Myocardial Ischemia-reperfusion Injury In Rats Research Articles

Cystatin C alleviates H2O2-induced H9c2 cell injury.

At present, the incidence of acute myocardial infarction is increasing year by year, and it has become one of the diseases with the highest mortality rate in humans. Myocardial ischemia-reperfusion injury (MIRI) is a major problem in the treatment of myocardial infarction, but clinically there is no effective way to treat MIRI. This study used Cystatin C (Cys C) to treat cardiomyocytes and rats to investigate the effect of Cys C on MIRI. We used H2O2 to induce rat cardiomyocytes (H9c2 cells) injury and stimulated the cells with Cys C. Cell counting kit 8 (CCK8) assay was used to determine the optimal concentration of H2O2 and Cys C to stimulate H9c2 cells. We determined the effects of Cys C on oxidative stress and apoptosis levels in H9c2 cells by measuring the activity of dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA), and the expression of apoptosis-related molecules (caspase3/8/9, Bax and Bcl-2). Changes in the activity of the NF-κB signaling pathway in H9c2 cells were also detected. In addition, we made rat MIRI models by ligating the coronary arteries and used Cys C to treat rats to verify the effect of Cys C on MIRI. According to the results of the CCK8 assay, 1000 μM of H2O2 and 15 μM of Cys C were used to stimulate H9c2 cells. Cys C alleviated H2O2-induced H9c2 cell injury, manifested as a decrease in LDH and MDA activity and an increase in SOD activity. Cys C also reduced the apoptosis level in H9c2 cells. The activity of NF-κB signaling pathway in injured H9c2 cells was increased, and stimulation of Cys C could inhibit the NF-κB signaling pathway in H9c2 cells. The application of Cys C in MIRI rats also verified its therapeutic effect on MIRI. Cys C reduced the oxidative stress and apoptosis levels of cardiomyocytes by inhibiting the activity of NF-κB signaling pathway in cardiomyocytes, thereby reducing cardiomyocyte injury and treating MIRI.

Effect of Vaspin on Myocardial Ischemia-Reperfusion Injury Rats and Expression of NLR Family Pyrin Domain Containing 3 (NLRP3)

Myocardial ischemia-reperfusion injury (MIRI) can cause myocardial damage. Vaspin can protect against myocardial damage. However, the effect of vaspin on MIRI rats and the expression of NLRP3 remains unclear. Sprague-Dawley rats were separated into sham group; MIRI group and Vaspin group, in which 100 ng/ml vaspin was administrated before model preparation followed by analysis of cardiac function by M-mode ultrasound, level of NLRP3, of type I collagen, IL-6 and TNF-α by ELISA, SOD activity and ROS by spectrophotometry and Bcl-2 and PI3K/AKT signaling protein expression by Western Blot. In MIRI group, left ventricular end-systolic diameter (LVESD), left ventricular mass index (LVMI), left ventricular end-diastolic diameter (LVEDD), NLRP3 expression, contents of type I collagen, IL-6, TNF-α as well as ROS were significantly increased and SOD activity was significantly decreased with decreased Bcl-2 expression and upregulated pAKT and pPI3K (P < 0.05). In Vaspin group, LVESD, LVMI and LVEDD and NLRP3 expression as well as type I collagen, IL-6, TNF-α and ROS was decreased, SOD activity and Bcl-2 expression was significantly increased with downregulated pAKT and pPI3K (P < 0.05). Vaspin can regulate PI3K/AKT signaling pathway, inhibit NLRP3 expression, regulate oxidative stress, inhibit inflammation, reduce apoptosis, improve and improve cardiac function of myocardial ischemia-reperfusion injury in rats.

Metabolomics Analysis of the Effect of Hydrogen-Rich Water on Myocardial Ischemia-Reperfusion Injury in Rats.

