Body water balance and body temperature in vasopressin V1b receptor knockout mice

Abstract In an attempt to determine whether there is a specific vasopressin receptor (V 1b ) subtype involved in the regulation of body water balance and temperature, vasopressin V 1b receptor knockout mice were used. Daily drinking behavior and renal excretory function were examined in V 1b -deficient (V 1b −/− ) and control (V 1b +/+ ) mice under the basal and stress-induced condition. In addition, body temperature and locomotor activity were measured with a biotelemetry system. The baseline daily water intake and urine volume were larger in V 1b −/− mice than in V 1b +/+ mice. V 1b −/− mice (V 1b −/− ) had significantly higher locomotor activity than wild-type, whereas the body temperature and oxygen consumption were lower in V 1b −/− than in the V 1b +/+ mice. Next, the V 1b −/− and V 1b +/+ mice were subjected to water deprivation for 48 hr. Under this condition, their body temperature decreased with the time course, which was significantly larger for V 1b −/− than for V 1b +/+ mice. Central vasopressin has been reported to elicit drinking behavior and antipyretic action, and the V 1b receptor has been reported to be located in the kidney. Thus, the findings suggest that the V 1b receptor may be, at least in part, involved in body water balance and body temperature regulation.