局灶性脑缺血耐受和星形胶质细胞反应

目的　研究短暂性局灶性脑缺血预处理对永久性局灶性脑缺血的保护作用 ,及最佳预处理时间剂量 ,并探讨星形胶质细胞在脑缺血耐受中的反应。方法　采用开颅方法阻断大鼠大脑中动脉 ,通过观察大鼠脑梗死后神经功能损伤状况、脑梗死体积分析及病理形态学变化 ,评价不同的缺血预处理时间剂量 (10分钟、2 0分钟、30分钟 )对永久性局灶性脑缺血的保护作用。采用胶质纤维酸性蛋白 (GFAP)免疫组化法观察星形胶质细胞在脑缺血耐受中的反应。结果　与对照组相比 ,缺血预处理 2 0分钟未引起明显的神经元损伤 ,但使永久性局灶性脑缺血后神经功能损伤减轻 ,梗死体积明显减小 (P <0 .0 1)。免疫组化显示 ,2 0分钟缺血预处理组及重复缺血组星形胶质细胞在损伤预处理侧广泛激活。结论　 2 0分钟局灶性脑缺血预处理能够有效诱导脑缺血耐受。星形胶质细胞的激活可能与脑缺血耐受中神经元的存活相关。     

大鼠局灶性脑缺血预处理的抗细胞凋亡作用机制的研究

目的研究大鼠短暂局灶性脑缺血预处理对再次脑缺血神经细胞凋亡的保护作用,及bcl-2、bax与脑缺血耐受的关系.方法用开颅方法阻断大鼠大脑中动脉(MCA)20分钟,3天后再次阻断6小时.观察大鼠脑梗死体积及组织病理学改变,采用TUNEL法观察神经细胞凋亡状况,采用免疫组织化学方法观察bcl-2、bax蛋白表达的改变.结果与假预处理组和缺血组相比,预处理后缺血组梗死灶体积明显减小(均P＜0.01),半影区凋亡细胞数明显减少(P＜0.01),bax蛋白表达下降(P＜0.05),bcl-2蛋白表达显著上升(P＜0.01).结论 20分钟局灶性脑缺血预处理能够通过bcl-2表达增加及bax表达下降对再次脑缺血神经细胞起保护作用.     

流式细胞仪检测大鼠局灶性脑缺血再灌流后细胞凋亡的研究

本研究采用流式细胞仪（ＦＣＭ）检测大鼠局灶性脑缺血再灌流后凋亡细胞ＤＮＡ断裂百分率。结果表明：随再灌流时间的增加，ＤＮＡ断裂百分率逐渐增加，再灌流１ｄ时达高峰，再灌流３～７ｄ逐渐下降。结果提示：细胞凋亡在局灶性脑缺血再灌流损伤中呈动态过程且系神经细胞死亡的重要形式。     

吡拉西坦抗短暂性局灶性脑缺血作用观察

目的 观察吡拉西坦的抗局灶性脑缺血作用。方法采用动脉腔内插线大鼠局灶性脑缺血模型及激光多普勒血流计测定半暗带脑血流、湿重-干重法测定缺血半球水含量、3％伊文氏蓝染色结合图像分析测定血脑屏障(BBB)的破坏、HE染色结合图像分析测定缺血后21h的梗死体积。结果100mg／kg体重吡拉西坦对半暗带脑血流无明显影响，200mg／kg体重吡拉西坦可明显升高再灌注期间半暗带脑血流；100mg／kg和200mg/kg体重的吡拉西坦均可明显降低局灶性脑缺血后缺血半球的水含量及BBB的损伤，缩小梗死体积。结论吡拉西坦具有明确的抗局灶性脑缺血作用，它可改善半暗带脑血流、减轻脑组织水肿和BBB的损伤、缩小梗死体积。     

大鼠局灶性脑缺血再灌注后CAD表达与细胞凋亡的关系

目的　探讨大鼠局灶性脑缺血再灌注后缺血半暗带 Caspase-3激活的 DNA酶 (CAD)基因的表达变化与细胞凋亡的关系。方法　线栓法建立大鼠大脑中动脉闭塞 (MCAO)及再通模型。应用 RT-PCR技术检测MCAO再通后不同时相缺血半暗带皮质 CAD基因的表达 ,同时利用 TU NEL法观察对应区域细胞凋亡的动态变化规律。结果　脑缺血再灌注 6h,半暗带皮质 CAD m RNA显著升高 ,密度比值为 0 .74± 0 .0 4,再灌注 2 4h达到高峰 (1.13± 0 .11)。对应各时相均可见神经细胞凋亡 ,凋亡细胞以再灌注 48h组为最高 (113 .10± 13 .88)。结论　脑缺血再灌注可致 CAD基因表达上调 ,可能参与了缺血后神经细胞凋亡过程     