To investigate the effect of hydrogen-rich water on myocardial tissue metabolism in a myocardial ischemia-reperfusion injury (MIRI) rat model. Twelve rats were randomly divided into a hydrogen-rich water group and a control group of size 6 each. After the heart was removed, it was fixed in the Langendorff device, and the heart was perfused with 37°C perfusion solution pre-balanced with oxygen. The control group was perfused with Kreb's-Ringers (K-R) solution, and the hydrogen-rich water group was perfused with K-R solution + hydrogen-rich water. Liquid Chromatograph Mass Spectrometer (LC-MS) analysis platform was used for metabolomics research. Principle component analysis (PCA), partial least squares discriminant analysis (PLS-DA), orthogonal partial least squares discriminant analysis (OPLS-DA), Variable importance in projection (VIP) value of OPLS-DA model (threshold value ≥1) were employed with independent sample T Test (p < 0.05) to find differentially expressed metabolites, and screen for differential metabolic pathways. VIP (OPLS-DA) analysis was performed with T test, and the metabolites of the control group and the hydrogen-rich water group were significantly different, and the glycerophospholipid metabolism was screened. Seven myocardial ischemia-reperfusion injury (MIRI)-related signaling pathways were identified, including glycerophospholipid metabolism, glycosylphosphatidylinositol (GPI) anchored biosynthesis, and purine metabolism, as well as 10 biomarkers such as phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine. Hydrogen-rich water regulates the metabolic imbalance that could change MIRI myocardial tissue metabolism, and alleviate ischemia-reperfusion injury in isolated hearts of rats through multiple signaling pathways.

Protective effect of intermediate doses of hydrogen sulfide against myocardial ischemia-reperfusion injury in obese type 2 diabetic rats

ObjectiveSubjects with type 2 diabetes (T2D) have lower circulating hydrogen sulfide (H2S) levels following myocardial ischemia and a higher risk of mortality. The aim of this study was to determine the dose-dependent favorable effects of sodium hydrosulfide (NaSH) on myocardial ischemia-reperfusion (IR) injury in rats with T2D. MethodsT2D was induced using a high-fat diet (HFD) and low-dose of streptozotocin. Rats were divided into control, T2D, and T2D + NaSH groups. NaSH (0.28, 0.56, 1.6, 2.8, and 5.6 mg/kg) was administered intraperitoneally for 9 weeks. At the end of the study, heart from all rats were isolated and left ventricular developed pressure (LVDP) and the peak rates of positive and negative changes in LV pressure (±dp/dt) were recorded during baseline and following myocardial IR injury. In addition, infarct size as well as mRNA expression of H2S- and nitric oxide (NO)-producing enzymes were measured. ResultsIn diabetic rats, NaSH only at doses of 0.56 and 1.6 mg/kg increased recovery of LVDP (16% and 42%), +dp/dt (25% and 35%) and –dp/dt (23% and 32%) as well as decreased infarct size (44% and 35%). At these doses, NaSH increased expressions of cystathionine γ-lyase (CSE) (440% and 271%) and endothelial NO synthase (eNOS) (232% and 148%) but it decreased the expressions of inducible NOS (iNOS) (55% and 71%). NaSH at 0.28, 2.8 and 5.6 mg/kg had no significant effects on these parameters. ConclusionNaSH had a bell-shaped cardioprotective effect against myocardial IR injury in rats with T2D. Higher tolerance to IR injury in heart isolated from type 2 diabetic rats treated with intermediate doses of NaSH is associated with higher CSE-derived H2S and eNOS-derived NO as well as lower iNOS-derived NO.

Periostin aggravates NLRP3 inflammasome-mediated pyroptosis in myocardial ischemia-reperfusion injury

Pyroptosis is a form of caspase-1-induced programmed cell death. This study aimed to investigate the effect of periostin (postn) on pyroptosis in myocardial ischemia-reperfusion injury (MIRI). To this end, the differentially expressed genes were obtained from the GSE4105 dataset using the “GEO2R” online tool. Protein-protein interaction networks were constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) database, and Module and Go analysis were conducted using the Cytoscape 3.6 plugs-in MCODE and BINGO, respectively. The analysis showed that postn was a critical gene in the most significant module. Experimental results, including triphenyltetrazolium chloride staining, pathological analysis, TUNEL staining, western blotting, and RT-qPCR assays, showed that MIRI induced caspase-1-mediated pyroptosis by activating the NLRP3 inflammasome. Postn was significantly upregulated in the heart tissues of MIRI rats and in H9C2 cells following hypoxia/reoxygenation (H/R) treatment. In addition, knockdown of postn suppressed the caspase-1-mediated pyroptosis and H/R-mediated NLRP3 inflammasome activation, as evidenced by flow cytometry, CCK8, RT-qPCR, western blotting, and ELISA assays. In contrast, overexpression of postn promoted NLRP3 inflammasome-mediated pyroptosis of H/R-treated H9C2 cells. According to the results of rescue experiments, a caspase-1 inhibitor reduced the increase in NLRP3 inflammasome-mediated pyroptosis induced by overexpression of postn, and the pyroptosis-promoting function of postn overexpression in H/R treated H9C2 cells was reversed by inhibition of NLRP3. In conclusion, postn overexpression promoted the caspase-1-mediated pyroptosis during MIRI by activating the NLRP3.

