七叶皂苷钠对大鼠脑缺血再灌注损伤的保护作用

目的 探讨七叶皂苷钠对大鼠脑缺血再灌注损伤的作用及机制。方法 60只成年SD大鼠随机分为假手术组、模型组和七叶皂苷钠组,各20只。采用线栓法建立大鼠局灶性大脑中动脉闭塞再灌注损伤模型,七叶皂苷钠组建模成功后1 h腹腔注射七叶皂苷钠（2.8 mg/kg）,假手术组和模型组腹腔注射等量生理盐水。造模后24 h,使用Longa评分评估大鼠神经功能损伤程度,使用称重法检测大鼠脑水肿程度,使用ELISA法测定大鼠损伤脑组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、丙二醛（MDA）、肿瘤坏死因子（TNF-α）、白细胞介素6（IL-6）及白细胞介素1β（IL-1β）的含量,使用TUNEL法检测损伤脑组织神经元凋亡率,使用蛋白免疫印迹法检测损伤脑组织双特异性磷酸酶1（DUSP1）、核转录因子-κB（NF-κB）p65、Bcl-2及Bax蛋白的表达。结果 与假手术组比较,模型组大鼠Longa评分显著增加（P<0.01）,脑含水量显著升高（P<0.01）,损伤脑组织MDA、TNF-α、IL-1β和IL-6水平显著增高（P<0.001）,损伤脑组织SOD和CAT水平显著降低（P<0.001）,损伤脑组织神经元凋亡率显著升高（P<0.01）,损伤脑组织DUSP1和Bcl-2蛋白表达水平显著降低（P<0.05）,损伤脑组织NF-kB p65和Bax蛋白表达水平显著增高（P<0.05）。七叶皂苷钠显著逆转大鼠上述反应（P<0.05）。结论 七叶皂苷钠显著改善大鼠脑缺血再灌注损伤,机制可能与减轻炎症反应、氧化应激反应、神经元凋亡等有关。     

特异性抑制JAK2/STAT3信号通路对大鼠急性脑缺血再灌注损伤后COX-2和VEGF表达水平的影响

目的 探讨特异性抑制蛋白酪氨酸激酶2/信号转导与激活子3(JAK2/STAT3)信号通路对急性脑缺血再灌注损伤大鼠脑组织环氧合酶-2(COX-2)和血管内皮生长因子(VEGF)表达水平的影响。方法 采用线栓法制备大鼠急性大脑中动脉闭塞再灌注模型; 大鼠随机分为假手术组、模型组和给药组; 给药组大鼠于再灌注前5 min腹腔注射JAK2/STAT3信号通路抑制剂AG490(1 mg/kg),其余2组给予等量生理盐水; 再灌注24 h后各组行神经功能缺损评分,用氯化三苯基四氮唑(TTC)染色法检测大鼠脑梗死体积,用实时荧光定量PCR(RT-qPCR)检测脑组织中JAK2、STAT3、环氧合酶2(COX-2)和血管内皮生长因子(VEGF)的mRNA相对表达水平,用蛋白印迹(Western blot)检测脑组织磷酸化JAK2(p-JAK2)、磷酸化STAT3(p-STAT3)、COX-2和VEGF的蛋白相对表达水平。结果 与假手术组比较,模型组大鼠神经功能缺损评分、脑梗死体积、JAK2和STAT3的mRNA,p-JAK2和p-STAT3蛋白、COX-2的mRNA和蛋白相对表达水平均显著升高(P<0.05),VEGF的mRNA和蛋白相对表达水平显著降低(P<0.05); 与模型组比较,给药组大鼠神经功能缺损评分、脑梗死体积、JAK2和STAT3的mRNA、p-JAK2和p-STAT3蛋白、COX-2的mRNA和蛋白相对表达水平均显著降低(P<0.05),VEGF的mRNA和蛋白相对表达水平显著升高(P<0.05)。结论 特异性抑制JAK2/STAT3信号通路可能通过降低脑组织中COX-2表达和促进VEGF表达来保护大鼠急性脑缺血再灌注损伤。     

