血脑屏障氧糖剥夺体外模型中缺氧诱导因子-1α的表达及血脑屏障通透性的变化

目的研究血脑屏障氧糖剥夺体外模型中缺氧诱导因子-1α和紧密连接相关蛋白claudin-5的表达及血脑屏障通透性变化。方法提取纯化大鼠脑微血管内皮细胞,建立血脑屏障氧糖剥夺模型,模拟在体缺血,在氧糖剥夺不同时间点(0、30、60、120、240min),应用EVOM测定仪测定培养的脑微血管跨内皮细胞内皮阻抗值,分析血脑屏障的通透性;应用辣根过氧化物酶渗漏实验分析血脑屏障的通透性;应用Westernblot法分析大鼠脑微血管内皮细胞的缺氧诱导因子-1α和紧密连接相关蛋白claudin-5的表达。结果与正常对照组相比,氧糖剥夺30min,缺氧诱导因子-1α表达增加,辣根过氧化物酶流量升高;氧糖剥夺60min达峰值;氧糖剥夺120min、240min,逐渐降低,但仍高于正常对照组。氧糖剥夺30min,跨内皮阻抗值降低,claudin-5表达减少,在60min最低;120min、240min表达逐渐升高,但仍低于正常对照组。结论氧糖剥夺30min至240min,缺氧诱导因子-1α和claudin-5表达及血脑屏障通透性改变明显,氧糖剥夺60min达峰值。     

大鼠脑缺血时紧密连接相关蛋白occludin和claudin-5表达的变化

目的研究脑缺血后血脑屏障通透性和紧密连接相关蛋白occludin和claudin-5的变化。方法线栓法制备大鼠大脑中动脉缺血模型,采用伊文氏兰(EB)法检测缺血后血脑屏障通透性的变化。应用免疫组织化学的方法观察occludin和claudin-5在缺血脑组织中的分布,采用RT-PCR、Wesrern blot法检测大鼠缺血脑组织occludin和claudin-5的mRNA和蛋白的表达变化。结果脑缺血2h后血脑屏障通透性显著增加(P0.01),紧密连接相关蛋白occludin和claudin-5在脑微血管内皮细胞上呈阳性表达,occludin和claudin-5的mRNA和蛋白均比正常对照组显著降低(P0.01)。结论脑缺血时血脑屏障通透性的增加可能与紧密连接相关蛋白occludin和claudin-5的降低相关。     

绿茶多酚对脑缺血大鼠血脑屏障通透性的影响

目的探讨绿茶多酚对局灶性脑缺血大鼠血脑屏障的通透性及紧密连接蛋白occludin、claudin-5和蛋白激酶PKCα表达的影响。方法采用线栓法制作大鼠局灶性脑缺血模型,伊文思蓝法检测血脑屏障通透性的变化,免疫组化方法检测缺血脑组织occludin、claudin-5的表达,western blot方法检测脑缺血组织PKCα蛋白的表达。结果大鼠局灶性脑缺血60min、120min的脑组织血脑屏障通透性显著增加,同时点的脑组织BBB紧密连接开放;而绿茶多酚显著降低血脑屏障的通透性(P0.01),使BBB紧密连接处于关闭状态。大鼠局灶性脑缺血60min及120min脑组织紧密连接相关蛋白occludin、claudin-5的蛋白表达水平显著降低,绿茶多酚显著上调这些蛋白表达水平(P0.01)。大鼠局灶性脑缺血30min至120min脑组织中PKCα的蛋白表达水平显著升高,绿茶多酚显著降低PKCα蛋白的表达水平(P0.01)。结论绿茶多酚降低缺血大鼠脑组织血脑屏障通透性可能与上调紧密连接蛋白occludin、claudin-5的表达及下调蛋白激酶PKCα的表达有关。     