Rno-microRNA-30c-5p promotes myocardial ischemia reperfusion injury in rats through activating NF-\u03baB pathway and targeting SIRT1

BackgroundThis study aimed to investigate the regulatory effect of rno-microRNA-30c-5p (rno-miR-30c-5p) on myocardial ischemia reperfusion (IR) injury in rats and the underlying molecular mechanisms.MethodsA rat model of myocardial IR injury was established. The infarct size was detected by 2,3,5-triphenyltetrazolium chloride staining. The pathologic changes of myocardial tissues were detected by hematoxylin-eosin staining. The apoptosis of myocardial cells was measured by TUNEL staining and flow cytometry. The mRNA expression of rno-miR-30c-5p and Sirtuin 1 (SIRT1) was detected by quantitative real-time PCR. The levels of IL-1β, IL-6 and TNF-α were detected by enzyme linked immunosorbent assay. The protein expression of Bax, Bcl-2, caspase-3, p-IκBα, IκBα, p-NF-κB p65, NF-κB p65 and SIRT1 was detected by Western blot. The interaction between rno-miR-30c-5p and SIRT1 was predicted by TargetScan, and further identified by dual luciferase reporter gene and RNA immunoprecipitation assay.ResultsThe myocardial IR injury model was successfully established in rats. IR induced the myocardial injury in rats and increased the expression of rno-miR-30c-5p. Overexpression of rno-miR-30c-5p enhanced the inflammation, promoted the apoptosis, and activated NF-κB pathway in IR myocardial cells. SIRT1 was the target gene of rno-miR-30c-5p. Silencing of SIRT1 reversed the effects of rno-miR-30c-5p inhibitor on the apoptosis and NF-κB pathway in IR myocardial cells.ConclusionsRno-miR-30c-5p promoted the myocardial IR injury in rats through activating NF-κB pathway and down-regulating SIRT1.

Ulinastatin improves myocardial ischemia-reperfusion injury in rats through endoplasmic reticulum stress-induced apoptosis pathway.

To investigate the protective role of ulinastatin (UTI) on myocardial ischemia-reperfusion (I/R) injury in rats via endoplasmic reticulum stress (ERS)-induced apoptosis pathway. A total of 60 rats were randomly divided into normal group (n=20), myocardial I/R model group (model group, n=20), and myocardial I/R model+UTI treatment group (treatment group, n=20). The myocardial function indicators [creatinine (Scr) and creatine kinase (CK)] were detected. Enzyme-linked immunosorbent assay (ELISA) was performed to measure serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and matrix metalloproteinase-9 (MMP-9). Meanwhile, the contents of reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) in rat left ventricular tissues were determined by ELISA as well. The cardiac function indexes were determined via magnetic resonance imaging (MRI) and echocardiography (ECG). Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining assay was carried out to detect the apoptosis of myocardial tissues. Additionally, the expression levels of endoplasmic reticulum stress and apoptosis genes were measured through quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assay and Western blotting analysis, respectively. Serum levels of alanine aminotransferase (ALT), CK, and Scr in model group were significantly higher than those in normal group (p<0.05). Besides, rats in model group had significantly lowered SOD, ejection fraction (EF, %), and fractional shortening (FS, %) than those in normal group (p<0.05). In addition, remarkably increased contents of TNF-α, IL-6, MMP-9, MDA, and ROS, as well as higher left ventricular end-diastolic diameter (LVEDd) and left ventricular end-systolic diameter (LVESd) were observed in model group in comparison with normal group (p<0.05). TUNEL staining results revealed that there were more apoptotic cells in model group than that in the other two groups (p<0.05). Expression levels of cysteine aspartic acid-specific protease 12 (Caspase-12) and glucose-regulated protein 78 (GRP78) were evidently higher in model group than those in normal group (p<0.05), while the expression level of B-cell lymphoma 2 (Bcl-2) was clearly lower in model group than that in normal group (p<0.05). UTI treatment partially reversed the above expression changes (p<0.05). UTI has a protective effect against myocardial I/R injury in rats by repressing the occurrence of ERS-induced apoptosis.