β-七叶皂苷钠对大鼠局灶性脑缺血再灌注后AQP4蛋白表达的影响

目的探讨大鼠局灶性脑缺血再灌注脑组织缺血区AQP4蛋白的表达情况及β-七叶皂苷钠的治疗作用和可能机制。方法采用大鼠大脑中动脉闭塞法(MCAO)制作局灶性脑缺血再灌注模型。应用干-湿比重法、TTC染色、免疫组化SABC法分别测定脑含水量、脑梗死体积及水孔蛋白4(aquaporin4,AQP4)的表达。结果假手术组AQP4蛋白有轻微的表达,而模型组、治疗组缺血损伤后表达升高,脑含水量增高,梗死脑组织出现,给予β-七叶皂苷钠的治疗组AQP4蛋白的表达下降,脑含水量明显降低,脑梗死体积减少,且β-七叶皂苷钠中高剂量组明显优于低剂量组(P<0.05)。结论脑缺血再灌注脑组织缺血区AQP4蛋白表达的上调与脑水肿的发生发展与有密切的关系,而β-七叶皂苷钠有抑制脑水肿发生的作用。     

rhEPO对大鼠颅脑损伤早期脑微血管内皮细胞紧密连接的保护作用

目的探讨重组人促红细胞生成素(rhEPO)对颅脑损伤早期脑微血管内皮细胞的保护作用及机制。方法将81只SD大鼠按随机数字表法随机分为假手术组(n=9)、颅脑损伤(TBI)组(n=36)和rhEPO治疗组(n=36)。用Marmarou等人的方法制作大鼠颅脑损伤模型,分光光度仪测定各组大鼠脑组织伊文氏蓝(EB)含量,实时荧光定量PCR和免疫组织化学法检测闭合蛋白-5(claudin-5)、咬合蛋白(occludin)和胞质紧密粘连蛋白-1(ZO-1)的表达。结果伤后3h、24h、3d,与假手术组对比,TBI组大鼠脑组织EB含量明显升高(P<0.05),claudin-5、occludin和ZO-1mRNA及其蛋白的表达显著降低(P<0.05);与TBI组对比,rhEPO治疗组大鼠脑组织EB含量显著降低(P<0.05),claudin-5、occludin和ZO-1mRNA及其蛋白的表达显著升高(P<0.05)。结论颅脑损伤早期应用rhEPO,可能通过增加紧密连接相关蛋白claudin-5、occludin和ZO-1的表达而保护脑微血管内皮细胞。     

大鼠静脉窦血栓形成后VEGF和VEGF mRNA的表达及意义

目的 观察大鼠颅内静脉窦血栓形成(CVST)后脑组织内血管内皮生长因子(VEGF)和VEGF mR-NA的动态表达并其意义.方法 采用大鼠上矢状窦结扎并注入脑磷脂白陶土法建立CVST模型,根据CVST后的不同时间分为1d、3d、7d组及假手术对照组.免疫组化法检测VEGF蛋白的表达;RT-PCR法检测VEGF mRNA动态变化.结果 CVST1d VEGF免疫组化呈显著阳性反应,之后逐渐增强,CVST 7d达高峰;同时CVST后VEGFm-RNA转录水平明显升高.结论 颅内静脉窦血栓形成可诱导脑组织内VEGF表达增强,VEGF持续表达可能与促进血管新生和侧支循环形成有关.     

