Effects of exercise and cold exposure on branched-chain amino acids catabolism

寒冷暴露的压力增加了蛋白质作为能量的利用。运动训练还能促进骨骼肌中的蛋白质降解，增加其氨基酸分解代谢。因此，与舒适条件下的运动相比，在寒冷条件下的运动中蛋白质的消耗更大，并且可能会损伤重要的运动肌肉。我们研究了运动训练和冷暴露应激对大鼠骨骼肌中支链α-酮酸脱氢酶（BCKD）活性的影响，BCKD是支链氨基酸（BCAAs）分解代谢的限速酶。大鼠骨骼肌BCKD的总活动和活动状态（实际活动/总活动）通过3周的冷暴露运动训练显著升高。上述结果提示，3周的冷暴露运动训练不仅能提高大鼠骨骼肌在静息状态下的支链氨基酸分解代谢，还能提高运动时的分解代谢能力。此外，冷暴露3周显著抑制体重增加。但在寒冷环境下进行3周的运动训练可以改善体重增长的停滞。

The stress of cold exposure increases utilization of protein for energy. Exercise training also promotes protein degradation in skeletal muscle and increases its amino acids catabolism. Therefore, protein consumption in cold-condition sports is greater compared to that in comfortable-condition sports, and the important muscles for performance may be damaged. We examined the effects of exercise training and the stress of cold exposure on a branched-chain α-keto acid dehydrogenase (BCKD) activity in rat skeletal muscle, which is the rate-limiting enzyme of branched-chain amino acids (BCAAs) catabolism. Total activity and activity state (actual activity / total activity) of BCKD in rat skeletal muscle were significantly elevated by exercise training in cold exposure for 3 weeks. These results suggest that exercise training in cold exposure for 3 weeks enhances not only BCAAs catabolism under the resting condition but also the capacity for catabolism during exercise in rat skeletal muscle. In addition, cold exposure for 3 weeks significantly inhibited weight gain. But exercise training in cold exposure 3 weeks led to improve the stagnation of weight gain.