The Regulation of AMPKα1/Nrf2/ HO-1 Pathway Mediated by Galantamine Hydrobromide Lycoremine in Myocardial Ischemia Reperfusion Rats

To investigate the effects of AMPKα1/Nrf2/heme oxygenase-1 (HO-1) pathway mediated by galantamine hydrobromide lycoremine (Gal) on endoplasmic reticulum stress apoptosis, myocardial apoptosis and fibrosis in rats with myocardial ischemia reperfusion (I/R). A myocardial ischemia reperfusion injury rat model was established, and the rats were randomly divided into 5 groups: Control group, I/R model group, Gal 1 mg/kg group, Gal 2 mg/kg group and Gal 4 mg/kg group. Left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular wall thickness (LVWT), and left ventricular short-axis shortening rate (FS) were detected by doppler ultrasound. Hematoxylin eosin staining was used to detect the pathological damage of myocardial tissue. The expression of Caspase-3 was detected by immunohistochemistry. Protein expression levels of CCAAT/enhancer-binding protein homologous protein (CHOP), cleaved Caspase-12, growth arrest and DNA damageinducible protein 34 (GADD34), immunoglobulin heavy-chain-binding protein (BiP), α-smooth muscle actin (α-SMA), Collagen Ⅰ, AMPKα1, Nrf2, and HO-1 were measured by western blot, and AMPK inhibitor Compound C was added for verification. Compared with the I/R model group, the grade of pathological damage of myocardial tissue in each group of Gal was improved, and cleaved Caspase-3 positive expression rate and Caspase-3 mRNA level were significantly reduced ( P<0.05) as well. The results showed that LVWT, FS and LVEF in Gal 2 mg/kg and Gal 4 mg/kg groups were significantly increased ( P<0.05), LVEDV and LVESV were significantly reduced ( P<0.05) compared with I/R model group. CHOP, cleaved Caspase-12, α-SMA, Collagen Ⅰ, AMPKα1, Nrf2, HO-1 protein levels were significantly reduced ( P<0.05), and GADD34 and BiP protein levels were significantly increased ( P<0.05) in Gal 2 mg/kg and Gal 4 mg/kg groups. The regulation of AMPKα1/Nrf2/HO-1 pathway mediated by Gal on endoplasmic reticulum stress apoptosis, myocardial apoptosis and fibrosis in myocardial ischemia reperfusion rats.

Ganoderic acid A alleviates myocardial ischemia-reperfusion injury in rats by regulating JAK2/STAT3/NF-κB pathway

This study aimed to investigate the protective effect of GanodericacidA (GA) on myocardial ischemia-reperfusion (MIR) injury. The myocardial injury model in rats was established by ligating left anterior descending coronary artery. We measured cardiac hemodynamic, antioxidant enzyme activity, and various biochemical indexes of myocardial tissue, and evaluated myocardial infarction and damage. Further, the expression of JAK2/STAT3/NF-κB signaling pathway-related proteins in myocardial tissue was measured by western blot. The results showed that the myocardial infarction extention was obviously reduced upon GA treatment. Compared with the control group, ischemia-reperfusion rats showed significant increase in lactate dehydrogenase (LDH) and creatine Kinase (CK), which were significantly decreased in GA group. Besides, GA pretreatment effectively decreased the levels of inflammatory cytokines in serum. The phosphorylation of Janus Kinase 2 (JAK2), signal transducer and activator of transcription (STAT3)and Nuclear factor-κB (NF-κB) in reperfusion group were significantly higher than that in control group, which were reversed upon GA treatment. In conclusion, GA may reduce myocardial injury by regulating JAK2/STAT3/NF-κB pathway.

Electroacupuncture preconditioning attenuates myocardial ischemia-reperfusion injury by inhibiting mitophagy mediated by the mTORC1-ULK1-FUNDC1 pathway

Myocardial ischemia/reperfusion (I/R) is an important complication of reperfusion therapy for myocardial infarction, and trimetazidine is used successfully for treatment of ischemic cardiomyopathy by regulating mitochondrial function. Moreover, electroacupuncture (EA) preconditioning was demonstrated to be cardioprotective in both in vivo rodent models and in patients undergoing heart valve replacement surgery. However, the mechanisms have not been well elucidated. Mitophagy, mediated by the mTORC1-ULK1-FUNDC1 (mTOR complex 1-unc-51-like autophagy-activating kinase 1-FUN14 domain-containing 1) pathway, can regulate mitochondrial mass and cell survival effectively to restrain the development of myocardial ischemia/reperfusion injury (MIRI). In this study, we hypothesized that EA preconditioning ameliorated MIRI via mitophagy. To test this, rapamycin, an mTOR inhibitor, was used. The results showed that EA preconditioning could reduce the infarct size and risk size, and decrease the ventricular arrhythmia score and serum creatine kinase-myocardial band isoenzyme (CK-MB), lactate dehydrogenase (LDH), and cardiac troponin T (cTnT) in MIRI rats. Moreover, it also attenuated MIRI-induced apoptosis and mitophagy accompanied by elevated mTORC1 level and decreased ULK1 and FUNDC1 levels. However, these effects of EA preconditioning were blocked by rapamycin, which aggravated MIRI, reduced adenosine triphosphate (ATP) production, and antagonized infarct size reduction. In conclusion, our results indicated that EA preconditioning protected the myocardium against I/R injury by inhibiting mitophagy mediated by the mTORC1-ULK1-FUNDC1 pathway.

