Myocardial Oxidative Stress Injury Research Articles

Upregulation of mitochondrial fusion as potential cardioprotective strategies against trastuzumab-induced cardiotoxicity in rats

Abstract Background Trastuzumab (TRZ) is a commonly used chemotherapeutic drug for treating advanced malignancies that express human epidermal growth factor receptor type 2. However, TRZ has been linked with cardiotoxicity, which is an unfavourable clinical side effect of cancer treatment. Alterations in mitochondrial dynamic mechanisms, particularly reduced fusion, have been shown to be a key mechanistic insight into the progression of chemotherapy-induced cardiotoxicity. Despite the cardioprotective benefits of a mitochondrial fusion promoter (M1) that have been established in various cardiovascular settings, its ability to counteract the cardiotoxicity caused by TRZ remains unknown. Purpose To examine the effect of M1 treatment on mitochondrial fusion, myocardial oxidative stress, apoptosis, and cardiac injury biomarker in TRZ-induced cardiotoxicity rats. Methods Male Wistar rats (n=18) were divided into the TRZ group (4 mg/kg/day for 7 days, I.P., n=12) and the control group (CON, n=6). In the TRZ group, at the time of first TRZ injection all rats also received the intervention with either the vehicle injection (VEH, n=6) or M1 (M1, 2 mg/kg/day, n=6) via I.P. injection for 7 days. The left ventricular ejection fraction (LVEF) was measured using echocardiography, and troponin-I levels were determined using blood serum. Then, the cardiac tissue was processed to assess the levels of malondialdehyde (MDA) for oxidative stress, mitochondrial fusion, and apoptotic proteins. Results TRZ induced cardiotoxicity via downregulation of mitochondrial fusion along with upregulation of myocardial oxidative stress and apoptosis, as indicated by decreasing Mfn1 protein expression and increasing the levels of MDA and Bax to Bcl-2 ratio, respectively (Fig. 1A, B, C, and E). TRZ also showed markedly higher levels of serum Troponin-I (Fig. 1D) and impaired LV function (77% LVEF for TRZ vs. 89% LVEF for CON). M1 co-treatment promoted Mfn1-mediated mitochondrial fusion, resulting in a reduction in MDA-associated oxidative stress, apoptosis, Troponin-I, and cardiac dysfunction (16% improvement over the TRZ group) (Fig. 1A-E). Conclusion M1 effectively protected the heart against TRZ-induced cardiotoxicity by promoting mitochondrial fusion and preventing oxidative stress and apoptosis-mediated myocardial injury. These findings suggest that the pharmacological promotion of mitochondrial fusion could be a novel anti-cardiotoxicity strategy in TRZ-induced cardiotoxicity.

Ahf-Caltide, a Novel Polypeptide Derived from Calpastatin, Protects against Oxidative Stress Injury by Stabilizing the Expression of CaV1.2 Calcium Channel.

Reperfusion after ischemia would cause massive myocardial injury, which leads to oxidative stress (OS). Calcium homeostasis imbalance plays an essential role in myocardial OS injury. CaV1.2 calcium channel mediates calcium influx into cardiomyocytes, and its activity is modulated by a region of calpastatin (CAST) domain L, CSL54-64. In this study, the effect of Ahf-caltide, derived from CSL54-64, on myocardial OS injury was investigated. Ahf-caltide decreased the levels of LDH, MDA and ROS and increased heart rate, coronary flow, cell survival and SOD activity during OS. In addition, Ahf-caltide permeated into H9c2 cells and increased CaV1.2, CaVβ2 and CAST levels by inhibiting protein degradation. At different Ca2+ concentrations (25 nM, 10 μM, 1 mM), the binding of CSL to the IQ motif in the C terminus of the CaV1.2 channel was increased in a H2O2 concentration-dependent manner. CSL54-64 was predicted to be responsible for the binding of CSL to CaV1.2. In conclusion, Ahf-caltide exerted a cardioprotective effect on myocardial OS injury by stabilizing CaV1.2 protein expression. Our study, for the first time, proposed that restoring calcium homeostasis by targeting the CaV1.2 calcium channel and its regulating factor CAST could be a novel treatment for myocardial OS injury.

