Effect Of Aerobic Exercise On Skeletal Muscle Of Adult Male Zebrafish And Its Mechanism

Objective: The zebrafish model was used to reveal the changes of biochemical indexes of zebrafish muscle fiber,the mechanism of calcineurin signal,IGF-1 / P13 K / AKT1 / ztor and its related genes in the induction of skeletal muscle phenotype changes and skeletal muscle hypertrophy in the process of aerobic training induced skeletal muscle adaptive changes,so as to provide theoretical reference for the formulation of scientific and reasonable exercise program.Methods: 30 wild-type AB male zebrafish with similar body length and weight were divided into normal quiet control group(n = 15)and aerobic exercise group(n = 15).Four weeks later,the body length and weight of the zebrafish tail were measured,and the proportion of slow muscle in the cross section of zebrafish tail was detected by fluorescence staining,and the size of skeletal muscle fiber was calculated by HE staining and Image J The m RNA expression levels of fast and slow muscle markers(fast muscle markers: tnnc2,myhc4,mylpfa,myhz2;slow muscle markers: smyhc1,smyhc2,tnnt1,tnnc1b)were detected.The activity of calcineurin was determined by colorimetry.The factors related to skeletal muscle transformation(NFATc1,PPARGC1 α,MEF2,Fox O1)and skeletal muscle hypertrophy,protein metabolism related factors(IGF-1)were detected by q PCR The expression levels of AKT1,m TOR and Fox O3 m RNA were detected;Results:(1)there was no significant difference in body length between the two groups(P>0.05),but the body weight of the aerobic exercise group was significantly lower than that of the control group(P<0.01);(2)Compared with the quiet control group,the ucrit of aerobic exercise group increased significantly(P<0.05).(3)In the morphological examination,immunofluorescence results showed that: compared with the quiet control group,the proportion of slow muscle fibers in aerobic exercise group was significantly higher than that in the quiet control group.At the same time,he staining results showed that: compared with the quiet control group,the average area of muscle fibers in zebrafish tail,exercise group increased significantly.(P<0.05)。(4)The m RNA expression levels of troponin C2(tnnc2),myosin heavy chain 4(myhc4)and myosin heavy chain 2(myhz2)in aerobic exercise group were significantly higher than those in control group(P<0.05);(5)Compared with the control group,aerobic exercise group up-regulated the m RNA expression levels of slow myosin heavy chain 1(smyhc1)(P<0.05),slow troponin C(tnnc1b)(P<0.05),slow myosin heavy chain 2(smyhc2),troponin T1(tnnt1)(P<0.05);(6)Compared with the quiet control group,the m RNA expression levels of NFATc1,PPARGC1α and MEF2 in aerobic exercise group were significantly increased(P<0.05)(7)Compared with the quiet control group,the m RNA expression levels of IGF-1,IGF-1R,IRS-1,P13 K,AKT1 and m TOR in aerobic exercise group were significantly increased(P< 0.05);(8)Compared with the quiet control group,the m RNA expression level of Fox O3 in aerobic exercise group was significantly higher(P< 0.05),but Fox O1 had no significant difference(P> 0.05).(9)The activity of can in aerobic exercise group was significantly higher than that in quiet control group(P < 0.05)Conclusion:(1)Four week aerobic exercise significantly increased the expression of slow muscle marker gene,increased the proportion of slow muscle,increased the activity of calcineurin,and up-regulated NFATc1,MEF2,PPARGC1 α These results suggest that aerobic exercise may affect the phenotype of fast and slow skeletal muscle through calcineurin signal.(2)Four weeks of aerobic exercise promoted the hypertrophy of zebrafish tail skeletal muscle,significantly increased the m RNA expression level of IGF-1 / P13 K / AKT1 / ztor in zebrafish skeletal muscle protein synthesis pathway,and down regulated the m RNA expression level of Fox O3 in skeletal muscle protein decomposition pathway,suggesting that aerobic exercise may promote skeletal muscle hypertrophy by up regulating IGF-1 and inhibiting Fox O3.