Physiological roles of corticotropin-releasing hormone receptor type 2

Recent investigations of the physiological roles of CRH-R2 are reviewed and summarized in Fig. 5. VMH CRH-R2 is more important than CRH-R1 in mediating anorexic effect of CRH or urocortin (UCN) and stress-induced reduction of food intake. CRH-R2 mediates a central anxiolytic response, opposing the anxiogenic effect of CRH mediated by CRH-R1. Hippocampal CRH-R1 mediates stress-induced enhancement of learning, while CRH-R2 in the lateral intermediate septum may act to impair learning. CRH-R1 mediates CRH-induced blood pressure elevation, while peripheral CRH-R2 mediates the hypotensive effect of systemically administered UCN and CRH. It is likely that CRH-R2 does not play an important role in hypothalamic-pituitary adrenal axis regulation, though it has been reported that CRH-R2-deficient mice showed hyperresponse of ACTH and corticosterone. Peripheral CRH-R2 mediates UCN-induced mast cell degranulation, vascular permeability, and abdominal surgery-induced gastric stasis. These recent investigations have revealed that the existence of two CRH receptors, which mediate some opposite effects, provides the CRH and UCN systems a high flexibility and dynamic role in the adaptation of the body to environmental challenge.