The importance of central nicotinic receptors in footshock-induced aggression in mice

The action of nicotine and other agonists of central cholinergic receptors on aggressiveness was tested in the footshock-induced fighting test in mice. Nicotine in doses 0.25-2 mg/kg ip and 5-30 micrograms ivtr potentiated the aggressiveness, but a dose of 4 mg/kg ip suppressed it in naive (not pretested) mice. Of other cholinergic agonists betanechol, a specific muscarinic agonist, facilitated the aggression. Similar effect was produced by arecoline, a muscarinic-nicotinic agonist, while carbachol, a compound of pharmacological profile similar to that of arecoline, was ineffective. Mecamylamine, a central nicotinic antagonist, in doses 2 and 4 mg/kg moderately facilitated the aggressiveness, while in a dose of 8 mg/kg inhibited it. Hexamethonium, a peripheral nicotinic antagonist, strongly potentiated aggressiveness. Mecamylamine and hexamethonium antagonized the facilitatory action of nicotine on aggression in non-pretested mice, and of arecoline both in non-pretested an pretested mice, but did not change the effect of betanechol. The results indicate that in addition to muscarinic receptors, the nicotinic receptors in the central nervous system may participate in evoking affective aggression in mice subjected to electric foot-shock.