Haloperidol-induced dyskinesia is associated with striatal NO synthase suppression: reversal with olanzapine

Modulatory effect of olanzapine on neuronal nitric oxide synthase (nNOS) expression in the rat striatum

Nitric oxide (NO) has been thought to be a novel factor involved in the mechanisms of mental disorders pathogenesis for quite some time. However, little is known about potential crosstalk between neuronal NO signaling and neuroleptics action. The present work was, therefore, focused on gene expression of neuronal NO synthase (nNOS) in the brains of rats chronically treated with olanzapine, an atypical antipsychotic drug. Studies were carried out on adult, male Sprague-Dawley rats that were divided into 2 groups: control and experimental animals treated with olanzapine (28-day-long intraperitoneal injection, at dose 5 mg/kg daily). All individuals were killed under anesthesia and the whole brains excised. Immunohistochemical procedure was used for histological assessment of the whole brain, and for both descriptive and quantitative analysis of nNOS protein distribution in selected brain structures. Long-term treatment with olanzapine is reflected in different changes in the number of enzyme-expressing cells in the rat brain. Olanzapine decreased the number of nNOS-expressing cells and possibly reduced NO synthesis in the rat striatum. Olanzapine can be taken into account as a potential inhibitor of NO synthesis in the rat striatum.

The effects of cannabidiol on behavioural and oxidative stress parameters induced by prolonged haloperidol administration

OBJECTIVES

We investigated the influence of oral cannabidiol (CBD) on vacuous chewing movements (VCM) and oxidative stress parameters induced by short- and long-term administration of haloperidol in a rat model of tardive dyskinesia (TD).

METHODS

Haloperidol was administered either sub-chronically via the intraperitoneal (IP) route or chronically via the intramuscular (IM) route to six experimental groups only or in combination with CBD. VCM and oxidative stress parameters were assessed at different time points after the last dose of medication.

RESULTS

Oral CBD (5 mg/kg) attenuated the VCM produced by sub-chronic administration of haloperidol (5 mg/kg) but had minimal effects on the VCM produced by chronic administration of haloperidol (50 mg/kg). In both sub-chronic and chronic haloperidol groups, there were significant changes in brain antioxidant parameters compared with CBD only and the control groups. The sub-chronic haloperidol-only group had lower glutathione activity compared with sub-chronic haloperidol before CBD and the control groups; also, superoxide dismutase, catalase, and 2,2-diphenyl-1-picrylhydrazyl activities were increased in the sub-chronic (IP) haloperidol only group compared with the CBD only and control groups. Nitric oxide activity was increased in sub-chronic haloperidol-only group compared to the other groups; however, the chronic haloperidol group had increased malondialdehyde activity compared to the other groups.

CONCLUSIONS

Our findings indicate that CBD ameliorated VCM in the sub-chronic haloperidol group before CBD, but marginally in the chronic haloperidol group before CBD. There was increased antioxidant activity in the sub-chronic group compared to the chronic group.

Studies on Haloperidol and Adjunctive α-Mangostin or Raw Garcinia mangostana Linn Pericarp on Bio-Behavioral Markers in an Immune-Inflammatory Model of Schizophrenia in Male Rats