Development of a Golgi-targeted superoxide anion fluorescent probe for elucidating protein GOLPH3 function in myocardial ischemia-reperfusion injury

Superoxide anion (O2•-) is an important reactive oxygen species (ROS) and participates in various physiological and pathological processes in the organism. The O2•- burst induced by ischemia-reperfusion (I/R) is associated with cardiovascular disease and promotes the cell apoptosis. In this work, a turn-on type Golgi-targeting fluorescent probe Gol-Cou-O2•- was rationally designed for sensitive and selective detection of O2•-. The minimum detection limit concentration for O2•- was about 3.9 × 10−7 M in aqueous solution. Gol-Cou-O2•- showed excellent capacity of detecting exogenous and endogenous O2•- in living cells and zebrafish, and was also used to capture the up-regulated O2•- level during the duration of I/R process in cardiomyocytes. Golgi Phosphoprotein 3 (GOLPH3) is a potential Golgi stress marker protein and plays a key role in cells apoptosis during I/R. The fluorescence imaging and flow cytometry assay results indicated that silencing GOLPH3 through siRNA could give rise to the down-regulated O2•- level and alleviation of apoptosis in I/R myocardial cells. Thus, development of Gol-Cou-O2•- provides a diagnostic tool for myocardial oxidative stress injury and distinct insights on roles of GOLPH3 in myocardial I/R injury.

MiR-340-5p Alleviates Oxidative Stress Injury by Targeting MyD88 in Sepsis-Induced Cardiomyopathy.

Background Sepsis-induced cardiomyopathy (SIC) is a sort of severe disease in the intensive care unit. This research focuses on exploring the influence of miR-340-5p on SIC and its specific mechanism. Methods Mice were administered with lipopolysaccharide (LPS) to construct a SIC animal model. Mice were intramyocardially injected with Adenoassociated Virus- (AAV-) 9 containing the miR-340-5p precursor to make the miR-340-5p overexpression in the myocardium. The expression level of myocardial miR-340-5p was evaluated by qRT-PCR. The cardiac function was measured by echocardiography, the myocardial morphology was observed by hematoxylin-eosin (HE) staining, and the oxidative stress level was detected by 4-hydroxynonenal (4-HNE) immunohistochemical staining and malondialdehyde (MDA) assay in mice. The cells were pretreated with miR-340-5p mimic, mimic-NC, miR-340-5p inhibitor, inhibitor-NC, MyD88 siRNA, or si-NC and then administered with LPS or PBS. The cell viability was measured with the CCK-8 assay. The level of intracellular oxidative stress was evaluated using reactive oxygen species (ROS), MDA, and glutathione (GSH) detection. The MyD88 level was assessed via Western blotting analysis. The interaction of miR-340-5p with the MyD88 mRNA was confirmed via dual-luciferase reporter assay and RNA pull-down assay. Results The miR-340-5p overexpression partially alleviated the increase of the MyD88 level, impairment of cardiac function, and oxidative stress injury in the SIC animal model. In the SIC cell model, miR-340-5p mimic pretreatment partially relieved oxidative stress injury, while the miR-340-5p inhibitor had the opposite effect. Besides, the miR-340-5p mimic and inhibitor could reduce and further increase the MyD88 level in the SIC cell model, respectively. Dual-luciferase reporter and RNA pull-down experiments confirmed the interaction between the MyD88 mRNA and miR-340-5p. Finally, it was found that MyD88 siRNA pretreatment also partially alleviates the oxidative stress injury in the SIC cell model. Conclusion In sum, our study demonstrated that miR-340-5p can improve myocardial oxidative stress injury by targeting MyD88 in SIC.

Lycopene Regulates Dietary Dityrosine-Induced Mitochondrial-Lipid Homeostasis by Increasing Mitochondrial Complex Activity.

Dityrosine (DT), a marker of protein oxidation, is widely found in many high-protein foods. Dietary intake of DT induces myocardial oxidative stress injury and impairs energy metabolism. Lycopene is a common dietary supplement with antioxidant and mitochondrial-lipid homeostasis modulating abilities. This study aimed to examine the effects of lycopene on DT-induced disturbances in myocardial function and energy metabolism. Four-week-old C57BL/6J mice received intragastric administration of either tyrosine (420µg kg-1 BW), DT (420µg kg-1 BW), or lycopene at high (10mg kg-1 BW) and low (5mg kg-1 BW) doses for 35 days. Lycopene administration effectively reduced oxidative stress, cardiac fatty acid accumulation, and cardiac hypertrophy and improved mitochondrial performance in DT-induced mice. In vitro experiments in H9c2 cells showed that DT directly inhibited the activity of the respiratory chain complex, whereas oxidative phosphorylation and β-oxidation gene expression is upregulated. Lycopene enhanced the activity of the complexes and inhibited ROS production caused by compensatory regulation. Lycopene improves DT-mediated myocardial energy homeostasis disorder by promoting the activity of respiratory chain complexes I and IV and alleviates the accumulation of cardiac fatty acids and myocardial hypertrophy.

