缺血再灌流时胶质源性神经营养因子在大鼠脑组织的分布特点

目的 观察大鼠脑缺血再灌流时胶质源性神经营养因子（GDNF）在脑组织的分布特点，及其在缺血性脑损伤中的作用。方法 阻断大鼠大脑中动脉（MCA）血流2小时，再灌流0．5－48小时制成局灶性脑缺血模型，HE染色评价缺血性脑损伤的组织学特点，免疫组化法观察GDNF在脑组织的分布特点。结果 再灌流0．5小时组有灶性缺血区，24小时组面积最大，包括视前区、纹状体和皮质。再灌注6小时组开始出现神经元不可逆变性，24小时组梗死形成。再灌注0．5小时组，缺血区皮质神经元GDNF弱阳性，缺血周边区中等阳性；再灌流3－48小时组，缺血区神经元GDNF阴性。再灌流48小时组视前区的梗死周边区巨噬细胞GDNF呈强阳性。GDNF阳性细胞计数显示缺血区各实验组与正常组相比均减少（均P＜0．01）；24小时和48小时组分别与0．5小时组和3小时组相比，GDNF阳性细胞数减少（分别P＜0．01）。结论 缺血性脑损伤时，变性死亡的神经元GDNF不表达，存活的神经元和活化的小胶质细胞或巨噬细胞的GDNF表达增加。     

小檗碱对大鼠海马CA_1区迟发性神经元坏死的影响

本文采用Ｐｕｌｓｉｎｅｌｌｉ－Ｂｒｉｅｒｌｅｙ４血管结扎致ＳＤ大鼠全脑缺血（１０ｍｉｎ）再灌流模型，分别观察了早期不同再灌流时间（１２、２４、４８ｈ）点上，大鼠海马ＣＡ１区神经元的超微结构以及再灌７ｄ时光镜结构变化，同时观察了小檗碱对ＣＡ１区迟发性神经元坏死的影响。结果显示脑缺血再灌流早期，ＣＡ１区神经元超微结构发生明显改变，７ｄ时光镜下绝大部分细胞脱失；而用药组大鼠海马ＣＡ１区神经元在相应时间点上超微结构变化相对较轻，７ｄ时仍有绝大多数（８２％）细胞存活，细胞密度为１７２±１２．２个／ｍｍ，显著高于缺血对照组２７±７．６个／ｍｍ，Ｐ＜０．００１。提示小檗碱对大鼠短暂脑缺血再灌流造成的海马ＣＡ１区迟发性神经元坏死具有显著的对抗作用。     

脑缺血选择性海马CA1区神经元损害的实验研究

采用Ｐｕｌｓｉｎｅｌｉ－Ｂｒｉｅｒｌｅｙ４血管阻塞脑缺血模型观察了大鼠全脑缺血２０ｍｉｎ再灌流８ｈ，ｃ－ｆｏｓ基因表达及再灌流７ｄ海马ＣＡ１区迟发性神经元损害。在缺血再灌流早期（８ｈ）海马ＣＡ１区极少ｃ－ｆｏｓ表达，而齿状回、海马ＣＡ３区、杏仁核大量ｃ－ｆｏｓ表达。缺血再灌流晚期（７ｄ）镀银染色显示海马ＣＡ１区神经元及其突触终末带呈黑色溃变相，而齿状回、海马ＣＡ３区、杏仁核呈金黄色正常相。相邻切片ＨＥ染色示缺血组海马ＣＡ１区核完整的锥体细胞数（５±２．６个／２００μｍ）与对照组（４０±２．９个／μｍ）比较差异有显著意义（Ｐ＜０．０１）。脑缺血诱导的ｃ－ｆｏｓ基因表达对于缺血易损海马ＣＡ１区迟发性神经元坏死可能起直接的调控作用。     