Schizophrenia is a severe brain disorder that is associated with neurodevelopmental insults, such as prenatal inflammation, that introduce redox-immune-inflammatory alterations and risk for psychotic symptoms later in life. Nutraceuticals may offer useful adjunctive benefits. The aim of this study was to examine the therapeutic effects of Garcinia mangostana Linn (GML) and one of its active constituents, α-mangostin (AM), alone and as adjunctive treatment with haloperidol (HAL) on schizophrenia related bio-behavioral alterations in a maternal immune-activation (MIA) model. Sprague-Dawley dams were exposed to lipopolysaccharide (LPS) (n = 18) or vehicle (n = 3) on gestational days 15 and 16. Male offspring (n = 72) were treated from PND 52-66 with either vehicle, HAL (2 mg/kg), GML (50 mg/kg), HAL + GML, AM (20 mg/kg), or HAL + AM. Control dams and control offspring were treated with vehicle. In order to cover the mood-psychosis continuum, prepulse inhibition (PPI) of startle, open field test (locomotor activity), and the forced swim test (depressive-like behavior) were assessed on PND's 64-65, followed by assay of frontal-cortical lipid peroxidation and plasma pro-inflammatory cytokines, viz. interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α). MIA-induced deficits in sensorimotor gating were reversed by HAL and HAL + GML, but not GML and AM alone. MIA-induced depressive-like behavior was reversed by AM and GML alone and both in combination with HAL, with the combinations more effective than HAL. MIA-induced cortical lipid peroxidation was reversed by HAL and AM, with elevated IL-6 levels restored by GML, AM, HAL, and HAL + GML. Elevated TNF-α was only reversed by GML and HAL + GML. Concluding, prenatal LPS-induced psychotic- and depressive-like bio-behavioral alterations in offspring are variably responsive to HAL, GML, and AM, with depressive (but not psychosis-like) manifestations responding to GML, AM, and combinations with HAL. AM may be a more effective antioxidant than GML in vivo, although this does not imply an improved therapeutic response, for which trials are required.

Haloperidol discontinuation in a herpes simplex encephalitis patient with atypical abnormal movements using the herbal medicine Ukgansan-gami: A case report

Recently, the herbal medicine Ukgansan (Yigansan in China, Yokukansan in Japan) was reported to be effective in the management of movement disorders. We report the case of a 62-year-old woman with herpes simplex encephalitis exhibiting atypical abnormal movements in the chronic stage. While controlling the abnormal movements with haloperidol, an antipsychotic agent, we prescribed Ukgansan-gami, an extract of a variant of Ukgansan, at a dose of 12 g/day to prevent the recurrence of abnormal movements and allow for the discontinuation of haloperidol. The patient was successfully treated with Ukgansan-gami, with no further recurrence of symptoms, making the use of haloperidol no longer necessary. The potential mechanism of action of Ukgansan involves the inhibition of nervous system hyperexcitability through the suppression of glutamate sodium channels, as well as attenuation of hypermotility through serotonin regulation. The present case suggests that herbal medicine therapy was likely to be an alternative to antipsychotics.

Cross-tolerance between nitric oxide synthase inhibition and atypical antipsychotics modify nicotinamide-adenine-dinucleotide phosphate-diaphorase activity in mouse lateral striatum

Previous research indicates that the subchronic administration of NG-nitro-L-arginine (L-NOARG) produces tolerance to haloperidol-induced catalepsy in Swiss mice. The present study aimed to further investigate whether intermittent subchronic systemic administration of L-NOARG induces tolerance to the cataleptic effects of haloperidol as well as olanzapine or clozapine (Clz) in C57Bl mice after subchronic administration for 5 consecutive days. Striatal FosB protein expression was measured in an attempt to gain further insights into striatal mechanisms in antipsychotic-induced extrapyramidal symptoms side effects. An nicotinamide-adenine-dinucleotide phosphate-diaphorase histochemical reaction was also used to investigate whether tolerance could induce changes in the number of nitric oxide synthase-active neurons. Subchronic administration of all antipsychotics produced catalepsy, but cross-tolerance was observed only between L-NOARG (15 mg/kg, intraperitoneally) and Clz (20 mg/kg, intraperitoneally). This cross-tolerance effect was accompanied by decreased FosB protein expression in the dorsal striatum and the nucleus accumbens shell region, and reduced icotinamide-adenine-dinucleotide phosphate-diaphorase activity in the dorsal and ventral lateral striatum. Overall, these results suggest that interference with the formation of nitric oxide, mainly in the dorsal and ventral lateral-striatal regions, appears to improve the cataleptic effects induced by antipsychotics acting as antagonists of low-affinity dopamine D2 receptor, such as Clz.

