Analysis of changes in body temperature rhythm during fasting

众所周知，体温（T_b）遵循昼夜节律。尽管近年来对体温调节的了解有所进展，但我们对T_b节律的机制知之甚少。在本次研讨会上，我们展示了几个证据，证明i)昼夜节律的主要机制是根据昼夜节律阶段改变体温调节过程的特征，ii)时钟基因和视交叉上核参与了这一机制。禁食期间的T_b节律。在随机喂养大鼠中，T_b节律与产热节律相关。反映主动热损失的尾表面温度也随T_b节律线性变化。因此，我们认为热的产生是决定供气条件下T_b节律的主要因素。禁食3天后，虽然产热减少，昼夜节律幅度变钝，但T_b节律得到很好的维持。此外，在活性阶段，尾部温度大幅下降。这些结果表明，动物通过调节体温调节反应来控制其昼夜T_b节律，这取决于饲养和/或营养状态。

It is well known that body temperature (T_b) follows a circadian rhythm. Despite recent advance in knowledge of thermoregulation, we know only a little about the mechanism of the T_b rhythm. In this symposium, we show several evidences proving that i) the prime mechanism for the circadian T_b rhythm is a change in characteristics of thermoregulatory processes according to circadian phases, ii) clock genes and the suprachiasmatic nucleus are involved in the mechanism.T_b rhythm during fasting. In ad-lib feeding rats, T_b rhythm was linked with heat production rhythm. Moreover, tail surface temperature reflecting active heat loss also changed linearly with the T_b rhythm. Thus it is thought that heat production dominantly determines the T_b rhythm in fed condition. Although heat production decreased and its circadian amplitude was blunted during 3-day fasting, the T_b rhythm was well maintained. Moreover, the tail temperature decreased greatly in the active phase. These results suggest that animals control their circadian T_b rhythm by modulating thermoregulatory responses, which depends on feeding and/or nutritional states.