猫持续性局灶脑缺血模型的改进

目的对猫持续性脑缺血模型加以改进,使其制作简便、模型标准、稳定。方法猫麻醉后,经眶后暴露大脑中动脉,在其发出外侧纹状体动脉的外侧部电凝闭塞,以医用耳脑胶及明胶海绵粘合硬膜和骨窗,术后行HE染色,计算梗死体积百分比。结果手术后在猫大脑中动脉（MCA）皮层分布区均产生梗死灶,梗死体积为19.3±0.70,动物无死亡及并发症的发生。结论该模型制作方便,重复性及稳定性好,适合于缺血性脑血管疾病的研究。     

EGb761对大鼠局灶性脑缺血再灌注损伤后细胞凋亡的影响

本实验用线栓法建立大鼠局灶性脑缺血再灌注损伤模型 ,观察银杏叶提取物的标准制剂 EGb76 1(含 2 4 %黄酮甙和 6 %萜烯 )对细胞凋亡以及脑缺血后脑组织病理变化的影响。1　材料与方法1.1　实验动物分组　健康 Wistar大鼠 2 0只 ,体重 2 5 0～ 30 0 g,随机分为假手术组 (A组 ) ,脑缺血再灌注组 (B组 ) ,生理盐水组治疗组 (C组 ) ,EGb76 1治疗组 (D组 ) ,每组 5只。1.2　实验方法　线栓法制作大鼠脑缺血再灌注损伤模型 ,假手术组仅分离血管 ,不插尼龙线。 D组于实验前 3d开始灌胃给 EGb76 1(Ginaton) ,15 0 mg/ kg,每日 2次 ,术前 1h灌…     

骨髓基质细胞移植治疗局灶性脑缺血

骨髓基质细胞 (ｍａｒｒｏｗｓｔｒｏｍａｌｃｅｌｌｓ,ＭＳＣｓ)是一种非造血组织干细胞 ,它易粘附、易增殖 ,有自我更新的能力和多向分化的潜能。将一定数量的骨髓基质细胞通过脑立体定向术、静脉或颈内动脉注射移植到脑内后 ,能够明显改善局灶性脑缺血动物的神经行为功能。但是有关骨髓基质细胞移植治疗局灶性脑缺血的机制尚有待研究。一、骨髓基质细胞的生物学特性目前发现至少存在 3种形态的ＭＳＣｓ。Ｗｏｏｄｂｕｒｙ等发现 ,以低密度种植的大鼠ＭＳＣｓ为大而扁平的细胞 ;当接近汇合时 ,它们即转变成小的梭形细胞[1] 。Ｃｏｌｔｅｒ…     

人尿激肽原酶对急性局灶性脑缺血再灌注损伤大鼠细胞凋亡的影响

目的 研究人尿激肽原酶(HUK)对大鼠急性局灶性脑缺血再灌注(FCIR)损伤后细胞凋亡数量及B细胞淋巴瘤/白血病-2(Bcl-2)、Bcl-2联合X蛋白(Bax)蛋白表达的影响.方法 84只雄性SD大鼠分为假手术组(12只)、脑缺血再灌注(IR)组(36只)、HUK处理组(36只),IR组和HUK处理组剩余大鼠又按照再灌注时间6 h、12 h、24 h、72 h、168 h分为5个亚组(均为6只).建立大鼠大脑中动脉FCIR模型.假手术组、IR组及HUK处理组中各取6只SD大鼠用于测定梗死体积,其余大鼠用于观察神经功能缺陷评分、TIJNEL法及免疫组化检测凋亡细胞数量及凋亡蛋白Bcl-2、Bax的表达.结果 HUK处理组神经功能缺陷评分、梗死灶体积、除168 h亚组外的各时 间点的凋亡细胞数及Bax蛋白表达均显著少于IR组(P＜0.05),除168 h亚组外的各时间点的Bcl-2蛋白表达均显著高于IR组(P＜0.05).结论 HUK对FCIR后的脑组织起保护作用,其机制可能为损伤后3 d内通过上调Bcl-2、下调Bax蛋白表达来抑制细胞凋亡.     

