Role of mPTP and ER stress in NECA-induced cardioprotection against ischemia / reperfusion injury

<正>We aimed to determine whether NECA,an adenosine receptor agonist,induces cardioprotection against myocardial ischemia/reperfusion(I/R)injury by modulation of endoplasmic reticulum stress(ERS)through inhibiting the mitochondrial permeability transition pore(mP TP)opening via inactivating glycogen synthase kinase 3β(GSK-3β).Heart tissue-derived H9c2 cells exposed to 800     

NADPH oxidases as a source of oxidative stress and molecular target in ischemia/reperfusion injury

Ischemia/reperfusion injury (IRI) is crucial in the pathology of major cardiovascular diseases, such as stroke and myocardial infarction. Paradoxically, both the lack of oxygen during ischemia and the replenishment of oxygen during reperfusion can cause tissue injury. Clinical outcome is also determined by a third, post-reperfusion phase characterized by tissue remodeling and adaptation. Increased levels of reactive oxygen species (ROS) have been suggested to be key players in all three phases. As a second paradox, ROS seem to play a double-edged role in IRI, with both detrimental and beneficial effects. These Janus-faced effects of ROS may be linked to the different sources of ROS or to the different types of ROS that exist and may also depend on the phase of IRI. With respect to therapeutic implications, an untargeted application of antioxidants may not differentiate between detrimental and beneficial ROS, which might explain why this approach is clinically ineffective in lowering cardiovascular mortality. Under some conditions, antioxidants even appear to be harmful. In this review, we discuss recent breakthroughs regarding a more targeted and promising approach to therapeutically modulate ROS in IRI. We will focus on NADPH oxidases and their catalytic subunits, NOX, as they represent the only known enzyme family with the sole function to produce ROS. Similar to ROS, NADPH oxidases may play a dual role as different NOX isoforms may mediate detrimental or protective processes. Unraveling the precise sequence of events, i.e., determining which role the individual NOX isoforms play in the various phases of IRI, may provide the crucial molecular and mechanistic understanding to finally effectively target oxidative stress.     

Role for the alternative complement pathway in ischemia/reperfusion injury

The terminal complement components play an important role in mediating tissue injury after ischemia and reperfusion (I/R) injury in rats and mice. However, the specific complement pathways involved in I/R injury are unknown. The role of the alternative pathway in I/R injury may be particularly important, as it amplifies complement activation and deposition. In this study, the role of the alternative pathway in I/R injury was evaluated using factor D-deficient (−/−) and heterozygote (+/−) mice. Gastrointestinal ischemia (GI) was induced by clamping the mesenteric artery for 20 minutes and then reperfused for 3 hours. Sham-operated control mice (+/− versus −/−) had similar baseline intestinal lactate dehydrogenase activity (P = ns). Intestinal lactate dehydrogenase activity was greater in −/− mice compared to +/− mice after GI/R (P = 0.02) thus demonstrating protection in the −/− mice. Intestinal myeloperoxidase activity in +/− mice was significantly greater than −/− mice after GI/R (P < 0.001). Pulmonary myeloperoxidase activity after GI/R was significantly higher in +/− than −/− mice (P = 0.03). Addition of human factor D to −/− animals restored GI/R injury and was prevented by a functionally inhibitory antibody against human factor D. These data suggest that the alternative complement pathway plays an important role in local and remote tissue injury after GI/R. Inhibition of factor D may represent an effective therapeutic approach for GI/R injury.     

Lutein protects against ischemia/reperfusion injury in rat skeletal muscle by modulating oxidative stress and inflammation

Abstract

Background: Lutein is an antioxidant compound with potential biological effects. The present study investigated the protective role of Lutein against I/R injury in skeletal muscle.

Methods: Animals were divided into three groups. Group I – sham operated; Group II- IR injury- Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4?h of ischemia, the clamp was removed and the animals underwent 2?h of reperfusion. Group III-Lutein?+?IR injury- Rats with Lutein treatment received intraperitoneal injection 1?h before reperfusion. The skeletal tissues were analyzed for oxidative stress parameters (reactive oxygen species, protein carbonylation and sulfhydryls, lipid peroxidation). Antioxidant status was determined by evaluating Nrf-2 levels and antioxidant enzyme activities. The inflammatory mechanism was determined through NF-κB and COX-2 expressions. Pro-inflammatory cytokines were determined by ELISA.

