Changes in oxidative stress,iNOS activity and neutrophil infiltration in severe transient focal cerebral ischemia in rats

Oxidative stress, inducible nitric oxide synthase (iNOS) and neutrophils all contribute to post-ischemic brain damage. This study has determined the time courses of these three phenomena after ischemia in parallel with histological and functional outcomes. Ischemia was produced in rats by occluding the left middle cerebral artery and both common carotid arteries for 20 min. Regional cerebral blood flow (rCBF) rapidly decreased to 20% of its preischemic value during occlusion and stabilized at 60% following reperfusion. The striatal infarction was maximal 15 h after reperfusion (50+/-3 mm(3)), whereas the cortical infarction reached its maximum at 48 h (183+/-10 mm(3)). This drastic decrease in rCBF followed by incomplete reperfusion and massive infarction is, thus, extremely severe. The cortical infarction was strongly correlated with the neurologic deficit and loss of body weight. Oxidative stress, evaluated by the decrease in glutathione concentrations, appeared in the striatum at 6 h after reperfusion and in the cortex at 15 h. Calcium-independent NOS activity, considered as inducible NOS activity, was significantly enhanced at 24 h in the striatum and at 48 h in the cortex. Myeloperoxidase activity, a marker of neutrophil infiltration, was significantly increased at 48 h in both the striatum and cortex. These time courses show that the delayed iNOS activity and neutrophil infiltration that occur after the maturation of infarction in severe ischemia may not contribute to ischemic brain damage. By contrast, early oxidative stress may well be implicated in cerebral injury.     

New therapeutic possibility of blocking cytokine-induced neutrophil chemoattractant on transient ischemic brain damage in rats

Earlier we indicated that neutrophilic invasion into cerebral parenchyma is an important step in rat cerebral ischemia-reperfusion injury and the production of chemotactic factors, cytokine-induced neutrophil chemoattractant (CINC) precede the neutrophilic invasion. The aim of the present study was to evaluate the role of CINC production and the therapeutic possibility of blocking CINC activity in the transient ischemic brain damage in rats. Focal transient ischemia was produced by intraluminal occlusion of the right middle cerebral artery for 60 min. An enzyme immunoassay was used to measure the brain concentration of CINC and myeloperoxidase activity in ischemic areas was measured as a marker of neutrophilic accumulation. An immunohistochemical staining technique was used to detect the immunopositive cells for anti-CINC antibody. Further, application of anti-CINC antibody or anti-neutrophil antibody to rats was used to evaluate the role of CINC production. In ischemic areas, CINC production was detected and peaked 12 h after reperfusion, which followed 60 min of ischemia. Intraperitoneal injection of anti-neutrophil antibody 24 h before and immediately after reperfusion significantly reduced the brain water content and partially reduced the CINC production in ischemic areas. Further, immunohistochemical staining showed that anti-CINC antibody was found on the endothelial surface of venules and on parts of neutrophils that had invaded the ischemic area 6 to 24 h after reperfusion. Also, treatment with anti-CINC antibody reduced ischemic edema formation 24 h after reperfusion and the size of infarction areas 7 days after reperfusion. It thus appears that CINC, mainly produced by endothelium activated by factors released from neutrophils, plays an important role in ischemic brain damage. Furthermore, the blocking of CINC activity with antibody suggests an immuno-therapeutic approach to the treatment of stroke patients.     

选择性COX2抑制剂对脑缺血再灌注损伤的影响

目的 :观察脑缺血再灌注损伤中COX2的表达以及选择性COX2抑制剂SC5 812 5对脑缺血再灌注后脑梗死体积、PGE2 含量的影响。方法 :应用小鼠短暂性局灶性脑缺血模型 ;脑梗死体积的测定采用TTC染色法 ;ELISA测定PGE2 含量 ;DNA单链损伤的测定采用PANT染色。结果 :缺血前 3 0min和缺血后 2h用药组脑梗死体积显著缩小 ,缺血后 6h延迟用药组脑梗死体积无明显变化。脑缺血再灌注后PGE2 含量显著升高。SC5 812 5的治疗显著降低了PGE2 的水平。SC5 812 5并可显著抑制缺血后DNA单链损伤的程度。结论 :提示COX2参与了脑缺血再灌注损伤 ,选择性COX2抑制剂在小鼠局灶性脑缺血再灌注损伤的模型中起着重要作用     

