Multiple hormone responses to stimulation with dl-fenfluramine in patients with major depression before and after antidepressive treatment.

The authors investigated 31 drug-free inpatients with major depression using dl-fenfluramine (dl-FEN) as a serotonin probe (fenfluramine stimulation test, FFT). The FFT was performed in the same individuals (intraindividual comparison) with and without application of dl-FEN and before and after antidepressive treatment. Blood samples were analyzed for prolactin, cortisol, thyrotropin (TSH), growth hormone (HGH), dl-FEN and its major metabolite dl-norfenfluramine. There was no difference in the conditions before and after treatment as regards peak plasma levels of dl-FEN. Compared with saline, significant (P less than 0.01) increases were detected for dl-FEN-stimulated cortisol and prolactin values. A significantly (P less than 0.01) lower increase in dl-FEN-stimulated prolactin values was found after treatment compared with the situation before treatment, a finding which was dependent on the type of medication which the patients were receiving at the time when the test procedure took place. Baseline and dl-FEN-stimulated cortisol values were significantly (P less than 0.001) lower and TSH values were significantly (P less than 0.01) higher in the condition after compared with the one before treatment. Patients' mean peak delta prolactin responses to dl-FEN before treatment were significantly (P less than 0.05) correlated with those of patients after subchronic treatment with fluvoxamine. Hormonal responses were neither associated with the severity of the illness nor with a specific psychopathological profile.