Arcuate Nucleus - Centrally-projecting Neurons

Centrally-projecting Neurons

• Centrally-projecting neurons contain neuropeptide Y (NPY), agouti-related protein (AGRP), and the inhibitory neurotransmitter GABA. These neurons, in the most ventromedial part of the nucleus, project strongly to the lateral hypothalamus and to the paraventricular nucleus of the hypothalamus, and are important in the regulation of appetite. When activated, these neurons can produce ravenous eating. These neurons are inhibited by leptin, insulin, and peptide YY and activated by ghrelin.

• Centrally-projecting neurons that contain peptide products of pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART). These neurons have widespread projections to many brain areas, including to all nuclei in the hypothalamus. These cells are important in the regulation of appetite, and, when activated, they inhibit feeding. These neurons are activated by circulating concentrations of leptin and insulin, and they are directly innervated and inhibited by the NPY neurons. POMC neurons that project to the medial preoptic nucleus are also involved in the regulation of sexual behavior in both males and females. The expression of POMC is regulated by gonadal steroids. The release of a POMC product, beta-endorphin is regulated by NPY.

• Centrally-projecting neurons that make somatostatin; the neurosecretory somatostatin neurons that regulate growth hormone secretion are a different population, located in the periventricular nucleus.