Reduced plasma nitric oxide metabolites before and after antipsychotic treatment in patients with schizophrenia compared to controls

Abstract

Background: Nitric oxide (NO) is believed to have a role in the pathophysiology of schizophrenia. We examined plasma levels of NO metabolites in patients with schizophrenia and normal controls. We also determined the impact of 6-week risperidone treatment on circulating NO metabolites in patients with schizophrenia. Method: Plasma NO metabolite ((NOx) levels were measured it) 55 schizophrenia patients before and after 6-week treatment with risperidone and in 55 normal controls. Severity of schizophrenia and response to treatment were assessed with the positive and negative syndrome scale (PANSS) for schizophrenia. NOx levels were estimated by the Griess method. Results: Pre-treatment plasma NOx levels in schizophrenia patients (8.97 +/- 6.74 mu mol/L) were lower than those of normal controls (14.51 +/- 6.30 mu mol/L) (p<0.01). Schizophrenia patients had lower post-treatment NOx levels (10.99 +/- 8.31 mu mol/L) than those of normal controls (p < 0.01). There was marginal significant change between plasma NO, levels before and after 6-week treatment (p = 0.056). Moreover, in 37 treatment responders (>= 30% improvement in PANSS score), post-treatment plasma NOx significantly increased in comparison to pre-treatment NOx (p = 0.028). Conclusions: Plasma levels of NOx in patients with schizophrenia were significantly lower than normal, controls both before and after the treatment. Out, findings suggest that the improvement of psychiatric symptoms can lead to partially normalize a deficiency of NO after treatment in schizophrenia patients. Our Findings support the hypothesis that the NO system is dampened in schizophrenia.(C) 2008 Elsevier B.V. All rights reserved.