Effect Of Paeonol On Diabetic Cardiomyopathy And Its Underlying Mechanism

Research background and purpose:Our country is experiencing an increase in diabetes morbidity rates recently.Diabetic cardiomyopathy(DCM)is a chronic complication of diabetes in the absence of other cardiac risk factors,such as coronary artery disease and hypertension.At the early stage of DCM,slight changes of cardiac structure are observed in diabetic hearts,while it gradually induce cardiac hypertrophy and fibrosis as well as cardiac dysfunction,eventually leading to heart failure.Therefore,it is of great significance to find effective therapeutic drugs for the treatment of DCM.Paeonol,a bioactive monomer isolated from a traditional chinese herbal medicine called Cortex Moutan,has been proven to exert anti-oxidant,anti-tumorigenic,anti-inflammatory,cardioprotective and calcium-regulating effects.However,the effects of paeonol on DCM are still unclear.This study was designed to explore the efficacy of paeonol on diabetic cardiomyopathy and its mechanism.Methods:1.The effect of paeonol on cellular damage caused by high glucose in vitro The primary cardiomyocytes were incubated with 33m M high glucose medium or high glucose with paeonol(100 μM)medium respectively,which were indicated as the high glucose(HG)group and high glucose with paeonol(HG-Pae)group.Apoptosis was measured by flow cytometry.Mito-Tracker Red and Mito-Tracker Sox were used to stain mitochondria.Mitochondrial morphology and oxidative stress were photographed by laser confocal microscope.Western Blotting was used to assess the expression of mitochondrial fusion and fision proteins.Mitochondrial oxidative capacity was assessed to evaluate mitochondrial function.2.Opa1 was knocked down and overexpressed in the cardiomyocytes respectively to investigate the mechanism of reduced cellular damage by paeonol Opa1 was knocked down by Opa1 RNA interference in primary cardiomyocytes to explore the effect of Opa1 knockdown on paeonol protection.The effects of Opa1 overexpression on mitochondrial morphology and oxidative stress under high glucose environment were explored.3.The effect of paeonol on diabetic cardiomyopathy(DCM)in vivo Type 1 diabetic cardiomyopathy was induced by streptozotocin(STZ)in Sprague Dawley rats.Diabetic rats were treated with paeonol at low,medium and high doses(75,150,300mg/kg/d),respectively.After 12 weeks of feeding,cardiac function was evaluated by echocardiography and hemodynamics.Cardiac hypertrophy,fibrosis,oxidative stress and myocardial apoptosis were measured by WGA,Masson,DHE,TUNEL respectively.Serum biochemistry,mitochondrial morphology and oxidative stress were detected.Mitochondrial fusion and fission protein expression was measured by Western Blotting.The level of ATP and the expression of mitochondrial respiratory chain compound protein was determinated to evaluate the function of mitochondria.Results:1.The rate of apoptosis and mitochondria-derived superoxide production were significantly increased in HG-treated cardiomyocytes.Moreover,HG inhibited while Opa1-mediated mitochondrial fusion and caused mitochondrial dysfunction in the cardiomyocytes.2.Silencing Opa1 expression blunted the promoting effect of paeonol on mitochondrial fusion and blocked the inhibitory effect of paeonol on mitochondrial oxidative stress in HG-treated cardiomyocytes.Upregulation of Opa1 promoted mitochondrial fusion and inhibited mitochondrial oxidative stress in HG-treated cardiomyocytes.3.There were increased blood glucose,plasma total cholesterol(TC)and triacylglycerol(TG)and decreased body weight in diabetic animals.Diabetic rats showed significant cardiac hypertrophy,fibrosis,myocardial apoptosis,oxidative stress,and cardiac dysfunction.Opa1-mediated mitochondrial fusion was inhibited in diabetic hearts.Paeonol treatment reduced plasma TC and inhibited cardiac hypertrophy,fibrosis,myocardial apoptosis,oxidative stress in diabetic rats.Moreover,paeonol treatment increased the expression of Opa1 and inhibited mitochondrial fisson,in diabetic hearts.Conclusions:Paeonol alleviates the development of diabetic cardiomyopathy,and its mechanism may be through promoting mitochondrial fusion and improving mitochondrial function in an Opa1-dependent way.