MCAO后鼠脑Glu.GluR变化规律及意义

为探索谷氨酸受体（GluR）在介导谷氨酸（Glu）对缺血神经元损伤的作用机制，本实验建立大鼠大脑中动脉阻塞（MCAO）局部脑缺血实验模型，应用受体的放射配基结合分析（RBA）等技术动．态监测了缺血及再灌流期缺血灶、海马和下丘脑Glu、GluR含量及其亲和力的变化。结果发现：缺血30min，各脑区Glu含量达高峰，再灌流6h，Glu含量回降至基线水平，再灌流48h后，Glu含量再次中等程度升高，并持续至再灌流72h。GluR和KD值与Glu含量密切相关。结果提示，缺血再灌流早期，GluR在高浓度Glu的作用下发生同种特异性反向调节，GluR亲和力为增敏反应；再灌流中晚期，GluR的变化属于同种特异性正向调节，而GluR亲和力测为减敏反应。     

局部脑梗塞再灌流边缘区血脑屏障超微结构改变

目的观察局部脑梗塞再灌流边缘区血脑屏障（ＢＢＢ）超微结构的动态变化。方法用改良的Ｌｏｎｇａ氏方法，在肾血管性高血压大鼠获得可靠的大脑中动脉闭塞及再灌流模型，观察梗塞灶边缘区超微结构改变。结果局部脑梗塞早期恢复血流对病灶边缘区并没有加重ＢＢＢ损害，多形核白细胞阻塞毛细血管也是加重微循环障碍和ＢＢＢ损害的因素。结论必须重视ＢＢＢ损害在脑梗塞时的重要作用，注意对ＢＢＢ损害的防治，早期主要是恢复供血，提示溶栓可能有益     

急性缺血性大鼠脑乳酸含量变化的实验观察

本研究通过四血管闭塞的非禁食动物脑缺血模型，旨在观察缺血再灌流不同时期大鼠脑乳酸含量的变化。结果再灌流１小时和再灌流２小时后大鼠脑乳酸含量无差异（Ｐ＞０．２）。提示再灌流后第一小时是脑乳酸产生的关键时期，这与此期出现的皮层神经元膜结构的病理改变密切相关。     

γ-羟基丁酸对大鼠局部脑缺血再灌流损伤的保护作用

目的观察γ-羟基丁酸(GHBA)对大鼠局部脑缺血再灌流兴奋性氨基酸(EAAs)含量的影响及对其缺血损伤的保护作用.方法建立大鼠局部脑缺血再灌流模型,观察并比较缺血再灌流对照组及GHBA组局部脑缺血再灌流后各时间点EAAs含量及神经计量病理损伤的差异.结果腹腔注射GHBA3.6ml@kg-1可明显减少局部脑缺血再灌流后各时间点EAAs的含量,缩小再灌流后各时间点脑梗死的体积.结论GHBA对局部脑缺血再灌流损伤有明显保护作用,这种保护作用与GHBA降低局部脑缺血再灌流区EAAs含量有关.     

小檗碱对小鼠海马CA1区迟发性神经元坏死的影响

本文采用Ｐｕｌｓｉｎｅｌｌｉ－Ｂｒｉｅｒｌｅｙ４血管结扎致ＳＤ大鼠全脑缺血（１０ｍｉｎ）再灌流模型，分别观察了早期不同再灌流时间（１２、２４、４８ｈ）点上，大鼠海马ＣＡ１区神经元的超微结构以及早灌７ｄ时光镜结构变化，同时观察了小檗碱对ＣＡ１区迟发性神经元坏死的影响。结果显示脑缺血再灌流早期，ＣＡ１区神经元超微结构发生明显改变，７ｄ时光镜下绝大部分细胞脱失，而用药组大鼠海马ＣＡ１区神经元在相应时间点     