Downregulation of miR-181a-5p alleviates oxidative stress and inflammation in coronary microembolization-induced myocardial damage by directly targeting XIAP.

BACKGROUNDCoronary microembolization (CME) is a complicated problem that commonly arises in the context of coronary angioplasty. MicroRNAs play crucial roles in cardiovascular diseases. However, the role and mechanism of miR-181a-5p in CME-induced myocardial injury remains unclear.METHODSWe established CME rat models. Cardiac function was detected by echocardiography. Haematoxylin-basic fuchsin-picric acid staining was used to measure micro-infarction size. Serum samples and cell culture supernatants were evaluated via enzyme-linked immunosorbent assay. Cellular reactive oxygen species were determined by dichloro-dihydro-fluorescein diacetate assay, and the other oxidative stress related parameters were assayed by spectrophotometry. The dual-luciferase reporter (DLR) assay and RNA pulldown were conducted to validate the association between miR-181a-5p and X-linked inhibitor of apoptosis protein (XIAP). The expression of miR-181a-5p and XIAP mRNA were determined by quantitative reverse transcription polymerase chain reaction. Proteins were evaluated via immunoblotting. The viability of the cell was evaluated via cell counting kit-8 assay.RESULTSThe miR-181a-5p level was significantly increased in CME myocardial tissues. Downregulation of miR-181a-5p improved CME-induced cardiac dysfunction and alleviated myocardial oxidative stress and inflammatory injury, whereas miR-181a-5p exhibited the opposite effects. Then, the DLR assay and RNA pulldown results revealed that miR-181a-5p directly targeting on XIAP. The XIAP level was found to be remarkably decreased after CME. XIAP overexpression attenuated CME-induced myocardial oxidative stress and inflammatory injury. Finally, in vitro rescue experiments revealed that knockdown of XIAP could abolish the protective effects of miR-181a-5p knockdown on hypoxia-induced cardiomyocyte oxidative stress and inflammatory injury. CONCLUSIONSDownregulation of miR-181a-5p alleviates CME-induced myocardial damage by suppressing myocardial oxidative stress and inflammation through directly targeting XIAP.

Attenuation of the Na/K‑ATPase/Src/ROS amplification signaling pathway by astaxanthin ameliorates myocardial cell oxidative stress injury.

The 3S, 3′S-ASTaxanthin (3S, 3′S-AST) isomer has strong antioxidant activity; however, its protective roles and potential mechanisms against oxidative stress damage in cardiomyocytes have not been investigated. Na+/K+-ATPase (NKA)/Src signal activation has an important role in increasing reactive oxygen species (ROS) production. The aim of the present study was to investigate the protective effects and mechanism of 3S, 3′S-AST on hydrogen peroxide (H2O2)-induced oxidative stress injury in H9c2 myocardial cells. The protective effects of 3S, 3′S-AST on H2O2-induced H9c2 cell injury was observed by measuring lactate dehydrogenase and creatine kinase myocardial band content, cell viability and nuclear morphology. The antioxidant effect was investigated by analyzing ROS accumulation and malondialdehyde, glutathione (GSH) peroxidase, GSH and glutathione reductase activity levels. The protein expression levels of Bax, Bcl-2, caspase-3 and cleaved caspase-3 were analyzed using western blotting to determine cardiomyocyte apoptosis. Western blot analysis of the phosphorylation levels of Src and Erk1/2 were also performed to elucidate the molecular mechanism involved. The results showed that 3S, 3′S-AST reduced the release of LDH and promoted cell viability, and attenuated ROS accumulation and cell apoptosis induced by H2O2. Furthermore, 3S, 3′S-AST also restored apoptosis-related Bax and Bcl-2 protein expression levels in H2O2-treated H9c2 cells. The phosphorylation levels of Src and Erk1/2 were significantly higher in the H2O2 treatment group, whereas 3S, 3′S-AST pretreatment significantly decreased the levels of phosphorylated (p)-Src and p-ERK1/2. The results provided evidence that 3S, 3′S-AST exhibited a cardioprotective effect against oxidative stress injury by attenuating NKA/Src/Erk1/2-modulated ROS amplification.

Role of adiponectin in diabetes myocardial ischemia-reperfusion injury and ischemic postconditioning.

