不同环境温度对精氨酸加压素引起的大鼠低温的影响及其与尾部散热变化的关系

 目的：探讨不同环境温度对精氨酸加压素（AVP）引起的大鼠低温及其与尾部散热变化的关系，以确定是否外周给予AVP能提高大鼠尾部散热反应。方法：实验用成年雄性SD大鼠，在3种不同环境温度（12 ℃、22 ℃和32 ℃）下，用无线遥测技术连续记录体核温度和尾部皮肤温度。上午10:00给大鼠腹腔注射AVP(10 μg/kg)或V1a受体阻断剂(30 μg/kg)。同时观察AVP或V1a受体阻断剂对大鼠背斜方肌微血管直径和理毛行为的影响。结果：(1)在3种不同环境温度中，AVP引起大鼠低温均伴有尾部皮肤温度降低反应。(2) V1a受体阻断剂能够阻断AVP引起低温和尾部皮肤温度降低效应。(3)AVP能明显引起背斜方肌微血管收缩反应。(4)AVP能提高大鼠的理毛行为(唾液理毛)，而且这种作用也能被外周给予V1a受体阻断剂所阻断。(5)内源性AVP不参与正常大鼠尾部散热过程。结论：外周给予AVP引起大鼠低温，不是由于其降低了体温调定点，可能是由于其抑制了体温调节性产热和提高唾液理毛活动以增加体表蒸发散热所致。

Effect of different ambient temperatures on arginine vasopressin-induced hypothermia in rats and its relationship with heat loss from the tail

AIM：To determine the effect of different ambient temperatures on arginine vasopressin (AVP)-induced hypothermia in rats and its relationship with the change of heat loss from the tail, and to assess if peripheral AVP administration increases heat loss from the tail. METHODS：The core temperature and tail skin temperature in adult male Sprague-Dawley rats at three different ambient temperatures (12 ℃, 22 ℃ and 32 ℃) were monitored by wireless telemetry. The rats were intraperitoneally injected with AVP (10 μg/kg) or vasopressin V1a receptor antagonist (30 μg/kg) at 10:00 AM. The diameters of microvessels in the spinotrapezius muscle and the grooming behavior in the rats were also observed after treatment with AVP or vasopressin V1a receptor antagonist. RESULTS：AVP-induced hypothermia in the rats at three ambient temperatures was accompanied by a decrease in tail skin temperature. V1a receptor antagonist attenuated the hypothermia and the decrease in tail skin temperature induced by AVP (10 μg/kg). AVP induced significant constriction of the microvessels in the spinotrapezius muscle. AVP also enhanced the grooming behavior (salivary grooming) in the rats and this effect was inhibited by peripheral administration of vasopressin V1a receptor antagonist. Endogenous AVP did not mediate the heat loss from the tail in normal rats. CONCLUSION：Peripheral AVP induces hypothermia in rats. It does not lower the set point of body temperature, and its hypothermic effect may attribute to the suppression of thermoregulatory heat production and the increase in salivary grooming (saliva spreading for evaporative heat loss).