The Therapeutic Potential of Mangosteen Pericarp as an Adjunctive Therapy for Bipolar Disorder and Schizophrenia

New treatments are urgently needed for serious mental illnesses including bipolar disorder and schizophrenia. This review proposes that Garcinia mangostana Linn. (mangosteen) pericarp is a possible adjunctive therapeutic agent for these disorders. Research to date demonstrates that neurobiological properties of the mangosteen pericarp are well aligned with the current understanding of the pathophysiology of bipolar disorder and schizophrenia. Mangosteen pericarp has antioxidant, putative neuroprotective, anti-inflammatory, and putative mitochondrial enhancing properties, with animal studies demonstrating favorable pharmacotherapeutic benefits with respect to these disorders. This review summarizes evidence of its properties and supports the case for future studies to assess the utility of mangosteen pericarp as an adjunctive treatment option for mood and psychotic disorders.

The α2C-adrenoceptor antagonist, ORM-10921, has antipsychotic-like effects in social isolation reared rats and bolsters the response to haloperidol

Early studies suggest that selective α2C-adrenoceptor (AR)-antagonism has anti-psychotic-like and pro-cognitive properties. However, this has not been demonstrated in an animal model of schizophrenia with a neurodevelopmental construct. The beneficial effects of clozapine in refractory schizophrenia and associated cognitive deficits have, among others, been associated with its α2C-AR modulating activity. Altered brain-derived neurotrophic factor (BDNF) has been linked to schizophrenia and cognitive deficits. We investigated whether the α2C-AR antagonist, ORM-10921, could modulate sensorimotor gating and cognitive deficits, as well as alter striatal BDNF levels in the social isolation reared (SIR) model of schizophrenia, comparing its effects to clozapine and the typical antipsychotic, haloperidol, the latter being devoid of α2C-AR-activity. Moreover, the ability of ORM-10921 to augment the effects of haloperidol on the above parameters was also investigated. Animals received subcutaneous injection of either ORM-10921 (0.01mg/kg), clozapine (5mg/kg), haloperidol (0.2mg/kg), haloperidol (0.2mg/kg)+ORM-10921 (0.01mg/kg) or vehicle once daily for 14days, followed by assessment of novel object recognition (NOR), prepulse inhibition (PPI) of startle response and striatal BDNF levels. SIR significantly attenuated NOR memory as well as PPI, and reduced striatal BDNF levels vs. social controls. Clozapine, ORM-10921 and haloperidol+ORM-10921, but not haloperidol alone, significantly improved SIR-associated deficits in PPI and NOR, with ORM-10921 also significantly improving PPI deficits vs. haloperidol-treated SIR animals. Haloperidol+ORM-10921 significantly reversed reduced striatal BDNF levels in SIR rats. α2C-AR-antagonism improves deficits in cognition and sensorimotor gating in a neurodevelopmental animal model of schizophrenia and bolsters the effects of a typical antipsychotic, supporting a therapeutic role for α2C-AR-antagonism in schizophrenia.

Role of nitric oxide and related molecules in schizophrenia pathogenesis: biochemical, genetic and clinical aspects

Currently, schizophrenia is considered a multifactorial disease. Over the past 50 years, many investigators have considered the role of toxic free radicals in the etiology of schizophrenia. This is an area of active research which is still evolving. Here, we review the recent data and current concepts on the roles of nitric oxide (NO) and related molecules in the pathogenesis of schizophrenia. NO is involved in storage, uptake and release of mediators and neurotransmitters, including glutamate, acetylcholine, noradrenaline, GABA, taurine and glycine. In addition, NO diffuses across cell membranes and activates its own extrasynaptic receptors. Further, NO is involved in peroxidation and reactive oxidative stress. Investigations reveal significant disturbances in NO levels in the brain structures (cerebellum, hypothalamus, hippocampus, striatum) and fluids of subjects with schizophrenia. Given the roles of NO in central nervous system development, these changes may result in neurodevelopmental changes associated with schizophrenia. We describe here the recent literature on NOS gene polymorphisms on schizophrenia, which all point to consistent results. We also discuss how NO may be a new target for the therapy of mental disorders. Currently there have been 2 randomized double-blind placebo-controlled trials of L-lysine as an NOS inhibitor in the CNS.