Results: The results showed that Lutein treatment significantly decreased the oxidative stress by reducing reactive oxygen species, protein carbonylation and sulphydryls, lipid peroxidation. Further, the levels of Nrf-2 and antioxidant status was significantly declined during IR injury compared to sham operated rats. Lutein treatment reduced the oxidative stress by enhancing Nrf-2 levels and antioxidant status. Skeletal IR injury enhanced the inflammatory signaling by up regulating NF-κB, COX-2 and various pro-inflammatory cytokines. NF-κB, COX-2 expressions were down regulated by Lutein treatment.

Conclusion: The study shows that Lutein protects against skeletal IR injury by down regulating oxidative stress and inflammatory mechanisms.     

Role of Zn~(2+) in endoplasmic reticulum stress inhibition-induced cardioprotection against ischemia / reperfusion injury

<正>We aimed to explore the mechanism of ERS inhibition-induced cardioprotection against I/R injury,focusing on the role of Zn2+and the mitochondrial permeability transition pore(mP TP).Exposure of H9c2 cells to 800μmol/L H2O2for 20 min increased the expression of GRP78 and GRP94,suggesting that H2O2induced ERS.The cells treated with H2O2showed a significant decrease in TM-     

高血糖通过氧化损伤加重局灶性脑缺血再灌注神经元损伤

目的:探讨在高血糖加重脑缺血再灌注损伤中神经元氧化损伤的作用及机制。方法:将SD大鼠分为正常血糖脑缺血再灌注组(正常血糖组)、糖尿病高血糖脑缺血再灌注组(糖尿病组)以及假手术对照组(假手术组),通过线栓大脑中动脉制备局灶性脑缺血再灌注损伤模型,于再灌注后1,7和14 d分别进行组织学、8羟基脱氧鸟苷(8-hydroxy-2’deoxyguanosine,8-OHdG)免疫组织化学、NeuN和8-OHdG免疫荧光双标记,对比观察各组神经元的氧化损伤。结果:正常血糖组再灌注1 d脑组织出现明显水肿,糖尿病组较正常血糖组有所加重,出现较多的固缩神经元;再灌注7 d正常血糖组神经元固缩和脑水肿明显减少,糖尿病组仍可见少数神经元固缩和脑水肿;再灌注14 d正常血糖组神经元固缩和脑水肿消失,胶质细胞增加,糖尿病组可见轻度脑水肿。免疫组化和免疫荧光双标记提示,再灌注1 d,正常血糖组及糖尿病组8-OHdG阳性细胞和阳性神经元数量均明显增加,高血糖组8-OHdG阳性细胞数量和阳性神经元均明显高于正常血糖组(P0.05)。再灌注7 d和14 d 8-OHdG免疫阳性细胞阳性神经元明显减少,但仍多于假手术组(P0.05)。结论:糖尿病高血糖加重脑缺血再灌注损伤,神经元的氧化损伤是高血糖加重脑缺血再灌注损伤的重要方式之一。     

Biomarkers of oxidative/nitrosative stress: an approach to disease prevention

Oxidative/nitrosative stress is responsible for a variety of degenerative processes in some human diseases. Measurement of oxidatively/nitrosatively modified DNA, proteins, lipids, and sugars in biological samples has been expected to detect appropriate biomarkers for diseases in which reactive oxygen/nitrogen species are involved. Recently, the application of these biomarkers to epidemiological studies has resulted in a new discipline, molecular epidemiology, which provides the opportunity for better understanding of their causal relation with disease outcomes in a population level. In this brief review, we cover some specific biomarkers of oxidative/nitrosative stress with regard to the commonly used analytical methods for these biomarkers, their integration with epidemiology, and their application in antioxidant intervention trials, with an emphasis on those applicable to human studies and their potentialities for disease prevention.     

Increased fibrosis and progression to heart failure in MRL mice following ischemia/reperfusion injury

