HORMONAL RESPONSES TO THE ADMINISTRATION OF M-CHLOROPHENYLPIPERAZINE IN PATIENTS WITH SEASONAL AFFECTIVE-DISORDER AND CONTROLS

We report on the plasma cortisol and prolactin responses to the seroto nergic agonist m-CPP (0.1 mg/kg) in 10 patients with winter seasonal a ffective disorder (SAD) and 10 controls during the winter, in both unt reated and bright light-treated conditions; and on 8 other SAD patient s and 8 other controls during the summer, Following m-CPP infusion, un treated patients had exaggerated prolactin (p < .05) and cortisol (p < .05) responses compared to controls. Light treatment significantly re duced responses of both hormones to m-CPP (prolactin: p < .01; cortiso l: p < .01), When untreated winter subjects and summer subjects were c ompared, cortisol, bur not prolactin responses to m-CPP were found to be higher in patients than in controls during the winter, and lower in patients than in controls during the summer (diagnosis by season: p < .05), These results are consistent with those of our previous report on the behavioral responses to m-CPP in the same patients and suggest an abnormality in serotonergic function in untreated SAD patients in w inter, which is normalized following treatment with light therapy and naturally during the summer.