降纤酶对大鼠局灶性脑缺血血管内皮细胞超微结构及内皮细胞凋亡的影响

目的 探讨降纤酶对缺血性脑水肿病理过程中血脑屏障（BBB）内皮细胞的保护作用以及其对内皮细胞凋亡的影响。方法 选用Wistar雄性大鼠42只，体重250－300g，鼠龄3－4个月，随机分成降纤酶组、盐水对照组和假手术组，参考Longa等方法建立大鼠大脑缺血动物模型，彩和电观察大鼠BBB的超微结构和TUNEL试剂盒检测内皮细胞的凋亡。结果 通过电镜观察发现降纤酶组的毛细血管内皮细胞膜完整，水肿较轻，其损伤程度明显较对照组轻。降纤酶组在缺血6h和缺血24h随缺血时间延长缺血中心区凋亡细胞数量减少，而缺血半影区凋亡细胞数量增加，其凋讯细胞数量明显少于盐水对照组同一时期值。结论 降纤酶对脑缺血的血管内皮细胞及BBB具有明显的保护作用。     

Enhanced phosphorylation of PTEN in rat brain after transient middle cerebral artery occlusion

A phosphatase PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a tumor suppressor gene that suppresses cell growth, inhibits cell migration, and induces apoptosis. Phosphorylated form of PTEN (p-PTEN) is a key survival factor relating PI3K-Akt pathway and their downstream effectors. A spatiotemporal profiles of PTEN and p-PTEN expression were immunohistochemically examined after 90 min of transient middle cerebral artery occlusion in rats. In the ischemic core, PTEN progressively decreased by 3 days, whereas a rapid but transient increase of p-PTEN was found with a peak at 1 h after the reperfusion. In contrast, in the ischemic penumbra, PTEN showed a minor change and a gradual but sustained p-PTEN expression was observed in the ischemic penumbra with a peak at 12 h. In addition, the balance of population among strongly, moderately, and weakly stained cells was different between the ischemic core and penumbra at their peak time points. These results suggest an important role of p-PTEN for cell survival after ischemia as an upstream regulator for PI3K-Akt.     

Dynamic platelet accumulation at the site of the occluded middle cerebral artery and in downstream microvessels is associated with loss of microvascular integrity after embolic middle cerebral artery occlusion

Information is lacking regarding dynamic platelet accumulation at the site of the occluded middle cerebral artery (MCA) and the relationship between platelet aggregation in downstream cerebral microvessels and loss of perfusion and vascular integrity of these microvessels. In the present study, we employed a model of embolic MCA occlusion in the rat to simultaneously measure temporal and spatial profiles of platelet accumulation at the site of the embolus occluding the MCA and within downstream cerebral microvessels. We also measured the integrity of microvessels and matrix metalloproteinase (MMP) activity in ischemic brain. Rats (n=36) were subjected to embolic MCA occlusion. Immunohistochemistry was used to detect microvascular integrity, plasminogen activator inhibitor 1 (PAI-1) and the deposition of fibrin. SDS-PAGE zymography was used to measure MMP2 and MMP9 activities. Accumulation of platelets and increases in PAI-1 immunoreactivity at the site of the embolus occluding the MCA were detected 1 h (n=7) and 4 h (n=7) after ischemia, respectively, and numbers of GPIIb/IIIa immunoreactive downstream cerebral microvessels increased significantly (209+/-59; n=7; P<0.05) 4 h after ischemia, suggesting dynamic platelet aggregation. A significant (n=7; P<0.01) diffuse loss of type IV collagen immunoreactivity in microvessels was temporally associated with platelet GPIIb/IIIa immunoreactivity within the vessels. Triple immunostaining revealed that microvessels containing platelet aggregates exhibited loss of type IV collagen immunoreactivity and both intra- and extra-vascular fibrin deposition, suggesting that intravascular platelet aggregation is associated with decreases in the integrity of the microvascular basal lamina and blood-brain barrier leakage. A significant increase (P<0.05) in MMP9 was detected at 4 h (n=3) and 24 h (n=3) after ischemia but levels of MMP2 were not significantly changed in ischemic brain. Our data suggest that dynamic platelet aggregation in ischemic brain may contribute to time-dependent resistance to fibrinolysis. In addition, platelet deposition and increased MMP9 coincided with degradation of type IV collagen and loss of vascular integrity. These data suggest an important role for post-occlusive distal platelet deposition in the pathophysiology of stroke.     

