Background: There is an increasing interest in the role of nitric oxide (NO) and pterines in the pathophysiology of neuropsychiatric disorders. The results so far show an inconsistent pattern. Methods: In the present study, neopterin and a measure of NO synthesis in plasma of symptomatic and euthymic bipolar affective patients were compared to those of patients with a major depression and healthy controls. As an index of NO synthesis, the ratio of the amino acids citrul-line and arginine (Cit-Arg ratio) was calculated. Neopterin is a bypass product in the synthesis of tetrahydrobiopterin, which is a cofactor of NO synthase. Results: The results indicate that both neopterin and the Cit-Arg ratio are decreased in bipolar affective patients, irrespective of their symptomatic status. In addition, an association between the values of the Cit-Arg ratio and the neopterin level was observed, which is suggestive for a low tetrahydrobiopterin activity. Conclusion: NO formation may be endangered in bipolar affective disorder. Copyright

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Department of Psychiatry

Hoekstra, R, Fekkes, D, Pepplinkhuizen, L, Loonen, A.J.M, Tuinier, S, & Verhoeven, W.M.A. (2006). Nitric oxide and neopterin in bipolar affective disorder. Neuropsychobiology, 54(1), 75–81. doi:10.1159/000096042