黄体酮对局灶性脑缺血再灌注大鼠水通道蛋白-4表达及血脑屏障通透性的影响

目的研究黄体酮对大鼠局灶性脑缺血再灌注后脑组织内水通道蛋白-4(AQP4)的表达及血脑屏障通透性的影响。方法健康雄性SD大鼠96只,随机分为4大组:假手术组、手术组、溶剂治疗组和黄体酮治疗组,建立大脑中动脉栓塞再灌注(MCAO/R)模型,分别在缺血2h再灌注6h、1d、3d、5d 4个时间点将大鼠麻醉后断头取脑,采用Western blot法、伊文氏蓝(EB)渗出量及干湿重法分别测定脑组织AQP4的表达、血脑屏障的通透性及脑含水量。结果手术组AQP4的表达、EB的含量及脑组织含水量明显高于假手术组;黄体酮组AQP4的表达、EB的含量及脑组织含水量较手术组及溶剂组明显降低,差异有统计学意义。结论黄体酮可以降低缺血再灌注大鼠脑组织AQP4的表达,从而降低血脑屏障的通透性,减轻脑水肿。     

大鼠脑缺血再灌注后神经细胞的细胞周期特征的比较研究

目的比较观察大鼠局灶性脑缺血后星形胶质细胞和神经元细胞周期的变化特征。方法采用线栓法大鼠大脑中动脉栓塞模型,利用流式细胞技术检测假手术组和缺血再灌注后不同时间点各组大脑皮层和海马中星形胶质细胞和神经元细胞周期的异常激活和动态变化。结果缺血后大脑皮层中神经元24h时即发生明显细胞周期变化,而3d时进入细胞周期的星形胶质细胞才明显增加;海马中星形胶质细胞却先于神经元进入细胞周期,于24h时细胞周期即发生明显变化,与假手术组比较有显著差异(P<0.01)。结论在不同脑区星形胶质细胞和神经元两者对缺血性脑损伤的敏感性互不相同,并且不同脑区的星形胶质细胞对缺血性脑损伤的敏感性也有不同,脑缺血后2种细胞均出现细胞周期的异常激活。     

Attenuation of temporary focal cerebral ischemic injury in the mouse following transfection with interleukin-1 receptor antagonist.

The proinflammatory cytokine interleukin-1 beta (IL-1beta) is thought to play an important role in the stimulation of the inflammatory response following ischemia and reperfusion. This study investigated the inflammatory effect of IL-1beta during transient focal cerebral ischemia and reperfusion in the mouse transduced with the interleukin-1 receptor antagonist (IL-1ra) gene. An adenoviral vector encoding, either the human IL-1ra gene (AdRSVIL-1ra) or the LacZ gene (AdRSVlacZ) or normal saline, were injected into the right lateral ventricles of adult CD-1 mice (n=96). Five days later, the mice received 1 h temporary middle cerebral artery occlusion (tMACAO) followed by 23 h reperfusion. Cerebral blood flow (CBF), infarct volume, blood-brain barrier (BBB) permeability, and the number of intracellular adhesion molecule-1 positive vessels were measured to determine the effect of IL-1beta during postischemic reperfusion. Infarct volume in the AdRSVIL-1ra-transduced mice was markedly reduced compared to the AdRSVlacZ-transduced and saline-injected mice (36.0+/-5.3 mm(3) vs. 60.0+/-6.2 mm(3), 69. 5+/-6.3 mm(3), after 23 h of reperfusion, n=6-8 per group, p<0.05). BBB disruption and intracellular adhesion molecule-1 expression (135+/-23 vs. 311+/-40 and 357+/-51, n=6-8 per group, p<0.05) in the AdRSVIL-1ra-transduced mice were also less than that of the AdRSVlacZ-transduced and saline-injected mice. Our studies demonstrated that overexpression of IL-1ra in the mouse brain can downregulate intracellular adhesion molecule-1 expression both in the cortex and basal ganglia, which suggests that IL-1beta may play an important role in the activation of the inflammatory response during focal cerebral ischemia by promoting leukocyte adhesion to endothelial cells. The decrease of BBB disruption in AdRSVIL-1ra-transduced mice suggests that the endothelial cells may be a target for IL-1beta during postischemic reperfusion.     

