Effects Of Simvastatin On TLR4in Liver Of Type2Diabetic Rats

Objective：Diabetes has become an epidemic and remained a major public healthissue, its chronic complications can be widely involved in heart, lung, retina, liver,kidney, vascular, neurological, skeletal muscle,skin and so on,and the liver lesionsmainly reflected for nonalcoholic fatty liver disease.Type2diabetes and NAFLD hadthe same mechanism of inflammation and insulin resistence.Toll-like receptor4was amajor pattern-recognition receptor that can recognize endogenous lignds regarding theinflammation, damage and stress besides exogenous ligands.It involved in theinflammation and immune response,which contributed to the occurrence and thedevelopment of a variety of chronic diseases. Zinc finger protein A20was an importantregulatory molecule, which was activated by the inflammation can inhibit the activationof TLR4mediated signalling pathway. Zinc finger protein A20was an importantnegative feedback regulation factor of TLR signalling pathway. Simvastatinparticipated in the oxidative stress, inflammation and immunity, aparting fromreducing the formation of cholesterol and low density lipoprotein. In this experiment,high-fat food and small dose of streptozotoc was used to repeat the rat model of type2diabetes.Through detedting the expression of TLR4in the liver to confirm the effectionof the TLR4and simvastatin in the development of diabetes.By detecting the expressionof zinc finger protein A20in liver to elucidate its role and mechanism in theinflammation.Methods: Fourty male heathy sprague-Dawlry rats were randomly divided intonormal control group (group A,n=10) and test group (n=30). Group A rats were fedwith normal food,but the test group rats were fed with high-fat food.Four weekslater,test group rats were induced to diabetes by injecting streptozotocin (STZ) at adosage of30mg/kg,but the group A rats were injected the same dose of citric acidbuffer.Two weeks later,the rats whose fasting blood glucose were higher by7.8mmol/L and present in the state of insulin resistance were choosed to be the type2diabetes model. Then the diabeteic models were divided into two groups:the diabetic group(group B) and the Simvastatin intervention group(group C).The rats in group Cwere given simvastatin at a dosage of20mg/kg by daily gavage and the ones in group Aand group B were received the equal volume normal saline,the gavage continued for8weeks.And at the end of the14week the body weight was measured.Then the rats werekilled to collect the blood sample and the liver. FBG, high-density lipoproteincholesterol,Low-density lipoprotein cholesterol,total cholesterol,triglyceride,alanineaminotransferase,aspartateaminotransferase were measured. The expression of TLR4and A20in the liver was detected by immunohistochemistry staining.The TLR4mRNAwere measured by RT-PCR.The data was dealt with SPSS13.0.Results:1Blood glucose and insulin: FBG12.02±2.7mmol/L of the test rats were higher thanFBG6.16±0.38mmol/L of the control. Three was no distinction between the FINS19.02(18.68,19.15) mIU/L of test rats and the FINS17.82(17.46,18.02)mIU/L of thecontrol group.The ISI0.0046(0.0038,0.0052)of the test rats was lower than the ISI0.0094(0.0088,0.0095).Until then,the T2DM rat model was accomplished.2Various biochemical indexes after14weeks:The FBG12.37±3.0mmol/L in group Band11.50±2.0mmol/L in group C were higher than5.72±0.43mmol/L in groupA,and the FBG obetween group B and group C was unstatistics distinction.TheHDL-C,AST among three groups were unstatistics distinction,but for ALT,LDL-C,TG,TC,the group B and group C was higher than the groupA.3Morphology： The hepatic lobule in group A was regular,karyon andintercellular space was normal,with no inflammatory cells infiltrating.while in T2DMmodel rats,the hepatic cells was disorganized and three were fatty drops in the cells withinflammatory cells infiltrating in hepatic lobule and portal area.The situation in groupC was not so severe like group B.4The expression of TLR4Immunohistochemistry results showed that compared withthe normal control group,TLR4expression was significantly increased in group B andgroup C. The TLR4expression in group C was decreased than the group B.The expression of A20in group A was lower than that in group B and the groupC,but the expression between the group B and group C was no statistical distinction.5The expression of the TLR4mRNA:The TLR4mRNA in group A was lower comparing with the group B and group C,and the TLR4in group B is higher than groupC.Conclusion:1The expression of TLR4on the liver of diabetic rats was increased,which involvedin the progress of the diabetic liver disease.2Simvastatin could reduce the expression of the TLR4and relieve the injury in theliver.3A20regulate the inflammatory reaction by reducing the level of the TLR4,whichprotect from the injure of the liver.