Leptin and the Neural Circuit Regulating Body Weight and Metabolism

摘要

In mammals, a robust physiologic system acts to maintain relative constancy of weight. A key element of this system is leptin. Leptin is an adipocyte hormone that functions as the afferent signal in a negative feedback loop regulating body weight. Leptin also functions as a key link between nutrition and the function of many other physiologic systems. When at their "normal" weight (i.e., normal for that individual), individuals produce a given amount of leptin and in turn maintain a state of energy balance. Weight gain results in an increased plasma leptin level which elicits a biologic response characterized in part by a state of negative energy balance. Weight loss among both lean and obese subjects results in decreased plasma levels of leptin, which leads to a state of positive energy balance and a number of other physiologic responses. Implicit in this construct is that weight is set at different levels among different individuals.