Urocortin reduces oxygen consumption in lean and ob/ob mice

A vast number of intensive studies have been undertaken to clarify the mech anisms of energy balance. This study was undertaken to investigate the effe ct of urocortin, an endogenous ligand for corticotropin-releasing factor (C RF) type 2 receptor, on oxygen consumption in lean and genetically obese (o b/ob) mice. Oxygen consumption was measured after intraperitoneal injection in unrestrained mice at an environmental temperature of 22 degreesC of one of the following: urocortin, deamidated form of urocortin (urocortin OH) o r CRF. The intraperitoneal injection of urocortin (0.3-3 nmol) dose-depende ntly decreased oxygen consumption in lean mice. The inhibitory effect induc ed by urocortin was more potent than that induced by CRF or urocortin OH. T he ranking potency was urocortin > urocortin OH > CRF. Urocortin significan tly reduced oxygen consumption in ob/ob mice as well as in lean mice. These results suggest that urocortin decreases oxygen consumption, and that the CRF type 2 receptor may influence energy balance in lean and ob/ob mice.