c-Jun氨基末端激酶与心肌保护

作为促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)超家族成员之一的c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)家族是与细胞增殖、分化或凋亡调控密切相关的细胞内信号转导通路.目前越来越多的报道证实了JNK信号途径具有促凋亡和抗凋亡的双重功能,这种双重功能受到细胞类型、刺激物的种类、剂量和持续时间以及胞内其他信号途径的影响.此综述主要探讨JNK在心肌缺血/再灌注(ischemic/reperfusion,I/R)损伤,缺血预处理(ischemic preconditioning,IPC)和缺血后处理中涉入机制及调节作用.     

心肌缺血/再灌注损伤分子信号保护机制的研究进展

缺血/再灌注损伤是一种常见的病理生理改变,近些年来,随着对其机制的大量研究,缺血/再灌注损伤的分子信号保护机制有了许多新的进展.腺苷激动腺苷2A受体(A2AAR),通过Gs蛋白-cAMP信号轴抑制与再灌注相关的炎症反应起保护作用.激活的阿片受体是通过抗细胞凋亡自身激酶信号路径的相互作用来减少再灌注损伤的.缺血后处理的机制也可能涉及到内源性腺苷释放增加.     

p38分裂原激活蛋白激酶在小肠缺血再灌注损伤中的作用研究进展

目前国内外学者对于小肠缺血再灌注损伤的发病机制已经进行了一系列研究,其中分子机制成为研究热点.本文就p38分裂原激活蛋白激酶（p38 mitogen activated protein kinase,p38MAPK）在小肠缺血再灌注损伤发病机制中的作用（包括p38MAPK与氧化应激、炎症细胞因子、肠黏膜屏障功能、细胞凋亡的关系）以及p38MAPK在脏器缺血预处理、缺血后处理等干预措施中的研究现状作一综述.     

缺血后处理减轻心肌缺血损伤的机制与pH假说

缺血后处理是近年来提出的一种减轻缺血/再灌注损伤的新方法,即在全面再灌注前进行反复、短暂的预再灌/停灌干预而达到心肌保护作用,其机制可能与蛋白激酶C和再灌注损伤挽救激酶通路的激活、有害信号转导通路的抑制有关.另有研究显示缺血后处理的心肌保护作用可能与其在缺血心肌再灌注初产生的延迟性酸中毒状态有关.     

七氟烷后处理的心肌保护作用及其机制

背景 大量实验证据表明缺血后处理和药物后处理对心肌再灌注损伤具有确切的保护作用.七氟烷是一种新型的、理想的吸入性麻醉药,被广泛应用于全身麻醉.实验证明七氟烷后处理可以保护心肌对抗缺血/再灌注损伤(ischemia/reperfusion injury,I/RI).目的 通过对近年研究进展的总结对七氟烷后处理的心肌保护作用及机制予以阐述.内容七氟烷后处理可以减少再灌注心肌的梗死面积、线粒体损害和再灌注室性心律失常的发生,改善心脏的血流动力学.七氟烷后处理心肌保护作用复杂且涉及多个方面,如阻断线粒体通透性转运孔(mitochondrial permeability transition pore,mPTP)、激活线粒体ATP敏感性K+通道(mitochondrial KATP-channel,mKATP),激活细胞外信号调节激酶1/2(extracellular signal-regulated kinase 1/2,ERK1/2)以及磷酯酰肌醇-3激酶-丝氨酸/苏氨酸激酶(phosphatidylin ositol-3-kinase-serine/threonine,PI3K-Akt)信号通道等. 趋势 未来的研究除进一步探究七氟烷后处理的心肌保护机制,同时应加强七氟烷后处理的临床应用,为实际工作提供可靠依据.     

肝脏缺血后处理的保护作用机制

肝脏缺血后处理是指肝脏在长时间缺血后,在再灌注之前进行一次或数次短暂重复的缺血再灌注,能提高肝脏对长时间缺血的耐受性,减轻缺血再灌注损伤.近几年被证实为一种有效、可控制的新的减轻再灌注损伤的方法.肝脏缺血后处理的保护机制与保护肝窦内皮和肝脏细胞超微结构,减轻活性氧引起的细胞损伤及炎症反应,减轻细胞内及线粒体内钙超载,调控凋亡基因,改变线粒体离子通道开放状态等有关.本文就缺血后处理的机制作一简要综述.     