表皮生长因子受体抑制剂AG1478联合Endophilin-1过表达增加血脑屏障通透性

目的研究表皮生长因子受体(EGFR)抑制剂AG1478联合Endophilin-1基因过表达对血脑屏障(BBB)通透性的影响。方法建立了体外BBB模型,实验分为四组:对照组,AG1478组,endophilin-1基因过表达(p IRES2-endophilin-1)转染组;AG1478+p IRES2-endophilin-1转染组。采用跨内皮阻抗值测定和辣根过氧化物酶渗透试验评估血脑屏障通透性变化,Western blot和免疫荧光法检测脑微血管内皮细胞中紧密连接相关蛋白ZO-1和occludin的表达和分布变化。结果与单独应用AG1478或p IRES2-endophilin-1组相比,AG1478+p IRES2-endophilin-1转染组体外血脑屏障模型跨内皮电阻值显著降低,辣根过氧化物酶透过率显著增高(0.01),脑微血管内皮细胞中紧密连接相关蛋白ZO-1和occludin的表达水平显著降低(0.05)。结论 EGFR抑制剂AG1478联合endophilin-1基因过表达增加BBB通透性可能与开放紧密连接相关。     

RNA干扰沉默神经轴突导向因子受体4基因增加血肿瘤屏障通透性

目的研究神经轴突导向因子受体(Robo4)对血肿瘤屏障(BTB)通透性的影响。方法建立了体外BTB模型,应用Real-time PCR和Western blot检测Robo4在正常人脑微血管内皮细胞和胶质瘤微血管内皮细胞中的表达变化。设计合成针对Robo4基因的小干扰RNA,转染至人脑微血管内皮h CMEC/D3细胞,下调体外血肿瘤屏障模型内皮细胞中Robo4的表达,跨内皮电阻测量系统和辣根过氧化物酶渗透试验分析血肿瘤屏障通透性变化;Western blot和免疫荧光法检测h CMEC/D3细胞中紧密连接相关蛋白occludin和ZO-1的表达和分布变化。结果和正常人脑微血管内皮细胞相比,Robo4在胶质瘤微血管内皮细胞中的表达显著上调。下调体外血肿瘤屏障模型内皮细胞Robo4的表达后,TEER值显著降低,辣根过氧化物酶透过率显著增高;同时胶质瘤微血管内皮细胞中紧密连接相关蛋白occludin和ZO-1的表达显著降低,在细胞膜上呈不连续分布。结论 RNA干扰沉默Robo4表达能够显著降低紧密连接相关蛋白occludin和ZO-1的表达,增加BTB通透性。     

ROCK介导缓激肽开放SD大鼠血肿瘤屏障

目的利用ROCK的特异性抑制剂Y-27632,研究ROCK是否介导缓激肽开放血肿瘤屏障。方法应用ROCK的特异性抑制剂Y-27632预处理大鼠原代脑微血管内皮细胞后,用缓激肽诱导血肿瘤屏障开放,测量跨内皮阻抗值(TEER),辣根过氧化物酶(HRP)渗漏量,分析血肿瘤屏障的通透性的改变;应用Western-blot法检测紧密连接相关蛋白ZO-1的表达;应用免疫荧光方法观察原代大鼠脑微血管内皮细胞紧密连接相关蛋白ZO-1和丝状肌动蛋白结构和分布的改变。结果 Y-27632显著抑制缓激肽诱导TEER值的降低,HRP的升高;Y-27632显著抑制ZO-1的表达;Y-27632抑制ZO-1由内皮细胞的边缘向细胞质转移,抑制丝状肌动蛋白由细胞膜边缘向细胞中央区分布,应力纤维形成明显减少。结论 ROCK介导缓激肽开放血肿瘤屏障。     