Purpose Patients with diabetes are vulnerable to myocardial I/R (ischaemia/reperfusion) injury, but are not responsive to IPO (ischaemic post-conditioning). We hypothesized that decreased cardiac Adiponectin (APN) is responsible for the loss of diabetic heart sensitivity to IPO cardioprotecton.Methods Diabetic rats were subjected to I/R injury (30 min of LAD occlusion followed by 120 min of reperfusion). Myocardial infarct area was determined by TTC staining. Cardiac function was monitored by a microcatheter. ANP, 15-F2t-isoprostane, nitrotyrosine and MDA were measured by assay kits. Levels of p-Akt, total-Akt and GAPDH were determined by Western Blot.Results Diabetic rats subjected to myocardial IR exhibited severe myocardial infarction and oxidative stress injury, lower APN in the plasma and cardiac p-Akt expression ( P <0.05). IPO significantly attenuated myocardial injury and up-regulated plasma APN content and cardiac p-Akt expression in non-diabetic rats but not in diabetic rats. Linear correlation analysis showed that the expression of adiponectin was positively correlated with p-Akt and negatively correlated with myocardial infarction area ( P <0.01).Conclusion Protective effect of IPO was tightly correlated with the expression of adiponectin, exacerbation of I/R injury and ineffectiveness of IPO was partially due to the decline of adiponectin and inactivation of Akt in diabetes mellitus.

LTBP2 knockdown by siRNA reverses myocardial oxidative stress injury, fibrosis and remodelling during dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is characterised by left ventricular dilation and associated with systolic dysfunction. Recent evidence has reported the high expression of latent transforming growth factor beta binding protein 2 (LTBP2) in heart diseases, which may play a role in regulating multiple biological functions of myocardial cells. Thus, this study set out to investigate the molecular mechanism and effects of LTBP2 in myocardial oxidative stress injury, fibrosis and remodelling in a rat model of DCM, with the involvement of NF-κB signalling pathway. The rat model of DCM was treated with si-LTBP2 and/or activator of NF-κB signalling pathway to examine the haemodynamic indexes, cardiac functions, oxidative stress injury, fibrosis and remodelling. Moreover, in vitro experiments were conducted to verify the regulatory role of LTBP2 and NF-κB signalling pathway in DCM. LTBP2 was up-regulated in DCM rats. After LTBP2 was knocked down, haemodynamic indexes, HW/BW ratio, collagen volume fraction (CVF) level, positive expression of LTBP2, levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), tumour necrosis factor beta 1 (TGF-β1) and brain natriuretic peptide (BNP) were all decreased. Meanwhile, levels of LTBP2, Col-I, Col-III, p65 and p52 were also reduced, while HW, BW and levels of SOD and TAOC were increased. In contrast, activation of NF-κB signalling pathway reversed effects of LTBP2 gene silencing. These findings were confirmed by in vivo experiments. LTBP2 silencing can attenuate myocardial oxidative stress injury, myocardial fibrosis and myocardial remodelling in DCM rats by down-regulating the NF-κB signalling pathway.

SGLT2 inhibition with empagliflozin attenuates myocardial oxidative stress and fibrosis in diabetic mice heart

BackgroundHyperglycaemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor has recently been reported to improve glycaemic control in patients with type 2 diabetes in an insulin-independent manner. The aim of this study was to investigate the effect of empagliflozin on myocardium injury and the potential mechanism in type 2 diabetic KK-Ay mice.MethodsThirty diabetic KK-Ay mice were administered empagliflozin (10 mg/kg/day) by oral gavage daily for 8 weeks. After 8 weeks, heart structure and function were evaluated by echocardiography. Oxidants and antioxidants were measured and cardiac fibrosis was analysed using immunohistochemistry, Masson’s trichrome stain and Western blot.ResultsResults showed that empagliflozin improved diabetic myocardial structure and function, decreased myocardial oxidative stress and ameliorated myocardial fibrosis. Further study indicated that empagliflozin suppressed oxidative stress and fibrosis through inhibition of the transforming growth factor β/Smad pathway and activation of Nrf2/ARE signaling.ConclusionsGlycaemic control with empagliflozin significantly ameliorated myocardial oxidative stress injury and cardiac fibrosis in diabetic mice. Taken together, these results indicate that the empagliflozin is a promising agent for the prevention and treatment of diabetic cardiomyopathy.

MicroRNA-98 attenuates cardiac ischemia-reperfusion injury through inhibiting DAPK1 expression.

