White mice are ubiquitous laboratory animals and have been extensively studied. To reveal potential undiscovered traits, we tested the hypothesis that during development, when heat loss in mouse pups is high, they can use daily torpor for energy conservation. We determined at what age individual mouse pups are able to defend their body temperature at room temperature (ambient temperature, T a = 20 °C) and whether they could use torpor from that time. Initially at 5/6 days (body mass, BM ~ 3 g), still naked mice cooled rapidly. In contrast, at ~ 14 days (BM ~ 6 g), they could maintain a high, constant body temperature and, therefore, had reached competent endothermy. These mouse pups at ~ 20% of adult BM were able to enter into and arouse from torpor as determined via the rate of oxygen consumption; this was the case for both individuals that were exposed to a cooling regime as well as those that were not. During torpor, metabolism fell by up to > 90% and torpor lasted for up to 12 h. As mice grew, torpor was still used but was less pronounced. Our study shows that although the physiology of laboratory mice has been widely examined, their functional capabilities have still not been fully revealed, which has implications for biomedicine. Our and other developmental data suggest that because torpor is so efficient in conserving energy, it is likely to be used during the growth phase by diverse mammals and birds to survive energetic and thermal challenges.

中文翻译：

---

白鼠幼崽可以利用麻木来节约能源

白鼠是无处不在的实验动物，并已被广泛研究。为了揭示潜在的未被发现的特征，我们测试了这样一个假设：在发育过程中，当小鼠幼崽的热量损失很高时，它们可以每天使用麻木来节省能量。我们确定了个体小鼠幼崽在室温（环境温度，T a = 20 °C）下能够保持体温的年龄，以及从那时起它们是否可以使用麻木。最初在 5/6 天（体重，BM ~ 3 g）时，仍然裸露的小鼠迅速冷却。相比之下，在 ~ 14 天（BM ~ 6 克）时，它们可以保持较高的恒定体温，因此达到了良好的吸热状态。根据耗氧率确定，这些处于成年 BM 约 20% 的小鼠幼崽能够进入麻木并从麻木中醒来；暴露于冷却方案的人和未暴露于冷却方案的人都是这种情况。在麻木期间，新陈代谢下降高达 > 90%，并且麻木持续长达 12 小时。随着小鼠的长大，仍然使用麻木，但不那么明显。我们的研究表明，尽管实验室小鼠的生理学已被广泛研究，但其功能能力仍未完全揭示，这对生物医学具有重要意义。我们和其他发育数据表明，由于麻木在节能方面非常有效，因此很可能在生长阶段被不同的哺乳动物和鸟类用于在能量和热挑战中生存。麻木仍然被使用，但不那么明显。我们的研究表明，尽管实验室小鼠的生理学已被广泛研究，但其功能能力仍未完全揭示，这对生物医学具有重要意义。我们和其他发育数据表明，由于麻木在节能方面非常有效，因此很可能在生长阶段被不同的哺乳动物和鸟类用于在能量和热挑战中生存。麻木仍然被使用，但不那么明显。我们的研究表明，尽管实验室小鼠的生理学已被广泛研究，但其功能能力仍未完全揭示，这对生物医学具有重要意义。我们和其他发育数据表明，由于麻木在节能方面非常有效，因此很可能在生长阶段被不同的哺乳动物和鸟类用于在能量和热挑战中生存。