Reinstatement of nicotine self-administration in rats by presentation of nicotine-paired stimuli, but not nicotine priming.

The objective of the present study was to determine the relative efficacy of nicotine priming and nicotine-paired stimuli in reinstating extinguished NSA in rats. The relative efficacy of different stimulus conditions in reinstating NSA was also determined. Rats were trained to self-administer nicotine (0.03 mg/kg/inf) under an FR 5 schedule. Onset of a light above the active lever was correlated with nicotine availability, while offset of the light was paired with each nicotine infusion. In Experiment 1, saline extinction was arranged in the presence of these light stimuli. After extinction criteria were met, the effects of priming doses of nicotine (0.01, 0.03. and 0.06 mg/kg/inf, i.v.) on active lever pressing were determined. In Experiment 2, extinction of NSA was arranged in the absence of the light stimuli. After extinction criteria were met, reinstatement sessions were arranged involving either (1) a priming infusion of nicotine (0.03 mg/kg), (2) presentation of the same light stimuli as during NSA training, (3) constant illumination of the cue light, or (4) a combination of a nicotine priming infusion with one of the stimulus-light conditions. In Experiment 1, nicotine generally failed to reinstate NSA at any priming dose. In Experiment 2, both stimulus conditions reinstated NSA, with the stimulus condition identical to training producing a greater effect. Nicotine priming alone failed to significantly reinstate NSA. Nicotine priming combined with either stimulus condition was no more effective than each stimulus condition alone in reinstating NSA. These findings suggest that nicotine-paired cues are more effective than nicotine alone in reinstating extinguished NSA and are consistent with other studies showing that nicotine-paired stimuli play an important role in the reacquisition of NSA.