血红蛋白致脑组织水肿机制研究

目的探讨血红蛋白(hemoglbin,HB)在脑组织水肿中的作用及其机制。方法采用HB 50μL直接注射到wistar大鼠脑尾状核为模型,对大鼠造模后各时间点的神经功能进行评分、脑组织含水量和水通道蛋白4(Aquaporin4)mRNA及蛋白的表达进行观察,并分析其间的联系。结果与对照组相比较注射HB 3 h神经功能评分、脑含水量及AQP4 mRNA和蛋白的含量即开始增高(P<0.05),评分以造模后12 h到24 h,后三项指标则均在术后第24 h达高峰。AQP4干预组注射HB后上述各项指标虽明显高于对照组(P<0.05),但均不如模型组增高明显(P>0.05)。结论大鼠脑尾状核直接注射HB可成功诱发脑水肿,AQP4mRNA和蛋白表达与注射HB后脑水含量的程度呈平行关系,提示AQP4直接参与了HB致脑水肿的病理生理过程。给予氯丙烯干预可抑制AQP4的表达、减轻HB引起的脑水肿,进一步说明AQP4的表达与功能是HB致脑水肿形成的重要病理生理机制之一。     

丹参酮ⅡA对脑出血大鼠脑组织HIF-1α和VEGF表达的影响

目的探讨丹参酮ⅡA对脑出血大鼠的干预作用以及对HIF-1α和VEGF表达的影响。方法将大鼠随机分为假手术组、脑出血组、丹参酮ⅡA干预I组和II组,除假手术组外,其余大鼠均通过注射胶原酶的方法建立脑出血模型,丹参酮IIA干预Ⅰ组和Ⅱ组分别腹腔注射丹参酮IIA30 mg/kg,每天一次和30 mg/kg,每天两次,共给药15 d。给药完成后,对各组大鼠进行神经功能缺损评分,称重法计算脑组织的含水量,免疫组化法与实时荧光定量PCR检测脑组织中HIF-1α和VEGF的蛋白表达与mRNA表达。结果与脑出血组相比,丹参酮IIA干预组大鼠的神经功能缺损评分显著升高,脑组织含水量显著下降,脑组织中HIF-1α和VEGF的蛋白表达与mRNA表达显著升高。结论丹参酮IIA对脑出血大鼠脑组织具有保护作用,其作用机制可能与HIF-1α和VEGF因子的表达有关。     

NO增加兔局灶脑缺血后缺血脑组织VEGF表达

目的一氧化氮(NO)和血管内皮生长因子(VEGF)参与血管再生并且可能在脑缺血相互影响,本实验探讨NO对局灶脑缺血后VEGF表达的影响。方法兔局灶脑缺血后应用NO合成底物:左旋-精氨酸(L-Arg),荧光RT-PCR分析缺血脑组织VEGF mRNA表达,ELISA分析VEGF蛋白,脑组织含水率评价脑水肿。结果L-Arg明显增加缺血区VEGF蛋白(1.180±0.433ng/ml vs0.649±0.274ng/ml,P<0.05)和mRNA表达(0.3402±8.876×10-3vs0.2025±0.0413,P<0.05),同时减轻脑水肿(P<0.01)。结论外源性NO增加缺血区VEGF表达,减轻脑水肿,提示联合应用NO合成底物和VEGF对脑缺血后神经保护可能起到更好的协同作用。     

AQP-9在大鼠感染性脑水肿脑组织中的表达及意义

目的 探讨水通道蛋白-9(AQP-9)在内毒素脂多糖(LPS)致大鼠感染性脑水肿脑组织中的表达及意义. 方法 1月龄普通级SD大鼠128只采用随机数字表法分为生理盐水(NS)组(64只)和LPS组(64只),采用颈内动脉注射LPS制作大鼠感染性脑水肿模型,模型成功后每组均选取6h、12h、24h和48 h4个时间点,在不同时间点采用HE染色观察脑组织形态学改变;干湿重法测定脑组织含水量(BWC);甲酰胺法测定脑组织伊文思蓝(EB)含量;免疫组织化学法检测脑组织AQP-9蛋白的表达量:采用逆转录多聚酶链反应(RT-PCR)方法 检测AQP-9 mRNA的表达水平并对结果 进行相关性分析. 结果 HE染色结果 显示LPS组血管周围间隙增宽、炎性细胞浸润、胶质细胞体积增大肿胀、神经元空泡变性、细胞核固缩等.与NS组相比,LPS组6 h、12 h、24 h和48 hBWC、EB含量、AQP.9蛋白及AQP.9mRNA表达水平均增高.差异具有统计学意义(P<0.05).同时LPS组BWC和EB含量、AQP-9蛋白、AQP.9 mRNA表达量、AQP-9 mRNA表达量与EB含量、AQP-9蛋白与mRNA表达量均呈正相关. 结论 AQP-9可能参与感染性脑水肿的发生和发展.     