Effect of dexmedetomidine post-treatment on oxidative stress and apoptosis induced by myocardial ischemiareperfusion injury in rats

Purpose: To study the effect of dexmedetomidine on myocardial ischemia-reperfusion injury (MI/RI)- induced imbalance on oxidant-prooxidant status and apoptotic changes in rats.&#x0D; Methods: Ninety (90) male Wistar rats were randomly divided into three groups – sham, model and post-treatment. In model rats, the anterior descending branch of the left coronary artery was ligated for 25 min, prior to their being subjected to reperfusion for 2 h. Rats in the post-treatment group were subjected to ligation at the anterior descending branch of the left coronary artery for 25 min, but they were intravenously injected with dexmedetomidine at a dose of 10 μg/kg prior to reperfusion. There was no ligation in the sham group. Malondialdehyde (MDA), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were assayed. Lactate dehydrogenase (LDH) and creatine kinase isoenzyme (CK-MB) levels were also evaluated. Apoptosis was measured with TdT-mediated dUTP nick end labeling (TUNEL) assay.&#x0D; Results: Compared with the sham group, MDA level in the model group was significantly rose, while SOD and GSH-Px activities were markedly decreased (p &lt; 0.05). Moreover, there were higher LDH and CK-MB activities in model rats than in the sham rats, but they were significantly lower in the posttreatment group than in the model group (p &lt; 0.05). Apoptosis was higher in model rats than in sham operation rats, but was markedly decreased in post-treatment rats than in model rats (p &lt; 0.05).&#x0D; Conclusion: Post-treatment with dexmedetomidine exerts myocardial protective effect via significant reduction in oxidative stress-induced myocardial injury and apoptosis.&#x0D; Keywords: Dexmedetomidine, Myocardial ischemia-reperfusion injury, Antioxidant status, Programmed cell death

Remifentanil improves myocardial ischemia-reperfusion injury in rats through inhibiting IL-18 signaling pathway.

To explore the protective effect of remifentanil against myocardial ischemia-reperfusion injury (MIRI) in rats and its mechanism. The rat models of IRI were established and randomly divided into 1) sham-operation group (S group), 2) IRI rat model group (M group), 3) low-dose remifentanil group (R-L group), 4) moderate-dose remifentanil group (R-M group), and 5) high-dose remifentanil group (R-H group). The rats in R-L group, R-M group, and R-H group were administrated with remifentanil at 0.4 μg/kg/min, 2 μg/kg/min, and 10 μg/kg/min, respectively. The activity of creatine kinase-MB (CK-MB), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) in myocardial cells was detected using the automatic biochemical analyzer, and the apoptosis rate of myocardial cells was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Moreover, the messenger ribonucleic acid (mRNA) and protein levels of related cytokines in myocardial cells were determined through quantitative Polymerase Chain Reaction (qPCR) and Western blotting, and the content of interleukin-1β (IL-1Symbol ) and IL-18 in peripheral blood was detected via enzyme-linked immunosorbent assay (ELISA). Remifentanil at different concentrations could protect myocardium from IRI, and remifentanil at 2 μg/kg/min and 10 μg/kg/min could significantly down-regulate the myocardial enzyme indexes in IRI myocardial cells (p<0.01). Besides, remifentanil reduced the mRNA expressions of IL-18, INF-γ, TNF-β, and IL-1β (p<0.01), significantly decreased the protein expression of IL-18, and raised the protein expression of IL-18BP, thereby improving myocardial pathological damage. The protective mechanism of remifentanil on the myocardium of MIRI rats may be related to the inhibition on the IL-18 signaling pathway.