大鼠急性脑缺血再灌注损伤精氨酸加压素变化和脑水肿实验研究

应用大鼠急性脑缺血再灌注动物模型，观察精氨酸加压素（ＡＶＰ）在急性脑缺血再灌注损伤中的变化及与脑水肿关系，结果表明丘脑下部ＡＶＰ含量在脑缺血３０ｍｉｎ明显增加，再灌注６０ｍｉｎ后进一步增加，且与大脑皮层水含量是显著相关性。提示，ＡＶＰ参与急性脑缺血再灌注损伤，丘脑下部ＡＶＰ含量增高，可加重或促进脑缺血再灌注后脑水肿形成。     

脑缺血再灌流大鼠脑胶质源性神经营养因子基因表达的变化

探讨脑缺血再灌流不同时程及不同程度缺血对海马及皮层胶质源性神经营养因子（ｇｌｉａｌｃｅｌｌｌｉｎｅ ｄｅｒｉｖｅｄ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ, ＧＤＮＦ）基因表达的影响,以及Ｎ甲基Ｄ天冬氨酸（Ｎｍ ｅｔｈｙｌＤｓａｐａｒｔａｔｅ, ＮＭＤＡ）受体拮抗剂,钙离子通道阻断剂是否能调节缺血病态下ＧＤＮＦｍ ＲＮＡ的表达。参照Ｓｍ ｉｔｈ 等方法建立大鼠前脑缺血再灌流动物模型。用ＤＩＧＯｌｉｇｏｎｕｃｌｅｏｔｉｄｅ ３′ｅｎｄ ｌａｂｅｌｉｎｇ Ｋｉｔ,标记５１ ｍ ｅｒ的ＧＤＮＦ寡核苷酸探针在含有海马结构的冰冻组织切片上进行原位杂交检测ＧＤＮＦｍ ＲＮＡ的表达。１０ ｍ ｉｎ 缺血再灌流２ ｈ,齿状回ＧＤＮＦｍ ＲＮＡ表达上调。再灌流６ ｈ,ＣＡ１,ＣＡ３ 和皮层ＰＡＲ区ＧＤＮＦｍ ＲＮＡ表达亦见增多,２４ ｈ 达高峰。Ｋｅｔａｍ ｉｎｅ 可使ＧＤＮＦ的基因表达在海马结构及皮层ＰＡＲ区明显低于相应的缺血再灌流组,统计学差异显著（Ｐ＜ ００５）。脑缺血再灌流时ＧＤＮＦ基因表达增加,对缺血神经元可能起保护作用。Ｋｅｔａｍ ｉｎｅ可阻断缺血后ＧＤＮＦｍ ＲＮＡ 的表达增加,提示ＮＭＤＡ谷氨酸受体很可能参与介导了缺     

大鼠脑局灶缺血后AC133抗原和AC133mRNA的表达

目的:探讨AC133抗原及AC133 mRNA在缺血再灌注脑组织中的表达。方法:将成年SD雄性大鼠随机分为3组:正常组,假手术组,脑缺血再灌注组。采用大鼠大脑中动脉缺血再灌注线栓法模型。取缺血再灌注2、3、47、d作为观察点。用免疫组化法检测脑组织AC133抗原表达,RT-PCR法检测AC133基因的表达。结果:大脑缺血再灌注后4 d,AC133抗原在缺血大脑半球梗死区周围的部分中、小血管内皮细胞胞质染色阳性。而再灌注后2、3和7 d无阳性染色。脑缺血再灌注37、d缺血脑组织AC133 mRNA上调。结论:大鼠脑局灶缺血后AC133在基因和蛋白水平上均有不同程度的表达,AC133可能参与大脑局灶缺血后血管内皮的功能。AC133 Expression in Brain of Ischemia-Reperfused Rat HU Xiang-Shu,ZHOU Dong,LUO Zu-Ming Department ofNeurology,Guangdong 999 Brain Hospital,Guangzhou 510510,China     

