Study On The Effect And Mechanism Of Shengmaisan On Myocardial Autophagy In Type 2 Diabetes

Objectives:Effective clearance of damaged organelles and proteins by autophagy is critical to the cellular health.Cumulative evidences have demonstrated that autophagy dysfunction is tightly associated with diabetes mellitus.Shengmai San is a compound and deemed as a typical reinforcing Qi and nourishing Yin recipe.Our previous studies have shown that Shengmai San restored ventricular and mitochondrial function in type 2 diabetic mice.In the present study,we will investigate the exact relationships between autophagy and diabetic cardiomyopathy(DCM).And also,we will explore whether the protective effects of Shengmai San on diabetic hearts were involved in the regulation of autophagic homeostasisMethods:In vivo study,male Leptin receptor-deficient db/db mice were utilized,the db/db mice were administrated with distilled water or different dosages of Shengmai san for 4 weeks by intragastric gavage,and their lean age-matched C57BLKS mice served as non-diabetic control group and received with distilled water.To investigate the effects of Shengmai san on DCM,serum glucose and lipid levels,heart structure,myocardial function and heart weight to tibia length ratio were detected respectively.To determine the roles of Shengmai San in energy metabolism,myocardial ATP,ADP and AMP contents were assessed by HPLC.In vitro study,the high glucose and palmitic acid-stimulated H9C2 cardiomyocytes model was established.The cellular viability,cellular and mitochondrial ROS levels were detected by CCK8 assay,DCFH-DA and Mito-SOX fluorescence incubation.Additionally,we also explored the changes of autophagy homeostasis in vivo and vitro using TEM,western blotting and adenovirus GFP-RFP-LC3 ? transfection.Results:Db/db mice exhibited obviously obesity,hyperglycemia,hyperlipidemia,myocardial hypertrophy and ventricular dysfunction.Treatment with Shengmai San contributed to a recovery of diabetes induced myocardial hypertrophy and diastolic dysfunction.Furthermore,Shengmai San markedly inhibited hyperlipidemia and energy metabolic disorder in diabetic mice.We also found that administration with Shengmai San preserved the cellular viability and alleviated oxidative stress in high glucose and palmitic acid-stimulated H9C2 cardiomyocytes model.Based on above findings,we further explored the role of Shengmai san in myocardial autophagy.The results shown that Shengmai San restored mitochondrial structure and decreased the accumulation of autophagosomes and autolysosomes in diabetic myocardium.Treatment with Shengmai San also reversed the changes of autophagy related proteins,the more importantly,the disorder autophagy flux in high glucose and palmitic acid-stimulated H9C2 cardiomyocytes was obviously improved by Shengmai San supplementary.Conclusions:Our data indicates that Shengmai San may alleviate diabetes-induced myocardial hypertrophy and diastolic dysfunction by improving autophagic homeostasis.The regulation of AMPK/mTOR dependent autophagic pathway was partly involved in the cardiac-protection of Shengmai san.