Dysfunction of the Purinergic System in Bipolar Disorder

Objective: To verify the purinergic hypothesis of bipolar disorder (BD), we assessed the concentration of various components of the purinergic system in manic and depressed bipolar patients. Methods: Sixty-two patients (19 male and 43 female), aged 22–69 (49 ± 14) years, with BD were studied. Twenty-three patients (9 male and 14 female) were assessed during a manic episode and subsequent remission, and 39 patients (10 male and 29 female) were investigated in a depressive episode and the following remission. Twenty-two healthy subjects (8 male and 14 female), aged 19–70 (41 ± 14) years, served as the control group (CG). The severity of symptoms was evaluated using the Hamilton Depression Rating Scale (HDRS) and the Young Mania Rating Scale (YMRS). The concentrations of uric acid (UA) were estimated by the uricase-based method, whereas xanthine dehydrogenase (XDH), adenosine (Ado), and adenosine deaminase (ADA) by ELISA. Results: The mean score in the acute episode was 32 ± 8 points in the YMRS for mania and 31 ± 8 in the HDRS for depression. UA levels were significantly higher in female bipolar patients compared to the females in the CG. The concentrations of XDH, Ado, and ADA were significantly lower in bipolar patients both during an acute episode and remission compared to CG. Conclusions: A significant dysfunction of the purinergic system in patients with BD was observed. In most instances, the disturbances were not different in the acute episode than in remission what qualifies them as trait dependent. The results may confirm the role of the purinergic system in the pathogenesis of BD.