LOWER SERUM ACTIVITY OF PROLYL ENDOPEPTIDASE IN FIBROMYALGIA IS RELATED TO SEVERITY OF DEPRESSIVE SYMPTOMS AND PRESSURE HYPERALGESIA

Background. The aims of the present study were to examine serum activi ties of peptidases, i.e. prolyl endopeptidase (PEP) and dipeptidyl pep tidase IV (DPP TV), in patients with fibromyalgia and to examine the e ffects of subchronic treatment with sertraline on these variables. Met hod. Serum PEP and DPP IV activity were measured in 28 normal voluntee rs and 21 fibromyalgia patients, classified according to the American College of Rheumatology criteria. Tenderness at tender points was eval uated by means of dolorimetry. Fibromyalgia patients had repeated meas urements of serum PEP and DPP IV both before and after repeated admini stration of sertraline or placebo for 12 weeks. Results. Patients with fibromyalgia had significantly lower serum PEP activity than normal v olunteers. There were significantly negative correlations between seru m PEP activity and severity of pressure hyperalgesia and the non-somat ic, cognitive symptoms of the Hamilton Depression Rating Scale. Fibrom yalgia patients with severe pressure hyperalgesia had significantly lo wer PEP activity than normal controls and fibromyalgia patients with l ess severe hyperalgesia. Fibromyalgia patients with severe non-somatic depressive symptoms had significantly lower serum PEP activity than n ormal volunteers. There were no significant changes in serum DPP IV ac tivity in fibromyalgia. There were no significant effects of repeated administration of sertraline on serum PEP and DPP IV activity in patie nts with fibromyalgia. Conclusions. The results show that fibromyalgia , and aberrant pain perception and depressive symptoms in fibromyalgia are related to lower serum PEP activity. It is hypothesized that lowe r serum PEP activity may play a role in the biophysiology of fibromyal gia through diminished inactivation of algesic and depression-related peptides.