Neurons and Neurotransmitters in the Hypothalamus That Stimulate or Inhibit Feeding.
Control of energy balance by two types of neurons of the arcuate nuclei: (1) pro-opiomelanocortin (POMC) neurons that release α–melanocyte-stimulating hormone (α-MSH) and cocaine- and amphetamine-regulated transcript (CART), decreasing food intake and increasing energy expenditure and (2) neurons that produce agouti-related protein (AGRP) and neuropeptide Y (NPY), increasing food intake and reducing energy expenditure. α-MSH released by POMC neurons stimulates melanocortin receptors (MCR-3 and MCR-4) in the paraventricular nuclei (PVN), which then activate neuronal pathways that project to the nucleus tractus solitarius and increase sympathetic activity and energy expenditure. AGRP acts as an antagonist of MCR-4. Insulin, leptin, and cholecystokinin (CCK) are hormones that inhibit AGRP-NPY neurons and stimulate adjacent POMC-CART neurons, thereby reducing food intake. Ghrelin, a hormone secreted from the stomach, activates AGRPNPY neurons and stimulates food intake. LepR, leptin receptor; Y1R, neuropeptide Y1 receptor. (Modified from Barsh GS, Schwartz MW: Genetic approaches to studying energy balance: perception and integration. Nature Rev Genetics 3:589, 20