EVIDENCE SUGGESTING THAT GALANIN (GAL), MELANIN-CONCENTRATING HORMONE(MCH), NEUROTENSIN (NT), PROOPIOMELANOCORTIN (POMC) AND NEUROPEPTIDE-Y (NPY) ARE TARGETS OF LEPTIN SIGNALING IN THE HYPOTHALAMUS

Leptin(OB protein) reduces food intake by acting at the hypothalamic l evel. The purpose of the present study was to identify potential targe ts of leptin signaling in the hypothalamus in ad-lib fed rats. Central administration of leptin (5 mu g) for 3 days decreased food intake an d body weight gain in association with a decrease in hypothalamic gala nin (GAL), melanin-concentrating hormone (MCH), proopiomelanocortin (P OMC) and neuropeptide Y (NPY) gene expression and with an increase in neurotensin (NT) gene expression. In pair-fed rats, NPY gene expressio n was increased and there was no change in either MCH, GAL, POMC or NT gene expression. This study identifies GAL, MCH, POMC and NT as non-N PY targets of leptin signaling and suggests that leptin's action on fo od intake and body weight is most likely mediated by inhibiting excito ry (e.g. NPY, MCH, GAL, POMC) and stimulating inhibitory (e.g., NT) si gnals in the feeding circuitry.