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Article Date: 10 Jun 2011 ? 2:00 PDT
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Healthcare Prof: Article Opinions:?1 postsA discovery of precisely how nicotine suppresses appetite, suggests it may be possible to develop drugs that help people stop
gaining weight when they give up smoking, something that puts many smokers off quitting, according to a new study published
online this week in the journal Science. The scientists discovered a brain pathway in mice that could be the target of new
drugs for smoking cessation and weight control without triggering a craving for tobacco.
Previous studies have shown that although on average people gain no more than 10 lbs (4.5 kg) in weight when they give up
smoking, the fear of weight gain is often what discourages some smokers from quitting.
Led by Yale School of Medicine, the research team found that a specific type of brain nicotine receptor in the hypothalamus, a
brain center that controls feeding, allows nicotine to reduce food intake in laboratory mice.
(A receptor is a ?gatekeeper? molecule that sits on the surface of cells and only allows a matching chemical ? in this case nicotine
- to activate specific instructions for cells to do things.)
In this study, the researchers found that nicotine activates a different set of receptors on the surface of brain cells to those that
trigger a craving for tobacco.
Senior author Dr Marina Picciotto, the Charles B.G. Murphy Professor of Psychiatry, and professor of neurobiology and
pharmacology at Yale School of Medicine, told the press that:
?We found that nicotine reduced eating and body fat through receptors implicated in nicotine aversion and withdrawal rather
than reward and reinforcement.?
?Ultimately, we would like to help people maintain their body weight when they kick the habit and perhaps help non-smokers
who are struggling with obesity,? said Picciotto.
Picciotto and colleagues showed that nicotine activated a specific type of nicotine receptor located on pro-opiomelanocortin or
POMC cells, a specific subset of neurons in the hypothalamus.
They also showed that when given nicotine, mice that did not have the POMC pathway did not lose weight, whereas mice
whose POMC pathway was still intact, did lose weight.
Plus, they found that these particular receptors were not the same as those known to trigger tobacco craving in
smokers.
Picciotto said this means it may be possible to get the effect of appetite suppression without triggering the reward centers in the
brain.
?We found that nicotine reduced eating and body fat through receptors implicated in nicotine aversion and withdrawal rather
than reward and reinforcement,? she said.
A nicotine-like drug, cytisine, also had the same effect: it specifically activated the nicotinic receptors in the hypothalamus,
leading to reduced food intake and body fat in the mouse model. The effect was very specific, since a drug that stopped cytisine
from binding to the receptor stopped the reduction in food intake.
So far this effect has only been shown in mice. More needs to be done to prove that these pathways behave in the same way in
humans, and that it is possible to achieve the same selective effect with nicotine-like drugs in humans.
Dr Nora Volkow, Director of the National Institute on Drug Abuse, part of the National Institutes of Health, which funded the
study, said:
?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,? she added.
?Nicotine Decreases
Food Intake Through Activation of POMC Neurons.?
Yann S. Mineur, Alfonso Abizaid, Yan Rao, Ramiro Salas, Ralph J. DiLeone, Daniela G?ndisch, Sabrina Diano, Mariella De
Biasi, Tamas L. Horvath, Xiao-Bing Gao, Marina R. Picciotto.
Science 10 June 2011: Vol. 332 no. 6035 pp. 1330-1332
DOI: 10.1126/science.1201889
Additional sources: NIDA News Release, Yale University News.
Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today
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posted by Luke Tunyich on 10 Jun 2011 at 3:24 am
There is no reliable evidence that suggests that after quitting smoking, people eat more. There is no one clinical study that suggests that smokers eat more after quitting smoking.
Even if some eat more after quitting smoking, the weight gain is not due to an increase of food intake. In reality, the majority of people after they quit smoking, they eat less, but still after quitting smoking they experience weight gain or accelerated weight gain.
Weight gain after quitting smoking is due to changes in the biomechanics of walking.
1. Smoking affects the neuromuscular control centre.
2. Walking is a physical activity and at the same time, is a neuromuscular control centre activity.
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