大鼠脑缺血-再灌注损伤早期DWI参数和AQP4蛋白表达相关性研究

目的脑水肿是脑缺血后主要的病理表现之一,研究表明水通道蛋白4(AQP4)在脑梗死后脑水肿的形成和发展中起着重要作用,目前尚缺乏磁共振弥散加权成像(DWS)与AQP4表达在急性脑缺血-再灌注早期相关性的研究。本文旨在评估大鼠脑缺血—再灌注早期脑损伤区水通道蛋白4表达、DWI信号强度(SI)及表观扩散系数(ADC)之间的相关性以及AQP4表达与缺血性脑水肿之间的关系。方法健康成年SD雄性大鼠(n=40),随机分成4组,分别为脑缺血—再灌注12h、1d、3d组和假手术组,采用线栓法制作大鼠右侧大脑中动脉缺血—再灌注(MCAO/R)模型,Zea Longa评分评价神经功能损伤程度,Philips Achieva 3.0T MRI扫描仪对假手术组和缺血—再灌注后不同时间点大鼠脑部行冠状位DWI扫描,在工作站上重建ADC图,测量基底核层面梗死灶DWI-SI和ADC值,计算相对ADC值(rADC)和相对DWI—SI(rDWI—SI)值。2,3,5-氯化三苯基四氮唑(TTC)染色评价梗死体积的变化。免疫组化染色测定AQP4蛋白表达,用平均吸光度(MOD)值评价染色程度。结果假手术组动物麻醉苏醒后未见神经功能缺损,脑缺血—再灌注后12h、1d和3d组大鼠出现不同程度神经功能损伤,1d组最重。假手术组TTC染色未见梗死体积,脑缺血—再灌注后12h、1d和3d梗死体积逐渐增加,3d时最大。水肿变化规律同梗死体积相仿。假手术组海马区及皮质区AQP4免疫组化染色较浅淡,MCAO/R后12h缺血侧海马区及皮质均可见AQP4阳性细胞,12h-3d AQP4的MOD值随时间延长逐渐增高,3d时达到高峰。12h、1d和3d组大鼠脑水肿体积与相应时间点缺血侧皮质区和海马区AQP4表达均呈正相关(r=0.642,r=0.605,均P0.05);三组大鼠基底核区梗死灶rADC值与缺血侧皮质区、海马区AQP4表达均呈正相关(r=0.542,P=0.037;r=0.655,P=0.008)。结论大鼠脑缺血—再灌注早期脑水肿体积、rADC值与AQP4的表达水平存在时间上的相关性。因此结合DWI检查对脑缺血后AQP4表达部位、作用及调节机制进行更深入系统的研究,可能为临床早期治疗缺血性脑水肿提供新的思路。     

胍丁胺与短暂性全脑缺血脑皮质一氧化氮合酶表达及过（氧化）亚硝酸盐的形成

背景：胍丁胺是一种由精氨酸在精氨酸脱羧酶的脱羧基作用下合成的内源性置换物质,在试管和动物实验中已被证实具有神经保护作用。短暂性的全脑缺血-再灌注损伤诱发迟发性的海马CA1部位和脑皮质的第三,第四层的神经细胞死亡。过去几年的报道,一氧化氮在诱导病理学上的发展作用和处理减少或增加一氧化氮的的生成,提供一个治疗上的靶向。一氧化氮是由L- 精氨酸的胍基连续性的氧化而产生的,胍丁胺是L-精氨酸的相似物。因此,暗示了在缺血损伤中,胍丁胺的处理干扰一氧化氮的信号机制,保护脑组织的作用。 目的：该研究调查在脑皮质中,胍丁胺对全脑缺血的影响,评价胍丁胺对一氧化氮合酶和一氧化氮表达的影响。 实验设计,时间,检测：随机对照动物试验是2008年六月至九月在韩国延世医科大学解剖教研室的组织学实验是进行的。 材料：胍丁胺是从Sigma公司购买的。 方法：总58只SD大鼠（300-350g）用于建立四血管阻断法的缺血损伤模型,随机分为三组：对照组,无处理胍丁胺的阴性实验组,胍丁胺处理组。随着缺血-再灌注,胍丁胺以100mg/kg用量,经由腹腔注射。 测量方法： 使用免疫印迹方法和免疫组织化学方法检测神经元型一氧化氮合酶和诱导型一氧化氮合酶的表达;使用TUNEL方法检测神经细胞调亡。 结果：随着4-VO/再灌注,阴性试验组显示有意义的神经损伤,但是,胍丁胺的处理明显的保护了皮质神经元（P<0.05）。在全脑缺血后24,48,72h ,与阴性对照组相比,胍丁胺的处理显著减少了TUNEL-阳性神经细胞的数量（P<0.01）;nNOS和iNOS表达（P<0.05）。而且,胍丁胺的处理明显的抑制了硝基酪氨酸的生成（P<0.05）。 结论：胍丁胺的处理不但减少了全脑缺血的脑皮质神经元损伤,而且,减少了NOS表达和NO的生成。证明了全脑缺血再灌注后,在不同时间点上,胍丁胺对NOS的调节作用。     

