d‐Fenfluramine/prolactin response throughout the menstrual cycle: evidence for an oestrogen‐induced alteration

Abstract

Summary: The prolactin (PRL) response to fenfluramine (FEN), a serotonin (S‐HT) releasing agent, is used as an index of 5‐HT sensitivity in studying disorders associated with central S‐HT abnormality. Plasma oestrogen levels are known to augment PRL responses to a variety of stimuli. In order to examine the effect that ovarian steroids have on this response nine, healthy women were tested twice at three time points in the menstrual cycle: early follicular, mid‐cycle and late luteal phase with either d‐FEN, a more specific 5‐HT agent than the racemic mixture, or placebo. Responses to d‐FEN were maximal at mid‐cycle, lowest during the early follicular phase, with responses premen‐strually being intermediate between the two. Responses to placebo did not vary. Plasma oestradiol levels fluctuated In parallel with neuroendocrine responses to d‐FEN. The possible mechanisms are discussed, Including an effect that oestradiol may exert at central serotonin sites.