Rajaratnam S M, Redman J R
Department of Psychology, Monash University, Clayton, Victoria, Australia.
Physiol Behav. 1998 Jan;63(2):271-7. doi: 10.1016/s0031-9384(97)00440-x.
Ambient temperature cycles entrain circadian rhythms of homeotherms. The phase that entrainment occurs at varies, particularly in diurnal species. We investigated whether ambient temperature cycles of 12 h warm (34 to 40 degrees C) and 12 h cool (24 to 28 degrees C) entrained locomotor activity rhythms of diurnal Indian palm squirrels (Funambulus pennanti) that were free-running in constant dim light (3.2 to 7.6 lux). Seven female squirrels were exposed to the temperature cycle for 21 days, after which a 5-h phase delay of the cycle was imposed. The cycle then continued for a further 50 days. Three of the seven squirrels showed entrainment to the temperature cycle. Of the three which entrained, one was warm-active and two were cool-active. Of the remaining squirrels, two showed entrainment or relative coordination of one component of the rhythm, and two did not show any entrainment. Positive and negative masking of activity by the warm and cool fractions were observed regardless of whether or not squirrels entrained. These results suggest that ambient temperature is an effective zeitgeber for F. pennanti. As has been reported for other diurnal species, interindividual differences exist in the phase of entrainment to temperature cycles.
环境温度循环可调节恒温动物的昼夜节律。发生调节的阶段各不相同，尤其是在昼行性物种中。我们研究了12小时温暖（34至40摄氏度）和12小时凉爽（24至28摄氏度）的环境温度循环是否能调节在恒定弱光（3.2至7.6勒克斯）下自由活动的昼行性印度棕榈松鼠（Funambulus pennanti）的运动活动节律。七只雌性松鼠暴露于温度循环21天，之后对循环进行5小时的相位延迟。然后循环再持续50天。七只松鼠中有三只表现出对温度循环的调节。在这三只调节的松鼠中，一只在温暖时段活跃，两只在凉爽时段活跃。在其余的松鼠中，两只表现出对节律的一个组成部分的调节或相对协调，两只没有表现出任何调节。无论松鼠是否调节，都观察到温暖和凉爽时段对活动的正向和负向掩盖。这些结果表明环境温度是印度棕榈松鼠的有效授时因子。正如已报道的其他昼行性物种一样，在对温度循环的调节阶段存在个体差异。