Cardiovascular ischemic disease is a large class of diseases that are harmful to human health. The significant role of microRNAs (miRNAs) in terms of controlling cardiac injury has been reported in latest studies. MiR-98 is very important in regulating the apoptosis, the differentiation, the growth as well as the metastasis of cells. Nevertheless, the effect of miR-98 in the cardiac ischemia reperfusion (I/R) injury has rarely been investigated. In the current research, we found that the miR-98 expression was down-regulated in the cardiomyocytes subjected to hypoxia/reoxygenation (H/R) and in the myocardium of the I/R rats. In addition, over-expression of miR-98 could significantly reduce the myocardial oxidative stress and ischemic injury as well as cell apoptosis. In agreement, similar findings were demonstrated in H9c2 cells subjected to H/R injury. Bioinformatic analysis using MiRanda and TargetScan and luciferase activity assay confirmed death-associated protein kinase 1 (DAPK1) as a direct target of miR-98. These findings suggest that miR-98 may be exploited as a novel molecular marker or therapeutic target for myocardial I/R injury. © 2018 IUBMB Life, 71(1):166-176, 2019.

PO-086 Exercise enhances cardiac antioxidant capacity in diabetic rats through the Keap1/Nrf2 signaling pathway

Objective To investigate the effects of exercise on the myocardial oxidative stress injury of diabetic rats, and discussed the role of Keap1/Nrf2 signaling pathway in this process&#x0D; Methods Tyep 2 diabetic rat model was established by streptozotocin injection through abdominal cavity and high fat diet. The all the diabetic rats were divided into three groups: control group (NC), diabetes group(T2DM) and diabetes exercise group, NC and T2DM group were kept quiet for 8 weeks, T2DME group was trained for 8 weeks. After the exercise, weight, heart weight and blood were measured. MDA, T-SOD and GSH-PX enzyme were measured by biochemical method. Ho-1, Keap1, Nrf2 gene and protein expression were detected by RT-PCR and WesternBlotting.&#x0D; Results Compared with NC group, the weight of rats in the T2DM group significantly decreased [(528+/-71g vs 362+/-33g), P&lt;0.05], HWI significantly increased [(2.845+/-0.22 vs 3.841+/-0.21, P &lt;0.05], blood glucose was significantly increased [(6.4±3.8 vs 26±7.5mmol/L), P &lt;0.01],T-SOD and GSH-PX activity decreased significantly (P&lt;0.05), Ho-1 protein expression increased (P&lt;0.01), Keap1 and Nrf2 showed no significant changes, and Nrf2 nuclear transposition decreased (P&lt;0.05). Compared with the T2DM group, no significant change in body weight and heart weight in the T2DME group, with significant decrease in HWI[（3.841±0.21 vs 3.235±0.23），P＜0.05], with significant decrease in blood glucose [（26.0±7.5 vs 21.0±6.8），P＜0.05]. Ho-1 gene and protein expression increased significantly（P＜0.05and P＜0.01）, with no significant change of Keap1, while Nrf2 expression increased significantly (P &lt; 0.05), and Nrf2 nuclear transposition increased significantly (P &lt; 0.01).&#x0D; Conclusions Exercise activates the myocardial Keap1/Nrf2 signaling pathway in rats, promotes the expression of downstream antioxidant enzymes, increases cardiac antioxidant capacity, and resists diabetic myocardial oxidative stress injury.

Inhibition of CYP2E1 attenuates myocardial dysfunction in a murine model of insulin resistance through NLRP3-mediated regulation of mitophagy

Insulin resistance leads to myocardial contractile dysfunction and deranged autophagy although the underlying mechanism or targeted therapeutic strategy is still lacking. This study was designed to examine the impact of inhibition of the cytochrome P450 2E1 (CYP2E1) enzyme on myocardial function and mitochondrial autophagy (mitophagy) in an Akt2 knockout model of insulin resistance. Adult wild-type (WT) and Akt2−/− mice were treated with the CYP2E1 inhibitor diallyl sulfide (100 mg/kg/d, i.p.) for 4 weeks. Cardiac geometry and function were assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate autophagy, mitophagy, inducible NOS (iNOS), and the NLRP3 inflammasome, a multi-protein intracellular pattern recognition receptor complex. Akt2 deletion triggered insulin resistance, compromised cardiac contractile and intracellular Ca2+ property, mitochondrial ultrastructural damage, elevated O2– production, as well as suppressed autophagy and mitophagy, accompanied with elevated levels of NLRP3 and iNOS, the effects of which were significantly attenuated or ablated by diallyl sulfide. In vitro studies revealed that the NLRP3 activator nigericin nullified diallyl sulfide-offered benefit against Akt2 knockout on cardiomyocyte mechanical function and mitophagy (using Western blot and colocalization of GFP-LC3 and MitoTracker Red). Moreover, inhibition of iNOS but not mitochondrial ROS production attenuated Akt2 deletion-induced activation of NLRP3, substantiating a role for iNOS-mediated NLRP3 in insulin resistance-induced changes in mitophagy and cardiac dysfunction. In conclusion, these data depict that insulin resistance through CYP2E1 may contribute to the pathogenesis of myopathic changes including myocardial contractile dysfunction, oxidative stress and mitochondrial injury, possibly through activation of iNOS and NLRP3 signaling.

