Attenuation of myocardial apoptosis by alpha-lipoic acid through suppression of mitochondrial oxidative stress to reduce diabetic cardiomyopathy

Background Cardiac failure is a leading cause of the mortality of diabetic patients. In part this is due to a specific cardiomyopathy, referred to as diabetic cardiomyopathy. Oxidative stress is widely considered to be one of the major factors underlying the pathogenesis of the disease. This study aimed to test whether the antioxidant α-lipoic acid （α-LA） could attenuate mitochondrion-dependent myocardial apoptosis through suppression of mitochondrial oxidative stress to reduce diabetic cardiomyopathy. Methods A rat model of diabetes was induced by a single tail intravenous injection of streptozotocin （STZ） 45 mg/kg. Experimental animals were randomly assigned to 3 groups： normal control （NC）, diabetes （DM） and DM treated with α-LA （α-LA）. The latter group was administered with a-LA （100 mg/kg ip per day）, the remainder received the same volume vehicle. At weeks 4, 8, and 12 after the onset of diabetes, cardiac apoptosis was examined by TUNEL assay. Cardiomyopathy was evaluated by assessment of cardiac structure and function. Oxidative damage was evaluated by the content of malondialdehyde （MDA）, reduced glutathione （GSH） and the activity of manganese superoxide diamutase （Mn-SOD） in the myocardial mitochondria. Expression of caspase-9 and caspase-3 proteins was determined by immunohistochemistry and mitochondrial cytochrome c release was detected by Western blotting Results At 4, 8, and 12 weeks after the onset of diabetes, significant reductions in TUNEL-positive cells, caspase-9,-3 expression, and mitochondrial cytochrome c release were observed in the α-LA group compared to the DM group. In the DM group, the content of MDA in the myocardial mitochondria was significantly increased, and there was a decrease in both the mitochondrial GSH content and the activities of Mn-SOD. They were significantly improved by α-LA treatment. HE staining displayed structural abnormalities in diabetic hearts, while α-LA reversed this structural derangement. The index of cardiac function （±dp/dtmax） in the diabetes group was aggravated progressively from 4 weeks to 12 weeks, but α-LA delayed deterioration of cardiac function （P 〈0.05）. Conclusions Our findings indicate that the antioxidant α-LA can effectively attenuate mitochondria-dependent cardiac apoptosis and exert a protective role against the development of diabetic cardiomyopathy. The ability of α-LA to suppress mitochondrial oxidative damage is concomitant with an enhancement of Mn-SOD activity and an increase in the GSH content of myocardial mitochondria.

Inhibitory Effect of Tetramethylpyrazine Preconditioning on Overload Training-Induced Myocardial Apoptosis in Rats

Objective： To investigate the inhibitory effect of tetramethylpyrazine （Tot） preconditioning on overload training-induced myocardial apoptosis in rats, and to explore cardioprotective mechanisms of Tot preconditioning. Methods： A total of 25 male Sprague-Dawley rats were randomly divided into three groups, including the control group （n=5）, the ovedoad training group （overload training for 8 weeks, n=10）, and the Tet preconditioning group （Tet preconditioning for 8 weeks before overload training, n=10）. After 8 weeks, cardiac structure and myocardial apoptosis were analyzed by histology, transmission electron microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay staining. The expressions of Bcl-2, Bax, Caspase-3, and Caspase-9 in myocardium were evaluated by immunohistochemical staining. Results： Overload training caused swelling, disorder, partial rupture, and necrosis of myocardial focal necrotic fibers, as well as mitochondrial vacuolization, cristae rupturing, and blurring. In contrast, Tet preconditioning attenuated the swelling of myocardial fibers, decreased the amount of ruptured fibers, and inhibited mitochondrial vacuolization, resulting in clear cristae. Overload training significantly increased Bax expression and decreased Bcl-2/Bax ratio when compared with the control group （P〈0.01）. Conversely, Tot preconditioning significantly increased Bcl-2 expression and the Bcl-2/Bax ratio as compared with the overload training group （P〈0.05）. Overload training dramatically increased the expressions of Caspase-3 and Caspase-9 when compared with the control group （P〈0.05）. Following Tot preconditioning, the expression of Caspase-3 was significantly reduced compared with the overload training group （P〈0.05）, while Caspase-9 expression showed a slight decline （P〉0.05）. Conclusion： let preconditioning increased the expression of Bcl-2 and reduced the expression of Caspase-3, thereby attenuating overload training-induced myocardial apoptosis, protecting against overload training-induced myocardial injury, and reducing damage to the myocardium due to overload training.

