Is prolidase a neuroprotective moleIs prolidase a neuroprotective molecule in post-traumatic stress disorder?cule in post-traumatic stress disorder?

Objective: Post-traumatic stress disorder (PTSD) is a psychiatric disorder which develops after exposure to a traumatic event. In recent years, researches on roles of biologic effects in PTSD’s etiology have increased. Prolidase is a manganese-dependent cytosolic exopeptidase that cleaves imidodipeptides containing Cterminal proline or hydroxyproline, and its activity has been documented in plasma and in various organs, such as the heart and the brain. In humans, the deficiency of the enzyme activity causes a rare autosomal recessive inherited disorder with a highly variable clinical phenotype such as chronic recurrent infections, mental retardation, splenomegaly, and skin lesion. The status of prolidase, which has significant biologic effects in PTSD’s etiology, has been assessed. In this study, we aimed to investigate the relationship between PTSD and serum prolidase activity.

Methods: Among the survivors of the Van earthquake on 23 October 2011, 25 patients who had been diagnosed with PTSD according to DSM-IV criteria and 26 cases who were traumatized but not diagnosed with PTSD as well as 25 healthy controls who never experienced an earthquake were enrolled in the study. Serum prolidase activity of all participants was measured and compared across groups. All traumatized cases were assessed using the PTSD Check List Civilian Version (PCL-C).

Results: The mean prolidase activity of PTSD patients was significantly lower than that of traumatized cases without PTSD diagnosis, which in turn is significantly lower than the prolidase activity of the cases who never experienced an earthquake (p<0.01).

Conclusion: Studies have also noted that glutamate and nitric oxide (NO) play a causal role in anxiety-related behaviors. Because of the prominent role of NO in neuronal toxicity, cellular memory processes, and as a neuromodulator, nitrergic pathways may have an important role in stress-related hippocampal degenerative pathology and cognitive defects seen in patients with PTSD. It has been shown that elevated prolin levels activated the NMDA receptor. It has been considered that prolidase has a role of regulation of nitric oxide synthesis. We observed in this research that while prolidase levels decreased, the substance tended to to reduce NO and the neurotoxic effects of glutamate. Therefore, we suggest that Prolidase is a neuroprotective molecule.