Extensive use of torpor in 13-lined ground squirrels in the fall prior to cold exposure.
Extensive use of torpor in 13-lined ground squirrels in the fall prior to cold exposure.
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DOI：
10.1007/s00360-010-0484-8
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发表时间：
2010-11
期刊：
影响因子：
--
通讯作者：
Martin SL
中科院分区：
文献类型：
--
作者：
Russell RL;O'Neill PH;Epperson LE;Martin SL
哺乳动物冬眠的特点是体温（Tb）和代谢率，心率和呼吸率的显著降低。这些减少是休眠的特征，休眠在时间上仅限于冬季。冬眠动物包括地松鼠在冬季是变温的，在低Tb的多天休眠期和短暂的复温期之间循环。与此相反，地松鼠在夏季保持恒温，就像非冬眠的哺乳动物一样。在冬眠研究中，冬眠年周期节律的恒温期和变温期之间的过渡往往被忽视。在这里，我们研究了在整个秋季过渡在实验室安置的13线地松鼠通过记录核心体温与植入的数据记录器的麻木使用。作为典型的基于实验室的冬眠研究，动物被关在标准的住房之前，被移动到一个寒冷，黑暗的房间，以模拟自然的冬眠条件。值得注意的是，绝大多数雄性和雌性地松鼠在秋季表现出麻木，而在寒冷暴露之前仍然保持常规。迟钝的表达没有预测体重或年龄，而是它似乎是预先编程的时间依赖性的方式是独立的，但增强，环境线索。在冷暴露之前发生的这些麻痹发作的时间和持续时间也是非常零星的。因此，在没有连续测量体温的情况下，不可能确定地知道哪些动物在冷暴露前是torpor-naïve。我们的结论是，秋季动物包含冬眠年周期夏季和冬季之间过渡的可变点，从而混淆了将它们用作非冬眠对照的研究。相反，这些秋季过渡动物提供了独特的机会来定义伴随和实现冬眠的分子变化。
Mammalian hibernation is characterized by profound reductions in body temperature (Tb) and metabolic, heart and respiratory rates. These reductions are characteristic of torpor, which is temporally confined to winter. Hibernators including ground squirrels are heterothermic in winter, cycling between multiday periods of torpor with low Tb and brief periods of rewarming. In contrast, ground squirrels remain homeothermic during summer, like non-hibernating mammals. The transition between the homeothermic and heterothermic phases of the circannual rhythm of hibernation is often overlooked in hibernation studies. Here, we examined the use of torpor throughout the fall transition in laboratory-housed 13-lined ground squirrels by recording core body temperature with an implanted data logger. As is typical of laboratory-based hibernation studies, animals were kept in standard housing prior to being moved into a cold, dark room to simulate natural hibernation conditions. Significantly, the vast majority of both male and female ground squirrels expressed torpor in the fall while still housed conventionally and prior to cold exposure. The expression of torpor was not predicted by body weight or age, rather it appears to be preprogrammed in a time-dependent manner that is independent of, yet enhanced by, environmental cues. The timing and duration of these torpor bouts occurring prior to cold exposure were also remarkably sporadic. Thus it is not possible to know with certainty which animals are torpor-naïve before cold exposure in the absence of continuous measurement of body temperature. We conclude that fall animals encompass variable points in the transition between summer and winter phases of the circannual cycle of hibernation, thereby confounding studies in which they are used as non-hibernating controls. Conversely, these fall transition animals offer unique opportunities to define the molecular changes that accompany and enable hibernation.
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影响因子：
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作者：
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通讯作者：
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DOI：
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