy and their ability to increase brain neurosteroid content, the present study was undertaken to investigate the effect of various 5-HT agents on catalepsy induced by 3alpha,5alpha-THP in mice. Pretreatment with selective serotonin reuptake inhibitor, fluoxetine (5 mg/kg, i.p.), 5-HT releaser, fenfluramine (10 mg/kg, i.p.), 5-HT(1A) receptor agonist, 8-OH-DPAT (0.3 mg/kg, s.c.), 5-HT1B/1C receptor agonist, TFMPP (3 mg/kg, i.p.), 5-HT2A/1C receptor agonist, DOI (1.5 mg/kg, s.c.) and 5-HT3 agonist, 2-methylserotonin (5 mg/kg, i.p.) potentiated the catalepsy induced by exogenous administration of 3alpha,5alpha-THP. Furthermore, FGIN 1-27, an MDR agonist that increases endogenous content of 3alpha,5alpha-THP although per se failed to exhibit any cataleptic effect but enhanced the cataleptic response in combination with these serotonergic agents. The potentiating action of 5-HT1A, 5-HT2A/1C or 5-HT3 receptor agonist on 3alpha,5alpha-THP induced catalepsy was not blocked by prior administration of sub-effective dose (1 mg/kg, s.c.) of their respective receptor antagonists pindolol, ritanserin or ondansetron or by pretreatment with serotonergic neurotoxin 5,7-DHT (100 microg/mouse, i.c.v.). However this effect of different serotonergic agents was antagonized by the GABA(A) receptor antagonist, bicuculline (1 mg/kg, i.p.) or the 3alpha-hydroxysteroid oxidoreductase enzyme inhibitor, indomethacin (5 mg/kg, i.p.). The 5-HT agents enhance neurosteroid-induced catalepsy by increasing GABAergic tone, likely as a consequence of increased brain content of 3alpha,5alpha-THP.

Effects of cocaine administration on receptor binding and subunits mRNA of GABA(A)-benzodiazepine receptor complexes

The effects of intermittent intraperitoneal (i.p.) administration of cocaine (20 mg/kg) on GABA(A)-benzodiazepine (BZD) receptors labeled by t-[(35)S]butylbicyclophosphorothionate (TBPS), and on several types of mRNA subunits were investigated in rat brain by in vitro quantitative receptor autoradiography and in situ hybridization. Phosphor screen imaging with high sensitivity and a wide linear range of response was utilized for imaging analysis. There was a significant decrease in the level of alpha 1, alpha 6, beta 2, beta 3, and gamma 2 subunits mRNA, with no alteration of [(35)S]TBPS binding in any regions in the brain of rats at 1 h following a single injection of cocaine. In chronically treated animals, the mean scores of stereotyped behavior were increased with the number of injections. The level of beta 3 subunit mRNA was decreased in the cortices and caudate putamen, at 24 h after a final injection of chronic administrations for 14 days. In the withdrawal from cocaine, the frontal cortex and hippocampal complexes showed a significant increase in [(35)S]TBPS binding and alpha1 and beta 3 subunit mRNA in the rats 1 week after a cessation of chronic administration of cocaine. These findings suggest that the disruption of GABA(A)-BZD receptor formation is closely involved in the development of cocaine-related behavioral disturbances. Further studies on the physiological functions on GABA(A)-BZD receptor complex will be necessary for an explanation of the precise mechanisms underlying the acute effects, development of hypersensitization, and withdrawal state of cocaine.

Signal transmission, rather than reception, is the underlying neurochemical abnormality in schizophrenia

OBJECTIVE

This review aims to summarise the outcome of studies on changes in the molecular architecture of the brain of subjects with schizophrenia and formulate a hypothesis on mechanisms involved in the pathology of the illness.

METHOD

The outcomes from key studies using neuroimaging techniques and tissue obtained post-mortem that have been directed toward identifying abnormalities in the molecular architecture of the brain in subjects with schizophrenia were summarised. Using the results from these studies hypotheses were formulated on the underlying pathological process that precipitate schizophrenia.

RESULTS

Studies using neuroimaging techniques or tissue obtained post-mortem have revealed changes in the dopaminergic, serotoninergic, glutamatergic, GABAergic and cholinergic systems of the brain in schizophrenia. Some of these studies have identified abnormalities in presynaptic proteins or functioning that may be central to the pathology of schizophrenia.

