[Participation of serotonin in demonstration of predatory aggression in the mouse]

The study was devoted to the influence of serotonin (5-HT) on the mice predatory aggression towards locusts which was estimated by the latency of attack and the number of aggressive mice in the experimental group. 10 mg/kg of 5-HT injected intraperitoneally, significantly decreased the percentage of aggressive mice and prolonged the attacks latency. 5-Hydroxytryptophan (5-HTP), 5-HT precursor, had a more prominent inhibitory effect which was significant when the dose amounted to 50 mg/kg. Imipramin, an inhibitor of 5-HT reuptake, diminished predatory aggression in dose-dependent manner. Pretreatment of metisergid (blockader of 5-HT receptors) prevented the inhibitory effect of 5-HTP. 5-HT suppressing influence on mice predatory aggression is due by its action on central mechanisms as the injection of small doses of 5-HT in the mice lateral ventricle considerably decreased their aggression towards locusts.