The aim of the present study was to analyze if alterations of peripheral-type benzodiazepine receptor (PBR) characteristics occurred in platelet membranes of patients affected by primary fibromyalgia (FM).
Platelets were obtained from 30 patients with FM. Evaluation of kinetic parameters of PBR was performed using [(3)H] PK11195 as specific radioligand compared with 16 healthy volunteers.
The results showed a significant increase of PBR binding sites value in platelet membranes from FM patients (B(max) was 5366+/-188 fmol/mg vs. controls, 4193+/-341 fmol/mg, mean+/-SEM) (**p<0.01) but not for affinity value (K(d) was 4.90+/-0.39 nM vs. controls, 4.74+/-0.39 nM, mean+/-SEM) (p>0.05). Symptom severity scores (pain and tiredness) were positively correlated with B(max).
Our results showed an up-regulation of PBR in platelets of FM patients, and this seems to be related to the severity of fibromyalgic symptoms.