Role Of MEF2/PGC-1 Signal Pathway In Skeletal Muscle Fiber Type Transformation

Object:Investigating the effects of endurance exercise on skeletal muscle fiber type transformation and mitochondrial energy metabolism,and the role of myocyte enhancer factor2?MEF2?/peroxisome proliferator activated receptor gamma coactivator?PGC-1?signaling pathway in this process.Methods:40 male SD rats were randomly divided into four groups:quiet group?C?,exercise group?E?,quiet drug group?CM?and exercise medicine?EM?,each group had 10rats.After a week of adaptive training,E group and EM group were trained for 6 days a week.After the endurance training for 2 weeks,the CM group and EM group were administered with 75mg PGC-1 of kg^-1day^-1 for a period of 6 weeks every day.At the end of the last exercise 48 hours after anesthesia to take the medial gastrocnemius of the left leg.Using Western blot method measures the content of PGC-1,MEF2,TNNI1 and TNNI2protein.Real-time RCR method was used to measure the expression of mRNA,PGC-1,TNNI1,and TNNI2 in gastrocnemius muscle MHC.The content of ATP was determined by HPLC.Results:?1?After 8 weeks of endurance training,the increase of ATP contents in the EM group was the most obvious,the E group and CM group were significantly increased compared with the C group?P<0.01?;?2?In group EM,the increase of MEF2 protein was most obvious,E group and EM group were significantly increased compared with C group?P<0.01?.?3?EM group PGC-1 alpha protein increased most obviously,E group was significantly increased compared with C group?P<0.01?,CM group was significantly increased?P<0.05?compared with C group.?4?The expression of TNNI1 protein in EM group was significantly increased?P<0.01?,CM group was significantly increased?P<0.05?;E group was significantly increased?P<0.01?.?5?The expression of TNNI2 protein in EM group was significantly decreased?P<0.01?,E group was significantly lower than that in C group?P<0.05?.?6?In group E,CM group and EM group PGC-1 and mRNA expression were significantly decreased?P<0.01?.?7?The expression of TNNI1mRNA in EM group was the most obvious,and TNNI2mRNA was the most obvious.The TNNI1mRNA in E group was significantly increased?P<0.01?,and TNNI2mRNA was very significant.?8?The expression level of MHCIand MHCIIb in EM group was significantly increased?P<0.01?,and MHCIIb and MHCIIx mRNA were significantly decreased in mRNA group.Conclusions:1.Endurance training induces the expression of ATP through the MEF2/PGC-1 signal pathway,which affects the level of mitochondrial energy metabolism2.The effects of endurance training on skeletal muscle fiber types were IIb to IIa3.The effect of PGC-1 modulator ZLN005 and endurance training was more obvious than that of pure endurance training on skeletal muscle fiber type transformation and mitochondrial energy metabolism4.Endurance training and ZLN005 promote the expression of MEF2,PGC-1,and MEF2,PGC-1 alpha protein expression trend is consistent...