Neuroprogression in schizophrenia: Pathways underpinning clinical staging and therapeutic corollaries

OBJECTIVE

Whilst dopaminergic dysfunction remains a necessary component involved in the pathogenesis of schizophrenia, our current pharmacological armoury of dopamine antagonists does little to control the negative symptoms of schizophrenia. This suggests other pathological processes must be implicated. This paper aims to elaborate on such theories.

METHODS

Data for this review were sourced from the electronic database PUBMED, and was not limited by language or date of publication.

RESULTS

It has been suggested that multiple 'hits' may be required to unveil the clinical syndrome in susceptible individuals. Such hits potentially first occur in utero, leading to neuronal disruption, epigenetic changes and the establishment of an abnormal inflammatory response. The development of schizophrenia may therefore potentially be viewed as a neuroprogressive response to these early stressors, driven on by changes in tryptophan catabolite (TRYCAT) metabolism, reactive oxygen species handling and N-methyl d-aspartate (NMDA) circuitry. Given the potential for such progression over time, it is prudent to explore the new treatment strategies which may be implemented before such changes become established.

CONCLUSIONS

Outside of the dopaminergic model, the potential pathogenesis of schizophrenia has yet to be fully elucidated, but common themes include neuropil shrinkage, the development of abnormal neuronal circuitry, and a chronic inflammatory state which further disrupts neuronal function. Whilst some early non-dopaminergic treatments show promise, none have yet to be fully studied in appropriately structured randomized controlled trials and they remain little more than potential attractive targets.

Free radicals, antioxidant defense systems, and schizophrenia

The etiopathogenic mechanisms of schizophrenia are to date unknown, although several hypotheses have been suggested. Accumulating evidence suggests that excessive free radical production or oxidative stress may be involved in the pathophysiology of schizophrenia as evidenced by increased production of reactive oxygen or decreased antioxidant protection in schizophrenic patients. This review aims to summarize the basic molecular mechanisms of free radical metabolism, the impaired antioxidant defense system and membrane pathology in schizophrenia, their interrelationships with the characteristic clinical symptoms and the implications for antipsychotic treatments. In schizophrenia, there is accumulating evidence of altered antioxidant enzyme activities and increased levels of lipid peroxidation, as well as altered levels of plasma antioxidants. Moreover, free radical-mediated abnormalities may contribute to specific aspects of schizophrenic symptomatology and complications of its treatment with antipsychotic drugs, as well as the development of tardive dyskinesia (TD). Finally, the potential therapeutic strategies implicated by the accumulating data on oxidative stress mechanisms for the treatment of schizophrenia are discussed.

The nature of relapse in schizophrenia

BACKGROUND

Multiple relapses characterise the course of illness in most patients with schizophrenia, yet the nature of these episodes has not been extensively researched and clinicians may not always be aware of important implications.

METHODS

We critically review selected literature regarding the nature and underlying neurobiology of relapse.

RESULTS

Relapse rates are very high when treatment is discontinued, even after a single psychotic episode; a longer treatment period prior to discontinuation does not reduce the risk of relapse; many patients relapse soon after treatment reduction and discontinuation; transition from remission to relapse may be abrupt and with few or no early warning signs; once illness recurrence occurs symptoms rapidly return to levels similar to the initial psychotic episode; while most patients respond promptly to re-introduction of antipsychotic treatment after relapse, the response time is variable and notably, treatment failure appears to emerge in about 1 in 6 patients. These observations are consistent with contemporary thinking on the dopamine hypothesis, including the aberrant salience hypothesis.

CONCLUSIONS

Given the difficulties in identifying those at risk of relapse, the ineffectiveness of rescue medications in preventing full-blown psychotic recurrence and the potentially serious consequences, adherence and other factors predisposing to relapse should be a major focus of attention in managing schizophrenia. The place of antipsychotic treatment discontinuation in clinical practice and in placebo-controlled clinical trials needs to be carefully reconsidered.

