LEPTIN AND THE REGULATION OF BODY-WEIGHT IN MAMMALS

The assimilation, storage and use of energy from nutrients constitute a homeostatic: system that is essential for life. In vertebrates, the ability to store sufficient quantities of energy-dense triglyceride in adipose tissue allows survival during the frequent periods of food de privation encountered during evolution. However, the presence of exces s adipose tissue can be maladaptive. A complex physiological system ha s evolved to regulate fuel stores and energy balance at an optimum lev el. Leptin, a hormone secreted by adipose tissue, and its receptor are integral components of this system. Leptin also signals nutritional s tatus to several other physiological systems and modulates their Funct ion. Here we review the role of leptin in the control of body weight a nd its relevance to the pathogenesis of obesity.