大鼠脑缺血-再灌流后脑内MPO活性变化及组织损伤病理进观察

目的 :通过测定大鼠局灶性脑缺血 -再灌流后不同时点脑组织中 MPO活性变化 ,探讨炎症反应与脑缺血 -再灌流损伤的关系。方法 :用线栓法制备大鼠大脑中动脉缺血 -再灌流模型 ,检测缺血 3小时后再灌流不同时点脑组织中 MPO活性、脑梗死体积及光镜病理学变化。结果 :缺血组脑组织有 MPO活性升高、中性粒细胞浸润 ,以再灌流后 4 8、 72小时最为明显 ,脑梗死体积、神经元变性程度随再灌流时间延长而加重。结论 :局灶性缺血脑组织中MPO活性与缺血 -再灌流损伤间具有一定的关系 ,炎症反应是加重脑组织损伤的重要因素。     

IL-1、TNF在局部脑缺血/再灌注中的表达

研究脑缺血／再灌流损伤中IL－1、TNF的来源、变化规律和作用。方法用免疫组化方法检测了局部脑缺血／再灌流大鼠模型中IL－1β、TNF－α的表达。结果缺血组（I）3hlL－1β表达增多并持续至120h,缺血再灌流组（IR）0．5hIL－1β即明显增高,高峰在24h,120h已降至对照组（C）水平,阳性细胞主要为纹状体区及顶叶皮层的神经元、胶质细胞和血管内皮细胞;I组和IR组0．5hTNF－α表达增多,12h达高峰,持续至120h,阳性细胞为纹状体和缺血皮层的神经元和胶质细胞。结论IL－1β、TNF－α参与缺血／再灌流脑损伤,其来源于损伤局部的神经元、胶质细胞及血管内皮细胞,并对其作用进行了探讨。     

Cortical infarct volume is dependent on the ischemic reduction of perifocal cerebral blood flow in a three-vessel intraluminal MCA occlusion/reperfusion model in the rat

Occlusion of the middle cerebral artery (MCA) causes a reduction of cerebral blood flow (CBF), which shows a progressive decrease from the periphery to the core of the MCA territory. The severity of ischemia is dependent on the duration of the ischemic episode and degree of CBF reduction. Fixing the ischemic episode to 1 h, we have examined whether or not cortical infarct size was related to the degree of CBF reduction in a perifocal cortical area in rats. One-hour intraluminal MCA occlusion accompanied with bilateral common carotid artery (CCA) occlusion (three-vessel occlusion/reperfusion model) was carried out in Sprague-Dawley rats and CBF was monitored with laser-Doppler flowmetry in the fronto-parietal cortex, an area which is perifocal to the core of the MCA territory. Finally, infarct size was measured 7 days later and was related to the corresponding CBF decrease. Sequential ipsilateral CCA, MCA and contralateral CCA occlusions produced reductions of CBF to 96%, 52% and 33% of baseline, respectively. Cortical infarct volume was found to be dependent on the corresponding reduction of perifocal cortical CBF during the ischemic episode. These results show that the reduction of CBF in the periphery of the MCA territory during 1-h focal ischemia determines infarct size in a three-vessel occlusion/reperfusion model.     

人工合成E-选择素治疗大鼠局灶脑缺血再灌注损伤的探讨

目的：探讨新的药物治疗脑缺血再灌注损伤。方法：用人工合成 Ｅ－选择素 ２ｍｇ·ｋｇ－１或 １０ ｍｇ·ｋｇ－１溶解于生理盐水中,静脉注入自发性高血压大鼠永久左侧大脑中动脉／颈总动脉（ＭＣＡ／ＣＣＡ）闭塞或ＭＣＡ／ＣＣＡ闭塞２ｈ后ＣＣＡ再灌注模型中。２４ｈ后,脑梗死体积用计算机扫描计算。结果：在永久性ＭＣＡ／ＣＣＡ闭死组中脑梗死体积没有差别,在ＭＣＡ／ＣＣＡ闭死后ＣＣＡ再灌注组中脑梗死体积有意义地缩小（Ｐ＜０．０１）。结论：Ｅ－选择素能够有效地减少大鼠脑缺血再灌注损伤。     