Plasma asymmetric dimethylarginine (ADMA) concentrations in patients with first and multiple episode schizophrenia

An increasing number of reports in the literature indicate that asymmetric dimethylarginine (ADMA) regulates nitric oxide generation in numerous disease states. ADMA has been less studied in psychiatric disorders. The purpose of this study was to determine plasma ADMA concentrations in patients with schizophrenia compared to healthy controls. The study was conducted in 49 male patients with schizophrenia and 30 healthy male control subjects. The patient group was 24 first episode and 25 multiple episode schizophrenia participants. All schizophrenic patients were administered the Scale for the Assessment of Negative Symptoms, the Scale for the Assessment of Positive Symptoms (SAPS) and the Brief Psychiatric Rating Scale. Measurement of plasma concentrations of ADMA was accomplished by HPLC. There was a significant increase in the plasma ADMA concentrations in patients with schizophrenia when compared to healthy controls. There were no significant correlations between the plasma concentrations of ADMA and scores of psychiatric rating scales. In the multiple episode schizophrenia subgroup, the mean plasma ADMA concentration was significantly higher than in the first episode schizophrenia subgroup. The study indicate that plasma ADMA concentrations in patients with schizophrenia are elevated.

Isolation rearing-induced deficits in sensorimotor gating and social interaction in rats are related to cortico-striatal oxidative stress, and reversed by sub-chronic clozapine administration

Social isolation rearing (SIR) in rats induces behavioral and glutamatergic changes akin to schizophrenia. We studied the effects of 8 weeks SIR on cortico-striatal redox and social and cognitive behaviors in rats. SIR increased superoxide dismutase activity, decreased oxidized:reduced glutathione ratio and increased lipid peroxidation in both brain regions, and induced deficits in prepulse inhibition and social and self-directed interactive behaviors. Both behavioral and cortico-striatal redox disturbances were corrected by clozapine (5 mg/kg/day×11days). Behavioral changes evoked by SIR are associated with cortico-striatal oxidative stress that is reversed by clozapine treatment, providing novel insight into the neurobiology and treatment of schizophrenia.

The NMDA receptor/nitric oxide pathway: a target for the therapeutic and toxic effects of lithium

Although lithium has largely met its initial promise as the first drug discovered in the modern era of psychopharmacology, to date no definitive mechanism for its effects has been established. It has been proposed that lithium exerts its therapeutic effects by interfering with signal transduction through G-protein-coupled receptor (GPCR) pathways or direct inhibition of specific targets in signaling systems, including inositol monophosphatase and glycogen synthase kinase-3 (GSK-3). Recently, increasing evidence has suggested that N-methyl-D-aspartate receptor (NMDAR)/nitric oxide (NO) signaling could mediate some lithium-induced responses in the brain and peripheral tissues. However, the probable role of the NMDAR/NO system in the action of lithium has not been fully elucidated. In this review, we discuss biochemical, preclinical/behavioral and physiological evidence that implicates NMDAR/NO signaling in the therapeutic effect of lithium. NMDAR/NO signaling could also explain some of side effects of lithium.

The effect of chronic antipsychotic drug administration on nitric oxide synthase activity and gene expression in rat penile tissues

Antipsychotic drug treatment may be associated with common and problematic sexual dysfunction, especially impotence, which can diminish quality of life and lead to treatment noncompliance. Nitric oxide synthase (NOS) is an important cellular modulator of erectile function. We have therefore investigated the effect of antipsychotic drug on activity and gene expression of NOS in rat penile tissues. The activity of constitutive NOS was significantly suppressed below control by a 21 days administration of 1 mg/kg haloperidol, which also significantly decreased expression of endothelial NOS (eNOS) and neural NOS mRNA. Risperidone at 0.5 mg/kg also reduced eNOS mRNA expression. Haloperidol or risperidone did not change gene expression and activity of inducible NOS (iNOS). Quetiapine significantly increased activity and mRNA expression of iNOS with 20 and 40 mg/kg doses. These preliminary results have important implications for enhancing our understanding of mechanisms by which antipsychotic drugs induce sexual dysfunction.