Matrix metalloproteinase-9 expression and blood brain barrier permeability in the rat brain after cerebral ischemia/reperfusion injury

BACKGROUND: The integrity of the blood brain barrier (BBB) plays an important role in the patho-physiological process of cerebral ischemia/reperfusion injury. It has been recently observed that metalloproteinase-9 (MMP-9) is closely related to cerebral ischemia/reperfusion injuryOBJECTIVE: This study was designed to observe MMP-9 expression in the rat brain after cerebral ischemia/reperfusion injury and to investigate its correlation to BBB permeability.DESIGN, TIME AND SETTING: This study, a randomized controlled animal experiment, was performed at the Institute of Neurobiology, Central South University between September 2005 and March 2006.MATERIALS: Ninety healthy male SD rats, aged 3-4 months, weighing 200-280g, were used in the present study. Rabbit anti-rat MMP-9 polyclonal antibody (Boster, Wuhan, China) and Evans blue (Sigma, USA) were also used.METHODS: All rats were randomly divided into 9 groups with 10 rats in each group: normal control group, sham-operated group, and ischemia for 2 hours followed by reperfusion for 3,6,12 hours, 1,2,4 and 7 days groups. In the ischemia/reperfusion groups, rats were subjected to ischemia/reperfusion injury by suture occlusion of the right middle cerebral artery. In the sham-operated group, rats were merely subjected to vessel dissociation. In the normal control group, rats were not modeled.MAIN OUTCOME MEASURES: BBB permeability was assessed by determining the level of effusion of Evans blue. MMP-9 expression was detected by an immunohistochemical method.RESULTS: All 90 rats were included in the final analysis. BBB permeability alteration was closely correlated to ischemia/reperfusion time. BBB permeability began to increase at ischemia/reperfusion for 3 hours, then it gradually reached a peak level at ischemia/reperfusion for 1 day, and thereafter it gradually decreased. MMP-9 expression began to increase at ischemia/reperfusion for 3 hours, then gradually reached its peak level 2 days after perfusion, and thereafter it gradually decreased.CONCLUSION: MMP-9 expression increases in rat brain tissue after focal cerebral ischemia/reperfusion injury, which correlates with increased permeability of the BBB.     

Specific Role of Tight Junction Proteins Claudin-5, Occludin,and ZO-1 of the Blood–Brain Barrier in a Focal Cerebral Ischemic Insult

Blood–brain barrier (BBB) leakage plays a key role in cerebral ischemia–reperfusion injury. It is quite necessary to further explore the characteristic and mechanism of BBB leakage during stroke. We induced a focal cerebral ischemia model by transient middle cerebral artery occlusion in male rats for defining the time course of BBB permeability within 120 h following reperfusion and evaluate the specific role of tight junction (TJ) associated proteins claudin-5, occludin, and ZO-1 as well as protein kinase C delta (PKCδ) pathway in BBB leakage induced by reperfusion injury. We verified a bimodal increase in the permeability of the BBB following focal ischemia by Evans blue assay. Two peaks of BBB permeability appeared at 3 h and 72 h of reperfusion after 2 h focal ischemia, respectively. The leak at the endothelial cell was represented at the level of transmission electron microscopy. TTC staining results showed increased infarct size with time after cerebral ischemia reperfusion. The mRNA and protein expression levels of these three TJ associated proteins were significantly decreased compared with the sham-operated group within 120 h of reperfusion, corresponding to the time-dependent change of the biphasic pattern in BBB leakage. The redistribution of claudin-5, occludin, and ZO-1 in ischemia brain microvascular endothelial cells was observed at the same time points. In addition, Western blot assay revealed PKCδ level was also significantly increased in a similar biphasic pattern to above results within 120 h after cerebral ischemia–reperfusion. This study demonstrates the timing of TJ associated proteins claudin-5, occludin, and ZO-1 in light of BBB permeability associated with cerebral ischemia reperfusion, and suggests PKCδ pathway may participate in TJ barrier open and BBB leakage during reperfusion injury in a time-dependent manner.     

