| Insulin resistance (IR) and the concurrent diseases it caused is a serious threat to human life now, insulin resistance in prevention and treatment has become a worldwide hotspot and difficulties. Chemical agents can control insulin resistance while caused irreversible damage to the others body organs and functions. Liver is the main place of body energy metabolism, and also is one of the important target organs of insulin, so the hepatic insulin resistance play a crucial role in the body insulin resistance. The lack of Myostatin have positive effect on energy metabolism and insulin resistance, also express in liver, so we can detect MSTN's protein level and molecular level in liver after MSTN antibody intervention to test whether can hinder its receptor normal combined to promote PI3K/Akt signal pathway activated through inhibiting MSTN protein expression or receptor expression, then activating downstream signal molecule to improve insulin resistance. Reasonable exercises has became an important way to improve insulin resistance, while restoring the body functions and preventing drug injury compared with chemotherapy. This study used low-intensity and medium load of treadmill exercise to intervene the rats, seeking the best programme to improve the hepatic insulin resistance. Purpose:Currently there are less studys of the functions and mechanism that MSTN and load of treadmill exercises effect on liver, so we explore the changes between gens of hepatic insulin receptor substrate and the protein expression under the above intervention that we can provide the theory and new method to prevent and treating the hepatic insulin resistance. Method:Selected 50 two months old, healthy and purebred male SD (Sprague-Dawley) rats after a week adaptive feeding we randomly divided into 5 cage, one group is the normal control rats (NC rats) which feed as the general rodent. The others are high fat feeded rats (HF rats) being induces the model of IR and after 12 weeks we will judge whether the model successful through the oral glucose tolerance test (OGTT) and the insulin tolerance test (ITT).Then we divide the HF rats into HF group, MSTN Antibody group (HM group), Medium Load Weight Treadmill Exercise group (HML group), Medium Load Weight Treadmill Exercise with MSTN Antibody group (HML+M group) and enforce 8 weeks intervention.Collect the weight and length of rats and do the OGTT and ITT before the dissection.Then use the kit to determin the blood indexes. Observe the liver cells through the he stain (HE). Detect the changes of signal molecules on insulin signal pathway by Western blot and RT-qPCR. Results:1 Lee's index shows that HF rats significantly above NC (P<0.05), HM rats and HML rats significantly below HF (P<0.05), HML+M rats and HF rats have no significant difference.And the results displayed the high fat dietary rats are significant obesity than other rats, HM rats and HML rats has significantly improved their obesity, but the combine of antibody and exercise has no significant effect on obesity.2 OGTT shows that the fasting blood-glucose (FBG) of HM rats, HML rats and HML+M rats are below HF rats, after oral glucose the blood-glucose level increase more flat, quickly reach the blood-glucose peak and fall down quickly, and the blood-glucose peak is also significant lower than HF rats; ITT shows that the blood-glucose of HM rats, HML rats and HML+M rats fall down quickly after intraperitoneal injection, and the blood-glucose's area under curve (AUC) at all point in time are less than HF rats.3 The lipid shows that the CHO level of HF rats is significantly above NC rats but significantly below HML rats and HML+M rats (P<0.01, and P<0.05), so the medium load weight treadmill exercise have significant effect on high blood cholesterol and better than HML+M rats. The HDL-c level of HF rats is significantly below HM rats, HML rats and HML+M rats (P<0.01), that display the MSTN antibody, medium load weight teadmill exercise, medium load weight treadmill exercise with MSTN antibody all can reduce the blood-glucose by stimulating islet cell ? secreting insulin; The LDL-c level of HM rats, HML rats and HML+M rats are below HF rats but no significantly difference, that means the three interventions have less effect on HDL-c and mainly effect on LDL-c to remove the cholesterol in blood and promote the lipid metabolism thereby improving the IR.4 The PI3KmRNA expression of HF rats is significantly less than NC rats (P<0.05),and have a decreasing trend with HM rats, HML rats and HML+M rats but have no significantly difference. The protein expression and mRNA expression of Akt display that the long-term high fat dietary made the HF rats liver's Akt protein expression lower than NC rats (P<0.05), mRNA expression is significantly lower than NC rats (P<0.01); HM rats liver's Akt protein expression and mRNA expression both have significantly improvement with HF rats (P<0.01); HML rats liver's Akt protein expression and mRNA expression also have significantly improvement with HF rats (P<0.05); HML+M rats liver's Akt protein expression and mRNA expression have no significant differences with HF rats. It prove that the MSTN antibody