Proteasome inhibition attenuates lung injury induced by intestinal ischemia reperfusion in rats

The aim of this study is to investigate the role of proteasome in the pathogenesis of lung injury induced by intestinal ischemia/reperfusion (I/R) by examining the effect of the proteasome inhibitor lactacystin on neutrophil infiltration, intracellular adhesion molecule-1 (ICAM-1) expression and nuclear factor kappa B (NF-κB) activation. Thirty-two Wistar rats were divided into (1) control, (2) intestinal I/R, (3) 0.2 mg/kg lactacystin pretreated, and (4) 0.6 mg/kg lactacystin pretreated groups (n = 8). Injuries in lung and intestine were induced by intestinal I/R, and were characterized by histological edema, hemorrhage and infiltration of inflammatory cells. The results showed a significant increase in serum creatine kinase B (CK-B) and lung water content in intestine and lung injuries. As compared with the control group, the myeloperoxidase (MPO) activity in intestine and lung as well as the serum TNF-α level increased significantly in intestinal I/R group. Simultaneously, expression of ICAM-1 and NF-κB p65 was also observed in the I/R group. Pre-treatment with lactacystin markedly reduced 20S proteasome activity in circulating white blood cells and ameliorated intestine and lung injuries. These results demonstrated that the proteasome participates in the pathogenesis of lung injury induced by intestinal I/R. Lactacystin as a proteasome inhibitor can prevent this kind of injury by decreasing ICAM-1 and TNF-α production via the inhibition of NF-κB activation.     

Glycine attenuates cerebral ischemia/reperfusion injury by inhibiting neuronal apoptosis in mice

Glycine is a cytoprotector to protect cells against ischemic damage by counteracting neuronal depolarization. However, whether it can directly inhibit neuronal apoptosis is unknown. In this study, we demonstrated that glycine could attenuate ischemia/reperfusion (I/R) induced cerebral infarction and improved neurological outcomes in mice. The protective effect of glycine was associated with reduction of terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) positive cells, deactivation of phosphor-JNK, inhibition of caspase-3 cleavage, down-regulation of FasL/Fas, and up-regulation of bcl-2 and bcl-2/bax in the mouse I/R penumbra. The beneficial effect of glycine against oxygen and glucose deprivation (OGD) induced injury was also confirmed in SH-SY5Y cells as well as in primary cultured neurons, which was significantly dampened by knockdown of glycine receptor α1 (GlyR α1) with siRNA transfection or by preventing glycine binding with glycine receptor using a specific antibody against glycine receptor. These results suggest that glycine antagonize cerebral I/R induced injury by inhibiting apoptosis in mice. Glycine could block both extrinsic and intrinsic apoptotic pathways for which GlyR may be required.     

Involvement of miR-1 in the protective effect of hydrogen sulfide against cardiomyocyte apoptosis induced by ischemia/reperfusion

The protective effect of hydrogen sulfide (H₂S) against myocardial ischemia/reperfusion (IR) injury via anti-apoptotic signaling is well established, but the underlying mechanism remains unclear. Recently, miRNAs have been identified as important mediators of myocardial injury by regulating apoptosis-related genes. It was found in our previous preliminary study that microRNA-1 (miR-1) expression underwent a significant change in IR group compared to H₂S preconditioned group, indicating that miR-1 possessed myocyte-specific properties. In the present study, we intended to see whether miR-1 participated in H₂S protection of cardiomyocytes against IR-induced apoptosis by regulating apoptosis-related genes. Cardiomyocytes of neonatal rats were subjected to hypoxia/reoxygenation (HR) injury with or without H₂S preconditioning, while the myocardium of adult SD rats was subjected to IR with or without H₂S preconditioning. It was found that HR injury increased apoptosis of cardiac myocytes, up-regulated the expression of miR-1, and down-regulated the expression of Bcl-2. H₂S preconditioning attenuated cardiomyocyte apoptosis and LDH release, as well as enhanced cell viability following HR injury. MiR-1 was up-regulated by HR and down-regulated by H₂S preconditioning. In contrast, Bcl-2 was down-regulated by HR and up-regulated by H₂S preconditioning. In addition, Bcl-2 protein was down-regulated by the miR-1 mimic in a dose-dependent manner. H₂S also attenuated IR-induced cardiomyocyte apoptosis in vivo. MiR-1 regulated H₂S protection of cardiomyocytes against IR-induced apoptosis by stimulating Bcl-2. These results implicate miR-1 as an important regulator of H₂S on the IR myocardium.     