Effect of mild hypothermia on the oxidative stress induced myocardial injury after cardiopulmonary resuscitation

Objective To observe the effects of mild hypothermia on the myocardial mitochondrial injury induced by oxidative stress after restoration of spontaneous circulation (ROSC) in rat of cardiac arrest model. Methods Eighteen male Wistar rats were randomly(raudom number)divided into normal temperature group and mild hypothermia group after ROSC. Ultrasound was used to measure the left ventricular ejection fraction (EF), shortening fraction (FS) and stroke volume (SV). The levels of glutathione (GSH), malondialdehyde (MDA) and adenosine triphosphate (ATP) in myocardium were detected. The ultramicroscopic structure of myocardial mitochondria was observed under transmission electron microscope at 4 h after ROSC. Results There were no significant differences in basic life support (BLS) time, dosage of epinephrine and number of defibrillation attempt between two groups (P > 0.05). The concentrations of GSH and ATP in myocardium of rats in hypothermia group were significantly higher than those in normal temperature group, while the level of MDA was significantly lower in hypothermia group than that in normal temperature group. Echocardiographic findings showed that hypothermia could significantly improve the EF, FS and SV after ROSC. The hypothermia decreased the myocardial mitochondria injury rather than normothermia[mitochondrial injury score: (0.21±0.04) vs.( 0.42±0.08), P<0.05]. Conclusions In this model, mild hypothermia can decrease myocardial oxidative stress injury, improving the cardiac function after ROSC. Key words: Cardiac arrest; Cardio-pulmonary resuscitation; Mild hypothermia; Ventricular fibrillation; Cardiac function; Oxidative stress; Myocardial mitochondria; Rats

Activation of nuclear β-catenin/c-Myc axis promotes oxidative stress injury in streptozotocin-induced diabetic cardiomyopathy

Myocardial oxidative stress injury plays a crucial role in the pathogenesis of diabetic cardiomyopathy (DCM). Wnt/β-catenin signaling has been reported to involve in various heart diseases. However, the underlying mechanism associated with β-catenin in DCM remains elusive. This study intended to explore the effect of β-catenin on oxidative damage of DCM by establishing streptozotocin (STZ)-induced diabetic mouse model and hydrogen peroxide (H2O2)-treated myocardial cell model. Cardiac oxidative stress in DCM was detected by measurements of lipid peroxidation and anti-oxidative enzyme activities as well as DHE staining. Nuclear β-catenin activity and oxidative damage degree were measured by western blotting, qPCR, MTT assay and TUNEL staining. Cardiac function and morphology were evaluated by echocardiography and histopathology. Under diabetic oxidative stress or H2O2 stimulation, nuclear β-catenin accumulation upregulated downstream c-Myc and further facilitated DNA damage and p53-mediated apoptosis as well as cell viability reduction, followed by phenotypic changes of cardiac dysfunction, interstitial fibrosis deposition and myocardial atrophy. Conversely, through directly inhibiting nuclear β-catenin/c-Myc axis, not only did siRNA knockdown of β-catenin or c-Myc attenuate cell injury in H2O2-stimulated cardiomyocytes, but also diabetic cardiac-specific β-catenin-knockout mice displayed the same prevention of heart injury as insulin-treated diabetic mice. The present study demonstrated that activated nuclear β-catenin/c-Myc axis was responsible for oxidative cardiac impairment of DCM. Therefore, repressing functional nuclear β-catenin may provide a hopeful therapeutic strategy for DCM.

SIRT1 signaling pathway mediated the protective effects on myocardium of rats after endurance training and acute exhaustive exercise

