To Establish MS Combined AMI Model In OLETF Rat And Explore The Mechanisms Of Oxidative Stress

Objective: In this study,the rat model of metabolic syndrome was established by high fat diet on OLETF rats.The left coronary artery was ligated of MS model,then a model of metabolic syndrome complicated with myocardial infarction in rats was established.This experiment aims to: 1 To establish a kind of metabolic syndrome model with myocardial infarction in rats which is more stable and more reproducible and closer to the clinical practice.2 To discuss the mechanisms of myocardial injury on myocardial damage from oxidative stress and explore the role of TRX and TXNIP in myocardial injury.Methods: 18 OLETF rats(male,4weeks age,SPF)and 18 LETO rats(male,4weeks age,SPF),the body mass were between 170 to 185 g,all purchased from the SLC,all placed in the Chinese academy of medical sciences institute of radiation medicine barrier environment.Put them into two groups after 2 weeks standard diet feeding.Then LETO rats in group N were still fed by standard diet and OLETF rats in group MS were fed by high-fat diet.The OGTT was performed weekly in rats(fasting after 12h);took SBP and DBP every week;weight was taken every two weeks;blood was taken in the inner canthus vein of the rats and serum total cholesterol(TC),triglyceride(TG)levels were measured every two weeks.After MS model was established,the MS group and the N group were divided into two groups by random number method: group MS(n=9),group MS-MI(n=9),group Sham(n=9),group MI(n=9);then the acute myocardial infarction model was made by using the method of ligating the left anterior descending branch of group MS-MI and group MI.There were nine rats reserved in both group because of considering the mortality.The cardiac function was evaluated by echocardiographic;the myocardial morphology was observed under light microscope after HE staining;the inflammatory response was assessed by semi-quantitative evaluation;the ultrastructural changes of myocardium were observed under transmission electron microscope.The level of GSH and T-AOC,SOD,MPO and MDA in myocardial tissue,fluorescence method to detect the contents of NADPH oxidase(NOX)were tested by spectrophotometric.The protein and m RNA expression of TRX and TXNIP in myocardial tissue were detected by Western blot and RT-PCR.Use SPSS 17.0 and Graphpad Prism 6.0 software to complete the statistics,analyze the data and plot.Results: 1.Comparisons of group MS and group N: at 24 week,blood glucose and insulin levels at each time point of OGTT in MS group were all is significantly higher than control group;the TC,TG,SBP and DBP levels were significantly higher than control group too(P< 0.05).2.Evaluated cardiac function by echocardiographic of MI model: LVEDD,LVESD in group MI and MS-MI increased significantly and LVFS,LVEF decreased significantly compared with group Sham and MS(P< 0.05).LVEDD,LVESD increased and LVFS,LVEF decreased more significantly in group MS-MI than MI(P< 0.05).3.Pathologic sample and HE staining semi-quantitative assessment:(1)there was no obvious change in group Sham and MS in pathologic sample,and the myocardial infarction area in group MI and MS-MI was pale.(2)Under the light microscope and electron microscopy,there was obvious change in group Sham,there was slight injury in group MS,the damage in group group MI and MS-MI was obvious.HE staining showed that there was almost no difference between group Sham and MS,group MS-MI and MI were in higher score compared with group Sham and MS(P < 0.05),and the score of group MS-MI was higher more obvious(P < 0.05).4.Oxidative stress: compared with group Sham and MS,the level of GSH,T-AOC,SOD were lower(P < 0.05)and MPO,NOX,MDA were higher(P < 0.05)in group MS-MI and MI;also,the level of GSH,T-AOC,SOD reduced and MPO,NOX,MDA rised more seriously in group MS-MI(all P < 0.05).5.The expression of TRX,TXNI protein and m RNA in myocardium:(1)result of Western blot: compared with group Sham and MS,the expression of TRX protein was in lower level and TXNIP protein was in higher level in group MS-MI and MI(all P < 0.05);also TRX protein was much less and TXNI protein was even more in group MS-MI with the comparison to group MI(all P < 0.05).Conclusion: 1.OLETF rat MS model was established triumphantly by high fat diet.The blood glucose and insulin levels,TC and TG levels,BP in the model rats were all remarkably increased.2.Successfully established MS combined MI model in OLETF rats by ligaturing the left anterior descending branch on the basis of MS rats,cardica function of ventriculus sinister descended significantly,the level of inflammation and oxidative stress were increased seriously.3.In myocardial infarction,the protection to myocardium by TRX was reduced,the damage to myocardium by TXNIP was increased.And MS may aggravate myocardial injury through oxidative stress by cutting the expression of TRX and increase expression of TXNIP.