Involvement of glutamate in retinal protection against ischemia/reperfusion damage induced by post-conditioning

Retinal ischemia could provoke blindness and there is no effective treatment against retinal ischemic damage. Brief intermittent ischemia applied during the onset of reperfusion (i.e., post-conditioning) protects the retina from ischemia/reperfusion injury. Multiple evidences support that glutamate is implicated in retinal ischemic damage. We investigated the involvement of glutamate clearance in post-conditioning-induced protection. For this purpose, ischemia was induced by increasing intra-ocular pressure for 40 min, and 5 min after reperfusion, animals underwent seven cycles of 1 min/1 min ischemia/reperfusion. One, three, or seven days after ischemia, animals were subjected to electroretinography and histological analysis. The functional and histological protection induced by post-conditioning was evident at 7 (but not 1 or 3) days post-ischemia. An increase in Müller cell glial fibrillary acidic protein (GFAP) levels was observed at 1, 3, and 7 days after ischemia, whereas post-conditioning reduced GFAP levels of Müller cells at 3 and 7 days post-ischemia. Three days after ischemia, a significant decrease in glutamate uptake and glutamine synthetase activity was observed, whereas post-conditioning reversed the effect of ischemia. The intravitreal injection of supraphysiological levels of glutamate mimicked electroretinographic and histological alterations provoked by ischemia, which were abrogated by post-conditioning. These results support the involvement of glutamate in retinal protection against ischemia/reperfusion damage induced by post-conditioning.     

神经途径在肢体缺血预处理抗脑缺血/再灌注损伤中的作用

目的：探讨神经途径在肢体缺血预处理（limbi schemic preconditioning,LIP）抗脑缺血／再灌注损伤中的作用。方法：脑缺血采用四血管闭塞模型,重复短暂夹闭放松大鼠双侧股动脉3次作为LIP。将凝闭椎动脉的大鼠随机分为sham组、脑缺血组、股神经切断＋脑缺血组、LIP＋脑缺血组、股神经切断＋LIP＋脑缺血组。于Sham手术和脑缺血后7d处死大鼠,硫堇染色观察海马CA1区锥体神经元迟发性死亡的变化。于Sham手术和脑缺血后6h心脏灌注固定大鼠,免疫组化法测定海马CAI区c-Fos表达的变化。结果：硫堇染色结果显示,与sham组比较。脑缺血组和股神经切断＋脑缺血组大鼠海马CAI区均有明显组织损伤。LIP＋脑缺血组CAI区无明显细胞缺失,神经元密度明显高于脑缺血组（P〈0．01）。而股神经切断＋LIP＋脑缺血组大鼠海马CA1区明显损伤,锥体细胞缺失较多,与LIP＋脑缺血组组比较,神经元密度显著降低（P〈O．01）,提示LIP前切断双侧股神经取消了LIP抗脑缺血／再灌注损伤作用。c—Fos免疫组化染色结果显示,Sham组海马CAI区未见明显的c-Fos蛋白表达。脑缺血组海马CAI区偶见c—Fm的阳性表达。LIP＋脑缺血组c—Fos表达增强,数量增加,与Sham组和脑缺血组比较。c-Fos阳性细胞数和光密度均明显升高（P〈0．01）。而股神经切断＋LIP＋脑缺血组c-Fos表达明显减少,仅见少量弱阳性e-Fos表达。结论：LIP可通过神经途径发挥抗脑缺血／再灌注损伤作用,而LIP诱导c—Fos表达增加可能是LIP诱导脑缺血耐受神经途径的一个环节。     

