Mechanical Stretch Improves Insulin Resistance In C2C12 Myotubes

Objective: Exercise can improve insulin resistance,but the mechanisms have not been clear.This study established a C2C12 myotube insulin resistance model,and used cyclic mechanical stretch to simulate exercise to explore the regulation of exercise on insulin signaling pathway,inflammation,endoplasmic reticulum stress,and fatty acid oxidation,thus demonstrates the possible mechanism of action of mechanical stretch to improve C2C12 myotube.Methods: 1.C2C12 myoblasts were differentiated and cultured with 2% horse serum for 6 days to become myotubes.In addition to the normal group,an insulin resistance model was established by induction with 0.5 m M palmitic acid for 16 h.2.Fat red deposition was detected by oil red O,oxidative stress was detected by ROS staining,glucose content was detected by glucose uptake method,and insulin signaling pathway related factors were detected by real-time PCR,including insulin receptor substrate 1,phosphoinositide 3-kinase,protein kinase B,glucose transporter 4,nuclear factor kappa B m RNA expression,to identificate of the insulin model was established successfully.3.The modeling group was simulated with 15%,1HZ,6h.The two groups of cells were detected by RT-PCR for the related factors of insulin signaling pathway(GLUT4,PI3 K,IRS-1,AKT,),inflammatory factors(IL-6,NF-κB,TNFα,TGF-β),endoplasmic reticulum Stress factors(ATF3,BIP,CHOP,HSP70,TRB3),lipid oxidation factor(PGC1α,PPARα,Acox1);glucose uptake method was used to detect the glucose content.Results: 1.Compared with the normal control group,the insulin resistance group showed obvious fat deposition and oxidative stress;at the same time,the glucose uptake was decreased,P<0.05;the insulin signaling pathway related factors(GLUT4,PI3 K,IRS-1,AKT)was significantly down-regulated,P < 0.01,indicating that the insulin resistance model was successfully established.2.The insulin resistance group compared with the normal control group,the immediate glucose uptake was significantly increased,P < 0.05;and there was no significant change in the 12 and 24 h time periods.At the genetic level,the insulin resistance group compared with the normal control group,the gene expression of insulin signaling pathway(GLUT4,PI3 K,IRS-1,AKT)was significantly down-regulated,P<0.01;inflammatory factors(IL-6,TNFα,TGF)-β)increased significantly,P<0.01;while NF-κB expression increased significantly,P<0.05;endoplasmic reticulum stress(ATF3,BIP,CHOP,HSP70,TRB3)increased significantly,P <0.01;The gene expression of fatty acid oxidation factors PGC1α and Acox1 was significantly down-regulated,P<0.01;the expression of PPARα was significantly down-regulated,P<0.05.3.Compared with the insulin resistance group,the glucose uptake was significantly increased in the immediate control group,P<0.05;12,24 h,P<0.01.At the gene level,the gene expression of the insulin signaling pathway(GLUT4,PI3 K,IRS-1,AKT)was significantly increased in the mechanical stretch group compared with the insulin resistance group,P < 0.01;inflammatory factors(IL-6,TNFα),TGF-β,NF-κB)gene expression was significantly down-regulated,P <0.01;endoplasmic reticulum stress(ATF3,BIP,CHOP,HSP70,TRB3)gene expression was significantly down-regulated,P <0.01;fatty acid oxidation factor PGC1α and Acox1 was significantly increased,P<0.01;the expression of PPARα was significantly increased,P<0.05.Conclusion: Mechanical stretch can improve insulin resistance in isolated skeletal muscle cells,and its mechanism may be related to mechanical traction improving myocyte inflammation,endoplasmic reticulum stress,and fatty acid oxidation levels.