缺血预处理联合后处理对大鼠肾缺血再灌注损伤的影响

目的 评价缺血预处理联合后处理对大鼠肾缺血再灌注损伤的影响.方法 健康雄性SD大鼠30只,体重250～280 g,随机分为5组(n=6):假手术组(S组)、缺血再灌注组(I/R组)、缺血预处理组(IP组)、缺血后处理组(IPo组)和缺血预处理联合后处理组(IP+IPo组).S组仅开腹,游离双侧肾脏,分离双侧肾蒂但不夹闭.采用夹闭双侧肾蒂45 min、再灌注6 h的方法 制备肾缺血再灌注模型.IP组夹闭双侧肾蒂5 min,再灌注5 min,反复3次,余操作同I/R组;IPo组夹闭双侧肾蒂45 min后,再灌注10 8,缺血10 s,反复3次,再灌注6 h.于再灌注6 h时,经心脏抽血后迅速处死大鼠取肾,测定血清肌酐(Cr)和尿素氮(BUN)的浓度;采用硫代巴比妥酸法测定肾组织丙二醛(MDA)含量,采用黄嘌呤氧化酶法测定肾组织超氧化物歧化酶(SOD)活性;光镜下观察肾组织病理学结果 ;TUNEL法检测肾组织凋亡细胞,计算凋亡指数(AJ).结果 与S组比较,其余各组血清Cr和BUN的浓度升高,肾组织SOD活性降低,MDA含量和AI升高(P<0.05);与I/R组比较,IP组、IPo组和IP+IPo组血清Cr和BUN的浓度降低,肾组织SOD活性升高,MDA含量和AJ降低(P<0.05),肾损伤减轻;与IP组和IPo组比较,IP+IPo组肾组织SOD活性升高,AI降低(P<0.05),肾损伤减轻.结论 缺血预处理联合后处理可减轻大鼠肾缺血再灌注损伤,较单独应用时效果好.     

肾脏缺血预处理信号转导机制研究进展

缺血预处理(IPC)是指给予机体一次或几次短暂重复的缺血/再灌注(I/R),便能够增强机体组织对以后较长时间缺血的耐受力,减轻组织的I/R损伤。关于肾脏IPC的具体机制,尤其是信号转导方面仍未完全阐明。本文拟对肾脏IPC的信号传导途径作一综述。     

肾缺血预处理对肾小管上皮细胞内钙超载的影响

目的：通过观察肾缺血预处理（IPC）和缺血再灌注（I/R）过程中血清超氧化物歧化酶（SOD）、丙二醛（MDA）和细胞内游离钙离子浓度（[Ca^2＋]i）含量的变化,进一步探讨肾IPC的保护机制。方法：将雄性SD大鼠88只随机分为11组,摘除右肾,分离并夹闭左肾动脉制备肾I/R和缺血预处理后缺血再灌注（IPC-I/R）动物模型。Ⅰa～Ⅴa（I/R）组为缺血再灌注0、1、24、48、72h组,Ⅰb～Ⅴb（IPC-I/R）组为缺血预处理后缺血再灌注0、1、24、48、72h组,Sham组为假手术组。比色法测定血清肌酐（Scr）、尿素氮（BUN）、SOD、MDA含量,流式细胞仪检测肾小管上皮细胞内[Ca^2＋]i水平,TUNEL原位标记法观察细胞凋亡情况。结果：除0h组外,IPC-I/R与I/R各组比较肾功能损害、细胞凋亡均明显减轻,SOD升高,MDA降低,[Ca^2＋]i水平下降;两种模型中均以再灌注24h组损伤最严重,Scr、BUN、MDA和[Ca^2＋]i水平最高,SOD水平最低,细胞凋亡最多;再灌注24h前损伤呈加重趋势,24h后逐渐减轻;组间比较,[Ca^2＋]i与血清SOD水平呈负相关,与MDA呈正相关。结论：肾IPC可以减轻I/R过程中膜脂质过氧化损伤和细胞内钙超载,从而减轻肾脏形态及功能损伤;膜脂质过氧化和细胞内钙超载相互作用,共同发挥对肾I/R损伤的保护作用。     

