Protection Of Acacetin Against Myocardial Senescence And Its Molecular Mechanism

Introduction:Senile cardiomyopathy is a degenerative disease in aging process of the elderly,which is one of important causes of heart failure and death.Myocardial senescence is a complex process,and current studies have shown that myocardial senescence is related to the decrease of myocardial mitochondrial autophagy(mitophagy)and the accumulation of damaged mitochondria.The purpose of this study was to investigate whether the natural flavone acacetin can alleviate myocardial senescence induced by D-galactose.Methods:The aging animal model was established in C57/BL6 mice by subcutaneous daily injection of D-galactose(150 mg/kg),acacetin(50 mg/kg)was employed by intragastric administration.The cardiac function were determined by echocardiography,the telomere length of myocardial tissue detected by PCR.Cellular senescence was induced in cultured H9C2 rat cardiomyoblasts by D-galactose(20 mg/mL)and the activity of β-galactosidase was detected by immunohistochemical staining and flow cytometry as an index of cell senescence.Mitochondrial membrane potential was detected by JC-1 staining.Western blots were employed to determine the proteins expression related to aging,mitophagy and their upstream signals.Moreover,gene silencing approach of small interfering RNA was used to explore the molecular mechanism of acacetin in alleviating myocardial aging.Results:Acacetin significantly improved the impaired heart function and the alteration of telomere length in aging mice and reduced the expression of heart tissue proteins related to aging such as p53,p21 in D-galactose-induced aging model of mice.Acacetin(0.3-3 μM)significantly alleviated the H9C2 cardiomyocyte senescence induced by Dgalactose in a concentration-dependent manner,It decreased the expression of p53,p21,p16,up-regulated the expression of mitochondrial autophagy-related proteins PINK1,Parkin,LC3II/LC3I and their upstream signal proteins Sirt6,pLKB and pAMPK,and restored the impaired mitochondrial membrane potential in aging cardiomyocytes.Moreover,both mitoghagy inhibitor 3-MA and silencing Sirt6 prevented the protective effect of acacetin against cardiomyocyte senescence induced by D-galactose.Conclusions:Acacetin significantly inhibits myocardial senescence induced by Dgalactose through activating Sirt6/AMPK signal pathway thereby reducing the injury of intracellular mitochondria,enhancing the mitophagy and reducing the accumulation of damaged mitochondria.This study suggests that acacetin may be a candidate for the treatment and prevention of senile cardiomyopathy.