D-FENFLURAMINE-INDUCED PROLACTIN RESPONSES IN MANIA - EVIDENCE FOR SEROTONERGIC SUBSENSITIVITY

Objective: The authors examined serotonergic-medicated prolactin relea se in bipolar mania, using d-fenfluramine as a probe. Method: Hospital ized patients with bipolar disorder, currently manic, were matched for age and sex to healthy comparison subjects. Each group consisted of n ine subjects (seven men and two women). After an overnight fast, all s ubjects had an intravenous cannula inserted into a forearm at 8:30 a.m ., and baseline blood samples for determination of prolactin and corti sol levels were drawn. d-Fenfluramine (30 mg p.o.) was then administer ed; plasma prolactin levels were measured 15 minutes before d-fenflura mine was given, immediately before, and 60, 120, 180, 240, and 300 min utes afterward. Results: Baseline serum cortisol levels were higher in the bipolar manic subjects than in the comparison subjects, although baseline prolactin levels were similar in the two groups. The plasma p rolactin responses to d-fenfluramine of the bipolar manic subjects wer e significantly lower than those of the comparison subjects. Conclusio ns: Bipolar mania appears to be associated with a state of decreased s erotonergic responsivity similar to that found in unipolar depression.