The cardiac regenerative capacity of MRL/MpJ mouse remains a controversy. Although the MRL mouse has been reported to exhibit minimal scarring and subsequent cardiac regeneration after cryoinjury of the right ventricle, multiple studies have been unable to replicate this cardiac regenerative capacity after both cryogenic and coronary ligation cardiac injury. Therefore, we evaluated the cardiac regenerative wound-healing response and functional recovery of MRL mice compared to C57 mice, in response to a clinically relevant left ventricular (LV) coronary ligation. Male MRL/MpJ+/+ and C57BL/6 mice underwent left coronary artery ligation followed by reperfusion. Cardiac function was evaluated by echocardiography [LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), LV mass, wall thickness] at 24 hours post-ischemia and weekly for 13 weeks thereafter. Hearts were also analyzed histologically for individual cardiomyocyte hypertrophy and cardiac fibrosis. Our results show that contrary to prior reports of cardiac regenerations, MRL mice progress to heart failure more rapidly following I/R injury as marked by a significant decrease in LVEF, increase in LVEDV, LV mass, individual myocyte size, and fibrosis in the post-ischemic myocardium. Therefore, we conclude that MRL mice do not exhibit regeneration of the LV or enhanced functional improvement in response to coronary ligation. However, unlike prior studies, we matched initial infarct size in MRL and C57 mice, used high frequency echocardiography, and histological analysis to reach this conclusion. The prospect of cardiac regeneration after ischemia in MRL mice seems to have attenuated interest, given the multiple negative studies and the promise of stem cell cardiac regeneration. However, our novel observation that MRL may possess an impaired compensated hypertrophy response makes the MRL mouse strain an interesting model in the study of cardiac hypertrophy.     

Influence of ezetimibe on selected parameters of oxidative stress in rat liver subjected to ischemia/reperfusion

Introduction

Ischemia/reperfusion (I/R) is considered to be one of the main causes of liver damage after transplantation. The authors evaluated the effect of ezetimibe on selected oxidative stress parameters in ischemic/reperfused (I/R) rat liver.

Material and methods

Rats were administered ezetimibe (5 mg/kg) (groups E and E-I/R) or saline solution (groups C and C-I/R) intragastrically for 21 days. Livers of animals in groups C-I/R and E-I/R were subjected to 60 min of partial ischemia (left lateral and median lobes) followed by 4 h of reperfusion. Alanine and asparagine aminotransferase (ALT, AST) activity was determined in blood before I/R and during reperfusion (at 15 and 240 min). After the reperfusion period, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GPx) were determined in liver homogenates using colorimetric methods.

Results

Ezetimibe caused a significant increase in GSH level in groups subjected to I/R (E-I/R (99.91 ±9.01) vs. C-I/R (90.51 ±8.87), p < 0.05). Additionally, under I/R the decrease of GPx activity in the drug-treated group was lower compared to the non-treated group (E-I/R (3.88 ±1.11) vs. E (5.31 ±1.83), p = 0.076). Neither ezetimibe nor I/R affected SOD or MDA levels. I/R produced a significant increase in aminotransferase levels (ALT240-0: C-I/R (42.23 ±43.56) vs. C (9.75 ±11.09), and E-I/R (39.85 ±26.53) vs. E (4.38 ±1.36), p < 0.05 in both cases; AST 240-0: E-I/R (53.87 ±17.23) vs. E (24.10 ±9.66), p < 0.05) but no effect of ezetimibe on those enzymes was found.

Conclusions

Ezetimibe demonstrates antioxidant properties in rat livers subjected to I/R. However, neither a hepatoprotective nor a hepatotoxic effect of ezetimibe was demonstrated, regardless of I/R.     

一氧化氮途径在大鼠肝移植缺血再灌注损伤中的作用

本实验应用三袖套法大鼠原位肝移植模型,探讨一氧化氮途径在大鼠原位肝移植缺血再灌注损伤中对移植肝的功能作用及可能机制。加强一氧化氮途径能显著延长受体的存活率,改善肝功能及抑制肿瘤坏死因子（Ｔｈ卜ａ）的合成与表达;而抑制ＮＯ合成则能明显降低术后受体存活率、加剧肝功能恶化,上调ＴＮＦ－ａ及Ⅰ型细胞间粘附分子（ＩＣＡＭ－１）的表达。提示：ＮＯ途径很可能是肝移植缺血再灌注损伤的关键因素。     

Apelin-13对离体缺血/再灌注大鼠心脏损伤的影响

目的观察apelin-13对离体大鼠缺血/再灌注心脏损伤的影响,并初步探讨其对apelin受体APJ(putative re-ceptor protein related to the angiotensin receptorAT1)及细胞信号Akt1/2的影响。方法Langendorff装置恒流灌注大鼠离体心脏,采用停灌/复灌方式复制缺血/再灌注模型;观察缺血/再灌注期间心脏收缩期左心室内压上升的最大变化速率( LVdp/dtmax)及舒张期左心室内压下降的最大变化速率(-LVdp/dtmax);RT-PCR和Western blot测定组织中APJ受体mRNA和Akt1/2蛋白的表达情况。结果Apelin-13可以增加缺血/再灌注损伤心脏的±dp/dtmax(P<0·01);可以明显增强心肌组织中Akt1/2的表达;缺血/再灌注可以引起心肌组织中APJ受体表达上调。结论Apelin-13拮抗缺血/再灌注引起的心脏收缩及舒张功能障碍;可能与组织中APJ受体表达上调引起Akt1/2表达增强有关。     