实验性糖尿病大鼠脑缺血纤溶酶原激活物和纤溶酶原激活物抑制剂活性测定

目的 :了解糖尿病大鼠脑缺血 /再灌注后纤溶系统的变化。方法 :糖尿病和正常大鼠于脑缺血 1h再灌注 1、2、5、11、2 3h后 ,用发色底物法测定脑组织中PA和PAI的活性。结果 :糖尿病大鼠脑梗死体积增大、再灌注时血流恢复显著降低 ;脑缺血后 ,正常组和糖尿病组PAI活性无变化 ,PA活性增高 ;再灌注 5h ,正常大鼠PA活性和PA/PAI比值增高。结论 :大鼠脑缺血 /再灌注后PA活性和PA/PAI增高 ,且呈动态变化 ;糖尿病大鼠实际的应激促纤溶功能降低     

实验性急性脑梗塞早期MRI表现与病理对照研究

目的　阻断狗大脑中动脉建立急性脑梗塞动物模型,观察早期 Ｍ Ｒ Ｉ表现及其病理改变。方法　将 １６ 只成年狗随机分为实验组（１０ 只）和对照组（６ 只）。经颞开颅阻断一侧大脑中动脉（ Ｍ Ｃ Ａ）,造成 Ｍ Ｃ Ａ 供应区急性缺血性脑梗塞,术后 ４、６、８、１２ｈ 行 Ｍ Ｒ Ｉ薄层扫描;取出动物大脑观察病理改变,测定不同时相梗塞区 Ｔ２ 时间和组织水含量。结果　梗塞 ２ｈ Ｍ Ｒ Ｉ Ｔ２ 加权可见尾状核头部、豆状核信号增高;６ｈ Ｍ Ｒ Ｉ可见尾状核、豆状核形成明确梗塞,并出现占位征象。２ｈ 电镜下已有缺血水肿改变,４ｈ 光镜下出现脑缺血水肿改变,电镜下见到血脑屏障受损。相关分析表明：病灶区 Ｔ２ 时间变化与组织水含量变化在时序上有密切关系（ｒ＝ ０．９５３７, Ｐ＜ ０．０１）。结论　 Ｍ Ｒ Ｉ可用于脑梗塞早期的诊断。急性脑梗塞早期 Ｍ Ｒ Ｉ表现的病理基础是脑水肿。     

Mannitol infusion immediately after reperfusion suppresses the development of focal cortical infarction after temporary cerebral ischemia in gerbils

Previously we found that, after temporary cerebral ischemia, microvasculogenic secondary focal cerebral cortical ischemia occurred, caused by microvascular obstruction due to compression by swollen astrocytic end‐feet, resulting in focal infarction. Herein, we examined whether mannitol infusion immediately after restoration of blood flow could protect the cerebral cortex against the development of such an infarction. If so, the infusion of mannitol might improve the results of vascular reperfusion therapy. We selected stroke‐positive animals during the first 10 min after left carotid occlusion performed twice with a 5‐h interval, and allocated them into four groups: sham‐operated control, no‐treatment, mannitol‐infusion, and saline‐infusion groups. Light‐ and electron‐microscopic studies were performed on cerebral cortices of coronal sections prepared at the chiasmatic level, where the focal infarction develops abruptly in the area where disseminated selective neuronal necrosis is maturing. Measurements were performed to determine the following: (A) infarct size in HE‐stained specimens from all groups at 72 and 120 h after return of blood flow; (B) number of carbon‐black‐suspension‐perfused microvessels in the control and at 0.5, 3, 5, 8, 12 and 24 h in the no‐treatment and mannitol‐infusion groups; (C) area of astrocytic end‐feet; and (D) number of mitochondria in the astrocytic end‐feet in electron microscopic pictures taken at 5 h. The average decimal fraction area ratio of infarct size in the mannitol group was significantly reduced at 72 and 120 h, associated with an increased decimal fraction number ratio of carbon‐black‐suspension‐perfused microvessels at 3, 5 and 8 h, and a marked reduction in the size of the end‐feet at 5 h. Mannitol infusion performed immediately after restitution of blood flow following temporary cerebral ischemia remarkably reduced the size of the cerebral cortical focal infarction by decreasing the swelling of the end‐feet, thus preventing the microvascular compression and stasis and thereby microvasculogenic secondary focal cerebral ischemia.     

