Effects Of BCAA Supplementation On Transcription Levels Of KLF-15 And Related Protein Degradation Pathway In Skeletal Muscle Of Rats During Eccentric Exercise

Objective:Skeletal muscle protein degradation after high-intensity eccentric exercise can induce Exercise induce muscle damage(EIMD),and thus affect the training effect.This study was conducted to investigate the effect of Branch chain amino acid(BCAA)supplementation on mRNA expression of Kruppel-like Factor 15(KLF-15)related protein degradation pathway during exercise-induced muscle injury.Methods:In this study,64 male SD rats were randomly divided into two groups:branched chain amino acid supplementation group(BCAA,n=32)and control group(distilled water,n=32),with an intragastric dose of 1g/kg body weight.There were 4 groups in each group,namely,group before exercise,group immediately after exercise,group 6 hours after exercise,and group 12 hours after exercise,with 8 rats in each group.Except for the pre-exercise group,rats in the other groups were subjected to a 2-hour downhill running(gradient-16°,speed 16m/min),and were killed immediately,6 hours and 12 hours after exercise,respectively.Rat gastrocnemius Muscle was taken and the morphological changes were observed by histological section.KLF-15,Forkhead Box Protein O1(FoxO-1),Muscle ring-finger protein-1(MuRF-1)were determined by RT-qPCR.Murf-1 and Myosin heavy chain-Ⅱ(MHC-Ⅱ)mRN A levels in skeletal muscle.Results:(1)Morphological changes showed that the size of muscle cells in the BCAA group and the control group was the same before exercise,without swelling or injury.Indicate that this motion model causes EIMD.(2)In the control group,the mRNA relative expression level of KLF-15 immediately after exercise was significantly higher than that before exercise(P<0.05).The relative expression levels of FOXO-1 and MURF-1 were the same as that of KLF15.Different from the above results,the relative expression level of MHC-Ⅱ was significantly higher immediately after exercise and 6h after exercise than before exercise(P<0.05).(3)The mRNA relative expression level of KLF-15 in BCAA group was not significantly different at all time points after exercise compared with before exercise(P>0.05),but immediately after exercise,the mRNA relative expression level of BCAA group was significantly lower than that of control group(P<0.01).The relative expression level of MURF-1 was similar to that of KLF-15 after exercise.The relative expression level of FOXO-1 immediately after exercise was significantly higher than that before exercise(P<0.05),and there was no significant difference between BCAA and control group at each time point after exercise.The relative expression of MHCⅡ was significantly higher than that before exercise immediately after exercise and 6h after exercise(P>0.05),and was significantly higher in BCAA group than that in control group before exercise(P<0.05).Conclusion:Eccentric exercise caused EIMD in rats and increased the gene transcription level in the KLF-15 related protein degradation pathway after exercise,while BCAA supplementation decreased the gene transcription level in the KLF-15 related protein degradation pathway,which may be one of the reasons for the reduction of muscle injury.