A new study by Yale researchers shows that prior nicotine exposure in mice can increase their motivation to respond work for food, weeks after their last exposure to nicotine, a finding that runs counter to the popular belief that nicotine exposure curbs appetite.
The study, to be published in an upcoming issue of Psychopharmacology, also sheds new light on the role played by certain nicotinic acetylcholine receptors when it comes to the reinforcing aspects of nicotine.
The study provides insight into one of the most vexing issues relating to smoking cessation, one that discourages many people from attempting to quit smoking, the prospect of weight gain. "Although acute nicotine can act as an appetite suppressant, these data are the first to suggest that repeated exposure to nicotine has the opposite effect, that nicotine increases motivation for food for weeks following exposure to the drug," said Darlene Brunzell, associate research scientist in the Department of Psychiatry and first author of the study.
"This research suggests that when young people take up smoking to regulate their weight, this may be counterproductive in addition to being harmful to their health," said Stephanie O'Malley, professor of psychiatry and principal investigator for the Center for Nicotine & Tobacco Use Research at Yale. "More research is needed to determine how exactly that works, but this does show that there could be a connection between exposure to nicotine and subsequent weight gain in some individuals."
In addition, the study identifies which nicotinic receptors are involved in nicotine's control over cues. "We knew previously that cues play a critical role in nicotine and tobacco consumption in animals and humans," said Brunzell. "These studies show that Beta 2 nicotinic receptors are necessary for nicotine's ability to increase the control that cues have over behavior." said Dr. Darlene Brunzell, Ph.D., first author of the study. he also said, in addition, that the findings run counter to the popular belief that acute nicotine exposure curbs appetite. "These data are the first to suggest that repeated exposure to nicotine has the opposite effect, that nicotine increases motivation for food for weeks following exposure to the drug."
O'Malley said that the research has significance when it comes to developing solutions for smokers who gain weight after they quit smoking. She noted that weight concerns keep many people, particularly women, from attempting to quit. Any information about the mechanism for weight gain could help the researchers at Yale and elsewhere figure out how to address that concern. In the meantime, she said, the research might help discourage people from starting to smoke to regulate their weight.