Effects of Promethazine on Proliferation and Apoptosis of Myocardial Cells in Rats with Myocardial Ischemia-Reperfusion Injury Through PI3K/Akt Signaling Pathway

Objective: To assess promethazine's effect on myocardial cells in rats with myocardial ischemiareperfusion injury (MIRI). Methods: The rat MIRI model was established and treated as the ischemia group. MIRI rats were treated with promethazine and included as the drug group. Rats only undergoing thoracotomy were enrolled as the control group. The physiological function of heart was assessed using the ultrasound cardiotachograph, and the apoptosis and proliferation of myocardial cells were detected using TUNEL assay and Ki67 staining, respectively. Moreover, the expressions of Caspase-3, Bcl-2, PI3K, GSK-3, PDK-1 and PKB were determined via Western blotting and qPCR. Results: There were significant differences in cardiac function indexes [left ventricular enddiastolic diameter (LVEDd), left ventricular end systolic diameter (LVESd), ejection fraction (EF) and fractional shortening (FS)] among the three groups (p= 0 002, 0.004, 0.025 and 0.012), and ischemia group had the highest LVEDd [(8.73± 0.31) mm] and LVESd [(7.98± 0.37) mm] and lowest EF [(42± 3.8)%] and FS [(40.3± 2.8)%]. The number of apoptotic myocardial cells was significant higher in ischemia group than control ( p&lt; 0 05), while it was significantly declined after treatment with promethazine ( p&lt; 0 05). Caspase-3 was significantly upregulated and Bcl-2 was downregulated in ischemia group which were all significantly reversed in drug group. Besides, Ki67 level was significantly reduced in ischemia group compared to control and higher in drug group than ischemia group, indicating that drug treatment increased cell proliferation ability. The levels of PI3K, GSK-3 and PKB in myocardial tissues were significantly declined in ischemia group and elevated after the treatment with promethazine without difference of PDK-1 level in myocardial tissues among the three groups. Conclusion: Promethazine inhibits apoptosis and promotes proliferation of myocardial cells in MIRI rats through PI3K/Akt signaling pathway.

Resveratrol Nanoparticle Complex: Potential Therapeutic Applications in Myocardial Ischemia Reperfusion Injury.

Resveratrol (RES) is a natural non-flavonoid polyphenol with cardioprotective activities, antioxidant, antiplatelet, and antiinflammatory. However, its low aqueous solubility, chemical stability, and oral bioavailability, as well as a short circulation half-life greatly limit its clinical applications. To overcome these limitations of RES, we synthesized a methoxy poly(ethylene glycol)-b-oligomerization(D, L-Leucine) (mPEG-b-O(D, L-Leu)) nanoparticle (NP) as the carrier of RES and evaluated the myocardial-protective effectiveness of this RES/NP complex in rat myocardial ischemia-reperfusion injury models. We gauged the characterization of the NP through proton nuclear magnetic resonance spectroscopy, gel permeation chromatography, transmission electron microscope, and Fourier transform infrared spectroscopy and then loaded RES on the nanocarrier by hydrophobic interactions under physiological pH to extend the release time of RES and prolong its circulation half-life. Subsequently, we used rat cardiomyocytes (H9C2 cells) and rat MI/RI model to investigate the relationship between drug composition and myocardial preservation properties. It was found that RES was encapsulated quickly and efficiently, and displayed an effectual loading-capacity and in vitro sustained-release. Anti-MI/RI effect of the RES/NP complex was found satisfactory in rat models in vivo using free RES as the control. This study suggested that NP may prove to be a potent nanocarrier to augment the pharmacotherapy of RES against MI/RI.

A study on protective effect of morphine against myocardial ischemia-reperfusion injury in rats via CAMP/PKA signaling pathway.

The purpose of this study was to explore the mitigating effect of morphine on the myocardial ischemia-reperfusion injury (MIRI) in rats through the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) pathway. A total of 30 male Wistar rats were assigned into sham group, MIRI group and morphine group using a random number table. The model of MIRI was routinely established. Then, the pathological changes in the morphology of myocardial tissues were observed via hematoxylin-eosin (HE) staining. The levels of the oxidative stress indicators superoxide dismutase (SOD) and malondialdehyde (MDA), the content of the inflammatory cytokine tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6 and the quantity of glutathione peroxidase (GSH-Px), lactate dehydrogenase (LDH), creatine kinase (CK), CK-MB and cardiac troponin I (cTnI) in the myocardial enzyme spectrum were determined and analyzed through enzyme-linked immunosorbent assay (ELISA). Moreover, the messenger ribonucleic acid (mRNA) and protein expressions of cAMP, PKA, cAMP-response element binding protein (CREB) and phosphorylated CREB (p-CREB) in the cAMP/PKA signaling pathway in the myocardial tissues were measured using real-time polymerase chain reaction (PCR) and Western blotting, respectively. The results manifested that compared with those in MIRI group, the levels of myocardial infarct size, LDH, CK, CK-MB, cTnI, MDA, TNF-α, IL-1β, IL-6 and p-CREB were decreased, while the levels of GSH-Px, SOD, PKA and CREB were increased in the morphine group. In conclusion, morphine may mitigate MIRI in rats through the cAMP/PKA signaling pathway.

