Like leptin, the pancreatic hormone insulin is an important adiposity signal to the brain. We
report that the hypothalamic melanocortin system is an important _target of the actions of
insulin to regulate food intake and body weight. Hypothalamic neurons expressing insulin
receptors were found to coexpress the melanocortin precursor molecule pro-
opiomelanocortin (POMC), and administration of insulin into the third cerebral ventricle of
fasted rats increased expression of POMC mRNA. Finally, a subthreshold dose of the …