EFFECTS OF PSYCHOLOGICAL STRESS ON SERUM PROLYL ENDOPEPTIDASE AND DIPEPTIDYL PEPTIDASE-IV ACTIVITY IN HUMANS - HIGHER SERUM PROLYL ENDOPEPTIDASE ACTIVITY IS RELATED TO STRESS-INDUCED ANXIETY

There is now some evidence that psychiatric disorders, such as major d epression, schizophrenia and post-traumatic stress disorder are associ ated with significant alterations in the serum activity of peptidases, such as prolyl endopeptidase (PEP) and dipeptidyl peptidase IV (DPP I V). The aims of the present study were to examine the effects of psych ological stress on serum PEP and DPP IV activity in humans. Thirty-eig ht university students had repeated measurements of serum PEP and DPP IV activity a few weeks before and after (baseline conditions) as well as the day before a difficult academic examination (stress condition) . Subjects were divided into anxiety responders and nonresponders to s tress according to their stress-induced increase in the Spielberger St ate Anxiety Inventory. Serum PEP activity was somewhat lowered by stre ss in female, but not male, students. Serum PEP activity was significa ntly higher in the two baseline conditions and during the stress condi tion in anxiety responders than in anxiety nonresponders. There were n o significant effects of stress on serum DPP IV activity and no signif icant differences between anxiety responders and nonresponders. Serum PEP and DPP IV activity were significantly higher in men than in women . The results suggest that increased baseline serum PEP activity is re lated to stress-induced anxiety. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.