UNRAVELING THE CENTRAL-NERVOUS-SYSTEM PATHWAYS UNDERLYING RESPONSES TO LEPTIN

Here we summarize recent progress in the biology of leptin, concentrat ing on its central nervous system (CNS) actions. The product of the ob gene, leptin is a circulating hormone produced by white adipose tissu e that has potent effects on feeding behavior, thermogenesis and neuro endocrine responses. Leptin regulates energy homeostasis, as its absen ce in rodents and humans causes severe obesity. We consider the physio logical mechanisms underlying leptin action, along with several novel hypothalamic neuropeptides that affect food intake and body weight. Th e molecular causes of several other obesity syndromes are discussed to illuminate how the CNS regulates body weight. We describe neural circ uits that are downstream of leptin receptors and propose a model linki ng populations of leptin-responsive neurons with effector neurons unde rlying leptin's endocrine, autonomic and behavioral effects.