Shido O, Sakurada S, Kohda W, Nagasaka T
Department of Physiology, School of Medicine, Kanazawa University, Japan.
Physiol Behav. 1994 May;55(5):935-9. doi: 10.1016/0031-9384(94)90082-5.
Male Wistar rats were divided into two groups. The controls (CN) were kept at a constant ambient temperature (Ta) of 24 degrees C throughout the experiment. Heat-acclimated rats (HA) were subjected to Ta of 33 degrees C in the last half of the dark phase for 16 consecutive days. After the schedule was terminated, hypothalamic temperature (Thy), oxygen consumption (VO2), heat loss, and feeding activity were measured for the following 2 days at Ta of 24 degrees C with a direct calorimeter in constant darkness. Hypothalamic temperature, VO2, and heat loss of the HA were significantly lower than those of the CN for 3-4 h during the period when the rats had been previously exposed to heat. Feeding activity during the specific period was significantly less in the HA than in the CN only on the first day. Under starved conditions, the decreases of Thy and VO2 during the previous heat exposure time were consistent in the HA. The results suggest that body core temperature and feeding behavior decrease during the previous heat exposure time in rats after subjection to repeated heat exposure at a fixed time daily. The characteristic fall in body core temperature is mainly attributed to the reduction of VO2. It also seems that a decrease in postprandial thermogenesis is not a predominant contributor to the depression of VO2 during the previous heat exposure time in heat-acclimated rats.
雄性Wistar大鼠被分为两组。对照组（CN）在整个实验过程中保持在24摄氏度的恒定环境温度（Ta）下。热适应大鼠（HA）在黑暗期的后半段连续16天暴露于33摄氏度的Ta下。在该实验安排结束后，在恒定黑暗环境中使用直接热量计，于24摄氏度的Ta下对下丘脑温度（Thy）、耗氧量（VO2）、热损失和进食活动进行接下来2天的测量。在大鼠先前暴露于热的时间段内，HA组的下丘脑温度、VO2和热损失在3 - 4小时内显著低于CN组。仅在第一天，HA组在特定时间段的进食活动显著少于CN组。在饥饿条件下，HA组在先前热暴露时间内Thy和VO2的下降是一致的。结果表明，在每天固定时间反复热暴露后，大鼠在先前热暴露时间内体温核心温度和进食行为会降低。体温核心温度的特征性下降主要归因于VO2的降低。似乎餐后产热的减少并不是热适应大鼠在先前热暴露时间内VO2降低的主要原因。
