AGGRESSION AND BRAIN SEROTONERGIC RESPONSIVITY - RESPONSE TO SLIDES IN MALE MACAQUES

The association between central serotonergic responsivity (measured by prolactin response to acute administration of fenfluramine hydrochlor ide) and aggressivity was examined in 40 adult male cynomolgus monkeys (Macaca fascicularis). Prolactin response to fenfluramine was distrib uted bi modally with 24 monkeys displaying a ''low'' prolactin respons e and 15 showing a ''high'' prolactin response to the fenfluramine cha llenge. Behavioral responsivity was assessed by placing the monkeys in dividually in an open-field enclosure and presenting a series of photo graphic slides depicting both threatening and nonthreatening images. M onkeys that were low prolactin responders displayed significantly more aggressive gestures in response to a threatening slide of a human bei ng than did the high responders (p < 0.05). Insofar as fenfluramine-st imulated prolactin release assesses serotonergic responsivity, these d ata support related findings in people and nonhuman primates linking r educed serotonergic activity and aggression.