The role of oxidative stress markers, neurotrophin 4 and homocysteine levels in patients with bipolar disorder and schizophrenia

Aim: In this study, we evaluated the levels of total GSH, SOD, NO and MDA, which are the major components of oxidant - antioxidant systems, and levels of neurotrophin 4 (NT-4), which has a suggested protective role in the neurons against an oxidative stress, and finally, levels of homocysteine, a neurotoxic aminoacid, in patients with schizophrenia and bipolar disorders and in healthy controls, in order to enlighten the roles of these molecules in the above mentioned disease pathogenesis.Materials - Methods: Between January 2010 and August 2011, 50 euthymic patients with a bipolar disorder and 50 schizophrenic patients who were in remission were recruited from Celal Bayar University, Medical Faculty, Department of Pschiatry. 50 healthy subjects who did not have any psychiatric disorders were chosen as the control group. In peripheral venous blood samples colllected from all the subjects, serum SOD, NT-4, homocysteine, vit B12 and folic acid levels, plasma MDA levels and whole blood GSH levels were measured by commercial kits. Serum NO levels were measured by the Griess method. SPSS 15.0 was used for the statistical analysis.Results: There was no statistical difference in gender and disease duration between the groups, but the mean age was statistically different between the patient and control groups. In schizophrenic patients, while glutathione and SOD levels were increased and NO levels were decreased, in bipolar patients there were increased levels of MDA and NO and decreased SOD levels compared to the controls. There were no statistical difference between the three groups in NT-4, homocysteine, vit B12 and folic acid levels. Although the disease duration had no effect on biochemical parameters in schiozphrenia, it was directly proportional with the NT-4 levels in bipolar group. In both of the disease groups, there was no significant effect of having an additional disease status on biochemical parameters and there was no relation between NT-4 and oxidative stress.Discussion: Observed changes in the oxidant-antioxidant systems in both schizophrenia and bipolar disorders indicate that the oxidative stress may play a role in their pathogenesis. Due to a lack of a relationship between disease duration and oxidative stress parameters, we postulated that during disease process; environmental, dietary and therapeutic interventions probably may have an affect on the oxidative patterns. Our study is the first which evaluates the NT-4 levels in both schizophrenia and bipolar disorders, and which reveals no relation between NT-4 levels and oxidative stress parameters. At this point, our study may contribute to the new studies about schizophrenia and bipolar disorder investigating the oxidative stress parameters in pathogenesis and therapeutic approaches.