Behavioral effects of intraventricularly administered (-)-nicotine on fixed ratio schedules of food presentation in rats

Abstract

The behavioral effects of intraventricularly (IVT) administered (-)-nicotine on food-maintained behavior were studied. Rats responded by pressing a lever under various fixed ratio (FR) schedules. Infusion of 5 μg of (-)-nicotine suppressed responding under an FR 16 schedule for 11–13 min. The effect was inversely related to the ratio size (16, 32, 64 responses per food delivery), but it was directly related to the infused (-)-nicotine dose (0.312, 0.624, 1.25, 2.5, 5.0, 10.0 μg) when ratio size was held constant. Response rates following the (-)-nicotine-induced suppression were similar to those obtained prior to infusion. The behavioral effects of (-)-nicotine were blocked, in a dose-related manner, by the centrally acting nicotinic-cholinergic antagonist, mecamylamine (0.05–3.0 mg/kg) but not by the peripherally acting antagonist, hexamethonium (0.5–3.0 mg/kg), suggesting that the behavioral effects of IVT infusions of (-)-nicotine are mediated by central nicotinic-cholinergic receptors.