Hydrogen-rich saline reduces lung injury induced by intestinal ischemia/reperfusion in rats

Objective. Hydrogen has been reported to selectively reduce the hydroxyl radical, the most cytotoxic of reactive oxygen species. In this study we investigated the effects of hydrogen-rich saline on the prevention of lung injury induced by intestinal ischemia/reperfusion (I/R) in rats. Methods. Male Sprague-Dawley rats (n = 30, 200-220 g) were divided randomly into three experimental groups: sham operated, intestinal I/R plus saline treatment (5 ml/kg, i.v.), and intestinal I/R plus hydrogen-rich saline treatment (5 ml/kg, i.v.) groups. Intestinal I/R was produced by 90 min of intestinal ischemia followed by a 4 h of reperfusion. Results. Hydrogen-rich saline treatment decreased the neutrophil infiltration, the lipid membrane peroxidation, NF-κB activation and the pro-inflammatory cytokine interleukin IL-1β and TNF-α in the lung tissues compared with those in saline-treated rat. Conclusion. Hydrogen-rich saline attenuates lung injury induced by intestinal I/R.     

细胞自噬在大鼠肺缺血/再灌注引发肝脏损伤中的作用*

目的: 探讨肺缺血/再灌注(LI/R)时肝脏损伤的影响,并初步探索细胞自噬(Autophagy)在其中发挥的作用。方法: 构建大鼠缺血/再灌注肺损伤(LI/RI)模型,模型制备方法为大鼠麻醉后切开气管进行机械通气,使用动脉夹将肺门夹闭模拟缺血过程,30 min后松开动脉夹,恢复灌注3 h。24只大鼠随机分为伪手术组(Sham组)、缺血/再灌注组(I/R组)、溶剂组(DMSO组)和自噬抑制剂组(3-MA组),每组均6只,后2组大鼠术前分别腹腔注射DMSO和3-MA,造模结束后使用肺湿/干重比判断造模是否成功;抽取静脉血测定肝脏转氨酶指标ALT与AST;取肝脏组织,光镜下观察肝脏形态改变,以及电镜下观察肝细胞超微结构;使用RT-qPCR和Western blot实验分别检测肝脏组织细胞中自噬相关蛋白的基因mRNA表达水平和蛋白表达水平。结果: 与Sham组相比,其余各组肺湿/干重比均升高;血AST和ALT均有大幅升高且肝脏组织损伤明显,其中以I/R组升高最为明显,光镜下组织形态学及电镜下细胞微细结构均有不同程度的破坏;肝脏中自噬相关蛋白的基因表达水平与蛋白表达水平均有明显不同,表现为自噬上升 (P＜0.01或P＜0.05)。I/R组和DMSO组肝脏组织均有较重损伤,肝细胞结构破坏严重,自噬小体形成,而AST、ALT、自噬相关蛋白转录和表达水平等各项指标均无统计学差异(P＞0.05)。而相较于DMSO组,3-MA组肝脏组织损伤有所减轻,肝细胞微细结构损伤程度低,且无自噬小体形成,血中AST和ALT下降,肝脏组织内自噬水平均下降 (P＜0.05)。结论: 肺缺血/再灌注可引起大鼠肝损伤;细胞自噬可介导大鼠肺缺血/再灌注引起的肝损伤,抑制细胞自噬可以有效减轻大鼠LI/R引起的肝损伤。     

川芎嗪对脑缺血/再灌注后所致肺损伤的影响

目的：观察川芎嗪对脑缺血／再灌注后肺损伤的影响。方法：采用Pulsinelli等的方法建立大鼠急性全脑缺血／再灌注模型。将Wistar大鼠随机分为三组,即：对照组（Control）、缺血／再灌注组（I／R）、川芎嗪＋缺血／再灌注组（TEP＋I／R）,分别测定各组肺功能（PaO2、PaCO2）,肺系数（LI％）、血浆和肺组织中与自由基有关物质的含量。结果：川芎嗪可有效改善脑缺血／再灌注后肺功能,减轻肺水肿,减少胞浆酶的漏出,增加自由基清除醇的活性,抑制组织脂质过氧化的发生。结论：川芎嗪对脑缺血／再灌注后肺损伤具有保护作用,其机制可能与其抗氧自由基和膜保护作用有关。     

