Cigarette smoking is a leading cause of cancer as well as cardiovascular and respiratory disease and is the leading preventable cause of death in the United States. Many factors contribute to cigarette smoking, including nicotine, other chemicals in tobacco smoke, and conditioned reinforcers. This R01 proposal focuses on the crucial role that nicotine plays in mediating the abuse and dependence liability of nicotine, and focuses on nicotine receptor mechanisms mediating the behavioral effects of currently prescribed medications for smoking cessation including nicotine (patch and gum), varenicline (low efficacy nicotine agonist), and bupropion (catecholamine reuptake inhibitor and nicotine antagonist). Drug discrimination will be used to examine nicotine receptor subtypes and pharmacologic (agonist) efficacy at nicotine receptors and their contribution to the behavioral effects of nicotine receptor ligands. A novel drug discrimination procedure will be developed to index nicotine withdrawal and the procedure will be evaluated for its pre-clinical utility as an index of medication effectiveness.
Aim 1 tests the hypothesis that the same 22-containing nicotine receptors, specifically 1422 receptors, mediate the effects of nicotine, varenicline, and cytisine, as evidenced by similar antagonism with nicotine antagonists (DH2E).
Aim 2 tests the hypothesis that varenicline and cytisine have lower agonist efficacy than nicotine in vivo. Experimental support for the hypothesis of Aim 2 will include greater loss of sensitivity (cross-tolerance) to varenicline and cytisine than tolerance to nicotine in nicotine-treated monkeys, failure of varenicline and cytisine to substitute for a relatively large dose of nicotine, and substitution of varenicline and cytisine for the discriminative stimulus effects of a nicotine antagonist in nicotine-dependent monkeys.
Aim 3 tests the hypothesis that discriminative stimulus effects are more sensitive to nicotine withdrawal than directly observable signs. Nicotine and other currently available pharmacotherapies are expected to attenuate more effectively the discriminative stimulus effects of nicotine withdrawal as compared to signs of withdrawal. Although currently available pharmacotherapies for smoking cessation are effective, there is considerable margin for improvement. These pre-clinical studies will help identify pharmacologic dimensions upon which to develop novel medications that could further reduce the devastating consequences of cigarette smoking.

Public Health Relevance

Cigarette smoking is a leading cause of cancer and cardiovascular disease and is the leading preventable cause of death in adults (10% annually). This grant investigates the receptor pharmacology of currently approved medications for smoking cessation and could lead to better treatment, thereby decreasing the devastating health consequence of tobacco use.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Research Project (R01)
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Study Section
Biobehavioral Regulation, Learning and Ethology Study Section (BRLE)
Program Officer
Rapaka, Rao
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University of Texas Health Science Center San Antonio
Schools of Medicine
San Antonio
United States
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Cunningham, Colin S; Moerke, Megan J; Javors, Martin A et al. (2016) Attenuated nicotine-like effects of varenicline but not other nicotinic ACh receptor agonists in monkeys receiving nicotine daily. Br J Pharmacol 173:3454-3466
Moerke, Megan J; de Moura, Fernando B; Koek, Wouter et al. (2016) Effects of nicotine in combination with drugs described as positive allosteric nicotinic acetylcholine receptor modulators in vitro: discriminative stimulus and hypothermic effects in mice. Eur J Pharmacol 786:169-78
de Moura, Fernando B; McMahon, Lance R (2016) Differential antagonism and tolerance/cross-tolerance among nicotinic acetylcholine receptor agonists: scheduled-controlled responding and hypothermia in C57BL/6J mice. Behav Pharmacol 27:240-8
McMahon, Lance R (2015) The rise (and fall?) of drug discrimination research. Drug Alcohol Depend 151:284-8
Rodriguez, Jesse S; Cunningham, Colin S; Moura, Fernando B et al. (2014) Discriminative stimulus and hypothermic effects of some derivatives of the nAChR agonist epibatidine in mice. Psychopharmacology (Berl) 231:4455-66
Cunningham, Colin S; Moerke, Megan J; McMahon, Lance R (2014) The discriminative stimulus effects of mecamylamine in nicotine-treated and untreated rhesus monkeys. Behav Pharmacol 25:296-305
Cunningham, Colin S; McMahon, Lance R (2013) Multiple nicotine training doses in mice as a basis for differentiating the effects of smoking cessation aids. Psychopharmacology (Berl) 228:321-33
Cunningham, Colin S; Javors, Martin A; McMahon, Lance R (2012) Pharmacologic characterization of a nicotine-discriminative stimulus in rhesus monkeys. J Pharmacol Exp Ther 341:840-9
Cunningham, Colin S; McMahon, Lance R (2011) The effects of nicotine, varenicline, and cytisine on schedule-controlled responding in mice: differences in α4β2 nicotinic receptor activation. Eur J Pharmacol 654:47-52
Giuffrida, Andrea; McMahon, Lance R (2010) In vivo pharmacology of endocannabinoids and their metabolic inhibitors: therapeutic implications in Parkinson's disease and abuse liability. Prostaglandins Other Lipid Mediat 91:90-103