| Insulin Resistance(IR) may be defined as a condition in which higher-than-normal insulin concentrations are needed to achieve normal metabolic responses or normal insulin concentrations fail to achieve a normal metabolic response.At present,the view that IR is not only the foundation of incidence for type 2 diabetes mellitus,but also the main line that through a variety of metabolic-related diseases,and ties among them.IR is the common pathology's physiological basis of the above diseases.Therefore,the study of IR has become a hot academic issue around the world.Mechanism of IR is a very complicated problem and the exact mechanism is still not completely clear.With the intensive study on receptor,some studies suggest that IR might be due to the deficiencies and reduce of certain signal transducer on the pathway of insulin signal transducer or abnormal structure.The main path of insulin's effect is PI-3K signal transducer. While protein kinase B(PKB),insulin receptor and downstream molecules of PI-3K,plays important role on insulin metabolism,hormone signal transducer and glucose transportation.Tumor Necrosis Factor(TNF)-alpha plays an important role on the occurrence of IR. Study has shown that TNF-alpha of liver expression in high-fat-diet rat significantly increased. The intervention of TNF-alpha monoclonal antibody can significantly improve PKB phosphorylation of insulin-induced in high-fat-diet rat,the change of which may have an important impact on the occurrence of IR.Exercise can effectively improve IR,however,its exact mechanism is not yet very clear. There are more studies about exercise in preventing IR in muscle and adipose tissue.And liver plays a key role on the whole body's IR,but there is few study about exercise in preventing IR in liver.So far,there is no relative report on the correlation between exercise and TNF-αof liver and PKB in high-fat diet rat.Purpose:The purpose of this study is to explore the effect of exercise,the experimental study of animal training,on preventing the formation and development of IR in high-fat-diet rat.What's more,to analysis the changes and roles of TNF-alpha and phosphorylation PKB of liver tissue may provide a pioneer way in the mechanism in comprehensive understanding of exercise on preventing IR,and also may provide a theoretical basis on exercise prescription in scientifically preventing IRResearch Methods:The study objects were 30 SD male rats,randomly divided into four groups,that is,control group(C),high-fat group(H),high-fat with exercise group(HE) and exercise group(E),the control group and exercise group rats were fed with ordinary diet, while high-fat group and high-fat with exercise group were fed with high fat diet.The fat calories of high fat diet and normal diet were 35%and 11%respectively.High-fat with exercise group and exercise group,at the same time,had 8 weeks' treadmill training(at the speed of 20m/min,slope 0°,5 times / week).After 8 weeks,compared body weight,visceral fat weight,body fat ratio,liver weight and liver index of rats in each group,in which the study also observe morphological changes of the liver of SD in each group and detect their blood glucose,serum insulin,serum TNF-alpha,expression in TNF-alpha and phosphorylation PKB of liver to compare differences.Results:1.After the experiment,there is no difference in fasting plasma glucose.And the values of serum insulin level of Group H was higher than that in Group C,while Group HE was lower than that in Group H,and there was significant difference(P＜0.05).What's more,the values of insulin sensitivity index were lower in Group H than that in Group C, significant difference(P＜0.05),and there is no significant difference,but increasing trend,in Group HE and Group H.2.After the experiment,the values of SD's body weight,visceral fat pad weight were higher in Group H than that in Group C,and there was significant difference(P＜0.05).What's more,there was no significant difference,but increase,in the values of body fat between Group H and Group C.Thirdly,the values of weight,visceral fat pad weight and body fat were decrease in Group HE than that in Group H,and there was significant difference (P＜0.01).Fourthly,the values of SD's liver weight and liver index were higher in Group than that in Group C and there was significant difference(P＜0.01).And the values of liver weight and liver index were lower in Group HE than that in Group H and there was significant difference(P＜0.01).3.After the experiment,the values of SD's TNF-alpha expression were higher in Group H than that in Group C,and the values of insulin-induced phosphorylation PKB expression of the liver were lower in Group H than that in Group C and there was significant difference (P＜0.05).What's more,the values of liver's TNF-alpha were lower in Group HE than that in Group H and higher than Group H and there was significant difference(P＜0.05).However, the values of serum's TNF-alpha were higher in Group HE than that in Group H(P＜0.05).Conclusion:The 8 weeks' high-fat diet could lead to IR in SD rats.And,to some extent, there was a preventive effect on treadmill training,which mechanism might inhibite PKB by reducing the high-fat diet rat liver expression of TNF-alpha.And thus,to some extent,it would prevent IR caused by high-fat diet.
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