| Objective:This article was to discuss how aerobic exercise influences the generation of insulin resistance of high-fat diet rats and to discuss how mTOR affected the forming of insulin resistance by studying mTOR and its upstream and downstream signals while the high-fat diet rats are doing aerobic exercise.Method:Six-week aged male Sprague-Dawleys rats,weighing150-180g, were kept in separate cages. After one week,they were divided into4groups:Normal Control Rats(Group C, n=10);High-Fat Diet Rats (Group H, n=10);Swimming Exercise Rats(Group E,n=10);High-Fat Diet+Swimming Exercise Rats(Group HE, n=10);According to the acquirement,they should be fed separately normal diet and high-fat diet.Rats in Group E and Group HE were both asked to swim for one hour with non-weight bearing everyday,which continues11weeks. After a fast in the final swimming, got their blood, pancreas and gastrocnemius to measure the content of FBG,FINS, muscle glycogen, skeletal muscles Glut4, AMPK, PI3K, Akt, mTOR, S6K1.At the same time, the experimentalist would observe the form of pancreas under a microscope by using HE staining.Result:(1) The high-fat rats were fed high-fat diet for11weeks and the swimming exercise rats were required to swim for the same days.The weight of the Sprague-Dawleys rats were increasing on the whole.The weights of rats in Group H were obviously higher than those in Group C (p<0.01)and those in Group HE (P<0.05)(2) After11-week experiment, compared with Group C, the content of FBG and FINS in Group H had both increased notably (P<0.01)(P<0.05), the HOMA-IR in Group H was also up, it was not significant (P>0.05);Compared with Group C, the FBG and HOMA-IR content in Group E had decreased slightly (P>0.05),but the FINS had decreased significantly (P<0.01);Compared with Group H, the FBG and the HOMA-IR of Group HE had decreased slightly (P>0.05, but the FINS had decreased significantly (P<0.05)(3) After11-week experiment,the resultsts of HE staining on pancreas were as follows:Compared with Group C,the area of Ins in Group H had increased vividly and the cells borders were indistinctive; While the area of Ins in Group E had decreased with distinctive cells borders;Group HE had showed no more remarkable change than Group H. Furthermore, the border outline were clear.(4) Compared with Group C,the muscle glycogen and the Glut4of skeletal muscles in Group E had greatly increased (P<0.01,while those in Group H had both decreased. Compared with Group H,the muscle glycogen and Glut4in Group HE had significantly increased (P<0.05).(5) Compared with Group C, the content and mRNA of mTOR, the S6K1mRNA in the skeletal muscle of Group H had increased significantly(P<0.05)(P<0.01).On the contrary, the content and mRNA of mTOR in the skeletal muscle of Group E had decreased indistinctively (P>0.05),but the S6K1mRNA had decreased distinctively (P<0.05). Compared with Group H, the content of mTOR in the skeletal muscle of Group HE had decreased slightly (P>0.05),but the mRNA of mTOR and S6K1had decreased significantly (P<0.05).(6) After11-week experiment, compared with Group C,the PI3K content in skeletal muscles in Group E has got a bit higher (P>0.05),while its AMPK and Akt Content have risen greatly (P<0.01).Compared with Group C, the PI3K,Akt and AMPK content in skeletal muscles in Group H had no notable difference (P>0.05).Compared with Group H, Group HE has got a bit increased in PI3k,Akt and AMPK (P>0.05)Conclusion:(1) The11weeks of high-fat diet could increase the FBG, FINS and HOMA-IR of rats greatly, which meaned that the high-fat diet could motivate the generation of insulin resistance.(2) Doing exercises while provided with high-fat diet, the rats got decreased in FINS distinctively, FBG and HOMA-IR indistinctively,which indicated that exercise played an intervention role in high-fat diet’s inducing insulin resistance.(3) The mTOR activated by high-fat diet could cause insulin resistance. And exercise could lower the production of mTOR, which may be a mechanism in the intervention of insulin resistance.(4) The changes of mTOR caused by Insulin Resistance and aerobic exercise were under the control of PI3K/Akt signals and AMPK signals.Exercise got activated AMPK while in return AMPK restrained mTOR. AMPK/mTOR/S6K1maybe play an important role for exercise intervening insulin resistance. |
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