Effect of AVP V1-receptor antagonist on normal body temperature in rats under light-dark cycle

AIM: To assess if endogenous arginine vasopressin is involved in normal thermoregulatory processes. METHODS: Core temperature was monitored in undisturbed rats using radiotelemetry. Effect of AVP V₁ antagonist on normal body temperature were observed in rats under a 12:12 light-dark cycle. RESULTS: Intraperitoneal injection of AVP V₁-receptor antagonist in rats induced a increase in normal body temperature. Under normal light (light on at 6:00 AM-6:00 PM), AVP V₁ antagonist induced a increase in body temperature persisting for about 6 hour, but male rats had higher hyperthermia than female. Under normal dark exposure (light off at 6:00 PM-6:00 AM), AVP V₁-receptor antagonist caused a increase in body temperature persisting for about 2 hour at the start of the dark phase, but no difference was found between sexes. CONCLUSION: Intraperitoneal injection of AVP V₁-receptor antagonist caused a increase in normal body temperature. The data indicated that endogenous vasopressin could be involved in tonic thermoregulatory process.