N‐myc downstream‐regulated gene 2 protects blood–brain barrier integrity following cerebral ischemia

Disruption of the blood‐brain barrier (BBB) following cerebral ischemia is closely related to the infiltration of peripheral cells into the brain, progression of lesion formation, and clinical exacerbation. However, the mechanism that regulates BBB integrity, especially after permanent ischemia, remains unclear. Here, we present evidence that astrocytic N‐myc downstream‐regulated gene 2 (NDRG2), a differentiation‐ and stress‐associated molecule, may function as a modulator of BBB permeability following ischemic stroke, using a mouse model of permanent cerebral ischemia. Immunohistological analysis showed that the expression of NDRG2 increases dominantly in astrocytes following permanent middle cerebral artery occlusion (MCAO). Genetic deletion of Ndrg2 exhibited enhanced levels of infarct volume and accumulation of immune cells into the ipsilateral brain hemisphere following ischemia. Extravasation of serum proteins including fibrinogen and immunoglobulin, after MCAO, was enhanced at the ischemic core and perivascular region of the peri‐infarct area in the ipsilateral cortex of Ndrg2‐deficient mice. Furthermore, the expression of matrix metalloproteinases (MMPs) after MCAO markedly increased in Ndrg2^?/? mice. In culture, expression and secretion of MMP‐3 was increased in Ndrg2^?/? astrocytes, and this increase was reversed by adenovirus‐mediated re‐expression of NDRG2. These findings suggest that NDRG2, expressed in astrocytes, may play a critical role in the regulation of BBB permeability and immune cell infiltration through the modulation of MMP expression following cerebral ischemia.     

黄体酮对脑缺血再灌注大鼠紧密连接蛋白ZO-1和occludin表达的影响

目的探讨黄体酮对大鼠局灶性脑缺血再灌注后血脑屏障紧密连接蛋白ZO-1、occludin表达及血脑屏障通透性的影响。 方法将42只健康雄性SD大鼠按随机数字表法分为假手术组（6只）和缺血再灌注组,后者再按再灌注时间分为缺血2h再灌注3h、6h、12h、24 h、48 h及72h组（各6只）。缺血再灌注组用线栓法制备成大鼠大脑中动脉缺血再灌注模型。采用荧光分光光度法测定缺血侧脑组织中伊文氏蓝(EB)含量来评价血脑屏障的通透性,Western blotting法检测脑组织ZO-1和occludin的表达。取EB漏出最多组的时间点,增设黄体酮干预组和溶剂对照组（各6只）,与相同时间点的缺血再灌注组比较,观察黄体酮对ZO-1、occludin表达及血脑屏障通透性的影响。 结果 缺血2h再灌注3h时脑组织EB含量开始增加,再灌注24 h时达高峰;ZO-1、occludin的表达在缺血2h再灌注3h时开始下降,再灌注24 h时达最低。黄体酮干预组EB含量明显低于缺血2h再灌注24 h组,差异有统计学意义(P＜0.05)。黄体酮干预组ZO-1和occludin的表达水平均明显高于缺血2h再灌注24 h组,差异有统计学意义(P＜0.05)。 结论 黄体酮町抑制缺血再灌注大鼠紧密连接蛋白ZO-1和occludin表达的降低,从而起到保护血脑屏障的作用。     

Early release of HMGB-1 from neurons after the onset of brain ischemia.

The nuclear protein high-mobility group box 1 (HMGB-1) promotes inflammation in sepsis, but little is known about its role in brain ischemia-induced inflammation. We report that HMGB-1 and its receptors, receptor for advanced glycation end products (RAGE), Toll-like receptor 2 (TLR2), and TLR4, were expressed in normal brain and in cultured neurons, endothelia, and glial cells. During middle cerebral artery occlusion (MCAO), in mice, HMGB-1 immunostaining rapidly disappeared from all cells within the striatal ischemic core from 1 h after onset of occlusion. High-mobility group box 1 translocation from nucleus to cytoplasm was observed within the cortical periinfarct regions 2 h after ischemic reperfusion (2 h MCAO). High-mobility group box 1 predominantly translocated to the cytoplasm or disappeared in cells that colabeled with the neuronal marker NeuN. Furthermore, RAGE was robustly expressed in the periinfarct region after MCAO. Cellular release of HMGB-1 was detected by immunoblotting of cerebrospinal fluid as early as 2 h after ischemic reperfusion (2 h MCAO). High-mobility group box 1 released from neurons, in vitro, after glutamate excitotoxicity, maintained biologic activity and induced glial expression of tumor necrosis factor alpha (TNFalpha). Anti-HMGB-1 antibody suppressed TNFalpha upregulation in astrocytes exposed to conditioned media from glutamate-treated neurons. Moreover, TNFalpha and the cytokine intercellular adhesion molecule-1 increased in cultured glia and endothelial cells, respectively, after adding recombinant HMGB-1. In conclusion, HMGB-1 is released early after ischemic injury from neurons and may contribute to the initial stages of the inflammatory response.     

