Osmolyte Depletion and Thirst Suppression Allow Hibernators to Survive for Months without Water
Osmolyte Depletion and Thirst Suppression Allow Hibernators to Survive for Months without Water
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DOI：
10.1016/j.cub.2019.07.038
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发表时间：
2019-09-23
期刊：
影响因子：
9.2
通讯作者：
Gracheva, Elena O.
中科院分区：
文献类型：
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作者：
Feng, Ni Y.;Junkins, Madeleine S.;Gracheva, Elena O.
十三线地松鼠（lctidomys tridecem-lineatus）是一种强制性的冬眠动物，一年中可以在地下洞穴或实验室冬眠室中存活超过6个月，而无需获得食物或水[1]。冬眠包括长时间的昏睡，持续长达18天，其特征是体温低和代谢受抑制。这种麻木状态伴随着短暂的间歇性觉醒，持续长达48小时，在此期间，松鼠暂时恢复到活跃状态，并因排尿和蒸发而失去少量水分[2]。由于身体的温度略高于周围环境而产生的正蒸汽压差，水分也会在休眠期间损失[2，3]。在这里，我们调查的生理机制，在长期失水和剥夺整个冬眠期间的生存。通过测量冬眠期间的水合状态，我们表明，松鼠保持水合在休眠期间消耗细胞外液中的渗透压。在短暂的觉醒期间，血清渗透压和抗利尿激素水平恢复，但口渴仍然受到抑制。这种口渴和利尿的分离使肾脏能够保持水分，同时抑制离开地下洞穴寻找水的安全性。血清渗透压的急剧增加恢复了找水行为，表明在冬眠期间生理口渴回路的保存。对内部渗透调节和口渴抑制的更好的机械理解可以转化为人类医学和长期载人航天的进步。
Thirteen-lined ground squirrels (lctidomys tridecem-lineatus) are obligatory hibernators who can survive over 6 months of the year in underground burrows or laboratory hibernaculum without access to food or water [1]. Hibernation consists of prolonged periods of torpor, lasting up to 18 days, which are characterized by low body temperature and suppressed metabolism. This torpidity is interspersed with short periods of interbout arousal, lasting up to 48 h, during which squirrels temporarily return to an active-like state and lose small amounts of water to urination and evaporation [2]. Water is also lost during torpor due to a positive vapor pressure difference created by the slightly higher temperature of the body compared to its surroundings [2, 3]. Here, we investigate the physiological mechanism of survival during prolonged water loss and deprivation throughout hibernation. By measuring hydration status during hibernation, we show that squirrels remain hydrated during torpor by depleting osmolytes from the extracellular fluid. During brief periods of arousal, serum osmolality and antidiuretic hormone levels are restored, but thirst remains suppressed. This decoupling of thirst and diuresis enables water retention by the kidney while suppressing the drive to leave the safety of the underground burrow in search of water. An acute increase in serum osmolality reinstates water-seeking behavior, demonstrating preservation of the physiological thirst circuit during hibernation. Better mechanistic understanding of internal osmolyte regulation and thirst suppression could translate to advancements in human medicine and long-term manned spaceflight.