Pan Qian, Li Min, Shi Yao-Long, Liu Huwei, Speakman John R, Wang De-Hua
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beichen Xilu, Chaoyang, Beijing, 100101, China.
Lipids. 2014 Jul;49(7):715-30. doi: 10.1007/s11745-014-3900-0. Epub 2014 May 7.
Mongolian gerbils (Meriones unguiculatus) have high physiological flexibility in response to acute temperature changes, and have the widest thermoneutral zone (TNZ, 26.5-38.9 °C) reported among small mammals. At the upper critical temperature (T(uc), 38.9 °C), body temperatures of gerbils were significantly increased (39-41 °C) while metabolic rates were maintained at the basal level. In contrast, below the lower critical temperature (T(lc), 26.5 °C), metabolism was elevated and body temperature stable. Rapid changes in mitochondrial membrane lipidome were hypothesized to play an important role during acute thermoregulation of gerbils. Taking advantage of a recent lipidomic technique, we examined changes in the membrane phospholipids environment and free fatty acids (FFA) production in mitochondria between 38 and 27 °C (in the TNZ), and between 27 and 16 °C (below the TNZ). At 38 °C, acute heat stress elicited distinct remodeling in mitochondrial membrane lipidome which related to a potential decrease in mitochondrial respiration and membrane fluidity compared to 27 °C. At 16 °C, a sharply decreased unsaturation index and increased chain lengths were detected in mitochondrial FFA production both in muscle and brown adipose tissue. Our results suggest that mitochondrial membrane lipid remodeling may stabilize membrane function and activity of respiration related membrane protein to maintain a stable metabolic rate at T(uc), and improve heat production by decomposing less fluid fatty acid conjugates of membrane lipids under acute cold exposure. These data therefore imply an important role of membrane remodeling during acute thermoregulation in a non-hibernating endotherm.
蒙古沙鼠（长爪沙鼠）对急性温度变化具有很高的生理适应性，并且在小型哺乳动物中拥有报道中最宽的热中性区（TNZ，26.5 - 38.9℃）。在临界高温（T(uc)，38.9℃）时，沙鼠的体温显著升高（39 - 41℃），而代谢率维持在基础水平。相反，在临界低温（T(lc)，26.5℃）以下，代谢率升高且体温保持稳定。据推测，线粒体膜脂质组的快速变化在沙鼠的急性体温调节过程中发挥重要作用。利用最近的脂质组学技术，我们检测了线粒体膜磷脂环境和游离脂肪酸（FFA）生成在38℃和27℃（在热中性区内）之间以及27℃和16℃（低于热中性区）之间的变化。在38℃时，急性热应激引发线粒体膜脂质组的明显重塑，与27℃相比，这与线粒体呼吸和膜流动性的潜在降低有关。在16℃时，在肌肉和棕色脂肪组织的线粒体FFA生成中均检测到不饱和度指数急剧下降和链长度增加。我们的结果表明，线粒体膜脂质重塑可能稳定膜功能以及呼吸相关膜蛋白的活性，从而在临界高温时维持稳定的代谢率，并在急性冷暴露下通过分解膜脂质中流动性较小的脂肪酸共轭物来提高产热。因此，这些数据表明膜重塑在非冬眠恒温动物的急性体温调节中起重要作用。