Experimental study of miRNA-210 modified MSCs in the treatment of myocardial ischemia-reperfusion injury in rats

Objective:To investigate the therapeutic effect of microRNA210(miRNA-210)modified mesenchymal stem cells(MSCs)on myocardial ischemia-reperfusion injury(MIRI)model rats.Methods:One SD rat was sacrificed,and the lower extremity tibia and femur were isolated.MSCs were cultured by whole bone marrow adherence method to construct miRNA-210 modified MSCs.40 SD rats were divided into the sham operation group,model group,MSCs group,and miRNA-210+MSCs group,with 10 rats in each group.The left anterior descending coronary artery was ligated to prepare a model of myocardial ischemia and reperfusion.After successful modeling,50μl of MSCs suspension was injected into the tail vein of the MSCs group,and 50μl of miRNA-210 modified MSCs suspension was injected into the tail vein of the miRNA-210+MSCs group.The sham operation group and the model group were injected with the same amount of normal saline.On the 10th day after modeling,the area of myocardial infarction,morphological changes of myocardial tissue,myocardial cell apoptosis rate,and miRNA-210 expression were compared in each group.Results:The area of myocardial infarction and the rate of myocardial cell apoptosis in the model group were significantly higher than those in the sham operation group(<0.05);The area of myocardial infarction and the rate of myocardial cell apoptosis in the MSCs group were significantly lower than those in the sham operation group(P<0.05);The area of myocardial infarction and the rate of myocardial cell apoptosis in the miRNA-210+MSCs group were significantly higher than those in the MSCs group(P<0.05);The area of myocardial infarction and the rate of myocardial cell apoptosis in the miRNA-210+MSCs group were significantly lower than those in the sham operation group(P<0.05).The expression level of miRNA-210 in the myocardial tissue of the model group was significantly higher than that in the sham operation group(P<0.05);There were no significantly different in the expression level of miRNA-210 in the myocardial tissue between the MSCs group and model group(P>0.05);The expression level of miRNA-210 in the myocardial tissue of MSCs group was significantly higher than in the MSCs group,model group and sham operation group(P<0.05).HE staining showed that the miRNA-210+MSCs group had normal morphology of myocardial tissues,more uniform cytoplasmic staining,and arranged neatly myocardial fibers.The inflammatory cell infiltration and interstitial edema of the miRNA-210+MSCs group were significantly improved compared with the model group and MSCs group.Conclusion:MiRNA-210 modified MSCs can inhibit myocardial cell apoptosis in myocardial ischemia-reperfusion injury model rats,reduce the area of myocardial infarction,and improve pathological damage of myocardial tissue in rats,which has a certain therapeutic effect on myocardial ischemia-reperfusion injury.

Research progress on pharmacological action and mechanism of injection Yiqi Fumai lyophilized injection in treating cardiomyopathy

The pharmacological studies of Yiqi Fumai lyophilized injection in cardiovascular system mainly include anti-cardiac failure,improvement of myocardial ischemia,improvement of myocardial hypertrophy and myocardial injury caused by ischemia and hypoxia.In recent years,a large number of studies have shown that Yiqi Fumai Lyophilized Injection has good protective effects on myocardial injury caused by ischemia and hypoxia by enhancing myocardial contractility and delaying ventricular remodeling.

