Nicotine Pretreatment Increases Sensitivity to Reward Devaluation in Extinction

Abstract

We examined the effects of nicotine preexposure on operant learning and habit formation. Rats were pretreated with 10 doses of 0.4 mg/kg nicotine (n = 9) or saline as a control (n = 9) for 10 consecutive days. Operant training was initiated in which rats learned to nose-poke for a sucrose reward. To examine whether nicotine pretreatment accelerated habitual responding, ad-lib feeding was used to devalue the sucrose reward prior to sessions 1 and 3 of extinction testing. Rats subsequently underwent reacquisition in order to further examine the influence of nicotine pretreatment on operant learning. Preexposure to nicotine did not affect the initial acquisition of the operant response for sucrose or the reacquisition of this response following extinction training. However, nicotine pretreatment expedited extinction learning, but only under conditions of reward devaluation by prefeeding. Because nicotine dosing was terminated 9 days prior to extinction testing, and nicotine was never paired directly with sucrose reinforcement, these results suggest that nicotine exposure has a durable influence on extinction learning.