外源性神经生长因子注射治疗对脑出血大鼠模型神经功能及VEGF和HMGB1表达水平的影响

目的 探讨神经生长因子(nerve growth factor,NGF)对脑出血(intracerebral hemorrhage,ICH)大鼠模型神经功能及血管内皮生长因子(vascular endothelial growth factor,VEGF)和高迁移率族蛋白1(high mobility group box-1 protein,HMGB1)表达水平的影响。方法 SD大鼠(60只)构建脑出血ICH模型,并随机分为对照组、模型组和治疗组,治疗组给予颅内NGF 1.0 μg血肿内注射1周后检测大鼠神经功能NSS评分; HE染色法观察血肿周围脑组织病理学改变; 采用TUNEL法检测神经细胞凋亡; 采用Western blot法检测NGF、VEGF和HMGB1蛋白的表达水平。结果 与模型组比较,治疗组大鼠NSS评分显著增高,脑组织含水量显著减少(P<0.05); 治疗组凋亡细胞数显著减少(P<0.05)。治疗组大鼠脑组织NGF和VEGF蛋白水平显著升高及HMGB1蛋白水平显著降低(P<0.05)。治疗组神经细胞肿胀程度、间隙及细胞核改变均较轻,周围炎症反应和病理学改变减轻。结论 外源性神经生长因子有助于改善脑出血大鼠的神经功能损伤,其机制可能通过上调VEGF和下调HMGB1来减轻脑水肿和神经细胞凋亡,从而产生神经保护作用。     

Aquaporin 4 expression and ultrastructure of the blood-brain barrier following cerebral contusion injury

This study aimed to investigate aquaporin 4 expression and the ultrastructure of the blood-brain barrier at 2–72 hours following cerebral contusion injury, and correlate these changes to the formation of brain edema. Results revealed that at 2 hours after cerebral contusion and laceration injury, aquaporin 4 expression significantly increased, brain water content and blood-brain barrier permeability increased, and the number of pinocytotic vesicles in cerebral microvascular endothelial cells increased. In addition, the mitochondrial accumulation was observed. As contusion and laceration injury became aggravated, aquaporin 4 expression continued to increase, brain water content and blood-brain barrier permeability gradually increased, brain capillary endothelial cells and astrocytes swelled, and capillary basement membrane injury gradually increased. The above changes were most apparent at 12 hours after injury, after which they gradually attenuated. Aquaporin 4 expression positively correlated with brain water content and the blood-brain barrier index. Our experimental findings indicate that increasing aquaporin 4 expression and blood-brain barrier permeability after cerebral contusion and laceration injury in humans is involved in the formation of brain edema.     

Vascular endothelial growth factor mediates vasogenic edema in acute lead encephalopathy