CONCLUSIONS

There appears to be diverse changes in the molecular cytoarchitecture of the brains from subjects with schizophrenia. It could be that it is by affecting these multiple systems that the atypical antipsychotic drugs produce their improved clinical outcomes. Abnormal functioning of presynaptic processes could be central to the pathology of schizophrenia. If the 'presynaptic' hypothesis is proven, future antipsychotic drug design should be directed away from post-synaptic receptor antagonism toward the modulating the functions of presynaptic neurones.

Diazepam treatment of early signs of exacerbation in schizophrenia

OBJECTIVE

Therapeutic intervention at the earliest phase of symptom exacerbation in schizophrenia is an important clinical need, but specific pharmacotherapeutic interventions for this phase of illness have not been established. This study examined diazepam efficacy for this phase of treatment.

METHOD

A double-blind, randomized clinical trial with 53 schizophrenic patients compared diazepam with placebo (with fluphenazine treatment for a comparison group). Treatment was initiated at the earliest signs of exacerbation, and symptom progression was the dependent measure used to evaluate efficacy.

RESULTS

Diazepam was statistically superior to placebo in preventing symptom progression and was comparable to fluphenazine.

CONCLUSIONS

Efficacy data support the use of diazepam in treating prodromal and early warning signs of symptom exacerbation in schizophrenia. This therapeutic strategy may be especially important for patients who refuse antipsychotic drugs or as a supplemental approach in a treatment plan that emphasizes low-dose antipsychotic therapy.

Schizophrenia, psychosis, and the basal ganglia

Schizophrenia is one of the most common and perhaps the most disabling of mental disorders, for which effective forms of treatment have not yet been established definitively. The findings reviewed in this article strongly suggest that basal ganglia abnormalities are involved in the pathophysiology of psychotic syndromes in general, and schizophrenia in particular.

Haloperidol, lorazepam, or both for psychotic agitation? A multicenter, prospective, double-blind, emergency department study

Rapid tranquilization is a routinely practiced method of calming agitated psychotic patients by use of neuroleptics, benzodiazepines, or both in combination. Although several studies have examined the efficacy of the three approaches, none have compared these treatments in a prospective, randomized, double-blind, multicenter trial. Ninety-eight psychotic, agitated, and aggressive patients (73 men and 25 women) were prospectively enrolled during an 18-month period in emergency departments in five university or general hospitals. Patients were randomly assigned to receive intramuscular injections of lorazepam (2 mg), haloperidol (5 mg), or both in combination. Patients in each treatment group received 1 to 6 injections of the same study drug within 12 hours, based on clinical need. They were evaluated hourly after the first injection until at least 12 hours after the last. Efficacy was assessed on the Agitated Behavior Scale (ABS), a modified Brief Psychiatric Rating Scale (MBPRS), Clinical Global impressions (CGI) scale, and an Alertness Scale. Effective symptom reduction was achieved in each treatment group with significant (P < .01) mean decreases from baseline at every hourly ABS evaluation. Significant (P < .05) mean differences on the ABS (hour 1) and MBPRS (hours 2 and 3) suggest that tranquilization was most rapid in patients receiving the combination treatment. Study event incidence (side effects) did not differ significantly between treatment groups, although patients receiving haloperidol alone tended to have more extrapyramidal system symptoms. The superior results produced by the combination treatment support the use of lorazepam plus haloperidol as the treatment of choice for acute psychotic agitation.

Clonidine plus haloperidol in the treatment of schizophrenia/psychosis

Because of the evidence for increased norepinephrine (NE) production in psychotic patients, we studied the effects of combining the alpha 2-adrenergic agonist clonidine with haloperidol for the treatment of schizophrenic psychosis. Twelve hospitalized schizophrenic patients were taken off their antipsychotic medication for 2 to 4 weeks before double-blind treatment with haloperidol (20 mg/day) combined with either clonidine or placebo. The group receiving clonidine was significantly more improved on the thought disorder subscale of the Brief Psychiatric Rating Scale (p = 0.02). The groups differed initially in the level of negative symptoms, but not controlling for this difference statistically by analysis of covariance did not change the finding with regard to the superiority of combining clonidine with haloperidol. We conclude that larger treatment trials of combining haloperidol with clonidine are warranted.