Deficiency of PAR4 attenuates cerebral ischemia/reperfusion injury in mice

Stroke is the third leading cause of death in the USA. Antithrombotic therapy targeting platelet activation is one of the treatments for ischemic stroke. Here we investigate the role of one of the thrombin receptors, protease-activated receptor 4 (PAR4), in a mouse transient middle cerebral artery occlusion (MCAO) model. After a 60 min MCAO and 23 h reperfusion, leukocyte and platelet rolling and adhesion on cerebral venules, blood–brain barrier (BBB) permeability, and cerebral edema were compared in PAR4-deficient mice and wild-type mice. Cerebral infarction volume and neuronal death were also measured. PAR4−/− mice had more than an 80% reduction of infarct volume and significantly improved neurologic and motor function compared with wild-type mice after MCAO. Furthermore, deficiency of PAR4 significantly inhibits the rolling and adhesion of both platelets and leukocytes after MCAO. BBB disruption and cerebral edema were also attenuated in PAR4−/− mice compared with wild-type animals. The results of this investigation indicate that deficiency of PAR4 protects mice from cerebral ischemia/reperfusion (I/R) injury, partially through inhibition of platelet activation and attenuation of microvascular inflammation.     

阿托伐他汀对大鼠脑缺血再灌注后血脑屏障通透性的影响

目的 评估阿托伐他汀对大鼠脑缺血再灌注后血脑屏障通透性的影响。方法 采用常规尼龙线栓法制备SD大鼠脑缺血再灌注模型,并将大鼠随机分为假手术组、大脑中动脉阻断再灌注(Middle cerebral artery occlusion/reperfusion,MCAO/R)(对照)组和MCAO/R阿托伐他汀(治疗)组; 对照组和治疗组分别于脑缺血2 h再灌注24 h处死; 标准湿干法测定脑组织含水量; 实时聚合酶链反应(Real-time polymerase chain reaction,RT-PCR)检测基质金属蛋白酶-2(Matrix metalloproteinases-2,MMP-2)和基质金属蛋白酶-9(Matrix metalloproteinases-9,MMP-9)的mRNA表达水平; 应用免疫组化法测定Ⅳ型胶原蛋白(Ⅳ type collagen,CoⅣ)水平; 电镜观察显示血脑屏障超微结构的改变。结果 治疗组与对照组比较,脑组织含水量减少(P<0.01); 阿托伐他汀治疗显著降低了MMP-2和MMP-9的mRNA表达水平; 治疗组脑组织CoⅣ水平高于对照组(P<0.01); 电镜观察显示治疗组血脑屏障超微结构的改变明显好于对照组。结论 阿托伐他汀可以降低脑缺血再灌注大鼠血脑屏障的通透性,从而减轻脑水肿。     

单核细胞趋化蛋白-1在大鼠脑缺血再灌注损伤中的表达变化

目的 观察大鼠大脑中动脉闭塞（MCAO）后再灌注不同时间点单核细胞趋化蛋白-1（MCP-1）与基因表达的变化．以探讨其在脑缺血再灌注损伤中的意义。方法 建立大鼠局灶性脑缺血再灌注模型，用免疫荧光双标染色、逆转录-聚合酶链反应（RT-PCR）技术检测MCP-1蛋白表达、mRNA转录水平。结果 （1）缺血再灌注后缺血脑组织中存在表达MCP-1／NSE和MCP-1／GFAP双阳性细胞．提示神经元和神经胶质细胞是产生MCP-1的细胞来源之一。（2）各缺血再灌注组MCP-1 mRNA表达均高于假手术组．再灌注1h MCP-1的mRNA转录即有升高．且随时间延长而进一步升高．24h达到高峰之后逐渐下降。结论 脑缺血再灌注引起MCP-1表达上调．提示MCP-1可能参与了局灶性脑缺血再灌注损伤。     

