Voluntary wheel running is beneficial to the amino acid profile of lysine-deficient rats
Voluntary wheel running is beneficial to the amino acid profile of lysine-deficient rats
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DOI：
10.1152/ajpendo.00763.2009
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发表时间：
2010-06-01
影响因子：
5.1
通讯作者：
Takahashi，Michio
中科院分区：
文献类型：
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作者：
Nagao，Kenji;Bannai，Makoto;Takahashi，Michio
当笼子里装有跑轮时，老鼠每晚会自愿跑十几公里。人们普遍认为每天自愿跑步可以提高蛋白质周转率。因此，我们试图确定跑步是否会恶化或改善由缺乏赖氨酸的饮食引起的蛋白质降解，以及它是否会改变蛋白质水解释放的游离氨基酸的利用。给大鼠喂食缺乏赖氨酸的饮食，并让其自由使用跑轮或保持静坐（对照）4 周。血浆、肌肉和肝脏中的氨基酸水平以及血浆胰岛素水平和组织重量一起被测量。缺乏赖氨酸的饮食会导致厌食、骨骼肌损失、丝氨酸和苏氨酸血症，并耗尽血浆胰岛素和骨骼肌中的必需氨基酸。让老鼠自愿奔跑可以改善这些症状；因此，自愿跑轮使老鼠不易受到膳食赖氨酸缺乏的影响。在跑步大鼠中观察到的肌肉亮氨酸和血浆胰岛素下降的改善可能有助于蛋白质合成以及骨骼肌中赖氨酸和其他必需氨基酸的可用性的增强。这些结果表明，在赖氨酸缺乏的条件下自愿轮运行不会增强蛋白质分解代谢；相反，它会加速蛋白质合成，有助于维持肌肉质量。啮齿动物特有的强烈的夜间自愿奔跑可能是缺乏赖氨酸的谷物食者的一种适应，这使它们能够最大限度地获取食物的机会。
Rats voluntarily run up to a dozen kilometers per night when their cages are equipped with a running wheel. Daily voluntary running is generally thought to enhance protein turnover. Thus, we sought to determine whether running worsens or improves protein degradation caused by a lysine-deficient diet and whether it changes the utilization of free amino acids released by proteolysis. Rats were fed a lysine-deficient diet and were given free access to a running wheel or remained sedentary (control) for 4 wk. Amino acid levels in plasma, muscle, and liver were measured together with plasma insulin levels and tissue weight. The lysine-deficient diet induced anorexia, skeletal muscle loss, and serine and threonine aminoacidemia, and it depleted plasma insulin and essential amino acids in skeletal muscle. Allowing rats to run voluntarily improved these symptoms; thus, voluntary wheel running made the rats less susceptible to dietary lysine deficiency. Amelioration of the declines in muscular leucine and plasma insulin observed in running rats could contribute to protein synthesis together with the enhanced availability of lysine and other essential amino acids in skeletal muscle. These results indicate that voluntary wheel running under lysine-deficient conditions does not enhance protein catabolism; on the contrary, it accelerates protein synthesis and contributes to the maintenance of muscle mass. The intense nocturnal voluntary running that characterizes rodents might be an adaptation of lysine-deficient grain eaters that allows them to maximize opportunities for food acquisition.