Objective: Prolidase enzyme, which exists in plasma, brain and various organs, is a cytosolic exopeptidase, that divisor the imidodipeptides with carboxyl terminal position of proline and hydroxyproline. The aim of the present study was to investigate serum prolidase activity level in major depressive disorder (MDD).
Methods: This study included 22 patients with MDD as the study group, and 26 healthy subjects without any psychiatric disorders as the control group. Each patient underwent a detailed diagnostic evaluation by experienced psychiatrists. The sociodemographic information form given to both patients and the control subjects, while Hamilton Depression Scale Scoring (HDS), Hamilton Anxiety Scale Scoring (HAS), Clinical Global Impression Scoring (CGI) applied to patients. Blood samples were obtained for biochemical analyses.
Results: The mean age of the patient group was 31.3±10.1 years old, whereas the mean age of the control group was 32.3±8.8 years old. The mean duration of the education for the patient group was 8.1±6.2 years, whereas for the control group was 10.2±3.8 years. There was no significant differences in terms of the mean age of participants and the mean duration of the education between two groups (p>0.05). The level of prolidase activity of patient group was 510.3±480.8 U/L, whereas the level of prolidase activity of control group was 457.8±386.0 U/L. No significant difference was observed in serum prolidase activity between patient and the control groups (p>0.05).
Conclusion: In our study similar level of prolidase activity was found in MDD and healthy subjects. We suggest that this finding may be an evidence indicating that MDD and bipolar depression may be different clinical entities.