钙拮抗剂对大鼠脑缺血后血脑屏障通透性的影响

目的 研究钙离子拮抗剂对大鼠脑缺血再灌注后血脑屏障(BBB)通透性和脑梗死灶体积的影响. 方法 插线法制作大鼠脑缺血再灌注模型.缺血2 h后再灌注.将150只大鼠按随机数字表法分尼莫地平组和对照组,每组分再灌注6h、12h、24 h、48h、72 h五个时间段,再灌注后尼莫地平组和对照组立即分别腹腔注射尼莫地平和生理盐水2 mg/kg.每12小时注射一次,用甲酰胺荧光法及透射电镜观察不同时段BBB通透性破坏的情况,TTC染色后计算梗死灶体积百分比.结果 大鼠脑缺血再灌注后BBB通透性和梗死灶体积百分比随时间延长逐渐增加.且BBB通透性的增加呈现两个高峰,第一个高峰在再灌注后12 h,第二个高峰在再灌注后48 h.尼莫地平组BBB通透性及脑梗死灶体积百分比的增加均较对照组明显,差异有统计学意义(P<0.05). 结论 脑缺血再灌注增加BBB的通透性和脑梗死灶体积百分比.再灌注后给予尼莫地平可加重这些病理变化.     

Early appearance of activated matrix metalloproteinase-9 and blood–brain barrier disruption in mice after focal cerebral ischemia and reperfusion

Blood–brain barrier (BBB) disruption is thought to play a critical role in the pathophysiology of ischemia/reperfusion. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that can degrade all the components of the extracellular matrix when they are activated. Gelatinase A (MMP-2) and gelatinase B (MMP-9) are able to digest the endothelial basal lamina, which plays a major role in maintaining BBB impermeability. The present study examined the expression and activation of gelatinases before and after transient focal cerebral ischemia (FCI) in mice. Adult male CD1 mice were subjected to 60 min FCI and reperfusion. Zymography was performed from 1 to 23 h after reperfusion using the protein extraction method with detergent extraction and affinity-support purification. MMP-9 expression was also examined by both immunohistochemistry and Western blot analysis, and tissue inhibitors to metalloproteinase-1 was measured by reverse zymography. The BBB opening was evaluated by the Evans blue extravasation method. The 88-kDa activated MMP-9 was absent from the control specimens, while it appeared 3 h after transient ischemia by zymography. At this time point, the BBB permeability alteration was detected in the ischemic brain. Both pro-MMP-9 (96 kDa) and pro-MMP-2 (72 kDa) were seen in the control specimens, and were markedly increased after FCI. A significant induction of MMP-9 was confirmed by both immunohistochemistry and Western blot analysis. The early appearance of activated MMP-9, associated with evidence of BBB permeability alteration, suggests that activation of MMP-9 contributes to the early formation of vasogenic edema after transient FCI.     

Cerebralcare Granule® attenuates blood-brain barrier disruption after middle cerebral artery occlusion in rats

Disruption of blood–brain barrier (BBB) and subsequent edema are major contributors to the pathogenesis of ischemic stroke, for which the current clinical therapy remains unsatisfied. Cerebralcare Granule® (CG) is a compound Chinese medicine widely used in China for treatment of cerebrovascular diseases. CG has been demonstrated efficacy in attenuating the cerebral microcirculatory disturbance and hippocampal neuron injury following global cerebral ischemia. However, the effects of CG on BBB disruption following cerebral ischemia have not been investigated. In this study, we examined the therapeutic effect of CG on the BBB disruption in a focal cerebral ischemia/reperfusion (I/R) rat model. Male Sprague–Dawley rats (250 to 300 g) were subjected to 1 h middle cerebral artery occlusion (MCAO). CG (0.4 g/kg or 0.8 g/kg) was administrated orally 3 h after reperfusion for the first time and then once daily up to 6 days. The results showed that Evans blue extravasation, brain water content, albumin leakage, infarction volume and neurological deficits increased in MCAO model rats, and were attenuated significantly by CG treatment. T2-weighted MRI and electron microscopy further confirmed the brain edema reduction in CG-treated rats. Treatment with CG improved cerebral blood flow (CBF). Western blot analysis and confocal microscopy showed that the tight junction proteins claudin-5, JAM-1, occludin and zonula occluden-1 between endothelial cells were significantly degradated, but the protein expression of caveolin-1, the principal marker of caveolae in endothelial cells, increased after ischemia, all of which were alleviated by CG treatment. In conclusion, the post-treatment with CG significantly reduced BBB permeability and brain edema, which were correlated with preventing the degradation of the tight junction proteins and inhibiting the expression of caveolin-1 in the endothelial cells. These findings provide a novel approach to the treatment of ischemic stroke.     