缺血后处理的关键——延迟再灌注初短暂酸性环境

缺血后处理(ischemic postconditioning,IP0)是近年来提出的一种减轻缺血,再灌(reperfusion injung,I/R)损伤的新方法,即在全面再灌注前进行反复、短暂的再灌注/停灌注.近来认为IPO的关键是通过造成I/R初期的一种短暂的延迟性酸性环境,从而保护缺血心肌免受再灌注损伤.     

线粒体通透件转换孔在缺血/再灌注损伤中的作用

背景 线粒体作为“能量工厂”提供细胞生长及代谢所需的三磷酸腺苷（adenosine triphosphate,ATP）,同时也是细胞存活与否的重要信号管理者.线粒体通透性转换孔（mitochondrial permeability transition pore,mPTP）是横跨线粒体内外膜之间的允许相对分子质量1.5 kD以下的分子自由通过的孔道.在脑缺血/再灌注（ischemia/reperfusion,I/R）损伤中,线粒体是研究的焦点,而mPTP作为线粒体的门户更是影响着线粒体膜电位（mitochondrial membrane potential,△ψm）、线粒体Ca2＋超载及促细胞死亡物质释放等一系列过程. 目的 对mPTP在I/R损伤中可能的作用机制及治疗方法进行综述. 内容 整理和阐述了mPTP的结构、mPTP与I/R损伤的机制和预防与治疗I/R损伤的可能方法. 趋向 随着mPTP在I/R损伤中的作用机制不断被揭示,其将成为治疗I/R损伤的重要靶点.     

缺血后处理与线粒体通透性转运孔

背景 缺血后处理(ischemic postconditioning,IPo)能明显减轻器官缺血/再灌注损伤(ischemia/reperfusion injury,I/RI),动物实验和临床研究均已经得到证实,其机制可能与增强组织抗氧化能力和抑制细胞凋亡有关.然而近些年提出线粒体通透性转换孔(mitochondria...     

缺血后处理对大鼠肝缺血再灌注时肝细胞线粒体膜通透性转换和膜电位的影响

目的 评价缺血后处理对大鼠肝缺血再灌注时肝细胞线粒体膜通透性转换和膜电位(△Ψm)的影响.方法 成年健康雄性SD大鼠40只,体重220～260 g,采用随机数字表法,将其随机分为5组(n=8):假手术组(S组)、苍术苷+假手术组(A+S组)、缺血再灌注组(IR组)、缺血后处理组(IPO组)和苍术苷+缺血后处理组(A+IPO组).采用阻断肝中叶和左叶60 min,恢复血流灌注6 h的方法 建立大鼠肝缺血再灌注模型.S组和A+S组仅游离肝门,不阻断血管;A+S组关腹前静脉注射苍术苷5 mg/kg;IR组制备肝缺血再灌注模型;IPO组于再灌注前行缺血后处理,再灌注1 min,缺血1 min,反复3次;A+IPO组于再灌注前静脉注射苍术苷5 mg/kg.于缺血前即刻和再灌注6 h时,采集左颈静脉血样,测定血清ALT和AST的活性.再灌注6 h时处死大鼠,取肝左叶组织,观察超微结构和细胞凋亡情况,计算凋亡指数,测定细胞色素c(Cyt c)的表达水平、△Ψm和线粒体通透性转换孔(MPTP)活性.结果 与S组比较,A+S组时血清ALT和AST的活性、凋亡指数、Cyt c表达、△Ψm和MPTP活性差异无统计学意义(P＞0.05),IR组、IPO组和A+IPO组再灌注6 h时血清ALT和AST的活性、凋亡指数升高,Cyt c表达上调,△Ψm降低,MPTP活性升高(P＜0.05);与IR组比较,IPO组血清ALT和AST的活性、凋亡指数降低,Cyt c表达下调,△Ψm升高,MPTP活性降低(P＜0.05),肝组织病理学损伤减轻,A+IPO组各指标差异无统计学意义(P＞0.05);与IPO组比较,A+IPO组血清ALT和AST的活性、凋亡指数升高,Cyt c表达上调,△Ψm降低,MPTP活性升高(P＜0.05),肝组织病理学损伤加重.结论 缺血后处理可抑制肝细胞线粒体膜通透性转换,减少线粒体△Ψm的耗散,从而减轻大鼠肝缺血再灌注损伤.