Objective: To detect the expression of SIRT1 and Ac-FOXO1 in rats after endurance training and acute exhaustive exercise, and explicit the myocardial protective effect of SIRT1. Methods: Rats were randomly divided into four groups: control group(n=20), exhaustive exercise group (E group, n=20), exhaustive exercise group + endurance training (TE group, n=18), exhaustive exercise group + endurance training + selective SIRT1 inhibitor (TSE group, n=17). The Control and E groups were fed routinely for 5 weeks. The TE and TSE groups were subjected to swimming exercise for 5 weeks for endurance exercising. The TSE group was intraperitoneally injected with selective SIRT1 inhibitor Sirtinol(2 mg/kg) at 30 minutes before endurance exercising. The E, TE and TSE groups were subjected to exhaustive exercise. The myocardial tissues of rats were collected after exhaustive exercise. Real-time polymerase chain reaction (PCR) and Western blot analysis were performed to detect the myocardial mRNA and protein expressions of SIRT1 and Ac-FOXO1. The myocardial protein expression of Bax and Bcl-2 was also detected by Western blot. Terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) assay was used to assess the apoptosis of myocardial cells. Results: Compared with Control group, the SIRT1 and Bcl-2 expression in the myocardial tissue was obviously decreased, while the Ac-FOXO1, Bax, and the myocardial cell apoptosis were significantly increased in E group (all P<0.01). Compared with E group, the expression of SIRT1 and Bcl-2 was obviously up-regulated (both P<0.01), while the Ac-FOXO, Bax and the myocardial cell apoptosis was significantly reduced in TE group (all P<0.01). Compared with TE group, the SIRT1 and Bcl-2 expression was obviously lower (both P<0.01), while Ac-FOXO1, Bax, and the cell apoptosis were significantly higher in group TSE (all P<0.01). Conclusion: Endurance training could protect myocardium by reducing the myocardial oxidative stress injury and apoptosis via activating SIRT1 signaling pathway, up-regulating the myocardial expression of SIRT1 and regulating the deacetylation of FOXO1.

Effects of sevoflurane postconditioning on myocardial oxidative stress in patients undergoing cardiac valve replacement with cardiopulmonary bypass

Objective To evaluate the effects of sevoflurane postconditioning on myocardial oxidative stress in the patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB).Methods Fifty ASA physical status Ⅱ or Ⅲ patients (NYHA Ⅱ or Ⅲ) of both sexes,aged 36-59 yr,weighing 42-71 kg,with rheumatic heart disease undergoing cardiac valve replacement under CPB,were randomly divided into control group (group C,n =25) and sevoflurane postconditioning group (group S,n =25).In group S,4 ％ sevoflurane was infused for 10 min via the extracorporeal circulation machines starting from the time point immediately after aortic unclamping.Before aortic clamping and at 15 min,30 min,6 h,and 24 h after aortic unclamping (T1-5),blood samples were collected from the central vein for determination of the levels of cardiac troponin I (cTnI) in plasma.Myocardial specimens were taken from the left auricle before CPB and after termination of CPB for determination of malondialdehyde (MDA) content and superoxide dismutase (SOD) activity.The restoration of spontaneous heart beat,reperfusion arrhythmia scores,and requirement for vasoactive drugs were recorded.Results Compared with group C,MDA content was significantly decreased,and SOD activity was increased after termination of CPB,the plasma cTnI concentration was decreased at T2-5,the rate of restoration of spontaneous heart beat was increased,reperfusion arrhythmia scores were decreased,and the requirement for dopamine and nitroglycerin was reduced in group S.Conclusion Sevoflurane postconditioning provides myocardial protection by reducing myocardial oxidative stress injury in the patients undergoing cardiac valve replacement with CPB. Key words: Oxidative stress ; Myocardium ; Sevoflurane

Relationship between post-cardiac arrest myocardial oxidative stress and myocardial dysfunction in the rat.

BackgroundReperfusion after resuscitation from cardiac arrest (CA) is an event that increases reactive oxygen species production leading to oxidative stress. More specifically, myocardial oxidative stress may play a role in the severity of post-CA myocardial dysfunction. This study investigated the relationship between myocardial oxidative stress and post-CA myocardial injury and dysfunction in a rat model of CA and cardiopulmonary resuscitation (CPR). Ventricular fibrillation was induced in 26 rats and was untreated for 6 min. CPR, including mechanical chest compression, ventilation, and epinephrine, was then initiated and continued for additional 6 min prior to defibrillations. Resuscitated animals were sacrificed at two h (n = 9), 4 h (n = 6) and 72 h (n = 8) following resuscitation, and plasma collected for assessment of: high sensitivity cardiac troponin T (hs-cTnT), as marker of myocardial injury; isoprostanes (IsoP), as marker of lipid peroxidation; and 8-hydroxyguanosine (8-OHG), as marker of DNA oxidative damage. Hearts were also harvested for measurement of tissue IsoP and 8-OHG. Myocardial function was assessed by echocardiography at the corresponding time points. Additional 8 rats were not subjected to CA and served as baseline controls.ResultsCompared to baseline, left ventricular ejection fraction (LVEF) was reduced at 2 and 4 h following resuscitation (p < 0.01), while it was similar at 72 h. Inversely, plasma hs-cTnT increased, compared to baseline, at 2 and 4 h post-CA (p < 0.01), and then recovered at 72 h. Similarly, plasma and myocardial tissue IsoP and 8-OHG levels increased at 2 and 4 h post-resuscitation (p < 0.01 vs. baseline), while returned to baseline 72 h later. Myocardial IsoP were directly related to hs-cTnT levels (r = 0.760, p < 0.01) and inversely related to LVEF (r = -0.770, p < 0.01). Myocardial 8-OHG were also directly related to hs-cTnT levels (r = 0.409, p < 0.05) and inversely related to LVEF (r = -0.548, p < 0.01).ConclusionsThe present study provides evidence that lipid peroxidation and DNA oxidative damage in myocardial tissue are closely related to myocardial injury and LV dysfunction during the initial hours following CA.

