Conditioned gustatory avoidance induced by three cholinergic agents.

Conditioned gustatory avoidance of sweetened condensed milk was induced in rats by drugs which differentially affect the cholinergic nervous system. After baseline water intake during a 15 minute daily session was established, sweetened condensed milk was presented in place of water, followed 15 minutes later by an IP injection of saline, physostigmine (0.5 mg/kg), atropine (25 mg/kg) or mecamylamine (25 mg/kg). Three presentations of milk were given, alternating daily with a water presentation. Atropine, a muscarinic blocker, and mecamylamine, a nicotinic blocker, both produced a strong avoidance. Physostigmine, an indirect agonist, produced a less pronounced avoidance at the dose employed. This study indicates that cholinergic agonists and antagonists are capable of inducing conditioned gustatory avoidance.