Basic aspects of GABA-transaminase in neuropsychiatric disorders

Over the last two decades, there have been several studies suggesting the major inhibitory amino acid neurotransmitter gamma-aminobutyric acid (GABA) is involved directly and/or indirectly in the pathogenesis of many neurologic diseases and psychiatric disorders. GABA is mainly degradated to succinic semialdehyde in a reaction catalyzed by the enzyme GABA-transaminase (GABA-T). Inhibition of this enzyme produces considerable elevation of GABA contents in the brain, and such elevation has been found to correlate with pharmacologic and behavioral effects. We focus attention, from the basic aspects, on brain and platelet GABA-T activities in various species, with a special reference to neuropsychiatric disorders. It seems that the activity of GABA-T in the brain and/or in the blood platelets is correlated to certain neuropsychiatric disorders such as alcoholism, epilepsy, and Alzheimer's disease. In animal and human studies, platelet GABA-T was identified with similar kinetic and inhibitor characteristics to those of the brain. Therefore, in this way, studies of the activity of the enzyme GABA-T in relation to neuropsychiatric disorders could be undertaken to understand, diagnose, and treat GABA-related disorders of the central nervous system.

In vivo effects of carbamazepine and haloperidol on GABA neurotransmission and LH secretion

The in vivo effects of carbamazepine (CBZ) and haloperidol (HAL) on the neuroendocrine pre-optico-pituitary feedback system were studied by local application of the drugs, in single and in combination mode, through a push-pull cannula into the pre-optic area and measurement of their local effects on γ-aminobutyric acid (GABA) and their distant effects on a subsequent biological response: the pituitary luteinizing hormone (LH) secretion. The perfusion flow rate was 20 μl cerebrospinal fluid (CSF)/min; the fraction period was 15 min. Perfusion with 8 μg CBZ/ml CSF caused a reduction in pre-optic pre-synaptic GABA release and, concomitantly, a suppression of plasma LH levels. Application of 100 ng HAL/ml CSF also caused a reduction in GABA release, but no significant change in plasma LH levels. During the combined perfusion, the effects of CBZ and HAL did not add up with regard to the pre-optic GABA release. These results suggest that both drugs interact with the GABA system, but they may involve two different mechanisms of action. Due to the known inhibitory role of pre-optic GABA in pituitary LH secretion, it can be inferred that, in contrast to HAL, CBZ increases post-synaptic GABAergic transmission.

GABA-transaminase in brain and blood platelets: basic and clinical aspects

Several lines of evidence suggest that the major inhibitory neuro-transmitter, gamma-aminobutyric acid (GABA) is involved, both directly and indirectly, in the pathogenesis of certain neurological and psychiatric disorders. The main enzyme responsible for GABA catabolism is gamma-aminobutyrate aminotransferase (GABA-T). Inhibition of this enzyme produces a considerable elevation of brain GABA concentrations, and such elevation has been correlated with many pharmacological effects. There seems to be that, as is discussed below, GABA-T activity in the brain and/or blood platelets is related to some neuro-psychiatric disorders such as alcoholism, epilepsy and Alzheimer's disease. GABA-T has been identified in the blood platelets with similar characteristics to those of brain GABA-T. In this way, studies on GABA-T activity in neuro-psychiatric disorders could be performed to understand, diagnosis and treat GABA-related disorders of the central nervous system (CNS).

Typical and atypical neuroleptics induce alteration in blood-brain barrier and brain 59FeCl3 uptake

Long-term neuroleptic medication of schizophrenic patients induces extrapyramidal motor side effects, of which tardive dyskinesia (TD) is the most severe. The etiology of TD is still obscure. Recently, it was suggested that abnormal iron metabolism may play a crucial role in neuroleptic-induced dopamine D2 receptor super-sensitivity. The apparent relationship between neuroleptics and iron is further supported by the increase of iron in the basal ganglia of patients with TD. We now report on the ability of neuroleptic to alter the blood-brain barrier in the rat and to potentiate the normally limited iron transport into the brain. Thus, chronic treatment of rats with chlorpromazine and haloperidol facilitated 59Fe3+ uptake into brain cells. In contrast, clozapine, an atypical antipsychotic neuroleptic with little extrapyramidal motor side effects, caused iron sedimentation in brain blood vessels with no sign of detectable iron in the cells. Moreover, chronic treatment with chlorpromazine and haloperidol caused a 43% and 24% reduction, respectively, in liver nonheme iron, whereas clozapine induced an 81% increase. The apparent different potentials of chlorpromazine, haloperidol, and clozapine to increase iron transport into the brain from its peripheral stores may be linked to the severity of extrapyramidal motor side effects they induce and to the pathophysiology of TD.

