Possible interrelationship between the biogenic amines involved in the modulation of footshock aggression in rats

Dopamine, 5-hydroxytryptamine and 4-methylhistamine facilitated whereas noradrenaline and 2-pyridylethylamine inhibited footshock aggression (FSA) in rats. Dopamine increased FSA in cyproheptadine and cimetidine but not in pimozide pretreated animals; 5-hydroxytryptamine potentiated FSA in cimetidine and pimozide but not in cyproheptadine pretreated rats; 4-methylhistamine facilitated FSA in pimozide and cyproheptadine but not in cimetidine pretreated groups. Also 2-pyridylethylamine inhibited FSA in phenoxybenzamine but not mepyramine pretreated animals. These effects were not significantly different from those seen with dopamine, 5-hydroxytryptamine, 4-methylhistamine and 2-pyridylethylamine, alone, respectively on FSA. It is inferred that each of the neurotransmitters involved in the modulation of footshock aggression acts through an independent mechanism which is not under the regulatory control of the other.