全反式维甲酸对大鼠脑缺血再灌注后血脑屏障通透性和claudin-5表达的影响

目的探讨全反式维甲酸(ATRA)对大鼠脑缺血再灌注后血脑屏障通透性和紧密连接蛋白claudin-5的影响。方法选取180只健康雄性大鼠,随机分为假手术组(Sham,60只),缺血再灌注组(I/R,60只)和全反式维甲酸干预组(ATRA,60只),每组又细分为1d、3d和7d三个亚组。采用Zea Longa法制作局灶性脑缺血再灌注模型,伊文思蓝渗透性实验检测血脑屏障通透性变化,免疫组织化学方法和Western blot方法检测各组大鼠脑组织claudin-5蛋白的表达,Real-time PCR方法检测各组大鼠脑组织claudin-5 m RNA的表达。结果缺血再灌注后,EB含量在1d时最高,3d时开始逐渐下降,而与相同时间点的I/R组相比,ATRA组EB含量显著降低(P0.01)。与Sham组相比,I/R组大鼠脑组织claudin-5蛋白及m RNA的表达水平均显著降低,而与相同时间点的I/R组相比,ATRA组则显著升高(P0.01)。结论全反式维甲酸降低大鼠脑缺血再灌注后血脑屏障通透性可能与上调脑缺血再灌注后脑组织中claudin-5的表达相关。     

siRNA-Tie1下调紧密连接相关蛋白claudin-5、occludin和ZO-1增加血肿瘤屏障通透性

目的研究Tie1 AS和Tie1表达变化对血肿瘤屏障通透性的影响和相关机制。方法建立体外血脑屏障和血肿瘤屏障模型,Real-time PCR检测h CMEC/D3细胞中Tie1 AS和Tie1的表达水平。转染p IRES2-EGFPTie1 AS表达载体上调体外血肿瘤屏障模型h CMEC/D3细胞中Tie1 AS的表达,Western blot检测Tie1的表达变化。将si RNA-Tie1转染人h CMEC/D3细胞并建立体外血肿瘤屏障模型,跨内皮电阻测量系统分析血肿瘤屏障通透性变化;Western blot和免疫荧光法检测h CMEC/D3细胞中紧密连接相关蛋白claudin-5、occludin和ZO-1的表达和分布变化。结果和正常脑微血管内皮细胞相比,体外血肿瘤屏障模型h CMEC/D3细胞中Tie1的表达显著增加,而Tie1 AS的表达显著降低。上调体外血肿瘤屏障模型内皮细胞中Tie1 AS的表达水平,能够显著降低Tie1的表达。下调体外血肿瘤屏障模型内皮细胞中Tie1的表达后屏障通透性显著下降,伴有claudin-5、occludin和ZO-1的表达下调以及在细胞膜上呈不连续分布。结论体外血肿瘤屏障模型内皮细胞中低表达的Tie1 AS能够负性调控Tie1的表达,进而通过调节紧密连接相关蛋白的表达和分布影响屏障的通透性。     

过表达miR-34a增加血肿瘤屏障通透性机制的研究

目的探讨过表达miR-34a增加血肿瘤屏障通透性的机制。方法将miR-34a模拟物转染至培养的人脑微血管内皮细胞NKIM-6,采用实时荧光定量PCR方法检测miR-34a的表达。用miR-34a模拟物转染的NKIM-6细胞和U87胶质瘤细胞建立体外血肿瘤屏障模型,跨内皮电阻测量系统检测血肿瘤屏障跨内皮阻抗值的变化;western blot和免疫荧光法检测体外血肿瘤屏障NKIM-6细胞中,紧密连接相关蛋白ZO-1和claudin-5的表达。结果经miR-34a模拟物转染后,NKIM-6细胞中miR-34a的表达水平显著升高;血肿瘤屏障跨内皮阻抗值显著下降;体外血肿瘤屏障NKIM-6细胞中紧密连接相关蛋白ZO-1和claudin-5的表达水平分别显著降低,在细胞膜上呈不连续分布。结论过表达miR-34a显著增加血肿瘤屏障的通透性,其机制之一可能与降低紧密连接相关蛋白相关。     