Brain injury from inorganic Pb(2+) is considered the most important environmental childhood health hazard worldwide. The microvasculature of the developing brain is uniquely susceptible to high level Pb(2+) toxicity (ie, Pb(2+) encephalopathy) characterized by cerebellar hemorrhage, increased blood-brain barrier permeability, and vasogenic edema. However, the specific molecular mediators of Pb(2+) encephalopathy have been elusive. We found that Pb(2+) induces vascular endothelial growth factor/vascular permeability factor (VEGF) in cultured astrocytes (J Biol Chem, 2000;275:27874-27882). The study presented here asks if VEGF dysregulation contributes mechanistically to Pb(2+) encephalopathy. Neonatal rats exposed to 4% Pb-carbonate develop the histopathological features of Pb(2+) encephalopathy seen in children. Cerebellar VEGF expression increased approximately twofold (p < 0.01) concurrent with the development of cerebellar microvascular hemorrhage, enhanced vascular permeability to serum albumin, and vasogenic cerebellar edema (p < 0.01). No change in VEGF expression occurred in cerebral cortex that does not develop these histopathological complications of acute Pb(2+) intoxication. Pb(2+) exposure increased phosphorylation of cerebellar Flk-1 VEGF receptors and the Flk-1 inhibitor CEP-3967 completely blocked cerebellar edema formation without affecting microhemorrhage formation or blood-brain barrier permeability. This establishes that Pb(2+)-induced vasogenic edema formation develops via a Flk-1-dependent mechanism and suggests that the vascular permeability caused by Pb(2+) is Flk-1 independent.     

Differential regulation of blood-brain barrier permeability in brain trauma and pneumococcal meningitis-role of Src kinases

Increased vascular permeability causing vasogenic brain edema is characteristic for many acute neurological diseases such as stroke, brain trauma, and meningitis. Src family kinases, especially c-Src, play an important role in regulating blood-brain barrier permeability in response to VEGF, but also mediate leukocyte function and cytokine signalling. Here we demonstrate that pharmacological inhibition of Src or c-Src deficiency does not influence cerebrospinal fluid (CSF) pleocytosis, brain edema formation, and bacterial outgrowth during experimental pneumococcal meningitis despite the increased cerebral expression of inflammatory chemokines, such as IL-6, CCL-9, CXCL-1, CXCL-2 and G-CSF as determined by protein array analysis. In contrast, inhibition of Src significantly reduced brain edema formation, lesion volume, and clinical worsening in cold-induced brain injury without decreasing cytokine/chemokine expression. While brain trauma was associated with increased cerebral VEGF formation, VEGF levels significantly declined during pneumococcal meningitis. Therefore, we conclude that in brain trauma blood-brain barrier tightness is regulated by the VEGF/Src pathway whereas c-Src does not influence brain edema formation and leukocyte function during bacterial meningitis.     

Signaling pathways for early brain injury after subarachnoid hemorrhage.

Few studies have examined the signaling pathways that contribute to early brain injury after subarachnoid hemorrhage (SAH). Using a rat SAH model, the authors explored the role of vascular endothelial growth factor (VEGF) and mitogen-activation protein kinase (MAPK) in early brain injury. Male Sprague-Dawley rats (n = 172) weighing 300 to 350 g were used for the experimental SAH model, which was induced by puncturing the bifurcation of the left anterior cerebral and middle cerebral arteries. The blood-brain barrier (BBB), brain edema, intracranial pressure, and mortality were evaluated at 24 hours after SAH. The phosphorylation of VEGF and different MAPK subgroups (ERK1/2, p38, and JNK) were examined in both the cortex and the major cerebral arteries. Experimental SAH increased intracranial pressure, BBB permeability, and brain edema and produced high mortality. SAH induced phosphorylation of VEGF and MAPKs in the cerebral arteries and, to a lesser degree, in the cortex. PP1, an Src-family kinase inhibitor, reduced BBB permeability, brain edema, and mortality and decreased the phosphorylation of VEGF and MAPKs. The authors conclude that VEGF contributes to early brain injury after SAH by enhancing the activation of the MAPK pathways, and that the inhibition of these pathways might offer new treatment strategies for SAH.     