青藤碱抗大鼠肝脏缺血/再灌注损伤作用的机制探讨

目的:观察青藤碱时大鼠肝脏缺血再灌注损伤的影响,探讨其保护大鼠肝脏缺血再灌注损伤作用的机制.方法:通过建立大鼠全肝缺血再灌注损伤模型,应用硝酸酶还原法测定肝脏缺血再灌注后60min血清NO水平变化;测定再灌注60 min后肝组织内MDA和SOD含量变化;再灌注60min取肝组织完成肝组织显微结构的观察.结果:肝脏缺血再灌注损伤后血清NO水平降低;青藤碱能提高再灌注后血清NO水平,且能改善肝脏缺血再灌注损伤的微循环,减轻肝细胞内超微结构的损害程度.结论:青藤碱对大鼠肝脏缺血再灌注损伤有保护作用,其主要作用机制是清除氧自由基和改善微循环.     

Cell-cycle regulators are involved in transient cerebral ischemia induced neuronal apoptosis in female rats

Recent evidence indicates that cell-cycle regulating proteins are involved in apoptotic process in post-mitotic neurons. In this study, we examined cell-cycle regulators for G1/S cell-cycle progression after a transient focal cerebral ischemia induced by middle cerebral artery (MCA) occlusion. In the cerebral frontoparietal cortex, we observed a marked induction of Cyclin D1 (a coactivator of Cdks), and proliferating cell nuclear antigen (PCNA), together with upregulated Cdk kinase activities. This process is accompanied with multiple phosphorylation of retinoblastoma (Rb) protein at Cdk phosphorylation sites in neurons from the ischemic cortex. We further examined DNA synthesis by the incorporation of BrdU, a nucleotide analog that incorporates into newly synthesized DNA. Within 24-h of reperfusion after 60-min occlusion, substantial BrdU-positive neurons were observed in the ischemic cortex. Inhibition of Cdk4 activity during this ischemia/reperfusion is highly neuroprotective. These results suggest that ischemia/reperfusion cerebral damage induces signalings at the G1/S cell-cycle transition, and may constitute a critical step in the neuronal apoptotic pathway in ischemia/reperfusion induced neuronal damage.     

Ischemic conditioning by short periods of reperfusion attenuates renal ischemia/reperfusion induced apoptosis and autophagy in the rat

Prolonged ischemia amplified iscehemia/reperfusion (IR) induced renal apoptosis and autophagy. We hypothesize that ischemic conditioning (IC) by a briefly intermittent reperfusion during a prolonged ischemic phase may ameliorate IR induced renal dysfunction. We evaluated the antioxidant/oxidant mechanism, autophagy and apoptosis in the uninephrectomized Wistar rats subjected to sham control, 4 stages of 15-min IC (I15 × 4), 2 stages of 30-min IC (I30 × 2), and total 60-min ischema (I60) in the kidney followed by 4 or 24 hours of reperfusion. By use of ATP assay, monitoring O₂ ^-. amounts, autophagy and apoptosis analysis of rat kidneys, I60 followed by 4 hours of reperfusion decreased renal ATP and enhanced reactive oxygen species (ROS) level and proapoptotic and autophagic mechanisms, including enhanced Bax/Bcl-2 ratio, cytochrome C release, active caspase 3, poly-(ADP-ribose)-polymerase (PARP) degradation fragments, microtubule-associated protein light chain 3 (LC3) and Beclin-1 expression and subsequently tubular apoptosis and autophagy associated with elevated blood urea nitrogen and creatinine level. I30 × 2, not I15 × 4 decreased ROS production and cytochrome C release, increased Manganese superoxide dismutase (MnSOD), Copper-Zn superoxide dismutase (CuZnSOD) and catalase expression and provided a more efficient protection than I60 against IR induced tubular apoptosis and autophagy and blood urea nitrogen and creatinine level. We conclude that 60-min renal ischemia enhanced renal tubular oxidative stress, proapoptosis and autophagy in the rat kidneys. Two stages of 30-min ischemia with 3-min reperfusion significantly preserved renal ATP content, increased antioxidant defense mechanisms and decreased ischemia/reperfusion enhanced renal tubular oxidative stress, cytosolic cytochrome C release, proapoptosis and autophagy in rat kidneys.     