High-dose methylprednisolone treatment in experimental focal cerebral ischemia

Previous studies using steroids for experimental focal stroke have demonstrated conflicting results, possibly related to dose used or ischemic models employed. In this study we examined high-dose methylprednisolone treatment following permanent and temporary focal cerebral ischemia in the rat. Focal stroke was induced in spontaneously hypertensive rats by permanent right common carotid and either permanent or 3 h of temporary middle cerebral artery (MCA) occlusion. Methylprednisolone (105 mg/kg) was administered intra-arterially. Infarct volume was measured at 24 h after permanent and temporary MCA occlusion. Cerebral edema was determined by measuring right and left hemispheric volumes and water content 24 h after permanent MCA occlusion in one experiment. Methylprednisolone, whether administered in divided doses over 12 h (n = 15 in each group) or a single bolus (n = 9 per group), had no effect on infarct volume after permanent MCA occlusion. Methylprednisolone treatment also had no influence on cerebral edema (n = 9 per group). In two different experiments, methylprednisolone given in divided doses over 12 h (n = 11, n = 25) after temporary MCA occlusion decreased infarct volume (P < 0.05) by 20% compared with saline controls (n = 10, n = 25). High dose methylprednisolone decreased infarct volume following temporary, but not permanent, focal ischemia. The benefit suggests that high dose methylprednisolone may prove useful clinically if reperfusion can be established with thrombolytic agents. Furthermore, the differential treatment effect in the setting of comparable ischemic insults implies that different modifiable biochemical processes may be present during temporary but not permanent focal ischemia, thus providing indirect evidence for reperfusion injury.     

Acute administration of Ginkgo biloba extract (EGb 761) affords neuroprotection against permanent and transient focal cerebral ischemia in Sprague-Dawley rats

We examined the neuroprotective action of a standardized extract of Ginkgo biloba leaves (EGb 761) in permanent and transient middle cerebral artery (MCA) occlusion models in Sprague-Dawley rats. Forty-four animals were given either EGb 761 (50-200 mg/kg) or vehicle intraperitoneally, 1 hr before permanent MCA occlusion, to evaluate the dose-response effects. An additional 58 animals received EGb 761 (200 mg/kg) or vehicle, 0.5- 4 hr after permanent MCA occlusion, for establishing the therapeutic window. Delayed treatment was also employed in 110 animals treated with either EGb 761 (100-200 mg/kg) or vehicle at 2-3 hr following transient focal cerebral ischemia induced by MCA occlusion for 2 hr. Neurobehavioral scores were determined 22-24 hr after permanent MCA occlusion and either 3 or 7 days after transient MCA occlusion, and brain infarction volumes were measured upon sacrifice. Local cortical blood flow (LCBF) was serially measured in a subset of animals receiving EGb 761 (100-200 mg/kg) or vehicle, 0.5 hr and 2 hr after permanent and transient MCA occlusion, respectively. Relative to vehicle-treated controls, rats pretreated with EGb761 (100 and 200 mg/kg) had significantly reduced infarct volumes, by 36% and 49%, respectively, and improved sensory behavior (P < 0.05). Delayed treatment with EGb 761 also significantly reduced brain infarction, by 20-29% and 31%, when given up to 2 and 3 hr following transient and permanent MCA occlusion, respectively, whereas improved neurobehavioral scores were noted up to 2 hr after the onset of MCA occlusion (P < 0.05). LCBF was significantly improved in the ipsilateral cortex following the EGb 761 treatment, whereas a higher dose showed a more sustained effect. In conclusion, EGb 761 protected against transient and permanent focal cerebral ischemia and was effective after a prolonged reperfusion period even when therapy is delayed up to 2 hr. This neuroprotection may be at least partially attributed to the beneficial effects of selectively improved LCBF in the area at risk of infarction.     

A new model of temporary focal neocortical ischemia in the rat.

