Prolidase activity and oxidative stress in patients with major depressive disorder.

Background: The aim of the current study was to determine whether the serum prolidase levels are associated with the etiopathogenesis of depression. Subjects and methods: This study included 29 patients with major depressive disorder (MDD), who were consecutively recruited from the psychiatric outpatient clinic, and 30 healthy individuals recruited from the general community. Each patient underwent a detailed diagnostic evaluation by two psychiatrists using the Structured Clinical Interview for DSM-IV (SCID-I). Serum prolidase activity and oxidative parameters were measured in the patient and control groups. The severity of depressive symptoms was assessed using the Hamilton Depression Rating Scale. Results: Serum prolidase level was significantly higher in patients with MDD compared to healthy subjects (p<0.001). Total Oxidant Status (TOS) levels and Oxidative Stress Index (OSI) were also significantly higher in patients with MDD (p<0.001), whereas no significant difference was observed between the groups in the TAS levels (p=0.297). Serum prolidase level did not show any correlation with markers of oxidative stress in patients with MDD. Conclusion: Increased serum prolidase levels in patients with MDD may be interpreted as the interaction of prolidase activity, glutamate transmission and oxidative stress. It is suggested that prolidase activity is involved in the etiopathogenesis of depressive disorder.