S-nitrosylated GAPDH mediates neuronal apoptosis induced by amyotrophic lateral sclerosis-associated mutant SOD1G93A

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with the selective loss of motor neurons in the brain, brain stem, and spinal cord. A number of the mutants of the human gene for superoxide dismutase 1 (SOD1) have been shown to cause familial ALS as a result of gain-of-function toxicity by an unknown mechanism. In this study, we show that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) functions as a critical mediator of the apoptotic cell death signaling cascade induced by the ALS-associated G93A mutant of human SOD1 [SOD1(G93A)]. We observed that SOD1(G93A) induces S-nitrosylation of GAPDH and the subsequent binding of GAPDH and Siah1 in NSC34 motor neuron-like cells. Furthermore, SOD1(G93A) promoted nuclear translocation of S-nitrosylated GAPDH in the cells. In addition, SOD1(G93A)-induced apoptotic cell death was inhibited by deprenyl, a chemical inhibitor of GAPDH S-nitrosylation, in NSC34 cells. Taken together, our findings suggest that S-nitrosylation of GAPDH plays a critical role in SOD1(G93A)-induced neuronal apoptosis.     

Propofol protects the autophagic cell death induced by the ischemia/reperfusion injury in rats

Autophagy has been implicated in cardiac cell death during ischemia/reperfusion (I/R). In this study we investigated how propofol, an antioxidant widely used for anesthesia, affects the autophagic cell death induced by the myocardial I/R injury. The infarction size in the myocardium was dramatically reduced in rats treated with propofol during I/R compared with untreated rats. A large number of autophagic vacuoles were observed in the cardiomyocytes of I/R-injured rats but rarely in I/R-injured rats treated with propofol. While LC3-II formation, an autophagy marker, was up-regulated in the I/R-injured myocardium, it was significantly down-regulated in the myocardial tissues of I/R-injured and propofol-treated rats. Moreover, propofol inhibited the I/R-induced expression of Beclin-1, and it accelerated phosphorylation of mTOR during I/R and Beclin-1/Bcl-2 interaction in cells, which indicates that it facilitates the inhibitory pathway of autophagy. These data suggest that propofol protects the autophagic cell death induced by the myocardial I/R injury.     

MK801对大鼠肢体缺血/再灌注致脑组织发生细胞凋亡的影响

目的:探讨肢体缺血/再灌注(LI/R)后,脑组织损伤的发生及MK801的影响。方法:采用文献[4]方法复制大鼠肢体缺血再灌损伤模型,给予MK801处理,观察各组动物脑组织中丙二醛(MDA)含量的变化,TUNEL法检测细胞凋亡情况,免疫组化和Western印迹法检测凋亡相关因子Bcl-2、细胞色素C(cytoC)、Caspase-3表达的变化。结果:大鼠LI/R后,脑组织中MDA含量升高,中脑红核区有大量胞浆呈棕色的Bcl-2、cytoC、Caspase-3蛋白阳性细胞分布,且细胞凋亡明显增加。MK801干预组与LI/R组相比MDA含量显著下降,Bcl-2、cytoC、Caspase-3蛋白表达降低,差异显著,且细胞凋亡相应降低。结论:凋亡相关因素Bcl-2、cytoC、Caspase-3变化介导的细胞凋亡参与大鼠LI/R后所致脑损伤过程。减弱谷氨酸兴奋性毒性作用及氧自由基损伤、影响凋亡相关基因表达可能是MK801脑保护的机制之一。     