MiR-346 Inhibited Apoptosis Against Myocardial Ischemia-Reperfusion Injury via Targeting Bax in Rats.

PurposeMyocardial ischemia-reperfusion injury (MIRI) is a common pathophysiological process after occlusion of the blood vessels to restore blood supply. Apoptosis is one of the ways of myocardial cell death in this process. MicroRNAs (miRNAs), a class of short and noncoding RNAs, are involved in multiple biological processes by post-transcriptionally targeting their downstream effectors. To date, whether miRNAs exert biological effects in myocardial ischemia-reperfusion (I/R) injury remains to be further studied.MethodsIn this study, we induced MIRI model by ligating rat left anterior descending artery (LAD) for 30 mins and reperfusion for 2 hrs. The differential expression profile of miRNAs in rat models of MIRI was analyzed by miRNAs sequencing.ResultsWe found that miRNAs sequencing analysis showed the expressions of 15 types of miRNAs, including miR-346, were downregulated and 29 types of miRNAs were elevated in the MIRI rat model. We observed the key regulator of apoptosis Bax was a predicted downstream target of miR-346 using online software TargetScan. And luciferase reporter assay was utilized to certify this prediction. Over-expression of miR-346 can attenuate myocardial injury and narrow infarct area by inhibiting myocardial cell apoptosis in rat models.ConclusionThis study revealed a novel pathway, miR-346/Bax axis, in the regulation of apoptosis in MIRI and which might be a new molecular mechanism and therapeutic target.

Attenuation of ROS-mediated myocardial ischemia-reperfusion injury by morin via regulation of RISK/SAPK pathways.

Oxidative stress plays an important role in the pathogenesis of myocardial ischemia-reperfusion (IR) injury. Morin, a bioflavonoid, has demonstrated antioxidant, anti-inflammatory and other diverse pharmacological activities in various experimental models such as isoproterenol-induced myocardial injury, doxorubicin-induced cardiotoxicity and neurotoxicity, as well as cisplatin-induced nephrotoxicity. Thus, this study aimed to evaluate the effect of morin in myocardial IR injury model and its underlying mechanisms. To accomplish this, male albino Wistar rats were pre-treated with morin (40 and 80mg/kg; po) for 28days and on 29th day, rats experienced 45-min myocardial ischemia followed by 60-min reperfusion. In comparison to IR-control group, morin pre-treatment significantly normalized hemodynamic parameters, restored antioxidant status, improved pathological changes, reduced the release of cardiac injury markers, inhibited inflammation (TNF-α/IL-6/NFκB/IKKβ) and apoptosis (increased Bcl-2, decreased Bax/Caspase-3 and TUNEL positivity) in the myocardium. This improvement in antioxidant, inflammation and anti-apoptosis markers could be due to downregulation of SAPK (p38/JNK) pathway and upregulation of survival kinase, i.e. RISK pathway (ERK/eNOS) in the myocardium. Thus, morin attenuated myocardial IR injury in rats by regulation of RISK/SAPK pathways.

Glutamine protects myocardial ischemia-reperfusion injury in rats through the PI3K/Akt signaling pathway.

To study the protective mechanism of glutamine (Gln) on myocardial ischemia-reperfusion (IR) injury in rats through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. A total of 30 healthy SD rats weighing 200-300 g were used in this experiment. They were randomly divided into 3 groups: sham group (n=10), myocardial IR injury group (IR group, n=10), IR+Gln group (n=10). The protein expression levels of phosphorylated Akt (p-Akt), total Akt (t-Akt), phosphorylated mammalian target of rapamycin (p-mTOR), mTOR, proliferating cell nuclear antigen (PCNA), P21, and Tubulin were determined by Western blotting (WB). Quantitative Polymerase Chain Reaction (qPCR) was applied to detect the messenger ribonucleic acid (mRNA) levels of Akt and mTOR. 3-(4,5)-dimethylthiazol(-z-y1)-3,5-diphenyl tetrazolium bromide (MTT) test was utilized to examine the proliferation ability of cardiomyocytes in vitro. Besides, the contents of the inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were measured via enzyme-linked immunosorbent assay (ELISA). Cell apoptosis in each group was examined through Hoechst staining. Compared with those in the sham group, ratios of p-AKT/AKT, p-mTOR/mTOR, and the level of PCNA extremely significantly decreased, but the level of P21 notably increased in IR group (p<0.01). In comparison with those in the IR group, ratios of p-AKT/AKT, p-mTOR/mTOR, and the level of PCNA were remarkably raised, while the level of P21 was remarkably reduced in IR+Gln group (p<0.05). QRT-PCR results manifested that there were no significant differences in the mRNA levels of Akt and mTOR among the three groups [no significant difference (NS)]. Moreover, the cell proliferation ability in IR group was remarkably lower than that in the sham group (p<0.01), while it was enhanced in the IR+Gln group compared with that in the IR group (p<0.05). Additionally, IR group had significantly elevated expression levels of TNF-α and IL-6 compared with the sham group (p<0.01), whereas the IR+Gln group had notably decreased expression levels of TNF-α and IL-6 compared with IR group (p<0.05). In comparison with that in the sham group, the apoptosis in IR group was significantly raised (p<0.01), and compared with that in the IR group, the apoptosis in the IR+Gln group prominently decreased (p<0.05). The contents of the inflammatory cytokines, TNF-α, and IL-6 presented the same trends among the three groups. Gln activates the PI3K/Akt signaling pathway by increasing the levels of p-AKT and p-mTOR. Gln can increase the PCNA level and reduce the P21 level, so as to enhance the proliferation ability of cardiomyocytes. Besides, Gln reduces the levels of inflammatory cytokines, TNF-α, and IL-6, and inhibits cell apoptosis. Finally, Gln can protect cells from myocardial IR injury by activating the PI3K/Akt signaling pathway.

