Why smokers have less hunger than non-smokers

Some people actually use smoking to control their weight. Others hesitate to quit smoking because they fear the weight gain that often accompanies smoking cessation.
Now researchers from Yale and Baylor have discovered a mechanism by which nicotine suppresses hunger in the brain.
What happens is that nicotine influences the melanocortin system in the hypothalamus, a structure in vertebrate brains that contains a variety of nuclei which produce hormones, neurotransmitters, and control and link to endocrine and metabolic functions elsewhere in the brain and end-organs. The hypothalamus also plays an important part in controlling things like temperature, hunger, and sleep and circadian rhythm.
When nicotine is around, nicotinic receptors in the hypothalamus get excited and activate so-called POMC neurons, nerve cells that then in turn fire to influence melanocortin receptors, with the end result being that hunger is reduced or suppressed.

By using a combination of pharmacological, molecular genetic, electrophysiological, and feeding studies, we found that activation of hypothalamic α3β4 nicotinic acetylcholine receptors leads to activation of pro-opiomelanocortin (POMC) neurons. POMC neurons and subsequent activation of melanocortin 4 receptors were critical for nicotinic-induced decreases in food intake in mice. This study demonstrates that nicotine decreases food intake and body weight by influencing the hypothalamic melanocortin system and identifies critical molecular and synaptic mechanisms involved in nicotine-induced decreases in appetite.

Now of course have people already realised that they might have a weapon here to fight excess weight, and to make this into a drug to help reduce obesity, but I think this is still some time away, mainly because nicotine has other systemic and central effects that are not all desirable, for example effects on the heart and some structures of the brain. But it is potentially a new approach to assist weight loss.

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