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Updated: Jun 8, 2026
Spectral Confocal Imaging of Fluorescently tagged Nicotinic Receptors in Knock-in Mice with Chronic Nicotine Administration
Published on: February 10, 2012
Varenicline blocks nicotine intake in rats with extended access to nicotine self-administration
Olivier George1, Allison Lloyd, F Ivy Carroll
1Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 North Torrey Pines Road, SP30-2400, La Jolla, CA 92037, USA. ogeorge@scripps.edu
Rationale:
Much evidence indicates that individuals use tobacco primarily to experience the psychopharmacological properties of nicotine. Varenicline, a partial α4β2 nicotinic acetylcholine receptor (nAChR) agonist, is effective in reducing nicotine craving and relapse in smokers, suggesting that α4β2 nAChRs may play a key role in nicotine dependence. In rats, the effect of varenicline on nicotine intake has only been studied with limited access to the drug, a model of the positive reinforcing effect of nicotine. Varenicline has not been tested on the increase in motivation to take nicotine in nicotine-dependent rats.
Objectives:
The present study evaluated the effects of varenicline on nicotine intake in rats with extended access to nicotine self-administration (23 h/day), a condition leading to the development of nicotine dependence. We hypothesized that varenicline's effects on nicotine self-administration would be greater in rats with extended than limited access to the drug and after forced abstinence rather than during baseline self-administration.
Results:
Varenicline dose-dependently decreased nicotine self-administration in rats with limited (1 h/day) and extended (23 h/day) access. Despite an increased sensitivity to the motivational effects of abstinence on nicotine intake compared with limited-access rats, varenicline was equally effective in decreasing nicotine intake in dependent rats with extended access to nicotine.
Conclusion:
These results suggest that α4β2 nAChRs are critical in mediating the positive reinforcing effects of nicotine but may not be a key element underlying the negative reinforcement process responsible for the increased nicotine intake after abstinence in dependent subjects.
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