大鼠局灶性脑缺血后再灌注期caspase—9 mRNA及Apaf—1mRNA表达的动态变化

目的探讨大鼠局灶性脑缺血后再灌注期caspase-9 mRNA及Apaf-1 mRNA表达的动态变化.方法采用线栓法制作大鼠局灶性脑缺血后再灌注模型,以逆转录聚合酶链式反应(RT-PCR)技术检测caspase-9 mRNA及Apf-1 mRNA的表达.结果缺血2 h后再灌注,缺血皮质中caspase-9 mRNA的表达在再灌注后24h达高峰,48h仍保持高水平,而Apaf-1 muRNA的表达无明显改变.结论局灶性脑缺血后再灌注48h内caspase-9 mRNA表达增强.     

大鼠急性脑缺血后Hephaestin的表达变化

目的 研究大鼠急性局灶性脑缺血后皮质和纹状体Hephaestin表达的变化。方法 线栓法制备大鼠急性大脑中动脉阻塞(MCAO)再灌注模型,在再灌注后的不同时间点应用免疫组化、图像分析以及SDS-PAGE Werstern blot方法检测缺血侧皮质和纹状体的表达变化。结果 MCAO再灌注后大鼠出现大脑中动脉梗死的神经系统损害体征,TTC染色有白色梗死区。Hephaestin在正常大鼠的皮质、纹状体有表达,在急性脑缺血再灌注后12h缺血侧皮质、纹状体表达明显增加并持续到再灌注后48h,在24h时到达高峰(P<0.01),至1周时表达较正常明显减少(P<0.01)。结论 大鼠急性脑缺血再灌注后Hephaestin的表达出现明显的变化,在急性脑缺血的病理生理变化中可能起着重要的作用。     

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 expression in early focal cerebral infarction following urokinase thrombolysis in rats

Activity of matrix metalloproteinase-9 increases following cerebral ischemia/reperfusion,and is associated with cerebral microvascular permeability,blood-brain barrier destruction,inflammatory cell infiltration and brain edema.Matrix metalloproteinase-9 also likely participates in thrombolysis.A rat model of middle cerebral artery infarction was established by injecting autologous blood clots into the internal carotid artery.At 3 hours following model induction,urokinase was injected into the caudal vein.Decreased neurological severity score,reduced infarct volume,and increased expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 were observed in the cerebral cortex 24 hours after urokinase thrombolysis.These results suggest that urokinase can suppress damage in the acute-early stage of cerebral infarction.     

Inhibition of transient receptor potential vanilloid 4 decreases the expressions of caveolin‐1 and caveolin‐2 after focal cerebral ischemia and reperfusion in rats

This study aimed to investigate the effects of transient receptor potential vanilloid 4 (TRPV4) inhibition on blood–brain barrier (BBB) integrity and the expressions of caveolae structural proteins caveolin‐1 and caveolin‐2 in rats with focal cerebral ischemia and reperfusion. BBB permeability was assessed by Evans blue extravasation. The mRNA and protein expressions of caveolin‐1 and caveolin‐2 were determined by RT‐PCR, Western blot and immunohistochemistry assays. We found that BBB permeability significantly increased and reaches its peak at 72 h of reperfusion in cerebral ischemia‐reperfusion rats and is able to be ameliorated by administration of HC‐067047, an antagonist of TRPV4. Additionally, it shows a significant upregulation of caveolin‐1 and caveolin‐2 expression in cerebral microvessels of ischemic tissue. However, treatment with HC‐067047 was shown to downregulate caveolin‐1 and caveolin‐2 expression during cerebral ischemia‐reperfusion. This study demonstrates that inhibition of TRPV4 ameliorates BBB leakage induced by ischemia‐reperfusion injury through the downregulation of caveolin‐1 and caveolin‐2.     

Expression of c-fos and inducible hsp-70 mRNA following a transient episode of focal ischemia that had non-lethal effects on the rat brain

Expression of c-fos and inducible hsp-70 mRNA was studied with in situ hybridization techniques at different times following an episode of middle cerebral artery (MCA) occlusion not resulting in any apparent lethal effect on the rat brain. hsp-70 and c-fos mRNA were found in the ipsilateral striatum and adjacent cortex. In the striatum, levels of hsp-70 mRNA increased from 1 to 2 and 4 h of reperfusion, whereas levels of c-fos mRNA decreased from 1 to 4 h of reperfusion. These results demonstrate that following non-lethal focal ischemia the brain areas within the MCA territory show high c-fos and hsp-70 mRNA expression response, illustrating the concomitant induction of these mRNAs in cells that survive the ischemic insult.     