缓激肽对脑胶质瘤大鼠紧密连接影响的形态学观察

目的研究缓激肽(BK)对脑胶质瘤大鼠血肿瘤屏障紧密连接的影响。方法采用伊文氏兰(EB)法检测缓激肽作用后血肿瘤屏障(BTB)通透性的变化;应用透射电镜(TEM)观察BK作用后内皮细胞间紧密连接的变化,同时应用硝酸镧[La(NO3)3]和辣根过氧化物酶(HRP)作示踪剂,检测缓激肽作用后,小分子和大分子示踪剂通过紧密连接的情况。结果缓激肽可使血肿瘤屏障对伊文氏兰的通透性增加,在15min时达到高峰,以后逐渐下降。透射电镜显示缓激肽作用15min时,肿瘤组织毛细血管内皮细胞间紧密连接的完整性明显破坏,缝隙指数显著增加,同时可见硝酸镧和辣根过氧化物酶在紧密连接处沉积。结论缓激肽能够通过开放紧密连接选择性增加血肿瘤屏障的通透性。     

沉默排斥性导向分子A对脑缺血再灌注损伤大鼠血脑屏障的保护作用

目的 观察沉默排斥性导向分子A（RGMa）对脑缺血再灌注损伤大鼠血脑屏障及紧密连接蛋白的影响。 方法 雄性成年 SD 大鼠立体定位侧脑室注射腺病毒后建立大脑中动脉闭塞(MCAO) /再灌注（I/R）模型。将成年雄性SD大鼠40只,分为空白对照组（sh-con）和RGMa干扰组（sh-RGMa）,分别在注射后1 d和3d观察腺病毒对RGMa的影响。将其余120只SD大鼠随机分为假手术组（sham）、缺血再灌注组（I/R）、空病毒组（I/R+sh-con）及病毒组（I/R+sh-RGMa）;I/R 72 h 后采用神经功能缺损评分评估各组大鼠神经功能恢复情况; 采用2,3,5-氯化三苯基四氮唑(TTC)染色测量脑梗死体积;采用静脉注射伊文思蓝观察血脑屏障通透性的改变;应用Western blotting和免疫组织化学染色检测RGMa的变化;应用Western blotting检测血脑屏障完整性相关紧密连接蛋白5（claudin-5）、基质金属蛋白酶9（MMP-9）和闭锁小带蛋白1（ZO-1）的表达。 结果 缺血再灌注后 72 h,I/R组较 sham 组神经功能评分降低,沉默RGMa能改善血脑屏障通透性,减少脑梗死体积;可下调MMP-9及上调claudin-5和ZO-1的表达。 结论 沉默RGMa对脑缺血再灌注损伤大鼠的血脑屏障有保护作用。     

Increased activity of Rho kinase contributes to hemoglobin-induced early disruption of the blood-brain barrier in vivo after the occurrence of intracerebral hemorrhage

This study is to examine whether the activation of Rho kinase (ROCK) accounts for hemoglobin (Hb)-induced disruption of blood-brain barrier (BBB) after the occurrence of intracerebral hemorrhage. A model of intracerebral injection of Hb was established in rats. Changes in the levels of mRNA of RhoA, ROCK2 and matrix metalloproteinase-9 (MMP-9) were measured using quantitative real-time polymerase chain reaction. Protein expression of RhoA, ROCK2, claudin-5 and MMP-9, as well as ROCK activity, were determined using Western blotting. Immunohistochemical assay was performed to visualize the expression of RhoA, ROCK2, claudin-5 and MMP-9 in endothelial cells. Hb injection produced a significant increase in BBB permeability and water content in the brain. Significant reduction of claudin-5 expression was detected by Western blotting and immunofluorescence in Hb group. The levels of RhoA and ROCK2 were significantly up-regulated from 6 h to 12 h after Hb injection and were concomitant with the increase in ROCK activity. Immunofluorescence double staining showed enhanced p-myosin light chain immunoreactivity but diminished claudin-5 staining in endothelial cells. Significant up-regulation of MMP-9 expression was detected after Hb injection, and statistical analyses further confirmed a positive correlation of MMP-9 expression with ROCK activity. The results showed that ROCK was activated in endothelial cells by Hb. This may account for the early disruption of the BBB via up-regulation of p-myosin light chain expression and aggravation of injuries to TJ proteins. The activation of ROCK may also increase MMP-9 expression, thereby leading to further BBB disruption.     

