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

In an attempt to determine whether there is a specific vasopressin receptor (V1b) subtype involved in the regulation of body water balance and temperature, vasopressin V1b receptor knockout mice were used. Daily drinking behavior and renal excretory function were examined in V1b-deficient (V1b−/−) and control (V1b+/+) 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 V1b−/− mice than in V1b+/+ mice. V1b−/− mice (V1b−/−) had significantly higher locomotor activity than wild-type, whereas the body temperature and oxygen consumption were lower in V1b−/− than in the V1b+/+ mice. Next, the V1b−/− and V1b+/+ 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 V1b−/− than for V1b+/+ mice. Central vasopressin has been reported to elicit drinking behavior and antipyretic action, and the V1b receptor has been reported to be located in the kidney. Thus, the findings suggest that the V1b receptor may be, at least in part, involved in body water balance and body temperature regulation.