Acanthopanax senticosus Protects Against Myocardial Ischemia Reperfusion Injury in Rats

The protective effects of Acanthopanax senticosus on myocardial ischemia reperfusion injury in rats was explored. A total of 60 male Sprague Dawley rats were randomly divided into the sham operated group (group C), the ischemia reperfusion group (group IR), the Acanthopanax senticosus plus blocker group (group ASS+Z), and the Acanthopanax senticosus group (group ASS). The rat myocardial ischemia reperfusion injury models were established through ligating left anterior descending branches of coronary artery in rats. TUNEL assay and Western Blot was used to detect the apoptotic index of myocardial cells and the expression levels of extracellular regulating kinase 1/2 (ERK1/2) and phosphorylation ERK1/2 (p-ERK1/2). Meanwhile, a total of 30 rats were randomly selected and divided into 5 groups; the control group (group c) was the simple ischemia reperfusion group, while groups P1, P2, P3, and P4 were given different dosage concentrations of Acanthopanax senticosus for pre-adaptation. The Langendorff isolated heart perfusion model was used to record the dynamic changes in cardiac functions and coronary artery flow in each group. The results have shown that the Acanthopanax senticosus had certain protective effects on the ischemia reperfusion injury of rat myocardium, as well as the pre-adaptive effects on the systolic functions of left ventricles after reperfusion, which would increase coronary flow and resist the arrhythmia, thereby reducing the apoptosis rates of myocardial cells and protecting the myocardium through activating the ERK1/2 pathway.

Euterpe Oleracea Mart. (Açaí) Reduces Oxidative Stress and Improves Energetic Metabolism in Myocardial Ischemia-Reperfusion Injury in Rats.

BackgroundEuterpe oleracea Mart. (açaí) is a fruit with high antioxidant capacity and could be an adjuvant strategy to attenuate ischemia-reperfusion injury.ObjectiveTo evaluate the influence of açaí in global ischemia-reperfusion model in rats.MethodsWistar rats were assigned to 2 groups: Control (C: receiving standard chow; n = 9) and Açaí (A: receiving standard chow supplemented with 5% açaí; n = 10). After six weeks, the animals were subjected to the global ischemia-reperfusion protocol and an isolated heart study to evaluate left ventricular function. Level of significance adopted: 5%.ResultsThere was no difference between the groups in initial body weight, final body weight and daily feed intake. Group A presented lower lipid hydroperoxide myocardial concentration and higher catalase activity, superoxide dismutase and glutathione peroxidase than group C. We also observed increased myocardial activity of b-hydroxyacyl coenzyme-A dehydrogenase, pyruvate dehydrogenase, citrate synthase, complex I, complex II and ATP synthase in the A group as well as lower activity of the lactate dehydrogenase and phosphofructokinase enzymes. The systolic function was similar between the groups, and the A group presented poorer diastolic function than the C group. We did not observe any difference between the groups in relation to myocardial infarction area, total and phosphorylated NF-kB, total and acetylated FOXO1, SIRT1 and Nrf-2 protein expression.Conclusiondespite improving energy metabolism and attenuating oxidative stress, açai supplementation did not decrease the infarcted area or improve left ventricular function in the global ischemia-reperfusion model.