Fukazawa Ayumi, Koike Atsuko, Karasawa Takuya, Tsutsui Momoko, Kondo Saki, Terada Shin
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan.
Nutrients. 2020 Apr 30;12(5):1269. doi: 10.3390/nu12051269.
Long-term intake of a ketogenic diet enhances utilization of ketone bodies, a particularly energy-efficient substrate, during exercise. However, physiological adaptation to an extremely low-carbohydrate diet has been shown to upregulate pyruvate dehydrogenase kinase 4 (PDK4, a negative regulator of glycolytic flux) content in skeletal muscle, resulting in impaired high-intensity exercise capacity. This study aimed to examine the effects of a long-term ketogenic diet containing medium-chain triglycerides (MCTs) on endurance training-induced adaptations in ketolytic and glycolytic enzymes of rat skeletal muscle. Male Sprague-Dawley rats were placed on either a standard diet (CON), a long-chain triglyceride-containing ketogenic diet (LKD), or an MCT-containing ketogenic diet (MKD). Half the rats in each group performed a 2-h swimming exercise, 5 days a week, for 8 weeks. Endurance training significantly increased 3-oxoacid CoA transferase (OXCT, a ketolytic enzyme) protein content in epitrochlearis muscle tissue, and MKD intake additively enhanced endurance training-induced increases in OXCT protein content. LKD consumption substantially increased muscle PDK4 protein level. However, such PDK4 increases were not observed in the MKD-fed rats. In conclusion, long-term intake of ketogenic diets containing MCTs may additively enhance endurance training-induced increases in ketolytic capacity in skeletal muscle without exerting inhibitory effects on carbohydrate metabolism.
长期摄入生酮饮食可提高运动期间酮体（一种特别节能的底物）的利用率。然而，已证明对极低碳水化合物饮食的生理适应会上调骨骼肌中丙酮酸脱氢酶激酶4（PDK4，糖酵解通量的负调节因子）的含量，从而导致高强度运动能力受损。本研究旨在探讨含中链甘油三酯（MCTs）的长期生酮饮食对大鼠骨骼肌酮解酶和糖酵解酶耐力训练诱导适应的影响。将雄性Sprague-Dawley大鼠分为标准饮食组（CON）、含长链甘油三酯的生酮饮食组（LKD）或含MCT的生酮饮食组（MKD）。每组一半的大鼠每周进行5天、每次2小时的游泳运动，持续8周。耐力训练显著增加了肱三头肌肌肉组织中3-氧代酸CoA转移酶（OXCT，一种酮解酶）的蛋白质含量，而摄入MKD可额外增强耐力训练诱导的OXCT蛋白质含量增加。摄入LKD可大幅提高肌肉PDK4蛋白水平。然而，在喂食MKD的大鼠中未观察到这种PDK4的增加。总之，长期摄入含MCT的生酮饮食可能会额外增强耐力训练诱导的骨骼肌酮解能力的增加，而不会对碳水化合物代谢产生抑制作用。