Effects of polyamines on apoptosis induced by simulated ischemia/reperfusion injury in cultured neonatal rat cardiomyocytes

We incubated neonatal Sprague-Dawley rat cardiomyocytes in primary culture in a medium simulating ischemia (consisting of hypoxia plus serum deprivation) for 2 h, then re-incubated them for 24 h in normal culture medium to establish a model of simulated ischemia/reperfusion (I/R) injury. Apoptotic cell death was measured by MTT assay, TUNEL staining and flow cytometry. Morphological alterations were assessed by transmission electron microscopy, the expression of caspases-3 and -9 and Bcl-2 and the release of cytochrome c by Western blotting, and the intracellular free-calcium concentration ([Ca2+]i) by laser confocal scanning microscopy. The results showed that pretreatment with 10 micromol/l spermine or spermidine significantly inhibited apoptosis in the I/R cells, suppressed the expression of caspases-3 and -9 and cytochrome c release, up-regulated Bcl-2 expression and decreased [Ca2+]i. However, pretreatment with 10 micromol/l putrescine had the opposite effects. Evidence for this "double-edged" effect of polyamines on apoptosis in I/R-injured cardiomyocytes is presented for the first time. It may suggest a novel pharmacological target for preventing and treating cardiac ischemia/reperfusion injury.     

Prevention of rat neonatal cardiomyocyte apoptosis induced by simulated in vitro ischemia and reperfusion

Apoptosis, or programmed cell death, is an active metabolic response to physiological signals or exposure to cytotoxic agents. Recent evidence has shown that the cell death response can be modified by agents presumed to be unrelated to the initial signal, but capable of interfering with the molecular mechanisms of the apoptotic pathway progression. Here we show the results of investigations on the use of a phospholipid-based pharmaceutical preparation for suppression of myocardial damage. First, we show that serum or serum/glucose deprivation, in vitro ischemia with subsequent simulated reperfusion, inhibition of protein synthesis, and treatment with ceramide, staurosporine, adriamycin, cis-platinum and menadione induce apoptotic death in a primary culture of rat neonatal cardiomyocytes. Then we demonstrate that a mixture of specific phospholipids, which has been originally purified from soy flour on the basis of its anti-apoptotic activity, prevents cardiomyocyte death induced by serum or serum/glucose deprivation, by ischemia with subsequent simulated reperfusion, and by ceramide, but not by other cytotoxic treatments. This suggests that ceramide, a lipid secondary messenger which triggers apoptosis induced by some cytotoxic agents, may be involved in the process of signaling ischemia/reperfusion induced apoptotic death of cardiomyocytes. These results further demonstrate that an active pharmaceutical preparation for the suppression of cardiomyocyte death can be formulated based upon a novel strategy of apoptosis modification.     

再灌注损伤诱导成年心肌细胞凋亡及Rb1对其抑制作用

曾认为末期已分化成熟的心肌细胞不发生细胞凋亡 ,但近来研究发现 ,某些因素可以诱导成年心肌细胞凋亡 ,并且许多心脏疾病的发病过程中有细胞凋亡参与。本实验采用定性定量方法 ,观察了缺血—再灌注损伤诱发心肌细胞凋亡的情况 ,以及人参皂甙单体Ｒｂ1对细胞凋亡的抑制作用1　材料与方法(1)再灌注损伤动物模型的建立　选用健康成年Ｗｉｓｔａｒ大鼠 ,体重 2 0 0～ 30 0ｇ ,雌雄不拘。用结扎左冠状动脉主干方法建立缺血 再灌注模型。动物分组 :缺血 再灌注组 (ｎ =2 2 ) ,缺血 45ｍｉｎ后再灌注 4ｈ ;假手术组 (ｎ =2 2 ) ,只在冠状动脉下穿…