Elevated plasma nitrate levels in depressive states

Background: Previous studies have shown that nitric oxide (NO) synthase inhibitors show preclinical antidepressant-like properties, suggesting that NO is involved in the pathogenesis of depression. The purpose of this study is to examine whether or not NO production increases in depressed patients. Methods: Plasma nitrate concentrations, an index of NO production, were measured by high-performance liquid chromatography in depressed patients (n = 17) and compared with patients suffering anxiety (rr = 6) and with healthy controls (n = 12). Results: Plasma nitrate concentrations were significantly higher in depressed patients than in patients with an anxiety disorder (P < 0.05) or in controls (P < 0.01). Limitations: The study group was small. The source of the surplus production of NO in patients with major depressive episode remains unclear. Conclusions: These results suggest that NO production is increased in depression. (C) 2001 Elsevier Science B.V. All rights reserved.