Zhang Xue-Ying, Wang De-Hua
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
School of Life Sciences, Shandong University, Qingdao, China.
Front Physiol. 2022 Apr 11;13:888324. doi: 10.3389/fphys.2022.888324. eCollection 2022.
The endotherms, particularly the small mammals living in the polar region and temperate zone, are faced with extreme challenges for maintaining stable core body temperatures in harsh cold winter. The non-hibernating small mammals increase metabolic rate including obligatory thermogenesis (basal/resting metabolic rate, BMR/RMR) and regulatory thermogenesis (mainly nonshivering thermogenesis, NST, in brown adipose tissue and skeletal muscle) to maintain thermal homeostasis in cold conditions. A substantial amount of evidence indicates that the symbiotic gut microbiota are sensitive to air temperature, and play an important function in cold-induced thermoregulation, via bacterial metabolites and byproducts such as short-chain fatty acids and secondary bile acids. Cold signal is sensed by specific thermosensitive transient receptor potential channels (thermo-TRPs), and then norepinephrine (NE) is released from sympathetic nervous system (SNS) and thyroid hormones also increase to induce NST. Meanwhile, these neurotransmitters and hormones can regulate the diversity and compositions of the gut microbiota. Therefore, cold-induced NST is controlled by both Thermo-TRPs-SNS-gut microbiota axis and thyroid-gut microbiota axis. Besides physiological thermoregulation, small mammals also rely on behavioral regulation, such as huddling and coprophagy, to maintain energy and thermal homeostasis, and the gut microbial community is involved in these processes. The present review summarized the recent progress in the gut microbiota and host physiological and behavioral thermoregulation in small mammals for better understanding the evolution and adaption of holobionts (host and symbiotic microorganism). The coevolution of host-microorganism symbionts promotes individual survival, population maintenance, and species coexistence in the ecosystems with complicated, variable environments.
恒温动物，尤其是生活在极地地区和温带的小型哺乳动物，在严寒的冬季维持稳定的核心体温面临着极端挑战。非冬眠的小型哺乳动物会提高代谢率，包括 obligatory thermogenesis（基础/静息代谢率，BMR/RMR）和调节性产热（主要是棕色脂肪组织和骨骼肌中的非颤抖性产热，NST），以在寒冷条件下维持热稳态。大量证据表明，共生肠道微生物群对气温敏感，并通过细菌代谢产物和副产物（如短链脂肪酸和次级胆汁酸）在冷诱导的体温调节中发挥重要作用。冷信号由特定的热敏瞬时受体电位通道（thermo-TRPs）感知，然后去甲肾上腺素（NE）从交感神经系统（SNS）释放，甲状腺激素也会增加以诱导 NST。同时，这些神经递质和激素可以调节肠道微生物群的多样性和组成。因此，冷诱导的 NST 受 Thermo-TRPs-SNS-肠道微生物群轴和甲状腺-肠道微生物群轴的控制。除了生理体温调节外，小型哺乳动物还依靠行为调节，如聚堆和食粪行为，来维持能量和热稳态，肠道微生物群落也参与这些过程。本综述总结了小型哺乳动物肠道微生物群与宿主生理和行为体温调节的最新进展，以便更好地理解全生物（宿主和共生微生物）的进化和适应性。宿主-微生物共生体的共同进化促进了在复杂多变环境的生态系统中的个体生存、种群维持和物种共存。