磷酸化Rb蛋白在正常成年大鼠与脑缺血大鼠神经元内的表达变化

目的观察正常成年大鼠与局灶性脑缺血大鼠神经元内磷酸化Rb蛋白(p-Rb)的表达及变化特点。方法应用免疫荧光组织化学染色方法观察成年大鼠不同脑区神经元内p-Rb表达特点,比较大鼠大脑中动脉闭塞(MCAO)后不同时间点(12h、1d、3d、7d)缺血半暗带内神经元p-Rb的变化特点。结果成年大鼠神经元内p-Rb主要在细胞核内表达;与对照组相比,MCAO再灌注后各时间点p-Rb免疫反应性均增强;再灌注1d,缺血半暗带内部分神经元p-Rb表达由细胞核转移到细胞浆。结论成熟神经元内p-Rb在细胞核内表达可能对于维持神经元的有丝分裂后状态有一定作用,当其发生核浆转移提示神经元细胞周期调控机制紊乱,可能再进入细胞周期。     

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.     

VEGF治疗脑缺血再灌注损伤的分子机制研究

目的 通过检测血管内皮生长因子（VEGF）治疗兔脑缺血再灌注损伤的有关分子表达情况,探讨其分子机制.方法 采用兔大脑中动脉阻塞（MCAO）2h再灌注72h模型,在再灌注即刻,应用微量进样器将VEGF立体定向导入梗死灶周,于再灌注72h断头取脑,应用免疫组化方法检测缺血半暗带区caspase-3和细胞外信号调节激酶1（estracellular signal-regulated kinase,ERK1）的表达情况.结果 VEGF治疗后缺血半暗带区caspase-3和ERK1表达明显减低.结论 VEGF可能通过抑制caspase-3和ERK1表达发挥治疗作用.     

实验性局灶性脑缺血不同脑区VEGF、VEGFR-1、2表达及意义

目的 通过探索血管内皮生长因子及其受体在局灶性脑缺血中的表达，进而探求血管内皮生长因子在局灶性脑缺血中的作用。方法 应用左侧颈总动脉结扎加缺氧诱导的方法，建立SD大鼠永久大脑中动脉闭塞模型，应用免疫组化方法检测血管内皮生长因子及其受体(VEGF、VEGFR-1、2)的表达，同时观察局灶性脑缺血后血管型成情况。结果 VEGF及VEGFR-1、2在局灶性脑缺血后6h表达增强，24h达高峰，在1周、2周恢复到对照水平。VEGF主要在缺血半影区(IP)神经元、胶质细胞及血管内皮细胞表达；VEGFR-1、2主要在缺血半影区血管内皮细胞表达。在缺血后48h半影区周边出现血管增生，1周后达高峰。结论 在局灶性脑缺血早期VEGF及VEGFR-1、2在神经细胞、胶质细胞、血管内皮细胞等均有表达，可促进缺血半影区的血管增生，对改善缺血半影区血供有重要作用。     

大鼠急性局灶性脑缺血再灌注脑组织NO含量和NOS活性的变化

目的探讨一氧化氮（ＮＯ）和神经元型ＮＯ合酶（ｎＮＯＳ）是否参与急性局灶性脑缺血再灌注的发病机理。方法采用栓红法建立大鼠大脑中动脉阻塞（ＭＣＡＯ）模型,观察脑组织ＮＯ含量和一氧化氮合酶（ＮＯＳ）活性的变化及ｎＮＯＳ抑制剂７－硝基吲唑（７－ＮＩ）对再灌注期两者的影响。结果缺血３０分种ＮＯ含量和ＮＯＳ活性显著升高,缺血３小进两者下降;再灌注３０分种ＮＯＴ和ＮＯＳ再次升高,而再灌注３小时两者又下降。７－Ｎ