LEPTIN INHIBITS PREHIBERNATION HYPERPHAGIA AND REDUCES BODY-WEIGHT INARCTIC GROUND-SQUIRRELS

The ob gene product leptin is thought to play a physiological role in the fine tuning of a homeostatic mechanism regulating satiety and adip osity. Mouse recombinant leptin was administered to seasonally hyperph agic arctic ground squirrels as a first step in demonstrating the evol utionary conservation of leptin function and the potential involvement of leptin in the seasonal regulation of adiposity in hibernators. Con tinuous infusion of leptin for 3 wk via miniosmotic pumps resulted in a reduction in food intake and body weight in a manner consistent with its proposed role as a satiety hormone. During the recovery period af ter leptin administration, squirrels that had received leptin became h yperphagic relative to controls. Percent body fat was estimated at wee kly intervals by measuring total body electrical conductivity and decr eased after 3 wk of leptin administration. Our observations support th e role of leptin as a regulatory hormone involved in the control of sa tiety, adiposity, and possibly energy expenditure in hibernating mamma ls.