Bcaa Alleviates Rats Skeletal Muscle Protein Degradation After Eccentric Exercise By Reducing KLF15 Expression

Abstract

PURPOSE: Exercise-induced muscle damage after high-intensity eccentric exercise can lead to degradation of skeletal muscle protein, thereby affecting the training effect. The purpose of this study is to explore the effect of branched-chain amino acid (BCAA) supplementation on muscle damage caused by one-time eccentric exercise, and the regulation of KLF15-mediated proteolytic pathways in the process. METHODS: 64 male SD rats were randomly divided into eight groups: placebo + control group (PC, n = 8), placebo + immediately after exercise group (PE, n = 8), placebo +6 h after exercise group (PE6, n = 8), placebo +12 h after exercise group (PE12, n = 8), BCAA + control group (BC, n = 8), BCAA + immediately after exercise group (BE, n = 8), BCAA +6 h after exercise group (BE6, n = 8), BCAA +12 h after exercise group (BE12, n = 8). Rats in BCAA groups were supplied BCAA (1 g/kg/day) 3 times before exercise. The placebo groups were supplied the same volume of distilled water. Rats in exercise groups underwent a bout of 2 h eccentric exercise on treadmill (-16° slope, a speed of 16 m/min). Blood and gastrocnemius were collected immediately after exercise in PE and BE, 6 h after exercise in PE6 and BE6, and 12 h after exercise in PE12 and BE12. The expression of 3-MH in blood was detected by ELISA. RT-qPCR was used to measure the mRNA expression of KLF15, Atrogin-1, MuRF-1 and MHC-II in gastrocnemius. RESULTS: The mRNA expression of MHC-II (P < 0.05), KLF15 (P < 0.05), Atrogin-1 (P < 0.05), MuRF-1 (P < 0.01) in PE were higher than those in PC, MHC-II (P < 0.05) in PE6 and Atrogin-1 (P < 0.05) in PE12 were higher than in PC. MHC-II (P < 0.05) was higher in BE6 than in BE. Compared with PE, the mRNA expression of KLF15 (P < 0.01), Atrogin-1(P < 0.05), MuRF-1 (P < 0.01) in BE were significantly lower, Atrogin-1 (P < 0.05) in BE12 was lower than that in PE12. 3-MH (P < 0.05) content was higher in PE12 than in PC, 3-MH (P < 0.01) content was lower in BE and BE6 than in BC, 3-MH (P < 0.01) content was higher in BC than in PC. CONCLUSIONS: BCAA may reduce skeletal muscle proteolysis by lowering the level of gene transcription in the KLF15-related protein degradation pathway, which occurs immediately after exercise.