GYY4137 protects against myocardial ischemia and reperfusion injury by attenuating oxidative stress and apoptosis in rats

Hydrogen sulfide（H₂S） is a gasotransmitter that regulates cardiovascular functions.The present study aimed to determine the protective effect of slow-releasing H₂S donor GYY4137 on myocardial ischemia and reperfusion（I/R） injury and to investigate the possible signaling mechanisms involved.Male Sprague-Dawley rats were treated with GYY4137 at 12.5 mg/（kg·day）,25 mg/（kg·day） or 50 mg/（kg·day） intraperitoneally for7 days.Then,rats were subjected to 30 minutes of left anterior descending coronary artery occlusion followed by reperfusion for 24 hours.We found that GYY4137 increased the cardiac ejection fraction and fractional shortening,reduced the ischemia area,alleviated histological injury and decreased plasma creatine kinase after myocardial I/R.Both H₂S concentration in plasma and cystathionine-γ-lyase（CSE） activity in the myocardium were enhanced in the GYY4137 treated groups.GYY4137 also decreased malondialdehyde and myeloperoxidase levels in serum,attenuated superoxide anion level and suppressed phosphorylation of mitogen activated protein kinases in the myocardium after I/R.Meanwhile,GYY4137 increased the expression of Bcl-2 but decreased the expression of Bax,caspase-3 activity and apoptosis in the myocardium.The data suggest that GYY4137 protects against myocardial ischemia and reperfusion injury by attenuating oxidative stress and apoptosis.     

人参皂苷Rg1预处理对大鼠离体心缺血/再灌注损伤的保护作用

目的:探讨人参皂苷Rg1对离体大鼠心缺血/再灌注(I/R)损伤的保护作用。方法:选取SPF级SD大鼠随机分为正常对照组、I/R组、人参皂苷Rg1(1、5、10、20μmol/L)处理组。利用Langendorff灌流系统建立大鼠离体心I/R损伤模型。IabOhart电生理系统实时监测心功能指标,血清生化检测心流出液中心肌酶含量,TTC染色法测定心肌梗死面积。结果:不同浓度人参皂苷Rg1均可改善心肌I/R损伤引起的左室发展压(LVDP)和左室内上升/下降最大速率(±dp/dt_(max))的下降,并降低流出液巾乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK MB)、肌红蛋白(MYO)和肌钙蛋白I(TroI)的含量,显著减少心肌梗死面积。其中5μmol/L和10μmol/L浓度的人参皂苷Rg1对心的保护作用最显著。结论:人参皂苷Rg1具有药物预适应作用,改善心肌I/R损伤后的心肌生理功能,减少流出液中心肌酶的释放和心肌梗死面积,从而发挥抗心肌I/R损伤的保护作用。     

白藜芦醇通过抑制内质网应激减轻大鼠脑缺血/再灌注损伤

目的:探讨白藜芦醇(Resveratrol,Res)对大鼠脑缺血/再灌注诱导的内质网应激反应的调控作用。方法:将72只健康雄性SD大鼠,采用随机数字表法分为3组(n=24):假手术组(S组)、脑缺血/再灌注模型组(I/R组)、Res组(R组)。采用阻断左侧大脑中动脉并阻断双侧颈总动脉30 min恢复灌注的方法制备大鼠脑缺血/再灌注模型。R组于缺血前7d给予腹腔注射Res(50 mg/kg),1次/日。对大鼠进行神经功能缺损评分后留取脑组织,采用TTC法检测脑梗死体积,干湿重法测定脑组织含水量,免疫组织化学及Western blot法检测大脑皮层内质网应激相关蛋白GRP78、p-PERK、CHOP的表达变化。结果:与S组比较,I/R组大鼠神经功能评分及脑含水量升高(P0.05),脑梗死体积增大(P0.05),皮层GRP78、p-PERK和CHOP蛋白表达均显著上调(P0.05)。与I/R组比较,P组大鼠神经功能评分及脑含水量降低(P0.05),脑梗死体积减小(P0.05),GRP78表达上调(P0.05),p-PERK和CHOP蛋白表达下调(P0.05)。结论:白藜芦醇通过抑制内质网应激反应,对大鼠脑缺血/再灌注损伤发挥保护作用。     