and medium load weight teadmill exercise both can improve the IR in high fat diet rats by improving the Akt's activation and promoting the signal transmission in the signal path PI3K/Akt, but the medium load weight treadmill exercise with MSTN antibody don't have the significant improvement.5 HF rats liver's mTOR protein expression and mRNA expression are significantly less than NC rats (P<0.01); HM rats and HML rats liver's mTOR protein expression is basic consistent with the mRNA expression, they have a increasing trend with HF rats but have no significant difference; HML+M rats liver's mTOR protein expression and the mRNA expression have no significant difference with HF rats. That means the MSTN antibody, medium load weight teadmill exerciset, medium load weight treadmill exercise with MSTN antibody not have significant improvement on high fat diet rats in the liver's signal path Akt/mTOR, and have no promotion in liver's protein synthesis.6 HF rats liver's FoxO1 protein expression have a increasing trend with NC rats but have no significant difference; HM rats liver's FoxO1 protein expression have a decreasing trend with HF rats but have no significant difference; HML rats liver's FoxO1 protein expression is less than HF rats (P<0.05); HML+M rats liver's FoxO1 protein expression is significantly less than HF rats (P<0.01). This show that the medium load weight teadmill exerciset, medium load weight treadmill exercise with MSTN antibody have significant inhibition to liver's FoxO1 protein expression and promote the transduction of liver's Akt/FoxO1 signal path to enhance liver's lipid metabolism thereby improving the hepatic insulin resistance.7 HF rats liver's Glut4 protein expression and mRNA expression both have the decreasing trend with NC rats but have no significant difference; HM rats liver's Glut4 protein expression and mRNA expression are significantly above HF rats (P<0.01, P<0.05), HML rats and HML+M rats liver's Glut4 protein expression and mRNA expression have no significant difference with HF rats. At the same time, HML+M rats liver's Glut4 protein expression is much below HM rats (P<0.01) and HML rats (P<0.01). It means that MSTN antibody significantly promote the expression of Glut4 protein and the transfer of glucose in liver to reduce the level of blood glucose. But the medium load weight teadmill exercise, medium load weight treadmill exercise with MSTN antibody can not promote the hepatic glucose metabolism by increasing the level to improve hepatic insulin resistance.8 The mRNA expression of HF rats liver's MSTN and its receptor are significantly above NC rats (P<0.01), HM rats liver's MSTN mRNA expression is significantly below HF rats (P<0.01) but MSTN receptor mRNA expression have no significant difference with HF rats, shows that MSTN antibody may improve hepatic insulin resistance by obstructing hepatic MSTN expression; The mRNA expression of HML rats liver's MSTN and its receptor are significantly below HF rats (P<0.01), shows that the medium load weight teadmill exercise have inhibition on MSTN and its receptor to improve hepatic insulin resistance; The MSTN mRNA expression of HML+M rats is significantly below HF rats (P<0.05) and its MSTN receptor mRNA expression have no significantly differences with HF rats, shows that the medium load weight treadmill exercise with MSTN antibody improve hepatic insulin resistance mainly by obstructing hepatic MSTN expression and improving the hepatic load and metabolism. Conclusion:1 The Lee's index of HM rats and HML rats decrease significantly, their quality of skeletal muscle have improved, their lean mass increased and betterd body composition. And their glucose tolerance and insulin sensitivity have improved significantly. Hepatic tissue slices show that the fatty degeneration and fatty hollow space are reduced comparing with HF rats. And the adipocyte infiltrating has been significantly improved. The increase of HDL-c can clear the cholesterol accumulation and promote the fat metabolism, so improve the Akt activation to continue transmitting signal. The medium load weight treadmill exercise inhibit FoxO1 the downstream signal molecules of Akt. MSTN antibody have good effect on Glut4 and promote the hepatic glucose transporter. The medium load weight treadmill exercise inhibit MSTN and its receptor expression. MSTN antibody can reduce the MSTN to improving the IR.2 The weight of medium load weight treadmill exercise with MSTN antibody rats is reduced, but the fat content have no significant difference with HF rats, the glucose tolerance and insulin sensitivity, the increase of HDL-c can promote pancreas islet ? secreting insulin. And the weight of medium load weight treadmill exercise with MSTN antibody have no obvious activation on PI3K/Akt signal pathway, but can promote Akt/FoxO1 pathway. And it obstruct hepatic MSTN expression. Overall it have no obvious effect on hepatic insulin resistance. The signal pathways is complex and affected by many factors, so it makes the signal pathways of medium load weight treadmill exercise with MSTN antibody unpredictably and need more study. |
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