POMC neuron
If hunger has a brake pedal in the brain, POMC neurons are pressing it. When energy is plentiful, these hypothalamic neurons fire, release appetite-suppressing signals, and tell the body “you have enough — stop eating and burn fuel.” They are the “stop” side of the central appetite system.
POMC stands for pro-opiomelanocortin, a large precursor protein that these arcuate-nucleus neurons cut into smaller active pieces, most importantly alpha-MSH (melanocyte-stimulating hormone). Alpha-MSH activates melanocortin-4 receptors (MC4R) on downstream neurons to reduce food intake and increase energy expenditure. POMC neurons are switched on by satiety signals such as leptin and insulin and by gut fullness hormones.
The importance of this pathway is shown by genetics: rare mutations that disable POMC or its receptor cause severe childhood obesity, hyperphagia, and (because POMC also yields ACTH) sometimes adrenal and pigmentation problems. A drug that activates MC4R (setmelanotide) can treat obesity in these specific genetic deficiencies.
The same POMC precursor is processed differently in the pituitary, where it mainly yields ACTH — a neat example of one gene serving very different endocrine roles in different tissues.