Atypical neuroleptic risperidone modulates glial functions in C6 astroglial cells

Risperidone has demonstrated therapeutic advantages over conventional neuroleptics and offers a valuable emerging option for the treatment of social behavior associated with autistic disorder. Considering the putative involvement of astroglial cells in neuropsychiatric disorders, we investigated the effect of risperidone on parameters of astrocyte activity - glutamate uptake, glutamine synthetase (GS) activity and glutathione (GSH) levels. Risperidone was able to induce a significantly increase on glutamate uptake (32%); GS activity (15%); GSH levels (58%). These findings imply the perspectives for further investigations directed on astrocytes from different brain areas. Our present results suggest that risperidone might exert its neuroprotective effects against brain illness at least partially via modulation of astrocyte functions.

A placebo-controlled study of sildenafil effects on cognition in schizophrenia

BACKGROUND

Phosphodiesterase 5 (PDE5) inhibitors increase cyclic guanosine monophosphate (cGMP) concentrations in the intracellular pathway activated by N-methyl-D-aspartic acid receptors which is believed to mediate long-term potentiation and memory consolidation. The PDE5 inhibitor sildenafil has been shown to enhance memory in animal models. In addition, neuronal nitric oxide synthase, another component of the NMDA/nitric oxide/cGMP intracellular pathway, has been reported to be dysregulated in schizophrenia patients.

MATERIALS AND METHODS

Seventeen adult schizophrenia outpatients treated with a stable dose of antipsychotic received a single oral dose of placebo, sildenafil 50 mg, and sildenafil 100 mg in random order with a 48-h interval between administrations. Psychiatric symptom ratings and a cognitive battery were performed at baseline and 1 hour following each administration of the study drug. In addition, memory consolidation was examined by testing recall 48 h later, prior to the next administration of the study drug.

RESULTS

Fifteen subjects completed all three treatment conditions. One subject developed irritability and required hospitalization 2 days after receiving sildenafil 100 mg. Neither dose of sildenafil significantly affected cognitive performance or symptom ratings compared to the placebo.

CONCLUSION

Despite evidence for cognitive-enhancing effects of sildenafil in animal models, the strategy for treating putative NMDA receptor-mediated memory deficits in schizophrenia with sildenafil 50 and 100 mg was not successful. It is possible that the doses used in this study were not optimal or that repeated dosing may be necessary to achieve therapeutic effects. Agents under development that inhibit other subtypes of PDE remain promising for schizophrenia and dementia.

Possible anti-oxidant and neuroprotective mechanisms of zolpidem in attenuating typical anti-psychotic-induced orofacial dyskinesia: a biochemical and neurochemical study

Tardive dyskinesia is a serious motor side effect of chronic anti-psychotic therapy. The pathophysiology of this disabling and commonly irreversible movement disorder continues obscure and may be caused due to GABAergic hypofunction or increased oxidative damage and free radical generation. Chronic treatment with typical antipsychotics leads to the development of abnormal hyperkinetic orofacial movements (vacuous chewing movements, tongue protrusions and facial jerking) in rats and is widely accepted as the animal model for tardive dyskinesia. Zolpidem, a GABA-mimetic drug is structurally related to melatonin and has been reported to possess anti-oxidant and neuroprotective effects both in vivo and in vitro. The study was carried out to investigate whether zolpidem can be used in the treatment of typical anti-psychotic-induced orofacial dyskinesia. Chronic haloperidol (1 mg/kg, i.p. for 21 days) and chlorpromazine (5 mg/kg, i.p. for 21 days) treatment significantly induced orofacial hyperkinetic movements and zolpidem [N, N, 6-trimethyl-2-p-tolyl-imidazo (1, 2-a) pyridine 3-acetamideL-(+)] dose dependently (1, 2, 5 mg/kg i.p. for 21 days) reduced these haloperidol and chlorpromazine-induced hyperkinetic orofacial movements. Biochemical analysis revealed that haloperidol and chlorpromazine treatment significantly induced increase in lipid peroxidation and decrease in the levels of total nitric oxide levels, non-protein thiols (NPSH) and of anti-oxidant defense enzymes, superoxide dismutase (SOD) and catalase in the striatum of rat brain. Co-administration of zolpidem (1, 2, 5 mg/kg i.p. for 21 days) significantly reduced the lipid peroxidation and restored the non-protein thiols and total nitric oxide levels induced by chronic haloperidol and chlorpromazine treatment. It also significantly reversed the haloperidol and chlorpromazine-induced decrease in brain SOD and catalase activity. Neurochemical analysis (Neurotransmitter and their metabolite level estimation) revealed that haloperidol and chlorpromazine significantly decreased the dopamine, norepinephrine and serotonin levels in brain homogenates where as it caused a significant increase in the metabolite (VMA and HVA) levels in urine, which were significantly reversed by zolpidem at higher doses. Result of the present study support the therapeutic use of zolpidem in the treatment of typical anti-psychotic-induced orofacial dyskinesia.