BACKGROUND AND PURPOSE: We describe a new rat model of temporary focal ischemia that produces neocortical ischemia without the need for prolonged anesthesia. METHODS: Temporary focal cerebral ischemia was initiated during halothane anesthesia, maintained for varying periods without anesthesia, and reversed by clip removal requiring brief anesthesia. Tandem carotid and middle cerebral artery occlusion for 1-4 hours and permanent occlusion were used to determine the duration and extent of ischemia necessary to produce predictable volumes of neocortical infarction in Wistar and spontaneously hypertensive rats. RESULTS: In Wistar rats, occlusion of the right middle cerebral and both common carotid arteries resulted in cerebral blood flow reductions to approximately 8% of baseline. One hour of transient ischemia with 23 hours of reperfusion did not result in infarction. Three hours of ischemia followed by 21 hours of reperfusion resulted in infarction comparable to that caused by 24 hours of permanent ischemia. In spontaneously hypertensive rats, unilateral right middle cerebral and common carotid artery occlusion reduced cerebral blood flow to approximately 11% of baseline. Minimal damage was seen with 1 hour of reversible ischemia, but intervals of 2 and subsequently 3 hours followed by 22-21 hours of reperfusion produced progressively larger infarcts. Damage indistinguishable from that seen with 24 hours of permanent ischemia was seen with 3 or 4 hours of transient ischemia followed by 21 or 20 hours of reperfusion. CONCLUSIONS: For unanesthetized normothermic rats, cerebral blood flow reductions to 10-20% of baseline resulted in maximal infarction once ischemic durations exceeded 2-3 hours. To be effective, experimental therapies aimed at lessening infarct size or restoring blood flow must be initiated within this critical time interval.     

Changes in xanthine and uric acid in rat brain after middle cerebral artery occlusion

Xanthine and uric acid, products of purine metabolism, were measured by reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection in rat forebrain following focal cerebral ischemia. Focal cerebral ischemia was induced in the rat by permanent occlusion of the left middle cerebral artery (MCA). Sprague-Dawley rats were anesthetized with halothane inhalation and left MCA was occluded via trans-retro-orbital approach. Normal and sham-operated rats were used as control animals. The animals were decapitated 2 (MCA = 5, Sham = 5), 4 (MCA = 7, Sham = 6), 8 (MCA = 5, Sham = 5), and 16 (MCA = 6, Sham = 6) hours or 1 (MCA = 5, Sham = 5), 2 (MCA = 6, Sham = 6), 7 (MCA = 7, Sham = 6), 14 (MCA = 6, Sham = 5), and 28 (MCA = 7, Sham = 5) days after the operation. The brains were removed and divided into right and left hemisphere. Each hemisphere was homogenized and centrifuged. The supernates were filtered with membrane filter. An aliquot of the filtrate was used for measurement of xanthine and uric acid in both of the ischemic and contralateral hemisphere by a HPLC system. In the normal group, xanthine and uric acid in the brain was 12.4 +/- 0.4 and 2.2 +/- 0.1 nmol/g tissue (mean +/- SEM), respectively. In the ischemic hemisphere, xanthine increased up to 57.7 +/- 5.2 nmol/g tissue 2 hours after MCA occlusion and reached a maximum value of 59.42 +/- 4.91 nmol/g tissue 4 hours following the induction of ischemia. Xanthine level was still high 8 hours after ischemia and then rapidly decreased to the normal value at day 2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Photothrombotic occlusion of rat middle cerebral artery: histopathological and hemodynamic sequelae of acute recanalization