大鼠重型颅脑损伤急性期水通道蛋白4的表达

目的探讨水通道蛋白（AQP4）在大鼠重型脑外伤急性期的表达变化及其与脑水肿间的关系。方法49只成年雄性SD大鼠,随机分为对照组及实验组（伤后4h、8h、12h、24h、5d共5组）。制作重度冲击加速性损伤模型,分别于伤后4h、8h、12h、24h、72h、5d采用干湿比重法测脑组织含水量,原子吸收分光光度法测定Na^＋、K^＋含量,Evans Blue（EB）测定法观察大鼠血-脑屏障（BBB）通透性变化,半定量逆转录聚合酶链反应（RT-PCR）检测脑组织AQP4 mRNA表达及其变化。结果脑组织AQP4 mRNA在伤后4h开始表达上调,8h、12h依次增高,24h达到峰值（P〈0.05）,3d时仍维持较高水平,伤后5d有所降低。脑含水量、Na^＋含量的变化与AQP4 mRNA表达变化一致。经相关性分析,AQP4 mRNA的表达与脑含水量及脑EB含量均呈正相关（P〈0.05）。结论重型脑损伤急性期,AQP4 mRNA表达的变化与颅脑损伤后BBB的破坏及脑水肿的形成和发展密切相关。AQP4可能参与重型脑损伤后脑水肿的形成并起重要作用。     

线粒体钙单向转运体对脑缺血再灌注大鼠脑水肿的影响

实验探讨线粒体钙单向转运体抑制剂钌红及激动剂精胺对缺血再灌注大鼠脑水肿的影响。采用线栓法建立大鼠左侧大脑中动脉闭塞大鼠模型,缺血再灌注24 h后,脑缺血再灌注模型大鼠、钌红及精胺干预的脑缺血再灌注大鼠神经功能评分均显著低于假手术大鼠,脑组织含水量,水通道蛋白4蛋白表达、IgG渗出含量均显著高于假手术大鼠;与脑缺血再灌注模型大鼠和脑缺血再灌注后精胺干预大鼠比较,钌红干预的脑缺血再灌注大鼠神经功能评分明显升高,脑组织含水量,水通道蛋白4蛋白表达及IgG渗出含量明显减少。提示预防性应用线粒体钙单向转运体抑制剂钌红可显著的降低水通道蛋白4和IgG的表达,影响血脑屏障通透性,进而降低脑水肿的程度。结论 线粒体钙单向转运体可能在大鼠脑缺血再灌注损伤中起重要作用,并能影响AQP4的表达和血脑屏障通透性。     

Correlation of aquaporin-4 expression to blood-brain barrier permeability in rats with focal cerebral ischemia

BACKGROUND: Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE: To analyze the correlation of aquaporin-4 expression to brain edema and blood-brain barrier permeability in brain tissues of rat models of ischemia/reperfusion. DESIGN, TIME AND SETTING: The randomized control experiment was performed at the Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, China from December 2006 to October 2007. MATERIALS: A total of 112 adult, male, Sprague-Dawley rats, weighing 220-250 g, were used to establish rat models of middle cerebral artery occlusion and reperfusion by the suture method. Rabbit anti-aquaporin-4 (Santa Cruz, USA) and Evans blue (Sigma, USA) were used to analyze the tissue. METHODS: The rats were randomized into sham-operated (n = 16) and ischemia/reperfusion (n = 96) groups. There were 6 time points in the ischemia/reperfusion group, comprising 4, 6, 12, 24, 48, and 72 hours after reperfusion, with 16 rats for each time point. Rat models in the sham-operated group at 4 hours after surgery and rat models in the ischemia/reperfusion group at different time points were equally and randomly assigned into 4 different subgroups. MAIN OUTCOME MEASURES: Brain water content on the ischemic side and the control side was measured using the dry-wet weight method. Blood-brain barrier function was determined by Evans Blue. Aquaporin-4 expression surrounding the ischemic focus, as well as the correlation of aquaporin-4 expression with brain water content and Evans blue staining, were measured using immunohistochemistry and Western blot analysis. RESULTS: Brain water content on the ischemic side significantly increased at 12 hours after reperfusion, reached a peak at 48 hours, and was still high at 72 hours. Brain water content was greater on the ischemic hemispheres, compared with the control hemispheres at 6, 12, 24, 48, and 72 hours after reperfusion, as well as both hemispheres in the sham-operated group (P<0.05). Evans blue content significantly increased on the ischemic side at 4 hours after ischemi',dreperfusion, and reached a peak at 48 hours. Evans blue content was greater on the ischemic hemispheres, compared with the control hemispheres at various time points, as well as both hemispheres in the sham-operated group (P<0.05). Aquaporin-4-positive cells were detected in the cortex and hippocampus, surrounding the ischemic penumbra focus, at 4-6 hours after ischemia/reperfusion. The number of positive cells significantly increased at 12 hours and reached a peak at 48-72 hours. Aquaporin-4 was, however, weakly expressed in the control hemispheres and the sham-operated group. The absorbance ratio of aquaporin-4 to β-actin was greater at 12, 24, 48, and 72 hours following cerebral ischemia/reperfusion, compared with the sham-operated group (P<0.05). Aquaporin-4 expression positively correlated to brain water content and Evans blue staining following cerebral ischemia/reperfusion (r1 = 0.68, r2= 0.81, P<0.05). CONCLUSION: Aquaporin-4 is highly expressed in brain tissues, participates in the occurrence of ischemic brain edema, and is positively correlated to blood-brain barrier permeability following cerebral ischemia/reperfusion.     