Prolonged postoperative altered mental status after methylene blue infusion during parathyroidectomy: a case report and review of the literature

Methylene blue (5 mg/kg) is routinely given at our institution during parathyroidectomy. The dye stains the parathyroid glands and helps in better surgical visualisation. The technique is generally considered to be safe except for causing pseudo-cyanosis. We report a case of a patient who had confusion, agitation and altered mental status during the early postoperative course probably secondary to methylene blue infusion.

Effects of clozapine, olanzapine and haloperidol on nitric oxide production by lipopolysaccharide-activated N9 cells

Schizophrenia is a devastating illness of unknown etiology and the basis for its treatment rests in the symptomatic response to antipsychotics. It was found that some of the patients with schizophrenia elicited microglia activation. The present study used lipopolysaccharide (LPS)-activated mouse microglial cell line N9 as an in vitro model to mimic microglia activation seen in the patients with schizophrenia. The effects of clozapine, olanzapine and haloperidol on the release of nitric oxide (NO) by LPS-stimulated N9 cells were investigated. The results showed that olanzapine significantly inhibited NO release by LPS-stimulated N9 cells. Clozapine and haloperidol did not show significant effects on this model. The present study suggested that the inhibiting effect of olanzapine on the NO release by LPS-stimulated microglial cells might be a new mechanism through which olanzapine exhibits its therapeutic effect in the treatment of schizophrenia.

Increased hippocampal nitric oxide synthase activity and stress responsiveness after imipramine discontinuation: role of 5HT 2A/C-receptors

Chronic depressive illness may cause shrinkage of the hippocampus with stress-induced release of glutamate and nitric oxide possibly causally linked to this pathology. Poor antidepressant compliance may contribute to this pathology as well as to long term morbidity. However, antidepressant withdrawal-associated symptoms in depressed patients often reflect hyperserotonergia. The effect of chronic imipramine (IMI; 15 mg/kg/d ip x 3wks) treatment and withdrawal on swim stress responsiveness was studied in Sprague-Dawley rats together with assay of hippocampal NO synthase (NOS) activity. The dependence of any biobehavioral changes following IMI withdrawal on 5HT(2A/C) receptor-mediated events was studied using the 5HT(2A/C) receptor antagonist, ritanserin (RIT; 4 mg/kg/day ip x 7 days), administered alone or during IMI withdrawal. IMI significantly inhibited the situational stress response to forced swimming while also significantly decreasing NOS activity. IMI withdrawal was associated with a significant increase in swim immobility together with a significant increase in NOS activity compared to both control and IMI-treated groups. RIT re-established the anti-immobility effects and reversed NOS hyper-function during IMI withdrawal, although alone it increased NOS activity. Antidepressant discontinuation therefore increases stress responsiveness together with disinhibition of hippocampal NOS through a mechanism involving 5HT(2A/C) receptor activation. The resulting increased nitrergic activity may have significant implications for depressive illness and its treatment.

Haplotype analysis of endothelial nitric oxide synthase (NOS3) genetic variants and tardive dyskinesia in patients with schizophrenia

OBJECTIVES

Several studies have indicated the involvement of nitric oxide (NO) in the pathogenesis of tardive dyskinesia (TD), an incapacitating adverse movement disorder associated with long-term antipsychotic treatment. In human brain, the NO could be generated by endothelial nitric oxide synthase (NOS3). In this study, we studied whether the genetic variants in human NOS3 gene is associated with TD in patients with schizophrenia.

