Plasma nitrite/nitrate concentrations in patients with schizophrenia

Abstract

Background: Nitric oxide (NO) is known to be a signaling molecule with many physiogical functions including apoptotic process regulation. Since apoptosis may contribute to the pathophysiology of schizophrenia, this study was undertaken to determine the plasma concentrations of NO in schizophrenics. Methods: Nitrite/nitrate (NO2–/NO3–) concentrations were measured in plasma from 40 patients with schizophrenia, and 36 age- and gender-matched healthy persons using a colorimetric test. Results: Plasma NO2–/NO3– concentrations were significantly higher in patients with schizophrenia (102.8±34.7 μmol/L, p<0.0001) than in controls (69.2±13.2 μmol/L). Also, mean NO2–/NO3– values in female patients and controls were significantly higher (118.2±44.7 μmol/L, p<0.001; 74.8±16.1 μmol/L, p<0.05, respectively) compared to males (94.7±25.3 μmol/L, 67.6±10.8 μmol/L). Significant correlation was seen between plasma NO2–/NO3– concentrations and heredity, number of episodes and peripheral blood mononuclear cell (PBMC) caspase-3 activity, which was significantly higher in patients than in controls (p<0.05). There was no significant difference in NO2–/NO3– concentrations between patients with different Positive and Negative Syndrome Scale (PANSS) scores or between patients treated with haloperidol (97.2±31.2 μmol/L) and those treated with other atypical antipsychotic drugs (109.8±33.7 μmol/L). Both parameters showed no significant differences between smokers and non-smokers. Conclusions: This study showed that plasma NO2–/NO3– concentrations were significantly increased in patients with schizophrenia, being significantly higher in female than male patients, and showing a significant correlation with heredity, number of episodes and PBMC caspase-3 activity. These results suggest that NO could be considered an inducer or regulator of apoptosis in patients with schizophrenia. Clin Chem Lab Med 2010;48:89–94.