构建大脑中动脉阻塞脑缺血模型大鼠的类型分析

背景：线栓法造成短暂性大脑中动脉阻塞是研究大鼠局灶性脑缺血普遍使用的模型制作方法。但制作大鼠脑缺血模型的类型存在一定差异,可能导致实验结果的偏差。 目的：分析大脑中动脉阻塞线栓法制作大鼠脑缺血模型的类型及其影响因素。 方法：雄性SD大鼠166只,参照Longa线栓法造模,术后24 h行MRI扫描,根据扫描结果将大鼠分成皮质梗死组、皮质下梗死组及无梗死组,分析造模时线栓插入的深度。 结果与结论：皮质梗死组、皮质下梗死组和无梗死组大鼠的线栓插入深度分别为(19.9±0.9),(19.0±1.1)和(17.7±1.3) mm,皮质梗死组大鼠的线栓插入最深,而无梗死组的线栓插入最浅(P < 0.01)。提示插入深度不同导致的大鼠脑梗死的类型也不同,线栓插入越深,皮质梗死的概率可能越大。     

Topical application of neurotrophin-3 attenuates ischemic brain injury after transient middle cerebral artery occlusion in rats

In order to examine the effect of neurotrophin-3 (NT-3) on ischemic brain injury, NT-3 was topically applied to brain surface just after 90 min of middle cerebral artery occlusion (MCAO) in rats. NT-3 significantly reduced the infarct size at 24 h of reperfusion. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick labeling (TUNEL) staining and immunohistochemical study for caspase-3 and heat shock protein 72 (HSP72) showed that NT-3 treatment decreased the number of cells with DNA fragmentation and caspase-3 and HSP72 expressions. These data suggest that NT-3 protects neuronal cells from ischemic injury, and it is possibly associated with inhibition of DNA fragmentation.     

脑梗死大鼠外周血促炎／抗炎细胞因子的动态变化

目的探讨脑梗死大鼠外周血促炎／抗炎细胞因子的动态变化规律。方法建立成年雄性SD大鼠大脑中动脉阻塞（MCAO）模型,分为MCAO后6h,12h,24h,48h,72h,1周,2周组和假手术组。采用双抗体夹心酶联免疫吸附法（ELISA）测定大鼠血清促炎细胞因子IL-1β、INF-γ和抗炎细胞因子IL-10的水平,以评估机体的免疫状态。结果与假手术组相比,脑梗死大鼠血清促炎细胞因子IL-1β和INF-γ,的水平在MCAO后6h和12h均升高,但自24h起逐渐下降,72h降至最低（P〈0．01）,其中血清INF-γ水平至2周仍低于假手术组（P〈0．01）;相反,抗炎细胞因子IL-10的水平则在脑卒中后6—12h时有短暂降低,12h起开始回升,在72h升至最高（P〈0．01）,至1周仍高于假手术组（P〈0．01）。结论MCAO后大鼠外周血促炎细胞因子降低和抗炎细胞因子升高,表明脑卒中后机体处于免疫抑制状态。     

Loss of bag-1 immunoreactivity in rat brain after transient middle cerebral artery occlusion

Although bag-1 is a strong apoptosis repressor protein, its functions in normal or injured brains are not fully understood. In the present study, we investigated expression of bag-1 protein in rat brain after transient middle cerebral artery (MCA) occlusion, and compared the results with that of terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL). Immunohistochemical analysis revealed that neuronal, choroid plexus, and ependymal cells were positively stained in the sham control brain. After 90 min of transient MCA occlusion, immunoreactivity for bag-1 progressively decreased from 3 to 48 h in the nuclei of neurons. Western blot analysis revealed that immunoreactive bag-1 was markedly decreased in the nuclear fraction. In contrast, cytosolic and mitochondrial fractions showed no or only slight change after the ischemia. TUNEL positive cells appeared at 48 h after the reperfusion, which was preceded by loss of bag-1 immunoreactivity. The present results suggest that bag-1 plays some roles in normal neuronal function, and its loss may be involved in neuronal cell death after ischemia.     

