Changes in platelet alpha-2-adrenoceptors in fibromyalgia: Effects of treatment with antidepressants

The aim of this study was to determine platelet alpha(2)-adrenergic recepto r (alpha(2)-AR) binding sites in fibromyalgia both before and after treatme nt with sertraline or placebo, The maximum number of binding sites (B-max) and their affinity (K-d) for [H-3]rauwolscine, a selective alpha(2)-AR anta gonist, were measured in 13 normal volunteers and 22 fibromyalgia patients. Severity of illness was evaluated by means of the Hamilton Depression Rati ng Scale (HDRS) and dolorimetric assessments of tenderness at tender points . Fibromyalgia patients had repeated measurements of [H-3]rauwolscine bindi ng characteristics both before and after subchronic treatment with sertrali ne or placebo for 12 weeks. [H-3]rauwolscine binding K-d values were signif icantly higher in fibromyalgia patients than in normal volunteers. There we re significant inverse correlations between [H-3]rauwolscine binding K-d va lues and duration of illness, age and lower energy. Significantly higher [H -3]rauwolscine binding K-d values were found in fibromyalgia patients in an early phase of illness (<3 years) than in fibromyalgia patients with a pro tracted illness (>3 years). Repeated administration of sertraline had no si gnificant effects on [H-3]rauwolscine binding B-max or K-d values. The resu lts suggest that fibromyalgia and, in particular, fibromyalgia in an early phase of illness, is accompanied by lowered affinity of platelet alpha(2)-A Rs.