Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, China.
Amino Acids. 2011 Nov;41(5):1185-93. doi: 10.1007/s00726-011-0983-2. Epub 2011 Jul 20.
Macronutrients, such as protein or amino acid, not only supply calories but some components may also play as signaling molecules to affect feeding behavior, energy balance, and fuel efficiency. Leucine, a branched-chain amino acid is a good example. After structural roles are satisfied, the ability of leucine to function as signal and oxidative substrate is based on a sufficient intracellular concentration. Therefore, leucine level must be sufficiently high to play the signaling and metabolic roles. Leucine is not only a substrate for protein synthesis of skeletal muscle, but also plays more roles beyond that. Leucine activates signaling factor of mammalian target of rapamycin (mTOR) to promote protein synthesis in skeletal muscle and in adipose tissue. It is also a major regulator of the mTOR sensitive response of food intake to high protein diet. Meanwhile, leucine regulates blood glucose level by promoting gluconeogenesis and aids in the retention of lean mass in a hypocaloric state. It is beneficial to animal nutrition and clinical application and extrapolation to humans.
宏量营养素，如蛋白质或氨基酸，不仅提供热量，而且某些成分还可以作为信号分子来影响摄食行为、能量平衡和燃料效率。亮氨酸就是一个很好的例子。在满足结构作用后，亮氨酸作为信号和氧化底物的能力基于足够的细胞内浓度。因此，亮氨酸水平必须足够高才能发挥信号和代谢作用。亮氨酸不仅是骨骼肌蛋白质合成的底物，而且还具有超出这一作用的更多功能。亮氨酸激活哺乳动物雷帕霉素靶蛋白（mTOR）的信号因子，促进骨骼肌和脂肪组织中的蛋白质合成。它还是 mTOR 对高蛋白饮食引起的食物摄入量敏感反应的主要调节剂。同时，亮氨酸通过促进糖异生来调节血糖水平，并有助于在低热量状态下保留瘦体重。它对动物营养和临床应用以及向人类的外推具有重要意义。
