Resolvin D1 Improves Insulin Resistance In Myocardium Of Type 2 Diabetic Mice And Its Possible Mechanism

Objective: Insulin resistance is one of the pathogenesis of type 2 diabetic cardiomyopathy.Relevant experimental studies have found that insulin resistance in type 2 diabetes mellitus is a kind of chronic low-grade inflammation.RvD1,a derivative of omega-3 polyunsaturated fatty acid,is a new type of anti-inflammatory medium,which has been proved to have anti-inflammatory effects in multiple tissues and organs.In this experiment,after RvD1 intervention was observed,the specific mechanism of RvD1 improving myocardial insulin resistance was clarified by observing the expression levels of IL-6,TNF-? in the serum of mice,IRS-1,TLR4,NF-?B,GLUT4 protein and GLUT4 mRNA in myocardial tissue,providing theoretical basis for its clinical application.Methods: 35 male C57BL/6 mice were selected as subjects for adaptive feeding for 7 days.The mice were randomly divided into control group(NC group)and high-fat diet group.Two groups of mice were given normal diet and high-fat diet.After 8 weeks,each mouse in the high-fat diet group was intraperitoneally injected with STZ(100 mg/kg).Three days later,tail vein puncture was performed to collect blood and measure the blood glucose level.The mice with blood glucose level 16.7 mmol/L were type 2 diabetes model mice.The mice that were successfully modeled were randomly divided into two groups: type 2 diabetes mellitus(T2DM)and type 2 diabetes mellitus + regressive hormone(T2DM+RvD1).After feeding the corresponding diet for 4 weeks,the subitrin group was intraperitoneally injected with RvD1 for 3 weeks.Type 2 diabetes mellitus group was intraperitoneally injected with the same amount of PBS for 3 weeks,and the blood glucose of the mice was regularly measured.After the experiment,all the mice fasted but could not refrain from drinking water for 12 hours,and the levels of IL-6,TNF-?,triglyceride,total cholesterol and insulin in the blood were measured,and the insulin resistance index was calculated.After the blood was taken,the mouse was dissected quickly,the heart was removed,and the myocardial tissue morphology was observed by HE staining.The rest of the heart tissue was stored at-80 ?in the refrigerator for reserve,and the expression levels of IRS-1,GLUT4,TLR4,and NF-?B protein were detected by western blot,and the mRNA levels of GLUT4 were detected by RT-qPCR.Results: 1.General condition of miceThe NC group mice had good mental state,shiny hair,active and flexible,good diet,no abnormal urine,no death cases.T2 DM group mice had poor mental state,reduced activity and inactivity,with adverse symptoms such as polyuria,polydipsia and polyphagia,and dark hair color.Compared with the T2 DM group,the T2DM+RvD1 group showed improved mental state,increased activity,improved symptoms of polyuria,polydipsia and polyphagia,and no significant difference in hair.2.Changes of blood lipid,blood glucose,insulin and insulin resistance index in mice 2.1 The change of blood lipid in miceCompared with NC group,T2 DM group and T2 DM + RVD1 elevated cholesterol and triglyceride in mice,the difference was statistically significant(P<0.05).Compared with T2 DM group,cholesterol and triglyceride in T2 DM + RVD1 mice fell,the difference was statistically significant(P<0.05).2.2 Mice blood glucose changesCompared with NC group,T2 DM group and T2 DM + RVD1 group blood sugar in mice increased significantly,difference was statistically significant(P <0.05)T2DM + RVD1 group compared with T2 DM group,a drop in blood sugar in mice,the difference was statistically significant(P < 0.05).2.3 Mice bloodserum insulin level changesCompared with NC group,serum insulin level change of T2 DM and insulin levels in T2 DM + RVD1 mice was increased,the difference was statistically significant(P< 0.05)to subsidise D1 3 weeks after treatment,compared with T2 DM group,insulin levels of mice T2 DM +RVD1 declined,the difference was statistically significant(P<0.05).2.4 The change of the insulin resistance indexCompared with the NC group,the insulin resistance index of the T2 DM and T2DM+RvD1 group increased,and the difference was statistically significant(P<0.05).After 3 weeks of treatment with the regression hormone D1,the insulin resistance index of the T2DM+RvD1 group decreased significantly,and the difference was statistically significant(P<0.05).3 Changes of inflammatory cytokines in miceCompared with the NC group,TNF-? and IL-6 in the serum of the T2 DM group were significantly increased,and the difference was statistically significant(P<0.05).Compared with the T2 DM group,the serum levels of TNF-? and IL-6 in the T2DM+RvD1 group decreased after 3 weeks of RvD1 treatment,and the difference was statistically significant(P<0.05).4 Changes in the expression level of NF-?B TLR4 IRS-1 GLUT4 protein in the mouse myocardiumCompared with the NC group,the expression level of TLR4 NF-?B protein in the myocardium of the T2 DM group and the T2DM+RvD1 group was significantly increased,and the difference was statistically significant(P<0.05).Compared with NC group,T2 DM group and T2 DM + RvD1 group in the myocardial tissue of mice significantly reduced the IRS-1?GLUT4 protein expression level,the difference was statistically significant(P < 0.05).Compared with T2 DM group,give RvD1 interfere 3 weeks,the above indexes in myocardial tissue in T2 DM + RvD1 mice was increased,the differences were statistically significant(P<0.05).5 Myocardial tissue HE dyeingControl group normal myocardial cells neatly arranged close together,the structure is clear,extracellular matrix is less,no inflammatory c-ell infiltration diabetes group of myocardial cells dissolved,adipose fill,water change and ballooning,cell arrangement is irregular,and there are obvious inflammatory cells infiltration compared with diabetes group,fade pigment group reduce myocardial cell lysis and degeneration.Conclusion:1.RvD1 can improve the general state of type 2 diabetic mice,and has the effect of regulating glucose and lipid metabolism and anti-inflammatory.2.RvD1 inhibited the dissolution of myocardial cells in type 2 diabetic mice,filled with fat,reduced the occurrence of myocardial cell water-like changes and balloon-like changes,and protected the myocardial tissue.3.RvD1 inhibited the expression of NF-?B and TLR4 in the myocardium of type 2 diabetic mice,and increased the expression of IRS-1 and GLUT4 in the myocardium of type 2 diabetic mice.4.RvD1 may further reduce the production of inflammatory factors such as TNF-? and IL-6 by reducing the expression of TLR4 and NF-?B in myocardial tissue,increase the expression of IRS-1,enhance the sensitivity of myocardial tissue to insulin,and finally increase the expression of GLUT4 and improve myocardial insulin resistance.