Abstract：

Objective To investigate the effects of ischemic postconditioning on mitochondrial permeability transition and mitochondrial transmembrane potential(△Ψm)following hepatic ischemia-reperfusion(I/R)in rats.Methods Forty male SD rats weighing 220-260 g were randomly divided into 5 groups with 8 animals in each group:sham operation group(group S);atractyloside+sham operation group(group A+S);I/R group;ischemic postconditioning group(group IPO)and atractyloside+ischemic postconditioning group(group A+IPO).The animals were anesthetized with intramuscular injection of atropine 0.05 mg/kg.Hepatic I/R was produced by occlusion of hepatic blood flow for 60 min followed by 6 h reperfusion.In group A+S,atractyloside 5 mg/kg was injected intravenously before abdomen Was closed.In group IPO,the animals were subjected to 3 cycles of 1 min reperfusion interspersed with 1 min hepatic isehemia at the end of 60 min hepatic ischemia.In group A+IPO,atractyloside 5 mg/kg was injected intravenously before reperfusion. Venous blood samples were collected for determination of serum ALT and AST activities immediately before ischemia and at 6 h of reperfusion. The animals were then sacrificed.Their livers were removed for microscopic examination, detection of apoptosis and determination of cytochrome c (Cyt c) expression, △Ψm and mitochonerial permeability transition pore (MPTP)activity. Apoptosis index (AI) was calculated. Results There was no significant difference in serum ALT and AST activities, AI, Cyt c expression, △Ψm and MPTP activity between S and A + S groups (P＞0.05). Compared with group S, serum ALT and AST activities and AI were significantly increased, Cyt c expression was up-regulated, △Ψm was decreased and MPTP activity was increased in groups I/R, IPO and A+IPO(P＜0.05).Compared with group I/R, serum ALT and AST activities and AI were significantly decreased,Cyt c expression was down-regulated, △Ψm was increased and MPTP activity was decreased in group IPO(P＜0.05), while no significant change was found in group A+IPO(P＞0.05).Compared with group IPO,serum ALT and AST activities and AI were significantly increased, Cyt c expression was up-regulated, △Ψm was decreased and MPTP activity was increased in group A + IPO(P＜ 0.05).Microscopic examination showed that hepatic injury was reduced in group IPO compared with group I/R, while aggravated in group A+ IPO compared with group IPO. Conclusion Ischemic postconditioning can protect liver from I/R injury by attenuating the I/R-induced increase in MPTP opening and decrease in △Ψm in rats.     

Mitochondrial permeability transition in liver ischemia and reperfusion: role of c-Jun N-terminal kinase 2

The mitochondrial permeability transition (MPT) mediates hepatic necrosis after ischemia and reperfusion (I/R). Here, we studied the role of c-Jun N-terminal kinase 2 (JNK2) in MPT-induced liver injury. Wildtype (WT) and JNK2 knockout (KO) mice underwent 70% liver ischemia for 1 hr followed by reperfusion for 8 hr, after which hepatocyte injury and animal survival was assessed. Compared with WT, JNK2 KO mice had 38% less alanine transaminase release and 39% less necrosis by histology. Survival out to 14 days was also greater in JNK2 KO mice (57% vs. 11%), and overall Kaplan-Meier survival was improved. No difference in apoptosis was observed. Intravital multiphoton microscopy of potential-indicating rhodamine 123 after reperfusion revealed depolarized mitochondria in 82% of WT hepatocytes, which decreased to 43% in JNK2 KO hepatocytes. In conclusion, JNK2 contributes to hepatocellular injury and death after I/R in association with increased mitochondrial dysfunction via the MPT.     

