The Effect Of Swimming Exercise On The Expression Of PPAR-γ And Lipid Metabolism In The ApoE Knockout Mice

OBJECTIVES:To establish a model of high-fat diet-induced insulin resistance, to observe the effect of swimming training on serum free fatty acid (FFA) level and the expressions of peroxisome proliferator-activated receptor-y (PPAR-y), carnitine palmitoyl transferase-1 (CPT-1), medium-chain acyl-coenzyme A dehydrogenase (MCAD) mRNA, and to explore the possible mechanisms that swimming training could improve insulin resistance of ApoE-null mice.METHODS:Twenty-six male ApoE knockout mice were randomly divided into two groups:the high-fat diet group (HFD,n=13) and the high-fat diet group with exercise training (HFD+Ex,n=13). The mice of HFD+Ex group were fed with high-fat diet with exercise training for 12 weeks. The intervention of the mice of HFD group were identical to the HFD+Ex group except to swimming training. Ten healthy male C57BL/6J (ND, n=10) mice, as the control group, were fed with normal diet for 12 weeks. After 12 weeks, the mice were dissected, and the liver tissues were excided off immediately. Serum insulin and glucose were determined, while Homa-IRI was calculated to ascertain the establishment of insulin resistance. Serum total cholesterol (TC), trigiyceride (TG), high-density lipoprotetn cholesterol (HDL), low-density lipoprotein cholesterol (LDL), free fatty acid (FFA) were determined. The peroxisome proliferator-activated receptor-y (PPAR-y), carnitine palmitoyl transferase-1b (CPT-1), medium-chain acyl-coenzyme A dehydrogenase (MCAD) mRNA in liver were estimated by reverse transcription polymerase chain reaction (RT-PCR).RESULTS:①.Compared with the ND group, the body weight of mice of the HFD group was significantly higher (P<0.05). Compared with the HFD group,the body weight of mice of the HFD+Ex group was significantly lower (P<0.05).②.Compared with the ND group, fasting glucose, insulin and Homa-IRI of the HFD group was significantly higher (P<0.01 all).Compared with the HFD group, fasting insulin,glucose and Homa-IR of the HFD+Ex group was significantly lower(P<0.05,0.01,0.01 separately).③. Compared with the ND group, TC, LDL, FFA of the HFD group was significantly higher (P<0.01 all) Compared with the HFD group, TC, LDL, FFA of the HFD+Ex group was significantly lower (P<0.05,0.05,0.01 separately), HDL was significantly higher (P<0.05).④. Compared with the ND group, the expression of PPAR-y, CPT-1, MCAD mRNA of the HFD group was significantly decreased (P<0.01 all); Compared with the HFD group, the expression of PPAR-y, CPT-1, MCAD mRNA was significantly increased (P<0.01 all).CONCLUSION:High-fat diet may induce insulin resistance in ApoE knockout mice. Swimming training can improve insulin resistance of ApoE-null mice which possibly acts by upregulating the expression of PPAR-γ, CPT-1 and MCAD mRNA.