Brain edema and cerebrovascular permeability during cerebral ischemia in rats.

Focal cerebral ischemia was produced by occluding the left middle cerebral artery in 769 rats. Permeability of the blood-brain barrier to small or large molecules was evaluated qualitatively using Evans blue or sodium fluorescein and quantitatively using the transfer indexes of iodine-125-labeled bovine serum albumin or [14C]sucrose. Water content was determined using wet and dry weights and sodium and potassium contents using flame photometry. Cortical tissue in the middle cerebral artery territory was sampled less than or equal to 14 days after occlusion. A significant increase in the albumin transfer index was first found 12 hours after occlusion, and the index remained approximately the same until water content peaked 3 days after occlusion. In contrast, the sucrose transfer index increased gradually, significantly correlated with increases in the water and sodium contents. Tissue staining by sodium fluorescein was more extensive than that by Evans blue. As edema fluid decreased gradually 4-10 days after occlusion, the albumin and sucrose transfer indexes increased markedly. These findings indicate that disruption of the blood-brain barrier to small molecules is accompanied by accumulation of edema fluid during the later stages of ischemia. Opening of the barrier to serum protein is probably related to the resolution of edema.     

两次线栓法构建脑缺血耐受模型大鼠血脑屏障通透性改变与基质金属蛋白酶9的表达☆

背景：诸多研究证实,短暂性脑缺血预处理可诱导脑缺血耐受。然而,脑缺血耐受的内源性保护机制尚未明确。 目的：观察脑缺血预处理诱导脑缺血耐受大鼠再灌注不同时间窗血脑屏障通透性改变及基质金属蛋白酶9表达的变化。 方法：将Wistar大鼠随机分为3组,缺血预处理组采用线栓法阻塞大脑中动脉10 min建立局灶性缺血预处理模型,分别在缺血预处理后1,3,7,14,21 d进行再次缺血2 h;模型组不进行缺血预处理,假手术组不阻塞血管。于再灌注22 h进行神经功能检测,采用TTC染色测定脑梗死体积,通过测定渗出血管外的伊文思蓝含量来评价血脑屏障通透性的变化,免疫组织化学和原位杂交法检测基质金属蛋白酶9蛋白及mRNA的表达。 结果与结论：与模型组比较,缺血预处理组1,3,7 d亚组的神经功能评分、脑梗死体积、血脑屏障通透性、脑含水量以及基质金属蛋白酶9蛋白和mRNA表达均明显减小/降低(P < 0.05或P < 0.01),其中以3 d亚组降低最为明显。提示缺血预处理诱导了脑缺血耐受,预缺血诱导的血脑屏障通透性改变以及基质金属蛋白酶9表达减低在脑缺血耐受中发挥重要作用。