Chronic administration of nicotine results in an increased number of nicotine receptors in specific regions of the brain (Perry et al., 1999). This upregulation of nicotine receptors leads to the development of tolerance. Tolerance is a phenomenon by which repeated doses of a drug produce less of an effect than did the initial exposure.

Perry DC, Davila-Garcia MI, Stockmeier CA, Kellar KJ. Increased nicotinic receptors in brains from smokers: membrane binding and autoradiography studies. J Pharmacol Exp Ther 1999;289:1545–1552.

Slide is used with permission, Rx for Change: Clinician-Assisted Tobacco Cessation. Copyright © 1999-2007 The Regents of the University of California, University of Southern California, and Western University of Health Sciences. All rights reserved.