PROOPIOMELANOCORTIN NEURONS ARE DIRECT TARGETS FOR LEPTIN IN THE HYPOTHALAMUS

Leptin is a protein product of the obese (ob) gene, which is secreted by adipocytes and functions as a satiety factor to regulate food intak e. The expression of the leptin receptor in several hypothalamic nucle i suggests that multiple neuronal subtypes are targets for leptin's ac tion. Products of the proopiomelanocortin (POMC) gene are known to aff ect feeding behavior, and POMC neurons share a similar distribution wi th leptin receptor mRNA in the arcuate nucleus. We used double label i n situ hybridization and computerized image analysis to test the hypot hesis that POMC neurons coexpress the leptin receptor. Quantitative an alysis confirmed that POMC neurons in the hypothalamus express leptin receptor mRNA. Based on this observation, we infer that POMC neurons a nd the products of the POMC gene may be part of the signaling pathway mediating leptin's action on feeding and perhaps other physiological f unctions.