METHODS

Two hundred and eighty-two chronic inpatients with schizophrenia treated with typical antipsychotics were recruited in this study. The patients were further grouped by the presence of TD or not according to the Research and Diagnostic Criteria for TD. The genetic variants in the NOS3 gene investigated in this study were -786T > C in the promotor region, 27-bp variable number of tandem repeats (27-bp VNTR) in intron 4, and Glu298Asp in exon 7. The frequencies of genotypes, alleles and haplotypes of the three markers were compared between the TD (n = 153) and non-TD (n = 129) groups.

RESULTS

There were no significant associations between the genotypes and alleles of the three markers and TD. However, in the haplotype-based case-control analysis, the frequency of haplotype T-4b-Glu was significantly higher in non-TD than in TD group (TD vs. non-TD = 72.7% vs. 81.0%, permutation P value = 0.021, OR = 0.648, 95% CI = 0.432-0.973).

CONCLUSIONS

We found that the haplotype T-4b-Glu represents a protective haplotype against TD after long-term antipsychotic treatment. This finding suggests that human NOS3 gene may be involved in the pathogenesis of TD.

Hyperpyrexia and prolonged postoperative disorientation following methylene blue infusion during parathyroidectomy

A 65-year-old man underwent parathyroidectomy for hyperparathyroidism secondary to renal failure. Intra-operatively he received methylene blue infusion (7.5 mg.kg(-1), a total of 650 mg in 500 ml 0.9% sodium chloride) for visualisation of parathyroid glands. At the end of surgery, following extubation he developed agitation, intense shivering and hyperpyrexia, and his level of consciousness decreased to a Glasgow Coma score of 7. The differential diagnoses included methylene blue toxicity or malignant hyperpyrexia. His lungs were ventilated, and intravenous dantrolene was administered to control hyperpyrexia. Haemodialysis was started to remove the methylene blue dye. We review the literature on the pharmacological actions of methylene blue, and discuss the differential diagnosis and management of this patient.

Morphological abnormalities in nitric-oxide-synthase-positive striatal interneurons of schizophrenic patients

Schizophrenia has been suggested to be a neurodevelopmental disorder, and nitric-oxide-synthase (NOS)-positive neurons were shown to be involved in distorted cortical development in schizophrenia. Here we investigated whether nitrinergic neurons in the striatum of schizophrenic patients also display abnormalities regarding distribution or morphology. To do so, postmortem putaminal sections of schizophrenic subjects were examined by means of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) staining and NOS immunohistochemistry. NOS-positive neurons were counted and analyzed morphologically. Abnormalities regarding morphology or number of NOS-containing neurons could be found in the putamen of schizophrenics (n = 3), but not controls (n = 5). Neurons were either of abnormal size and branching pattern, or they were markedly reduced (130 +/- 44 vs. 54 +/- 62 NADPHd-positive somata/mm(3) putamen; p < 0.0001). Striatal nitrinergic interneurons might thus be involved in the pathogenesis of at least some forms of schizophrenia. Studies on larger samples are however needed to further corroborate this finding.

The many faces of nitric oxide in schizophrenia. A review

Intense research has been conducted in an effort to identify specific biological markers of schizophrenia. The gas nitric oxide (NO) is one of the most important signaling molecules involved in a plethora of cellular events that take place in the cardiovascular, immune and nervous systems of animals. This survey aims to demonstrate that NO and its metabolites play important roles in schizophrenia and have a significant influence on our understanding of the development, progression and treatment of the disease. Special emphasis is given to the impact of NO metabolism on processes known to be disturbed in schizophrenia (i.e., cell migration, formation of synapses, NMDA receptor mediated neurotransmission, membrane pathology and cognitive abilities). However, when comparing data on the NO metabolism in the brain tissue and body fluids of schizophrenics with those obtained from patients with other neurological and psychiatric diseases, it becomes clear that alterations of NO metabolism are not unique to, or indicative of, schizophrenia. Thus, NO and its metabolites are not suitable diagnostic tools to distinguish schizophrenia from psychically healthy control cases or from other brain disorders.