Leptin decreases food intake induced by melanin-concentrating hormone (MCH), galanin (GAL) and neuropeptide Y (NPY) in the rat.

Recent evidence suggests that leptin reduces food intake (FI) by acting at the hypothalamic level. Leptin decreases hypothalamic neuropeptide Y (NPY), melanin-concentrating hormone (MCH) and galanin (GAL) gene expression in rats. The purpose of the present study was to test the hypothesis that leptin decreases FI by additionally modulating the action of NPY, MCH or GAL in the hypothalamus. Intracerebroventricular (i.c.v.) administration of NPY, MCH or GAL induced FI in satiated rats. A prior i.c.v. injection of leptin (4 microg) completely prevented the increase of FI either by MCH, GAL or NPY. These results suggest that modulation of post-synaptic actions of MCH, GAL and NPY is one of the mechanisms of leptin signaling in the hypothalamus.