CSF diazepam binding inhibitor and schizophrenia: clinical and biochemical relationships

Diazepam-binding inhibitor (DBI) is a 9-kD neuropeptide that interacts with the benzodiazepine (BZD) binding sites of the neuronal gamma-aminobutyric acid type A (GABAA) receptor and with the glial mitochondrial BZD receptor (MBR). We explored the involvement of CSF DBI-LI in schizophrenia, based on the potential role of GABA in the negative symptoms associated with schizophrenia, the relationship of its receptors with dopamine and norepinephrine release, and the proposed therapeutic efficacy of BZDs in schizophrenia. Clinical data, CSF DBI-LI and CSF monoamine measures were obtained in 65 drug-free male chronic (DSM-IIIR) schizophrenic patients, 53 of whom were also tested prior to haloperidol withdrawal. Following haloperidol withdrawal, CSF DBI-LI increased significantly. Drug-free CSF DBI-LI did not correlate with CSF monoamines. CSF DBI-LI was significantly higher in paranoid compared to chronic undifferentiated schizophrenic patients. The data suggest that DBI may have a symptom modulatory rather than an etiological role in schizophrenia.

Neuroendocrine and psychosocial mechanisms in post-partum psychosis

(1) Results from a study investigating psychosocial and neuroendocrine influences on post-partum psychosis are presented. Subjects were 43 pregnant women with histories of affective disorder (bipolar or schizoaffective disorder, n = 26; major depressive disorder, n = 17), together with 45 pregnant women without any psychiatric history. (2) At 36 weeks antenatal assessments were carried out of the women's psychiatric histories, current psychiatric state and also the occurrence of life events in the preceding year. They were then monitored for 6 months after delivery during which time psychiatric state and any further life events were recorded. Illness was defined according to Research Diagnostic Criteria (RDC); 22 high risk women and 3 control women were categorised as RDC 'cases' during the post-partum follow-up period. Fifteen of the bipolar/schizoaffective women (8 of whom subsequently became ill within 3 months of delivery) and 15 controls (all of whom remained well) also participated in a neuroendocrine test at 4 days post-partum when their growth hormone response to a challenge dose of the dopamine agonist, apomorphine, was measured. (3) The results showed that women with histories of depression and control women who became ill after delivery were three times more likely to have had a life event in the year preceding onset of illness than women from these subgroups who remained well. In contrast, for women with histories of bipolar or schizoaffective disorder, life events appeared to be unimportant. Instead bipolar/schizoaffective women who became ill showed an enhanced growth hormone response to the apomorphine challenge test compared to those who remained well and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Gamma-aminobutyrate aminotransferase activity in brains of schizophrenic patients

The activity of gamma-aminobutyrate aminotransferase (GABA-T) was estimated in twelve regions of brains from 22 control subjects and 6 cases with schizophrenia. In the controls, no significant correlation was found between the enzyme activity and age or postmortem interval (PMI) in any of the brain regions studied. In experiments on rat brains, the enzyme activity decreased about 20% during the first 2 hours of storage at room temperature and at 4 degrees C but remained steady thereafter. A similar initial decline in activity in the human brain material cannot be excluded. In the human brains, a slightly lower activity was found in the group below 75 years (n = 8) when compared with the group above 75 years (n = 8). A tendency to higher activities was found in female brains (n = 10) compared with male brains (n = 12). No significant difference in the enzyme activity was found between schizophrenic brains, in any of the regions studied, when compared to controls, matched for age, sex and PMI.

Chronic neuroleptic administration decreases extracellular GABA in the nucleus accumbens but not in the caudate-putamen of rats

The extracellular levels of gamma-aminobutyric acid (GABA) in the caudate-putamen and the nucleus accumbens of rats following administration of haloperidol decanoate, fluphenazine decanoate, or vehicle for 8 months were assessed using intracranial microdialysis. Basal levels of extracellular GABA were significantly decreased in the nucleus accumbens of both neuroleptic-treated groups while levels of GABA in the caudate-putamen were not significantly different between groups. These results provide evidence for selective chronic neuroleptic-induced effects on in vivo GABA function in different terminal regions containing dopamine receptors.