Ziprasidone attenuates brain injury after focal cerebral ischemia induced by middle cerebral artery occlusion in rats

Ziprasidone is an atypical antipsychotic drug used for the treatment of schizophrenia. Recent studies have reported that atypical antipsychotics have neuroprotective effects against brain injury. In the present study, the effect of ziprasidone on ischemic brain injury was investigated. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in rats. All the animals experienced ischemia for 1h and then underwent reperfusion. The infarct size induced by MCAO was significantly reduced in the animals that received acute treatment with 5mg/kg ziprasidone and subchronic treatment with 2.5mg/kg ziprasidone for 7 days compared with that in the vehicle-treated animals. The acute treatment with ziprasidone significantly improved neurological functions, as measured by the modified neurological severity score, in a dose-dependent manner. The subchronic treatment produced more rapid recovery from functional deficits than the vehicle treatment. The immunohistochemical investigation revealed that the subchronic treatment prevented severe loss of neuronal marker intensity and attenuated the increased in microglial marker intensity in the infarcted cortical area. These results suggest that ziprasidone has neuroprotective effects in a rat model of ischemic stroke and provide new insight for its clinical applications.     

NF-kappaB protects neurons from ischemic injury after middle cerebral artery occlusion in mice

Knowledge about the molecular mechanisms of neuronal survival following ischemia is crucial to the development of therapeutic interventions for victims of stroke. Previous research in our laboratory has implicated nuclear factor-kappaB (NF-kappaB) as contributing to neuronal survival in response to toxic or ischemic brain insult, with in vivo models having focused on the rat. To take advantage of genetic alterations available in the mouse, we utilized a murine transient endovascular middle cerebral artery occlusion (MCAO) model to examine the influence of NF-kappaB on neuronal survival. When brains were immunostained for the nuclear localization sequence (NLS) of the p50 subunit of NF-kappaB, a unilateral increase in immunoreactivity was seen, especially in pyramidal cell layers of the ipsilateral (stroked) hippocampus. When transgenic mice lacking p50 were compared with non-transgenic counterparts using Fluoro-Jade, a marker for neurodegeneration, both the hippocampus and striatum showed enhanced neurodegeneration at various survival times after 1 h of MCAO. In the hippocampus specifically, there was an eightfold increase in Fluoro-jade staining in the p50 knockout group vs. the non-transgenic group. Sections double stained for Fluoro-Jade and NF-kappaB activity (using a mouse engineered with a NF-kappaB responsive promoter driving a LacZ gene to produce beta galactosidase) demonstrated neuronal degeneration only in regions sparsely showing NF-kappaB activity, and those demonstrating NF-kappaB activity failed to degenerate. These data provide evidence that NF-kappaB participates in survival signaling following temporary focal ischemia, and thus may represent an attractive target for pharmacologic activation in the treatment of stroke.     

Reduction of ischemic brain injury by topical application of insulin-like growth factor-I after transient middle cerebral artery occlusion in rats

In order to examine the effect of insulin-like growth factor-1 (IGF-1) on ischemic brain injury, IGF-1 was applied topically on the surface of reperfused rat brain after 60 min of transient middle cerebral artery occlusion (MCAO). In contrast to the cases treated with vehicle, the infarct area was greatly reduced at 24 h of reperfusion by treatment with IGF-1. Terminal deoxynucleotidyl transferase mediated dUTP-biotin in situ nick labeling (TUNEL) staining and immunoreactivity for glycogen synthase kinase 3beta (GSK3beta) were also markedly reduced in the brains with IGF-1 treatment. The present results suggest that the treatment with IGF-1 significantly ameliorates brain injury after transient focal brain ischemia associated with the reduction of TUNEL and GSK3beta stainings.     

Growth-associated protein GAP-43 detection in the neuronal somata following middle cerebral artery occlusion in the rat

Aabstract

We first detected growth-associated protein (GAP-43) immunoreactivity in the neuronal somata following middle cerebral artery occlusion in the rat. Four days after the middle cerebral artery occlusion, GAP-Lt.3 immunoreactivity was detected in some cortical neurons of the ischemic penumbra at the level of the hippocampus. [Neural Res 1997; 19: 160–164]