INFLUENCE OF ANTAGONISM AT 5-HT1A AUTORECEPTORS ON DEXFENFLURAMINE-INDUCED PROLACTIN-RELEASE DURING TREATMENT WITH FLUOXETINE

We have conducted a placebo-controlled study to compare the effects of fluoxetine, with or without the 5-hydroxytryptamine(1A) (5-HT1A) anta gonist pindolol, on dexfenfluramine-induced prolactin release and thus on 5-HT turnover. 20 healthy male Caucasians participated. Following a single-blind, random design, on each experimental day each volunteer received 60 mg dexfenfluramine taken with 250 ml water at zero time. Two regimens were followed: (1) 20 mg fluoxetine plus a placebo tablet daily for 14 days; (2) 20 mg fluoxetine plus 20 mg pindolol daily for 14 days. Although some of the post-dexfenfluramine pro lactin levels were lower after 14 days with both regimens, there were no significant differences in prolactin response between the two regimens. These res ults do not validate the suggestion that blockade of 5-MT1A autorecept ors may lead to a reduction in feedback inhibition of 5-HT release fro m neuronal terminals. However, both fluoxetine and pindolol can interf ere with the release of either serotonin or prolactin. Med Sci Res 26: 585-586 (C) 1998 Lippincott Williams & Wilkins.