Positron emission tomography and magnetic resonance imaging: a review and a local circuit neurons hypo(dys)function hypothesis of schizophrenia

A review of brain imaging (PET and MRI) studies on schizophrenia and recent data from neuroanatomy, neurophysiology, neuropathology, neurochemistry, neuropsychology, and cortical organization theory is integrated with the concept of local circuit neurons (LCNs) in a new hypothesis--the local circuit neurons hypo(dys)function hypothesis of schizophrenia--that attempts to explain the pathogenesis and pathophysiology of schizophrenia through a hypofunction (or dysfunction) of the local circuit neurons in prefrontal and limbic-temporal areas. This hypofunction (dysfunction) is then related to the neurocircuitry, neuropsychology, and psychopathology of schizophrenia.

"Panic-like" symptomatology in schizophrenic and schizoaffective patients with postpsychotic depression: observations and implications

Approximately one quarter of a series of 45 schizophrenic and schizoaffective patients with operationally diagnosed episodes of postpsychotic depression were also found to have anxiety symptoms consistent with the panic-attack syndrome. The incidence of such attacks was distributed across all demographic groups. Heuristic and treatment implications of this observation are considered.

Schizophrenia, tardive dyskinesia, and brain GABA

We measured the contents of gamma-aminobutyric acid (GABA) and of other amino compounds in five regions of autopsied brain from 18 patients with schizophrenia and from a large group of adult control subjects dying without any neurological or psychiatric disorder. In addition, concentrations of GABA were measured in the cerebrospinal fluid (CSF) of living schizophrenic patients and control subjects. No deficiency of GABA was found in the frontal cortex, caudate nucleus, putamen, nucleus accumbens, or medial dorsal thalamus of patients dying with schizophrenia, nor were GABA concentrations low in the CSF of living schizophrenic patients. These results do not confirm our earlier report of low levels of GABA in the nucleus accumbens and thalamus of some schizophrenic patients. We do not find neurochemical evidence favoring an involvement of GABAergic neuronal hypofunction in the etiology either of schizophrenia or of neuroleptic-induced tardive dyskinesia.

Doubleblind evaluation of the antimanic properties of carbamazepine as a comedication to haloperidol

1. Today carbamazepine is the most important alternative to neuroleptic drugs for the treatment of manic psychoses. Often carbamazepine is administered as a comedication to a neuroleptic. 2. A doubleblind study with 20 patients suffering from manic or schizomanic psychoses was performed to determine whether carbamazepine and haloperidol in comedication are more effective than haloperidol alone. 3. Under the tested conditions (24 mg haloperidol p.d.) only the smaller amount of additional medication with levomepromazine in the experimental group gave evidence for the antimanic effect of carbamazepine in combination with haloperidol. 4. Especially the patients with pure manic psychoses seem to benefit from carbamazepine as an adjunct to haloperidol.

Inhibition of non-dopamine cells in the ventral tegmental area by benzodiazepines: relationship to A10 dopamine cell activity

Previous electrophysiological studies have demonstrated that non-dopaminergic (non-DA) neurons within the substantia nigra pars reticulata (SNR) are extremely sensitive to the inhibitory effects of GABA and GABA-mimetic drugs, including benzodiazepines, whereas dopaminergic (DA) neurons in the substantia nigra pars compacta (SNC) are less sensitive to these compounds and may be influenced indirectly by SNR neurons. The interactions between A10 DA and non-DA neurons within the adjacent ventral tegmental area (VTA) are not as well characterized. In the present experiments, single unit recording and microiontophoretic techniques were used to determine the effects of benzodiazepines on DA and non-DA neurons in the VTA of chloral hydrate anesthetized rats. Diazepam, administered intravenously (i.v.), potently inhibited non-DA, SNR-like cells within the VTA. The effects of diazepam on A10 DA cells were more variable than those observed on non-DA, SNR-like cells in this region, but 77% of such cells showed moderate to marked excitation. Both of these effects were reversed by the benzodiazepine antagonist Ro 15-1788; on many cells, this agent produced marked rebound effects beyond the original basal firing rates. However, when administered alone, Ro 15-1788 exerted no effect on either cell population. Microiontophoretic administration of the benzodiazepines chlordiazepoxide and flurazepam resulted in marked inhibition of non-DA SNR-like cells, but produced either mild inhibition or no effect on A10 DA cells; excitation of DA cells was never observed even though the same neuron was excited by i.v. diazepam. These findings suggest that benzodiazepines act directly upon non-DA, SNR-like cells in the VTA to produce inhibition of activity and a disinhibition of A10 DA cells. This relationship makes it unlikely that benzodiazepines would enhance feedback inhibition of DA cells following neuroleptic administration. In fact, when administered following haloperidol, i.v. diazepam failed to reverse haloperidol-induced increases of A10 DA cell firing; if anything, diazepam further depolarized the cell. If antipsychotic drugs produce their clinical effects, in part, by inducing depolarization inactivation of DA cells, then benzodiazepines might be a useful adjunctive therapy in the treatment of schizophrenia.