MMP-9促进间充质干细胞穿越血脑屏障的作用研究

目的 探讨基质金属蛋白酶-9（MMP-9）开放血脑屏障（BBB）,促进大鼠间充质干细胞（rMSCs）穿越BBB的作用.方法 构建体外BBB模型,运用Transwell细胞迁移率实验明确MMP-9对体外BBB模型的穿透效果.体内实验：4周龄SD大鼠随机分为假手术组、缺氧缺血性脑损伤（HIBD）组、MMP-9处理组及MMP-9抑制剂（TIMP-1）干预组;HE染色观察各实验组不同时间点（0.5、1、3、7、14d）的大脑皮质病理变化和检测其脑含水量,EB值法检测BBB通透性;同时采用Western Blot测定大鼠皮质中MMP-9蛋白表达和免疫组织化学法测定大脑皮质内5-溴-2-脱氧嘧啶（Brdu）标记rMSCs阳性细胞数量.结果 Transwell细胞迁移率实验显示,缺氧状态下各组穿过小室的rMSCs数量均明显高于常氧,差异有统计学意义（P＜0.01）;MMP-9处理组穿过小室的rMSCs数量明显高于阴性对照组和TIMP-1干预组,差异有统计学意义（P＜0.01）.体内实验结果表明：与HIBD组相比,MMP-9处理组脑含水量、BBB通透性增加程度均有所提高;TIMP-1干预组的相应指标均有所降低.大鼠皮质中MMP-9蛋白表达水平具有时间依赖性,MMP-9处理组1～3 d时含量达到最高,明显高于HIBD组和TIMP-1干预组,差异有统计学意义（P＜0.01,P＜0.05）,之后表达开始回落,但仍有稳定表达.MMP-9处理组穿越BBB的Brdu阳性细胞数比HIBD组多,差异有统计学意义（P＜0.01,P＜0.05）.结论 大鼠缺氧缺血后MMP-9表达升高,可介导开放BBB,促进rMSCs穿越BBB.     

雌激素对大鼠脑缺血再灌注后血脑屏障作用研究

目的观察雌激素对大鼠脑缺血再灌注后血脑屏障(blood-brain barrier,BBB)的通透性、Occludin表达的影响,探讨雌激素在脑缺血中的作用。方法随机将去势雌性大鼠分为假手术组、模型组、雌激素预处理组,选取缺血再灌后4 h,24 h,3 d3个时间点作为观察点,对各个时间点脑水肿情况、Occludin蛋白表达、血脑屏障通透性改变进行考察分析,并选取24 h和3 d作BBB超微结构电镜观察,脑水肿改变情况采用脑含水量百分数测定;蛋白质表达采用western blot方法;血脑屏障通透性改变采用伊文思蓝(EB)比色法。结果与假手术组比较,局灶性脑缺血再灌4 h模型组大鼠脑组织含水量及EB含量均增加(P0.05),随缺血再灌时间延长,脑组织含水量、脑组织EB含量持续增加,至24 h,达到高峰(P0.01),与同时间点模型组比较,各治疗组大鼠脑组织含水量、EB含量均有不同程度降低(P0.05或P0.01),以24 h组降低最为显著(P0.01)。电镜观察雌激素预处理组较模型组同时间点比较BBB TJ开放减轻,星形胶质细胞足突及毛细血管管周水肿较轻,以3 d组显著。Western blot检测Occludin蛋白表达,发现模型组4 h时Occludin蛋白表达较假手术组减弱,但无显著性差异(P0.05),24 h组Occludin蛋白表达较假手术组减弱,有显著性差异(P0.05),3 d组Occludin蛋白表达进一步减弱,有明显差异(P0.01),雌激素组4 h时Occludin蛋白表达较同时间点模型组比较无显著性差异(P0.05),雌激素24 h及3 d组Occludin蛋白表达较同时间点模型组比较均升高,有显著性差异(P0.05)。结论局灶性脑缺血大鼠动物血脑屏障超微结构可见紧密连接发生断裂,内皮细胞内小泡数量增加及星形胶质细胞足突肿胀,可能是大鼠局脑缺血时血管源性脑水肿的重要因素。大鼠局灶性脑缺血,随缺血再灌时间延长,紧密连接相关蛋白occludin的表达明显下降,提示occludin在调节紧密连接通透性变化的过程中有重要作用。雌激素上调紧密连接Occludin蛋白的表达,有可能是其维护血脑屏障完整性减轻脑水肿的机制之一。     

