The Effects Of Swimming Training On Myocardial PPAR-γ Expression And Glucose And Lipid Metabolism In Mice With Insulin Resistance

Objective:As we all known, Insulin resistance is the common pathogenesis of some diseases, such as hypertension, coronary heart disease, atherosclerosis and diabetes, etc. There is a great clinical meaning to explore the mechanisms and methods on how to improve insulin resistance. In the present study, ApoE gene knockout mice models with insulin resistance induced by high-fat diet were used to observe the microstructure changes and PPAR-γ,GLUT-4,MCADmRNA expression in myocardium. Futher, we investigated the effects of swimming trainning on serum glucose, lipids and free fatty acids levels, and observed the microstructure changes and PPAR-γ,GLUT-4 MCADmRNA expression levels in myocardium to find the possible mechaisms.Methods:(1) Twenty-six male ApoE knockout mice were randomly divided to the high-fat diet (H, n=13) and the high-fat diet with swimming training (HE, n=13). The HE group were fed with high-fat diet and swimming training for 12 weeks. The treatment of H group was identical to the HE group except to swimming training. As the control group, ten healthy male C57BL/6J (N, n=10) mice were fed with normal diet for 12 weeks. After 12 weeks, fasing insulin and glucose, serum lipids and free acids were examined to make sure the estabolishment of insulin resistance model.Then the mice were sacrificed, the left ventricular and septal tissues were excided off immediately to observe the changes of myocardial morphology under electrical microscopy and the expression of PPAR-y, GLUT-4, MCAD by reverse tanscription PCR(RT-PCR).Results:(1) Compared with the N group, fasting glucose, insulin and LnHoma-IRI of the H group were significantly higher (p<0.01). Compared with the H group, fasting insulin, glucose and LnHOMA-IR of the HE group were significantly lower (p<0.05; p<0.01; p<0.01). (2) Compared with the N group, TC, LDL, FFA of H group were significantly higher (p<0.01). Compared with the H group, TC, LDL, FFA of the HE group were significantly lower (p<0.05;p< 0.05, p<0.01). (3) For the microstrcture of cardiocyte, N group appeared normal structure, while the H group displayed edema around myofibrils, mitochondrial damaged, myofibrils dissolved and lipofuscin in the cardiocyte.The structure of HE group cardiocyte was normal except few mitochondria vacuolated and increased the number of mitochondria. (4) Compared with the N group, the expression of PPAR-γ, GLUT-4 mRNA in the heart of the H group were significantly decreased (p<0.01), MCAD mRNA were significantly increased(p<0.01); Compared with the H group, the expression of PPAR-y,GLUT-4mRNA of the HE group were significantly increased (p<0.01),while MCAD mRNA were significantly decreased(p<0.01). Conclusions:(1) ApoE gene knockout mice models with insulin resistance had significantly injury in myocardium and myocardial glucose and lipids metabolism disorders, such changes may have some connection with myocardial insulin resistance. (2) Swimming trainning could improve insulin resistance and maintain the balance of glucose and lipid metabolism in the heart through up-regulating the expression of PPAR-γ, GLUT-4, and down-regulating the expression of MCAD, improving myocardial insulin resistance.