Three‐dimensional structural changes in cerebral microvessels after transient focal cerebral ischemia in rats: Scanning electron microscopic study of corrosion casts

Pathological changes of cerebral microvessels in transient ischemia were investigated by scanning electron microscopy of vascular corrosion casts. Wistar rats were treated with middle cerebral artery (MCA) occlusion for 30 min, 1 h, 3 h, 4 h, 5 h or 7 h and subsequent reperfusion for 2 h. The ultrastructures of the cast were observed and computer‐aided montage micrographs were obtained for visualization of the whole microvasculature in the ischemic brain hemisphere. Avascular areas representing ischemic areas were detected in the frontotemporal cortex and caudate putamen in the groups from 30 min to 5 h occlusion. Extravasation of the resin, which probably corresponded to the leakage of plasma or hemorrhage, was seen as spheroidal, conglomerative, large massive and worm‐like types. The spheroidal type, which probably indicated a small leakage or minor hemorrhage, began to appear in the 30‐min occlusion group. The conglomerative type, which probably indicated a larger leakage or moderate hemorrhage, appeared in the 3‐ to 5‐h occlusion groups. The large massive and worm‐like types, which probably indicated a significant hemorrhage, appeared in the 4‐ and 5‐h occlusion groups. The number of these extravasations increased significantly in the 4‐h occlusion group. Arterioles near the avascular area frequently showed vasospastic appearances, such as corrugations, fusiform indentations of endothelial nuclei, continuous circulatory constrictions and severe narrowing with interrupted branches. Arteriolar vasospasm possibly caused prolonged hypoperfusion even if reperfusion was achieved. The capillaries had a thin stringy appearance in the 4‐ and 5‐h occlusion groups. These changes seemed to relate closely with increased intracranial pressure by brain edema or hemorrhage. The present study suggested that the risk of brain edema or hemorrhagic infarction increased beyond 3 h of MCA occlusion, and vasospasm of the arterioles might participate in stroke pathophysiology.     

Reduction of copper, zinc-superoxide dismutase in knockout mice does not affect edema or infarction volumes and the early release of mitochondrial cytochrome c after permanent focal cerebral ischemia

Copper,zinc-superoxide dismutase (SOD1) was shown to be highly protective against ischemia/reperfusion injury in the brain. We have recently reported that SOD1 prevents the release of mitochondrial cytochrome c and subsequent apoptosis after ischemia/reperfusion in mice. To investigate its dose dependent effect on permanent focal cerebral ischemia, we examined neurological deficit scores, infarction volume, and the amount of hemisphere enlargement after 24 h of focal cerebral ischemia in both knockout mutants of SOD1 (Sod1 -/+ and Sod1 -/-) and wild-type littermates. We also examined the release of cytochrome c and subsequent DNA fragmentation after ischemia. There were no differences in the neurological deficit scores, infarction volumes and edema formation. There was also no difference of the amount cytosolic cytochrome c at 2 h and of the amount of DNA fragmentation at 24 h after focal cerebral ischemia. The results indicate that the SOD1 enzyme does not appear to affect cerebral infarction, cerebral edema nor the mitochondrial signaling pathway for apoptosis following permanent focal cerebral ischemia where there is no reperfusion injury.     

大鼠局灶性脑缺血/再灌注后单、双链DNA断裂的实验研究

目的 :观察大鼠脑缺血 /再灌注后脑细胞单、双链DNA损伤情况 ,以揭示该病的损伤机制。方法 :分别用Klenow及TdT(TUNEL)标记染色法检测大脑中动脉阻塞 (MCAO)模型组、假手术组及正常大鼠脑细胞的单、双链DNA断裂 ,观察缺血侧、对照侧皮质及海马阳性细胞数的动态变化。结果 :MCAO模型组缺血侧皮质及海马Klenow及TUNEL阳性细胞数均逐渐增多 ,Klenow阳性细胞的出现早于TUNEL阳性细胞 ,皮质的出现早于海马。结论 :大鼠MCAO模型中DNA单、双链断裂均参与了脑损伤机制