THE M-CHLOROPHENYLPIPERAZINE TEST IN CLUSTER HEADACHE - A STUDY ON CENTRAL SEROTONINERGIC ACTIVITY

The central serotoninergic agonist m-chlorophenylpiperazine (m-CPP) st imulates several 5HT receptor subtypes. It induces the release of both cortisol and prolactin (PRL). In this study we investigated central s erotoninergic responsiveness in cluster headache by monitoring cortiso l and PRL responses to m-CPP administration. Twenty-three patients wit h episodic cluster headache and 17 sex-matched and age-matched healthy subjects were studied. The cluster headache patients were tested duri ng a cluster period, and none were receiving prophylaxis. A single ora l dose of m-CPP, 0.5 mg/kg, was given at time 0. Blood samples were dr awn at -30, 0, 30, 60, 90, 120, 150 and 180 min. PRL and cortisol leve ls were assayed in the samples. PRL and cortisol delta maxima (delta m aximum=maximum response-baseline level at time 0/baseline level at tim e 0) were evaluated in each patient and mean values compared. Serum le vels of m-CPP were detected by HPLC and correlated to hormonal respons es. Reduced cortisol (p<0.02) and increased PRL (p<0.05) delta maxima were observed in cluster headache patients. Increased basal cortisol p lasma levels (p<0.05) and reduced basal PRL plasma levels (p=0.06) als o characterized cluster headache patients. This is the first study eva luating central serotoninergic responsiveness to m-CPP in cluster head ache and these data suggest impaired central serotoninergic function i n this pathology.