Effect of histaminergic drugs on footshock-induced aggressive behaviour in rats

Histamine and 2-pyridylethylamine decreased and 4-methylhistamine increased footshock-induced aggression after their intracerebroventricular administration to rats. Mepyramine and cimetidine had no effect on the fighting response but blocked the effects of the respective agonists. Histamine when given after mepyramine increased and after cimetidine decreased the fighting score, this decrease being more than that with histamine alone. It is inferred that central H1-receptors are inhibitory and H2-receptors facilitatory in footshock aggression and that this is independent of catecholaminergic mechanisms.