Therapeutic approaches for ischemia/reperfusion injury in the liver

Organ injury caused by transient ischemia followed by reperfusion is associated with a number of clinically and environmentally induced conditions. Ischemia/reperfusion (I/R) conditions arise during surgical interventions such as organ transplantation and coronary bypass surgery, and in diseases such as stroke and cardiac infarct. The destructive effects of I/R arise from the acute generation of reactive oxygen species subsequent to reoxygenation, which inflict direct tissue damage and initiate a cascade of deleterious cellular responses leading to inflammation, cell death, and organ failure. This review summarizes existing and potential approaches for treatment that have been developed from research using model systems of I/R injury. Although I/R injury in the liver is emphasized, other organ systems share similar pathophysiological mechanisms and therapeutic approaches. We also review current knowledge of the molecular events controlling cellular responses to I/R injury, such as activation of AP-1 and NF-kappaB pathways. Therapeutic strategies aimed at ameliorating I/R damage are focused both on controlling ROS generated at the time of oxygen reperfusion and on intervening in the activated signal transduction cascades. Potential therapies include pharmacological treatment with small molecules, antibodies to cytokines, or free-radical scavenging enzymes, such as superoxide dismutase or catalase. Additionally, the use of gene therapy approaches may significantly contribute to the development of strategies aimed at inhibiting of I/R injury.     

Immunofluorescent studies for alpha-actinin in cultured cardiomyopathic hamster heart cells

Primary cultures of cardiac myocytes from normal and genetically cardiomyopathic (CM) newborn hamsters (strain UM X7.1) were analyzed by indirect immunofluorescent microscopy after 3, 5, 7, and 9 days in culture. The cultures were fixed in cold acetone and immunostained by an indirect method using FITC-labelled anti-alpha-actinin to label the myofibrillar Z bands. Most normal and CM myocytes appeared round in shape after 3 days in culture. Normal cardiac myocytes began to exhibit cytoplasmic projections after 5 days in culture and their myofibrils usually showed parallel arrangements with respect to each other. The cardiac cells from CM hearts showed an obvious myofibril disarray. Moreover, projections formed later than normal. As the size of the cells increased, more and more projections formed in normal hamster myocytes during development. By contrast, most of the cardiomyopathic myocytes showed few projections even as late as 9 days in culture. Hence, the number of projections per cell was much less in cardiomyopathic myocytes than in normal, especially after 7 and 9 days in culture. These results suggest that cardiomyopathic cells have abnormal shapes in culture and, in particular, fail to form projections as in normal cells. Whether this unusual behavior is related to an abnormality of the membranes or cytoskeletal system in cardiomyopathic heart cells or to some other factor requires further study.     

Comparison of the effect of adaptation to stress and to high altitude hypoxia on resistance of the heart to reperfusion injury after total ischemia

Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 7, pp. 18–20, July, 1991.     

苦参素降低大鼠肾脏缺血-再灌注损伤

目的观察苦参素的抗大鼠肾缺血再灌注损伤的作用并从抗氧化方面探讨其机制。方法用双肾肾蒂夹闭45 min建立IRI模型,将SD大鼠随机分为假手术组(sham);缺血再灌注组(I/R);苦参素治疗组(oxymatrine+I/R)。苦参素治疗组又分为高、中和低3个剂量组,在缺血再灌注前,连续7 d经腹腔注射。用自动生化仪测定血清肌酐(Scr)和尿素氮(BUN)水平,观察苦参素对肾缺血再灌注的保护作用及确定最优剂量;以最优剂量干预用分光分析法测定肾组织丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)水平。结果不同剂量组均能明显减轻肾脏IRI的病理形态学改变,改善肾功能。与I/R组相比,再灌注72 h后,MDA水平,血清肌酐(Scr)和尿素氮(BUN)水平明显降低(P<0.05);苦参素治疗组的CAT、T-SOD、GSH-Px活性改善明显(P<0.05)。苦参素无体外抗氧化作用。结论苦参素对大鼠肾缺血再灌注损伤具有保护作用,作用机制可能与调控机体的抗氧化系统有关。