Role of mitochondrial damage during cardiac apoptosis in septic rats

Background Myocardial apoptosis is involved in the pathogenesis of sepsis-related myocardial depression. However, the underlying mechanism remains unknown. This study investigated the role of mitochondrial damage and mitochondria-induced oxidative stress during cardiac apoptosis in septic rats. Methods Seventy-two Sprague-Dawley rats were randomly divided into a control group and septic group receiving lipopolysaccharide injection. Heart tissue was removed and changes in cardiac morphology were observed by light microscopy and scanning electron microscopy. In situ apoptosis was examined using terminal transferase-mediated dUTP nick end-labeling assay and nuclear factor-kappa B activation in myocardium by Western blotting to estimate myocardial apoptosis. Appearance of mitochondrial cristae and activation of cytochrome C oxidase were used to evaluate mitochondrial damage. Oxidative stress was assessed by mitochondrial lipid and protein oxidation, and antioxidant defense was assessed by mitochondrial superoxide dismutase and glutathione peroxidase activity. Results Sepsis-induced inflammatory cell infiltration, myocardium degeneration and dropsy were time-dependent. Expanded capillaries were observed in the hearts of infected rats 24 hours post-challenge. Compared with sham-treated rats, the percentage of cell apoptosis increased in a time-dependent manner in hearts from septic rats at 6 hours, 12 hours and 24 hours post-injection （P 〈 0.05）. The expression of nuclear factor-kappa B p65 decreased gradually in the cytosol and increased in the nucleus during sepsis, indicating that septic challenge provoked the progressive activation of nuclear factor-kappa B. Mitochondrial cristae and activation of cytochrome C oxidase increased in a time-dependent manner. Both superoxide dismutase and glutathione peroxidase activities decreased, while mitochondrial lipid and protein oxidation increased between 6 and 24 hours after lipopolysaccharide challenge. Conclusions Septic challenge induced myocardial apoptosis and mitochondrial damage. Furthermore, mitochondrial damage via alteration of defenses against reactive oxygen species might play an important role in myocardial apoptosis during sepsis.

Xuefu Zhuyu Oral Liquid (血府逐瘀口服液) Prevents Apoptosis of Ischemic Myocardium Cells in Rats by Regulating SIRT1 and Its Pathway-Related Genes

Objective:To observe the changes of ischemic myocardial cells apoptosis in rats following intervention with Xuefu Zhuyu Oral Liquid(血府逐瘀口服液,XFZY),as well as changes of protein expression of silent information regulator 1(SIRT1)and SIRT1 pathway-related genes.Methods:H9c2 rat myocardial cells were divided into 6 groups:control group,oxygen glucose deprivation(OGD)group,SIRT1 siRNA group,OGD+SIRT1 siRNA group,OGD+XFZY group,and OGD+SIRT1 siRNA+XFZY group.Quantitative fluorescent polymerase chain reaction(PCR)and Western blot were used to detect the concentration variations of SIRT1 and its pathway-related genes and corresponding protein expression after XFZY intervention and SIRT1 transfection.Results:Compared with the control group,the mRNA and protein expressions of SIRT1 were decreased obviously,while the mRNA and protein levels of P53,forkhead box protein O1(FoxO1),FoxO3,FoxO4 and nuclear factor kappa B(NF-κB)were increased in the OGD group,SIRT1 siRNA group,and OGD+SIRT1 siRNA group(P<0.01).Compared with the OGD group and OGD+SIRT1 siRNA group,the treatment of XFZY inhibited the decline in SIRT1 mRNA and protein expressions(P<0.01),and down-regulated the mRNA and protein levels of P53,FoxO1,FoxO3,FoxO4 and NF-κB,respectively(P<0.05 or P<0.01).Conclusion:XFZY could prevent myocardial cells apoptosis probably by increasing the mRNA and protein expressions of SIRT1 and inhibiting the mRNA and protein expressions of P53,NF-κB,FoxO1,FoxO3 and FoxO4.