NLRP3通过下调claudin-1增加早期蛛网膜下腔出血大鼠血脑屏障通透性

目的:研究NLRP3炎性小体在大鼠蛛网膜下腔出血(SAH)早期脑损伤(EBI)过程中对血脑屏障(BBB)的影响。方法:36雄性SD大鼠分为假手术组(sham)、SAH组(SAH)和NLRP3抑制剂MCC950处理组(SAH+MCC950),利用注射自体血液的方法制备SAH大鼠模型,利用尾静脉注射给予SAH大鼠MCC950处理。利用改良神经功能缺损评测大鼠神经功能变化,利用伊文斯蓝渗透实验(EBP)检测BBB的完整性,利用Western Blot方法检测大鼠脑组织中NLRP3和claudin-1等分子的表达变化,利用酶联免疫吸附试验(ELISA)试剂盒检测脑组织中细胞因子肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β)的水平。结果:SAH组大鼠神经功能严重受损,血脑屏障完整性破坏,NLRP3表达增加,claudin-1的表达下降,SAH大鼠脑组织中TNF-α和IL-1β水平显著增加。给予MCC950处理的大鼠神经功能有了显著改善,血脑屏障完整性破坏程度减轻,NLRP3表达下降,claudin-1的表达部分恢复,TNF-α和IL-1β水平显著降低。结论:NLRP3通过下调claudin-1表达增加早期SAH大鼠BBB通透性,这一机制可能参与了SAH大鼠EBI的发生。     

A narrow time-window for access to the brain by exogenous protein after immunological targeting of a blood-brain barrier antigen

The endothelial barrier antigen (EBA) is a membrane protein expressed by endothelial cells of the rat blood-brain barrier (BBB). A previous short-term non-recovery study demonstrated that immunological targeting of EBA by intravenous administration of a monoclonal antibody (anti-EBA) led to acute opening of the BBB to exogenous and endogenous tracers. The aims of the present study were to determine whether opening of the BBB was reversible and compatible with survival, and whether a "therapeutic window" existed. A single intravenous injection of one of three doses (high, medium and low) of anti-EBA was used. Animals were allowed to survive for periods ranging from 17 min to 4 days. The tracer horseradish peroxidase (HRP) was administered intravenously 10 min before perfusion fixation, and its distribution was assessed in Vibratome sections of the brain and spinal cord. Leakage of HRP into the central nervous system was dose- and time-dependent. The medium dose produced incipient HRP leakage at 17 min and widespread pronounced leakage at 30 min. Progressive reduction in HRP permeability occurred from 45 min to 2 h, with barrier restoration by 3 h. At all subsequent time intervals (6 h-4 days) the BBB remained impermeable to HRP. The low and high doses produced less and greater HRP leakage, respectively, but restoration of the barrier still occurred at 3 h. The high dose, however, produced a number of deaths. Animals treated with an isotype control antibody showed no HRP leakage at comparable time intervals. The results indicated that (1) this model was compatible with survival, (2) opening of the BBB was monophasic and transient, occurring during a narrow "time-window", and (3) the barrier, once reconstituted, maintained its integrity.     

