Tu Longlong, Poppi Lauren, Rudd John, Cresswell Ethan T, Smith Doug W, Brichta Alan, Nalivaiko Eugene
School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, NSW, Australia.
Physiol Behav. 2017 May 15;174:114-119. doi: 10.1016/j.physbeh.2017.03.012. Epub 2017 Mar 14.
Hypothermic responses accompany motion sickness in humans and can be elicited by provocative motion in rats. We aimed to determine the potential role in these responses of the efferent cholinergic vestibular innervation. To this end, we used knockout (KO) mice lacking α9 cholinoreceptor subunit predominantly expressed in the vestibular hair cells and CBA strain as a wild-type (WT) control. In WT mice, circular horizontal motion (1Hz, 4cm radius, 20min) caused rapid and dramatic falls in core body temperature and surface head temperature associated with a transient rise in the tail temperature; these responses were substantially attenuated in KO mice; changes were (WT vs. KO): for the core body temperature-5.2±0.3 vs. -2.9±0.3°C; for the head skin temperature-3.3±0.2 vs. -1.7±0.2°C; for the tail skin temperature+3.9±1.1 vs+1.1±1.2°C. There was a close correlation in the time course of cooling the body and the surface of the head. KO mice also required 25% more time to complete a balance test. We conclude: i) that the integrity of cholinergic efferent vestibular system is essential for the full expression of motion-induced hypothermia in mice, and that the role of this system is likely facilitatory; ii) that the system is involvement in control of balance, but the involvement is not major; iii) that in mice, motion-induced body cooling is mediated via increased heat flow through vasodilated tail vasculature and (likely) via reduced thermogenesis. Our results support the idea that hypothermia is a biological correlate of a nausea-like state in animals.
体温过低反应伴随着人类的晕动病，并且可由大鼠的诱发运动引起。我们旨在确定传出胆碱能前庭神经支配在这些反应中的潜在作用。为此，我们使用了敲除（KO）小鼠，其缺乏主要在前庭毛细胞中表达的α9胆碱能受体亚基，并使用CBA品系作为野生型（WT）对照。在野生型小鼠中，圆周水平运动（1Hz，4cm半径，20分钟）导致核心体温和头部表面温度迅速且显著下降，同时尾巴温度短暂升高；这些反应在敲除小鼠中显著减弱；变化情况如下（野生型与敲除小鼠相比）：核心体温为-5.2±0.3℃ 对 -2.9±0.3℃；头部皮肤温度为-3.3±0.2℃ 对 -1.7±0.2℃；尾巴皮肤温度为+3.9±1.1℃ 对 +1.1±1.2℃。身体和头部表面冷却的时间进程密切相关。敲除小鼠完成平衡测试所需的时间也多25%。我们得出以下结论：i）胆碱能传出前庭系统的完整性对于小鼠运动诱发的体温过低的充分表现至关重要，并且该系统的作用可能是促进性的；ii）该系统参与平衡控制，但参与程度不大；iii）在小鼠中，运动诱发的身体冷却通过扩张的尾巴血管增加热流以及（可能）通过减少产热来介导。我们的结果支持体温过低是动物中类似恶心状态的生物学关联这一观点。
