Scientists pinpoint why smoking kills the appetite

Smoking suppresses the appetite but causes a myriad other health problems. Now scientists think they understand how nicotine switches the hungry signal off. Flickr

For the first time, scientists have seen how nicotine depresses appetite signals in the brain, unlocking potential treatments for obese people and smokers who want to quit without gaining weight.

Some smokers have cited fear of weight gain as a reason they are reluctant to quit, despite the many other health problems cause by smoking, including cancer, emphysema and heart disease.

In experiments on mice, U.S. scientists were able to see how nicotine affects the hypothalamic melanocortin system, part of the central nervous system, by waking up a certain set of receptors. The receptors then activate a set of neurons called pro-opiomelanocortin or POMC neurons, which suppress the urge to eat.

The mice that were exposed to nicotine during the experiment ate half the food they normally would and lost 15-20% of their body mass, although they drank water at a normal rate.

“Understanding the neurobiological mechanisms underlying the anorexic effects of smoking would facilitate the development of novel treatments to help with smoking cessation and to prevent or treat obesity,” the scientists said in their paper, which was published in the journal Science.

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