Pálková M, Sigmund L, Erkert H G
Department of Zoology, Faculty of Sciences, Charles University, Prague 2, Czech Republic.
Chronobiol Int. 1999 Mar;16(2):149-61. doi: 10.3109/07420529909019082.
Whereas the (zeitgeber) effect of ambient temperature Ta and temperature cycles TaC's on circadian rhythmicity has been well documented for heterothermic mammals, inconsistent results have been obtained for strictly homeothermic species. Hence, it might be inferred that the susceptibility of the mammalian circadian timing system (CTS) to Ta and TaC's depends on the range of the animals' core and/or brain temperature rhythm. This hypothesis was tested in the common marmoset (Callithrix j. jacchus, n = 12), a small diurnal primate with an amplitude in body temperature rhythm that is larger than for other homeothermic primates studied so far. Within the range 20-30 degrees C, no systematic effects of constant Ta on most parameters of the marmosets' light-dark (LD)-entrained and free-running circadian activity rhythm (CAR) were found. Significant differences could be established in the average amount of activity per circadian cycle. It was highest at Ta 25 degrees C (LD) and 20 degrees C (light-light, LL) and most probably reflected a temperature-induced masking effect. A 24 h trapezoidal TaC of 20:30 degrees C entrained the free-running CAR in two of six marmosets and produced relative coordination in all others. Accordingly, in all animals tested, it had an effect on the CTS. In marmosets free running in LL at a Ta of 20 degrees C or 30 degrees C, 3 h warm and cold pulses of 30 degrees C and 20 degrees C, respectively, produced neither systematic phase responses nor period responses of the CAR. So, there is no evidence of a phase-response mechanism underlying circadian entrainment. The results show that large-amplitude TaC's function as a weak zeitgeber for the marmosets' CTS. Since this zeitgeber effect is significantly larger than that found in owl monkeys, the results are consistent with the starting hypothesis that the zeitgeber effect of a given TaC on the mammalian CTS may be related to the amplitude of the species' core and/or brain temperature cycle.
尽管环境温度Ta和温度循环TaC对变温哺乳动物昼夜节律性的（授时因子）影响已有充分记录，但对于严格的恒温物种，结果却不一致。因此，可以推断哺乳动物昼夜节律计时系统（CTS）对Ta和TaC的敏感性取决于动物核心体温和/或脑温节律的范围。本假设在普通狨猴（Callithrix j. jacchus，n = 12）中进行了测试，普通狨猴是一种小型昼行性灵长类动物，其体温节律的振幅比迄今研究的其他恒温灵长类动物都要大。在20 - 30摄氏度范围内，未发现恒定Ta对狨猴明暗（LD）同步和自由运行的昼夜活动节律（CAR）的大多数参数有系统性影响。在每个昼夜周期的平均活动量上可确定显著差异。在Ta 25摄氏度（LD）和20摄氏度（光 - 光，LL）时最高，很可能反映了温度诱导的掩盖效应。20:30摄氏度的24小时梯形TaC使六只狨猴中的两只的自由运行CAR同步，并在其他所有狨猴中产生了相对协调。因此，在所有测试动物中，它对CTS有影响。在20摄氏度或30摄氏度的Ta下于LL中自由运行的狨猴中，分别为30摄氏度和20摄氏度的3小时温热和冷脉冲既未产生CAR的系统性相位响应也未产生周期响应。所以，没有证据表明昼夜节律同步存在相位响应机制。结果表明，大幅度的TaC对狨猴的CTS起到了较弱的授时因子作用。由于这种授时因子效应明显大于夜猴中的效应，结果与最初的假设一致，即给定TaC对哺乳动物CTS的授时因子效应可能与该物种核心体温和/或脑温周期的振幅有关。
