Higher serum prolyl endopeptidase activity in patients with post-traumaticstress disorder

Background: It is reported that psychiatric disorders, such as depression a nd schizophrenia, are associated with changes in serum activity of prolyl e ndopeptidase (EC 3.4.21.26), a cytosolic endopeptidase, which cleaves pepti de bonds on the carboxylside of proline in proteins of relatively small mol ecular mass. Aims and methods: The aims of the present study were to examin e serum PEP activity in patients with post-traumatic stress disorder (PTSD) versus healthy volunteers. PEP activity has been determined by a fluorimet ric assay. Results: Serum PEP activity was significantly higher in patients with PTSD than in normal volunteers. Serum PEP activity was significantly higher in patients with PTSD and concurrent major depression than in patien ts with PTSD without major depression. In PTSD patients, there were no sign ificant correlations between serum PEP activity and severity of PTSD sympto ms. Conclusions: The results show that PTSD and, in particular, PTSD with c oncurrent major depression is associated with increased activity of PEP. Re levance: these results may be of importance for the (i) neuroendocrine path ophysiology of PTSD since PEP degrades neuropeptides, such as arginine vaso pressin (AVP) and thyrotropin releasing hormone (TRH); and (ii) etiology of PTSD, since PEP degrades behaviorally active neuropeptides, such as AVP, T RH, oxytocin, neurotensin and substance P, which play a key role in positiv e reinforcement, social interactions, emotions and stress responsivity. (C) 1999 Elsevier Science B.V. All rights reserved.