Programmed necrosis in acute kidney injury

Programmed cell death (PCD) had been widely used synonymously to caspase-mediated apoptosis until caspase-independent cell death was described. Identification of necrosis as a regulated process in ischaemic conditions has recently changed our understanding of PCD. At least three pathways of programmed necrosis (PN) have been identified. First, receptor-interacting protein kinase 3 (RIP3)-dependent necroptosis causes organ failure following stroke, myocardial infarction and renal ischaemia/reperfusion injury. Necroptosis can be mediated either by a large intracellular caspase-8-containing signalling complex called the ripoptosome or by the RIP1-/RIP3-containing necroptosome and is controlled by a caspase-8/FLICE inhibitory protein(long) heterodimer at least in the latter case. Second, mitochondrial permeability transition mediates apoptotic or necrotic stimuli and depends on the mitochondrial protein cyclophilin D. The third PN pathway involves the poly(ADP-ribose) polymerase-calpain axis that contributes to acute kidney injury (AKI). Preclinical interference with the PN pathways therefore raises expectations for the future treatment of ischaemic conditions. In this brief review, we aim to summarize the clinically relevant PCD pathways and to transfer the basic science data to settings of AKI. We conclude that pathologists were quite right to refer to ischaemic kidney injury as 'acute tubular necrosis'.     

Augmenter of liver regeneration-mediated mitophagy protects against hepatic ischemia/reperfusion injury

Augmenter of liver regeneration (ALR) is an anti-apoptotic protein found mainly in mitochondria. It protects hepatocytes from ischemia-reperfusion (I/R) injury, but the underlying mechanism is not clear. We found that in rats, delivery of the ALR gene alleviated hepatic I/R injury during orthotopic liver transplantation as evidenced by reduced serum aminotransferase, oxidative stress and apoptosis, and increased expression of autophagy markers. In an in vitro hypoxia/reoxygenation (H/R) model, overexpression of the ALR gene activated autophagy and relieved defective mitophagy via the PINK1/Parkin pathway. Mechanistically, ALR transfection induced the expression of mitofusin 2 (Mfn2) in the H/R model, which led to PINK1 accumulation and mitochondrial translocation of Parkin. Deletion of Mfn2 abolished mitophagy activation induced by ALR transfection, promoted mitochondrial dysfunction, and eventually increased cell apoptosis. Mfn2 administration prevented the inhibition of mitophagy in ALR-knockout (KO) cells, thus attenuated mitochondrial dysfunction and cell apoptosis. In heterozygous ALR-knockout mice treated with a warm I/R injury, marked aggravation of liver injury was associated with mitophagy inhibition and reduction in Mfn2 expression. Taken together, our results confirm that ALR accelerated Parkin translocation and mitophagy via Mfn2, and protected hepatocytes from I/R-induced injury. Our findings provide a novel rationale for the treatment of hepatic I/R injury.     