The histopathological and hemodynamic consequences of photochemically induced middle cerebral artery (MCA) thrombosis and recanalization were studied in the rat. Recanalization of the thrombosed MCA segment was achieved by the topical application of nimodipine at 1 h following photochemically induced occlusion. Pathological consequences of permanent and temporary occlusion were compared by morphometric procedures 7 days following thrombus formation. Rats with permanent thrombosis exhibited consistent infarction of both striatum and cortex. MCA recanalization at 1 h was associated with a significant reduction in total infarct volume. In recanalized rats, small cortical infarcts, confined to the peripheral MCA territory, were observed in only three of six rats. In contrast, a mixed pattern of infarction and ischemic cell damage was documented throughout the striatum in all rats. Local CBF (1CBF), measured autoradiographically, was significantly reduced in the MCA territory following 1 h of MCA occlusion, especially within the striatum. At 1 h after recanalization, 1CBF recovered within the previously ischemic brain regions to greater than 50% of control. Perfusion deficits were detected by carbon black infusion within focal areas of the striatum following reperfusion. Thus, cortical neurons appear to tolerate 1 h of MCA occlusion in this model. In contrast, reperfusion following 1 h of photochemically induced MCA occlusion gives rise to selective injury to the striatum.     

Neurological deficit and cerebral infarction after temporary middle cerebral artery occlusion in unanesthetized cats

Forty-four unanesthetized cats underwent temporary middle cerebral artery (MCA) occlusion with an implanted, externally controlled balloon cuff occluder. The occlusion was reversed to allow reperfusion of the MCA after 2 min to 24 hr of ischemia. Fourteen cats had temporary occlusions lasting 2 min to 3 hr; their neurological deficits improved or resolved after reperfusion, and brain sections showed only scattered microscopic areas of necrosis. After a 4-hr occlusion, five of nine cats (55%) recovered completely within 24 hr; two had persistent deficit when sacrificed, 10 days later, and each had a circumscribed infarct. All 18 cats undergoing 5-, 6-, 8-, and 24-hr occlusions sustained permanent neurological deficits. Three 3-hr occlusions at 2-day intervals in three cats resulted in permanent deficits and infarcts that were 25% larger than those after single 8-hr occlusions. Ten cats underwent permanent MCA occlusion; three deteriorated neurologically and died, and the survivors showed no improvement. Infarcts after 5-, 6-, and 8-hr occlusions followed by reperfusion were 66% smaller (p less than 0.05) than those after permanent occlusion; reperfusion after 24 hr of occlusion did not reduce infarct size. Hemorrhagic infarction occurred after two permanent occlusions, but after only one 5-hr temporary occlusion. The results obtained with this method of temporary regional ischemia indicate that restoration of flow after 1-8 hr, but not after 24 hr, of MCA occlusion resulted in less severe neurological deficit and smaller infarcts than did permanent occlusion. The infarct size correlated with the duration of MCA occlusion (p less than 0.05) rather than with the degree of deficit during occlusion.     

Reproducibility of cerebral cortical infarction in the wistar rat after middle cerebral artery occlusion

Although middle cerebral artery (MCA) occlusion in the rat is often used to study focal cerebral ischemia, the model of ischemia affects the size and reproducibility of infarction. The purpose of this experiment was to methodically examine different preparations to determine the optimum focal cerebral ischemia model to produce a reproducible severe ischemic injury. Eighty-two Wistar rats underwent either 1 hour, 3 hour, or permanent MCA occlusion combined with no, unilateral, or bilateral common carotid artery artery (CCA) occlusion. Three days after ischemia, the animals were prepared for tetrazolium chloride assessment of infarction size. One-hour MCA occlusion produced a coefficient of variation (CV) of 200% with an infarction volume of 20.3+/-10.5 mm(3). Adding unilateral or bilateral CCA occlusion resulted in a CV of 134% and 101%, respectively. Three-hour MCA occlusion combined with bilateral CCA occlusion decreased the CV to 58% with a cortical infarction volume of 82.6+/-12.1 mm(3), P<05, compared with 1-hour MCA occlusion with or without CCA occlusion. Permanent MCA occlusion combined with 3 hours of bilateral CCA occlusion resulted in a CV of 47% with a cortical infarction volume of 89.6+/-16.0 mm(3). These results indicate that 3-hour MCA occlusion combined with bilateral CCA occlusion provide consistently a large infarction volume after temporary focal cerebral ischemia.