Research On Relationship Between Nrf2-ARE Signal Pathway And The Pathogenesis Of With Type2Diabetic Cardiomyopathy

Abstract:objective:This study aims at using Wistar rats to establish the diabetic cardiomyopathy model so as to observe the ultrastructural changes of the cardiomyocytes, apoptosis and myocardial fibrosis, oxidative stress and other related indexes and the expressing of Nrf2after the successful modeling. The relationships between Nrf2/ARE signal pathway and the above changes will be observed after giving CPDT, the activator of Nrf2/ARE signal pathway. Through studying the relationship between the activation of Nrf2/ARE signal pathway with myocardial apoptosis and changes of the related indexes, it is to discuss the role of Nrf2/ARE signal pathway in occurrence and development of diabetic cardiomyopathy(DCM).Methods:1. Type2diabetic cardiomyopathy model was established in Wistar rats.30male Wistar rats were randomly divided into normal control group (NC group, n=10) and high-sugar high-fat diet group (n=20). Fed for4weeks, the rats were fasted for10-12hours, and then, fasting blood glucose (FBG) were detected. At6week, the rats were administrated with streptozotocin (STZ,30mg/kg) once through enterocoelia, thus the rat type2diabetic cardiomyopathy model was established. One week later, the measured FBG was≥16.7mmol/L, suggesting the model was successful. Rats successfully established were divided into two groups:diabetic cardiomyopathy group (DCM group) and the intervention group (IV group, invention with CPDT of500umol/kg/d, phase Ⅱ enzyme inducer). The rats were continued to give high-sugar and high fat fodder, and CPDT for14days, then the experiment was ended.2. Blood of the rat heart was sampled for determination of FBG.3. After the second step, the heart was rapidly taken out, washed with isotonic saline, dried out by the filter paper and then weighted, to calculate the left ventricular mass index (LVMI).4. HE staining and Masson staining:tissue of the left ventricular free wall (LVFW) was taken, fixed conventionally, and embedded with paraffin, the size of the cardiomyocytes and its fibrosis were observed.5. Ultrastructural changes of the cardiomyocytes were observed under the transmission electro microscopy (TEM).6. TUNEL method was used to detect myocardial apoptosis index (AI).7. Western blot was used to detect the expression of heme HO-1、MDA、Nrf2in myocardial tissue.8. Statistical treatment:SPSS17.0was applied for statistical analysis, and the data was represented as mean±standard deviation (x±s). T-test was used to compare the mean independent sample between groups, while linear correlation analysis was for the related indexes. Inspection level was a=0.05, and P<0.05referred to statistical significance. Results:1. General information of the rat’s indicators:(1) Blood glucose:FBGs in DCM group and IV group were higher than that of the NC group (P< 0.01).(2) Body weight (BW):BWs in DCM group and IV group were significantly reduced, compared with the NC group (P<0.01).(3) Heart-body ration and the LVMI:Compared with the NC group (P<0.01), both of the two indexes were increased in the DCM group and IV group, and it was lesser in the Ⅳ group (P<0.01).2. HE staining:Sizes of the cardiomyocytes were increased in DCM group and Ⅳ group han the NC group(P<0.01).3.TUNEL:Diabetes group than the control group, AI was increased in the Ⅳ group (P<0.01), Intervention group and diabetes group. AI was To reduce in the IV group(P<0.01).4. TEM: Cardiomyocytes were normal in the NC group with rich myofilament, the cells were ranged closely and the mitochondria was normal; in TCM group, the cardiomyocytes became hypertrophy, myofilament was scattered, some of which even fractured or dissolved, and the mitochondria was swollen.5. Western blot:HO-1expression was reduced in DCM group than that in the NC group (P<0.01), and higher in Ⅳ group compared with the group(P<0.01); MDA expression was lower in DCM group than that in the NC group (P<0.01), and increased in Ⅳ group compared with the group (P<0.01); Nrf2expression was lower in DCM group than that in the NC group (P<0.01), and increased in Ⅳ group compared with the DCM group (P<0.01).Conclusion:CPDT (phase Ⅱ enzyme inducer) through activation of Nrf2/ARE increase the expression of Nrf2signaling pathways, inducing expression HO-1the expression of increase and decrease MDA,thus increasing the antioxidant ability of cardiomyocytes, which it plays an important role in the occurrence and development of diabetic cardiomyopathy (DCM).