七氟烷预处理对局灶性脑缺血再灌注损伤大鼠线粒体通透性转换孔的影响

目的 探讨七氟烷预处理对局灶性脑缺血再灌注损伤大鼠线粒体通透性转换孔(mPTP)的影响.方法 成年雄性SD大鼠60只,体重250～300 g,随机分为5组(n=12):假手术组(S组)、缺血再灌注组(I/R组)、七氟烷预处理组(Sev组)、线粒体ATP敏感性钾离子通道(mito-KATP通道)阻断剂5-羟癸酸(5-HD)+Sev组和5-HD组.采用大脑中动脉阻断法制备局灶性脑缺血再灌注模型.S组只分离血管不置入线栓;I/R组制备局灶性脑缺血再灌注模型;Sev组吸入2.4%七氟烷60 min行预处理,24 h后制备局灶性脑缺血再灌注模型;5-HD+Sev组腹腔注射5-HD 40mg/kg,30 min后行七氟醚预处理,其余处理同Sev组;5-HD组腹腔注射5-HD 40 mg/kg,30 min后制备局灶性脑缺血再灌注模型.于再灌注24 h时断头取缺血侧顶叶皮层组织,测定mPTP活性,Western blot法测定Bcl-2、Bax表达水平,并计算Bcl-2/Bax比值,采用TUNEL法检测神经元凋亡情况.结果 与S组比较,I/R组、Sev组、5-HD+Sev组和5-HD组凋亡神经元计数升高,Bcl-2和Bax表达上调,Bcl-2/Bax比值升高,mPTP活性升高(P＜0.05);与I/R组比较,Sev组凋亡神经元计数减少,Bcl-2表达上调,Bcl-2/Bax比值升高,mPTP活性降低(P＜0.05);与Sev组比较,5-HD+Sev组和5-HD组Bcl-2表达下凋,Bcl-2/Bax比值降低,mPTP活性升高(P＜0.05);5-HD+Sev组与5-HD组上述指标比较差异无统计学意义(P＞0.05).结论 七氟烷预处理可能通过激活神经元mito-KATP通道,上调Bcl-2的表达,从而抑制mPTP的大量开放减轻大鼠局灶性脑缺血再灌注时的神经元凋亡.     

ATP敏感性钾通道及其心肌保护作用机制的研究进展

背景心肌缺血／再灌注损伤（myocardial ischemia／reperfusion injury,MI／RI）引起严重的后果。虽然,缺血或药物预处理、缺血或药物后处理等处理方法均能达到心肌保护的作用,但是其心肌保护机制有待深入研究。目的总结ATP敏感性钾通道（ATP-sensitive potassium channel,KATP）及其心肌保护作用机制的研究进展。内容各种心肌保护方法能够直接开放KATP通道或通过激活G蛋白耦联受体间接开放KATP通道。与此同时,开放的KATP通道能够于再灌注早期刺激产生活性氧物质（reactiveoxygenspecies,ROS）及关闭线粒体通透性转换孔（mitochondrial permeability transition pore, mPTP）等方式减轻MI／RI。趋向各种心肌保护方法需要广泛应用于实践,包括KATP在内的各种机制需要更深入地研究。     

缺血预处理对再灌注脊髓神经细胞凋亡及细胞凋亡信号调节激酶-1蛋白活化的影响

目的 研究缺血预处理对再灌注脊髓神经细胞凋亡及细胞凋亡信号调节激酶-1(ASKI)蛋白活化的影响.方法 取健康成年新西兰大白兔35只,随机分为空白对照组(5只)、缺血再灌注(1/R)组(15只)、缺血预处理+缺血再灌注(IPC+I/R)组(15只),制作脊髓缺血预处理及缺血再灌注损伤模型.HE染色、电镜检测脊髓神经细胞的形态学变化;Westem-Blot、免疫共沉淀检测ASKl的活化及ASK1-14-3-3相瓦作用的变化.结果 形态学观察:IPC+I/R组脊髓神经细胞凋亡程度、间质出血程度和再灌注相14时段I/R组相比明显减轻.Western.Blot检测ODpASKI/ODASKI定量分析结果显示:空白组为0.142±0.019,I/R组再灌注30 rain、2 h、8 h分别为0.356 4-0.030、0.608±0.029、0.864±0.039,IPC+I/R组再灌注30 min、2 h、8 h分别为0.154±0.029、0.162±0.042、0.462±0.047,IPC+I/R组ASKI活化程度较相同再灌注时段I/R组明显被抑制(P<0.05).免疫共沉淀检测ODASKI/ODl4-3-3定量分析结果显示:空白对照组为0.916±0.058,I/R组再灌注30 min、2 h、8 h分别为0.794±0.040、0.582±0.053、0.270±0.045,IPC+I/R组再灌注30 min、2 h、8 h分别为0.888±0.059、0.830±0.067、0.518±0.043,IPC+I/R组ASKI.14.3.3解离程度较相同再灌注时段I/R组明显被抑制(P<0.05).结论 缺血预处理可减少缺少缺血再灌注损伤过程巾脊髓神经细胞的凋亡,而这种抗凋亡作用可能是通过抑制ASKl-14-3-3的解离进而抑制ASK1的活化来介导的.