地塞米松对海人酸致（癇）大鼠脑P-糖蛋白表达的影响

目的：探讨地塞米松对海人酸致痫大鼠脑P-糖蛋白（P-gp）表达的影响.方法：将SD大鼠随机分为假手术组（Sham组,n=8）、癫痫组（EP组,n=12）、地塞米松干预癫痫组（DEX组,n=12）.后两组采用海马注射海人酸方法制作癫痫模型,DEX组癫痫造模前30 min给予腹腔注射地塞米松0.4 mg/kg.分别记录各组大鼠达到Ⅲ级和Ⅴ级发作时所需的时间（潜伏期）,初次至第6次≥Ⅳ级发作的间隔时间作为评价癫痫发作严重程度的指标;大鼠术后24 h处死,使用HE染色和免疫组织化学方法,比较各组海马CA3区、齿状回、杏仁核复合体区P-gp表达及脑损伤情况.结果：①Sham 组未见癫痫发作;DEX组与EP组达到Ⅲ级发作的潜伏期分别为（87.92±45.80）min和（67.50±22.91）min,达到Ⅴ级发作的潜伏期分别为（103.33±51.27 ）min和（75.60±22.10）min,差异均无统计学意义（P〉0.05）;与EP组相比,DEX组样发作严重程度降低（P=0.004）;②与EP组相比,DEX组于所观察的脑区损伤均减轻,以海马CA3区和杏仁核复合体区较为显著;③与Sham组比较,EP组各观察脑区P-gp表达均明显升高（P〈0.01）;与EP组相比,DEX组海马CA3区和杏仁核复合体区P-gp表达显著减少（P〈0.05）,而在齿状回表达量差异无统计学意义（P=0.078）.结论：地塞米松可降低海人酸致痫大鼠发作严重程度和脑损伤,抑制P-gp表达上调,其中以海马CA3区和杏仁核区较为显著.     

Activation of AMPK attenuates lipopolysaccharide-impaired integrity and function of blood–brain barrier in human brain microvascular endothelial cells

The blood–brain barrier (BBB), formed by specialized brain endothelial cells that are interconnected by tight junctions, strictly regulates paracellular permeability to maintain an optimal extracellular environment for brain homeostasis. Lipopolysaccharide (LPS) is known to alter the integrity of the BBB in sepsis, although the underlying mechanism remains unknown. The aim of this study was to elucidate the molecular mechanisms underlying the disruption of the BBB in LPS-induced sepsis and to determine whether the activation of AMP-activated protein kinase (AMPK) prevents LPS-induced BBB dysfunction. The exposure of human brain microvascular endothelial cells (HBMECs) to LPS (1 μg/ml) for 4 to 24 h a week dramatically increased the permeability of the BBB in parallel with the lowered expression levels of occludin and claudin-5, which are essential to maintain tight junctions in HBMECs. In addition, LPS significantly increased the reactive oxygen species (ROS) productions. All effects induced by LPS in HBVMCs were reversed by adenoviral overexpression of superoxide dismutase, inhibition of NAD(P)H oxidase by apocynin or gain-function of AMPK by adenoviral overexpression of constitutively active mutant (AMPK-CA) or by 5-amino-4-imidazole carboxamide riboside (AICAR). Finally, the upregulation of AMPK by either AMPK-CA or AICAR abolished the levels of LPS-enhanced NAD(P)H oxidase subunit protein expressions. We conclude that AMPK activation improves the integrity of the BBB disrupted by LPS through suppressing the induction of NAD(P)H oxidase-derived ROS in HBMECs.