Effects Of BCAA Supplementation On NF-κB And Skeletal Muscle Protein Catabolism In Rats After A Bout Of Eccentric Exercise

Objective:Exercise induced muscle damage by high-intensity eccentric exercise can lead to increased protein catabolism,thus affecting athletic performance.Muscle protein catabolism in muscle atrophy is associated with NF-κB,based on the study to explore the relationship between NF-κB and protein degradation in gastrocnemius muscle after a single eccentric exercise,and the effects of BCAA supplementation on NF-κB and protein degradation,providing a theoretical basis for the effect of BCAA regulates protein metabolism.Method:Sixty-four 8-week-old SD rats(body weight of 236.7～270.6 g)were randomly divided into control group(32 rats)and BCAA group(32 rats)and given a strenuous downhill run(-16°,16m/min,120min),and BCAA(1g/kg)or control(distilled water)supplement before exercise.The samples were collected before exercise,immediately,6h and 12h after exercise.The morphology,serum concentrations of TNF-α and 3-MH,mRNA expression of NF-κB,Atrogin-1,MuRF-1 and protein expression of NF-κB of gastrocnemius muscle in each group was detected by HE,Elias,RT-PCR and Western Blot.Result:(1)A single eccentric exercise would change the shape of muscle fibers,the space between the muscle fibers becomes larger,the nucleus overflows,leading to EIMD;(2)After a single eccentric exercise,TNF-α levels in serum of control group were not significantly changed immediately,but the levels of NF-κB mRNA,MuRF-1 mRNA and atrogin-1 mRNA in gastrocnemius muscle of rats were in the trend of increasing,and the protein expression of NF-κB was in the trend of notable increasing,while the serum 3-MH levels were not significantly changed.TNF-α decreased significantly at 12h after exercise compared with immediately after exercise.The level of NF-κB mRNA in gastrocnemius was significantly increased at 6h and 12h after exercise,the level of atrogin-1 mRNA in gastrocnemius was significantly increased at 12h after exercise,the level of MuRF-1 mRNA was significantly decreased at 6h after exercise,the protein expression level of NF-κB was significantly increased at 12h after exercise,and the serum 3-MH was significantly increased at 12h after exercise.(3)The serum TNF-α of BCAA supplementation group did not change during the whole process of a single eccentric exercise.Compared with before exercise,there was no significant change of NF-κB mRNA in gastrocnemius muscle immediately after exercise.The expressions of atrogin-1 mRNA,MuRF-1 mRNA and NF-κB protein were increased,and the serum 3-MH was significantly decreased.Compared with immediately after exercise,the mRNA transcription level and protein expression of NF-κB decreased significantly at 6h and 12h after exercise,the mRNA levels of Atrogin-1 and MuRF-1 decreased significantly at 6h after exercise,and the concentration of 3-MH increased significantly at 12h after exercise.(4)Control group compared with BCAA group,BCAA group at 12 h after exercise TNF-α levels significantly higher than the control group,before exercise NF-κB mRNA transcription level higher than control group,compared with the control group,the concentration of Atrogin-1 mRNA decreased significantly at 12h and 6h after exercise.There was no significant difference in MuRF-1 mRNA at each time point.Immediately after exercise,the NF-κB protein expression of BCAA supplements is higher than the control group.Supplement of BCAA made the protein expression of NF-κ B in 12 h group was significantly lower than that in control group.Supplement of BCAA made 3-MH concentration was significantly higher than control group before exercise.Conclusion:(1)After a single eccentric exercise,the gene transcription and protein expression of NF-κB in skeletal muscle were both increased,and the expression of ubiquitin-related genes in skeletal muscle was increased.(2)BCAA supplementation before exercise increased the gene transcription and protein expression of NF-κB in skeletal muscle at a higher level before exercise,and then decreased rapidly after exercise,suggesting that BCAA can shorten the adaptation time of the body and contribute to the recovery of exercise-induced EIMD.(3)BCAA can significantly reduce Atrogin-1 gene and promote the expression of NF-κB in a short period of time,thus accelerating the recovery after eccentric exercise.