Research scientists have discovered a new class of nicotinic receptor located in the hypothalamus of the brain that may alleviate hunger. The new research study uncovered a brain mechanism that could be targeted for new medications designed to help people quit smoking without gaining weight.
Nicotine is one of the most heavily used addictive drugs in the United States, and the leading preventable cause of disease, disability, and death.
The Centers for Disease Control and Prevention reports that cigarette smoking results in more than 440,000 preventable deaths each year — about 1 in 5 U.S. deaths overall. Many smokers realize the health benefits of not smoking but are unable to quit.
This research, funded by the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health, shows that a specific subclass of brain nicotinic receptor is involved in nicotine's ability to reduce food intake in rodents.
Previous research shows that the average weight gain after smoking is less than 10 pounds, but fear of weight gain can discourage some people who would like to quit.
In the study, to be published in the June 10 issue of Science, researchers found that a nicotine-like drug, cytisine, specifically activated nicotinic receptors in the hypothalamus - a brain center that controls feeding.
This resulted in the activation of a circuit that reduced food intake and body fat in a mouse model. This effect was very specific, since a drug that prevented cytisine from binding to its hypothalamic receptors blocked the reduction in food intake.
These mouse models allow us to explore the mechanisms through which nicotine acts in the brain to reduce food intake. We found that nicotine reduced eating and body fat through receptors implicated in nicotine aversion and withdrawal rather than reward and reinforcement, said Marina Picciotto, of Yale University, New Haven, Conn. and senior author for the article.
These results indicate that medications that specifically target this pathway could alleviate nicotine withdrawal as well as reduce the risk of overeating during smoking cessation. Although more research is warranted, such a highly selective compound might be more effective than drugs that act on more than one type of nicotinic receptor, said NIDA Director Nora Volkow.