Smooth pursuit eye movement disorder and its psychobiologic correlates in unmedicated schizophrenics

The accuracy of smooth pursuit eye movements (SPEMs) was evaluated electrooculographically in 14 medication-free schizophrenics. Concentrations of monoamine metabolites and gamma-amino-butyric acid (GABA) were measured in their cerebrospinal fluid (CSF). Ventricular-brain ratios (VBR) were determined by computed axial tomography (CT scan). Premorbid adjustment was evaluated by the Phillips Scale. The SPEMs of eight of the patients were reevaluated after 2 weeks of treatment with either prazosin or pimozide. No consistent significant correlations were found between SPEM accuracy and CSF metabolite concentrations, VBR, or premorbid adjustment. SPEM accuracy was not correlated with number of days off medication and was significantly correlated when measured before and during medication.

Gamma-vinyl-GABA treatment of tardive dyskinesia and other movement disorders

We conducted a single-blind trial of gamma-vinyl-GABA (GVG) in nine patients: seven with tardive dyskinesia, one with Meige syndrome, and one with Tourette syndrome. Five tardive dyskinesia patients completed the entire 11-week study and, as a group, demonstrated significant decreases in dyskinesia scores. Four of these five tardive dyskinesia patients showed clinically evident improvement, with approximately 30% reduction in dyskinetic symptoms. Other patients had no clinical benefit from GVG. Three patients had transient exacerbation of psychiatric symptoms after sudden withdrawal of GVG, and one patient experienced dose-related confusional episodes. Our results suggest that GABAergic drugs may have a role in treating patients with tardive dyskinesia.

The use of sodium valproate, carbamazepine and oxcarbazepine in patients with affective disorders

During recent years alternatives to lithium prophylaxis have been developed using primary dipropylacetamide and, later on, sodium valproate, as a mono-therapy as well as in combination with low-dosage lithium treatment. It has been shown in a placebo-controlled ABA design that sodium valproate exerts an acute antimanic effect and a prophylactic action of sodium valproate has also been established. Carbamazepine represents another important contribution to the arsenal of drugs to be used as alternatives for the prophylactic treatment in patients not responding to lithium and/or experiencing too many side effects. The keto-derivative of carbamazepine, oxcarbazepine, has been shown to exert acute antimanic effects in a similar way to carbamazepine itself.

Dopamine in manic depressive illness. A pharmacological synthesis

If the clinical symptoms of mania are a consequence of increased activity in central dopaminergic (DA) pathways in predisposed individuals, then drugs increasing DA neurotransmission should precipitate or exacerbate mania in such people, whereas drugs which reduce DA neurotransmission should ameliorate manic symptoms. Of the drugs which enhance DA neurotransmission, those which increase synthesis of DA (levodopa), those which promote DA release (amphetamine), and those which act directly as agonists or DA receptors (bromocriptine) have all been shown to precipitate mania. Conversely, drugs which reduce DA neurotransmission by inhibiting synthesis (alpha-methylparatyrosine) or by blocking DA receptors (pimozide) are effective in reducing manic symptoms. DA systems are not working in isolation; evidence is presented showing an influence on manic illness of central cholinergic and GABA-ergic processes. It is suggested that there is an interacting set of neurotransmitter pathways linking the limbic system and the ventral tegmental (A10) area involving DA, acetylcholine and GABA upon which drugs can act to influence the course of a manic illness.

Neuroleptic catatonia and its relationship to psychogenic catatonia

Neuroleptics are among those pharmacological agents that can cause a nonpsychogenic catatonic state. Neuroleptic malignant syndrome (NMS) is marked by a change in state of consciousness, ranging from withdrawal through stupor to coma. In addition, it is characterized by autonomic dysfunction, hyperthermia, mutism, and rigidity. It is included in the differential diagnosis of the catatonic syndrome. Evidence is reviewed to suggest that agents responsible for improving NMS act on the dopamine (DA) gamma aminobutyric acid (GABA) connections in the mesostriatal and mesolimbic systems and also in the hypothalamus. In addition, based on symptomatology, pathophysiology, and therapeutic mechanisms, the relationship between nonpsychogenic neuroleptic-induced catatonia and psychogenic catatonia is examined.