Resveratrol-enhanced autophagic flux ameliorates myocardial oxidative stress injury in diabetic mice.

Autophagic dysfunction is observed in diabetes mellitus. Resveratrol has a beneficial effect on diabetic cardiomyopathy. Whether the resveratrol-induced improvement in cardiac function in diabetes is via regulating autophagy remains unclear. We investigated the mechanisms underlying resveratrol-mediated protection against heart failure in diabetic mice, with a focus on the role of sirtuin 1 (SIRT1) in regulating autophagic flux. Diabetic cardiomyopathy in mice was induced by streptozotocin (STZ). Long-term resveratrol treatment improved cardiac function, ameliorated oxidative injury and reduced apoptosis in the diabetic mouse heart. Western blot analysis revealed that resveratrol decreased p62 protein expression and promoted SIRT1 activity and Rab7 expression. Inhibiting autophagic flux with bafilomycin A1 increased diabetic mouse mortality and attenuated resveratrol-induced down-regulation of p62, but not SIRT1 activity or Rab7 expression in diabetic mouse hearts. In cultured H9C2 cells, redundant or overactive H2O2 increased p62 and cleaved caspase 3 expression as well as acetylated forkhead box protein O1 (FOXO1) and inhibited SIRT1 expression. Sirtinol, SIRT1 and Rab7 siRNA impaired the resveratrol amelioration of dysfunctional autophagic flux and reduced apoptosis under oxidative conditions. Furthermore, resveratrol enhanced FOXO1 DNA binding at the Rab7 promoter region through a SIRT1-dependent pathway. These results highlight the role of the SIRT1/FOXO1/Rab7 axis in the effect of resveratrol on autophagic flux in vivo and in vitro, which suggests a therapeutic strategy for diabetic cardiomyopathy.

Effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction

To explore the effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction. Male Sprague-Dawley rats were asphyxiated for 9 minutes and resuscitated. They were randomly divided into 4 groups: sham-operated, cardiopulmonary resuscitation (CPR), hemin and hemin + ZnPP (zinc protoporphyrin IX). Resuscitated groups had 2 observation points: 6 and 24 hours post-CPR (n = 8 for each time point). And the sham-operated group of 12 rats were divided in two observation points, according to 6 or 24 hours post-operation (n = 6 each). Hemodynamic was observed. The expression of heme oxygenase-1 (HO-1) in cardiac tissue was detected by Western blot. And the activity of cardiac homogenate superoxide dismutase (SOD) was determined by xanthine oxidase method and the level of malondialdehyde (MDA) measured by the thiobarbituric acid method. Nitrotyrosine protein expression in cardiac tissue was analyzed by immunohistochemistry. (1) The mean blood pressure (MAP) significantly decreased in resuscitated groups after resuscitation (all P < 0.05). No difference existed between the subgroups. The scores of dP/dt40 and -dP/dt significantly decreased in CPR and hemin + ZnPP groups after resuscitation (all P < 0.05). But dP/dt40 in hemin group did not differ significantly after resuscitation and -dP/dt decreased only 0.5 hour and 1 hour post-resuscitation (3341.60 ± 524.85 and 3711.40 ± 502.39 vs 4284.20 ± 800.87, all P < 0.05). The scores of dP/dt40 and -dP/dt in hemin group at all time points post-resuscitation were significantly higher than those in CPR and hemin + ZnPP groups (all P < 0.05). (2) Compared with the sham-operated group, the HO-1 expression, MDA level and nitrotyrosine protein expression significantly increased while the activities of SOD decreased after resuscitation in the CPR, hemin and hemin + ZnPP groups (all P < 0.05). Compared with the CPR and hemin + ZnPP groups, the expression of HO-1 and the activity of SOD increased, while MDA level and nitrotyrosine protein expression were decreased in group hemin (all P < 0.05). No difference existed in the above indices between the CPR and hemin + ZnPP groups. HO-1 can reduce myocardial oxidative stress injury after cardiopulmonary resuscitation and effectively improve post-resuscitation myocardial function in rats.