BACKGROUND: The aims of the present study were to examine
serum activities of peptidases, i.e. prolyl endopeptidase
(PEP) and dipeptidyl peptidase IV (DPP IV), in patients with
fibromyalgia and to examine the effects of subchronic
treatment with sertraline on these variables.
PEP and DPP IV activity were measured in 28 normal volunteers
and 21 fibromyalgia patients, classified according to the
American College of Rheumatology criteria. Tenderness at
tender points was evaluated by means of dolorimetry.
Fibromyalgia patients had repeated measurements of serum PEP
and DPP IV both before and after repeated administration of
sertraline or placebo for 12 weeks.
RESULTS: Patients with
fibromyalgia had significantly lower serum PEP activity than
normal volunteers. There were significantly negative
correlations between serum PEP activity and severity of
pressure hyperalgesia and the non-somatic, cognitive symptoms
of the Hamilton Depression Rating Scale. Fibromyalgia patients
with severe pressure hyperalgesia had significantly lower PEP
activity than normal controls and fibromyalgia patients with
less severe hyperalgesia. Fibromyalgia patients with severe
non-somatic depressive symptoms had significantly lower serum
PEP activity than normal volunteers. There were no significant
changes in serum DPP IV activity in fibromyalgia. There were
no significant effects of repeated administration of
sertraline on serum PEP and DPP IV activity in patients with
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 lower serum PEP activity may play a role in
the biophysiology of fibromyalgia through diminished
inactivation of algesic and depression-related peptides.