The Effect Of Exercise On The Expression Of PPAR-α And Lipid Metabolism In Skeletal Muscle Of ApoE Knockout Mice

OBJECTIVES:To establish a model of ApoE knockout mice with insulin resistance induced by high fat diet, and explore the possible mechanisms that swimming training could improve insulin resistance by examining on the concentrations of serum free fatty acid(FFA) and glucose, and the mRNA expression of peroxisome proliferator-activated receptor(PPAR-α), acyl-CoA oxidase1 (ACYL), enoy-CoA-hydratase and 3-hydroxyacyl-CoA dehydrogenase (ENOY) in the skeletal muscle,METHODS:Twenty male ApoE knockout mice were randomly divided into two groups:the high-fat diet group (HFD, n=10)and the high-fat diet group with exercise training (HFD+Ex, n=10). The HFD group were fed with high-fat diet, which was identical to the HFD+Ex group except 12 weeks'swimming training. And as the control group, ten healthy male C57BL/6j(ND,n=8) mice were fed with normal diet for 12 weeks. After 12 weeks intervention, the mice were sacrificed. Serum insulin and glucose were determined, and Homa-IRI was calculated to certain the establishment of insulin resistance. Serum total cholesterol (TC), trigiyceride (TG), high-density lipoprotein cholesterol (HDL),low-density liporeotein cholesterol (LDL) and free fatty acid (FFA) were determined. The bilateral gastrocnemiuses were cut for analyzing ultrastructure of sketletal muscle by the transmission electron microscope and measuring the mRNA expression of PPAR-a, ACYL and ENOY in skeletal muscle by reverse transcription polymerase chain reaction(RT-PCR).RESULTS:①Compared with the ND group, fasting glucose, insulin and Homa-IRI of the HFD group were significantly higher (P<0.01). Compared with the HFD group, fasting insulin, glucose and HOMA-IR of the HFD+Ex group were significantly lower (P<0.05,0.01,0.01)。②Compared with the ND group,TC, LDL, FFA of HFD group were significantly higher (P<0.01). Compared with the HFD group, TC, LDL and FFA of the HFD+Ex group were significantly lower (P<0.05,0.05, 0.01), while HDL was significantly higher (p<0.05).③The transmission electron microscope showed that the myofibrils of ND group remained intergrity, the structure of sarcomere weas intact and clear.; HFD group appeared the sarcolemma edema, mitochondrial swelling, focal myocytolysis and edema within myofibrils, while HFD+Ex group reveresed pathological changes of the above.④Compared with the ND group, the mRNA expression of PPAR-a, ACYL and ENOY of the HFD group were significantly deceased(P<0.01); Compared with the HFD group, the mRNA expression of the above in the HFD+Ex group were significantly increased(P<0.01).CONCLUSION:①Swimming training could improve insulin resistance of ApoE knockout mice.②Swimming training could improve insulin resistance possibly through upregulating the expression of PPAR-a, ACYL and ENOY mRNA.