大鼠局灶性脑缺血再灌注损伤模型

大鼠局灶性脑缺血再灌注损伤模型...     

TRPV4通道在大鼠局灶性脑缺血再灌注损伤中的作用

目的建立大鼠脑缺血再灌注损伤模型,探讨TRPV4通道在脑缺血再灌注损伤中的作用和可能机制。方法制备大鼠局灶性脑缺血再灌注损伤模型;检测脑缺血再灌注后0h、6h、12h、24、48h、72h、96h、7d的血脑屏障(BBB)通透性变化;给予TRPV4抑制剂HC067047或生理盐水进行处理,检测脑缺血再灌注后6h、72h、7d的BBB通透性变化,Western bolt检测脑缺血组织中MMP-9的表达水平。结果大鼠局灶性脑缺血再灌注后,BBB通透性明显增加,于72h达峰值。脑缺血再灌注6h,72h,7d分别给予TRPV4抑制剂HC067047后,其BBB通透性较相同时间点的生理盐水处理组明显降低;同时脑缺血再灌注6h,72h,7d分别给予HC067047后,其MMP-9的表达较相同时间点的生理盐水处理组明显减少。结论抑制TRPV4通道可以减轻脑缺血再灌注诱发的BBB开放,其机制可能与减少MMP-9的表达相关。     

阿托伐他汀对脑缺血再灌注大鼠血脑屏障的保护作用

目的:研究在脑缺血再灌注(ischemia-reperfusion,IR)损伤中阿托伐他汀对血脑屏障的保护作用及相关机制。方法:SD大鼠72只随机分为3组:假手术组、IR组和阿托伐他汀组。阿托伐他汀组大鼠术后予以阿托伐他汀(20 mg·kg-1·d-1)灌胃治疗,每天1次,连续3 d。利用线栓法制作脑IR模型,缺血2 h后再灌注72 h,对各组大鼠的神经功能进行评分,并检测梗死侧大脑半球脑组织含水量、伊文思蓝(Evans blue,EB)渗出量、紧密连接相关蛋白occludin和炎症因子磷脂酰肌醇3-激酶p110γ(PI3K-p110γ)的表达水平。结果:与假手术组相比,IR组大鼠脑组织含水量、EB的渗出量及神经功能评分均增加(P0.01),同时occludin表达下降(P0.01),PI3Kp110γ表达增加(P0.01);而阿托伐他汀治疗组大鼠脑水肿程度减轻(P0.01),EB渗出量减少(P0.01),occludin表达增加(P0.01),PI3K-p110γ表达减少(P0.01),神经功能评分下降,但差异无统计学意义(P0.05)。结论:阿托伐他汀可以减轻脑IR损伤,可能与抑制炎症反应、增加紧密连接蛋白表达从而维持血脑屏障稳定性有关。     

大鼠局灶性脑缺血再灌注后皮质神经元微血管构筑和血脑屏障的变化及丁苯酞的保护作用

目的:观察大鼠脑缺血再灌注损伤后皮质微血管的变化,探讨丁苯酞对其作用。方法:线栓法制备大鼠脑缺血再灌注模型;单宁酸-氯化铁媒染法显示大脑皮质微血管,Mivnt图像分析系统定量分析微血管密度(MVD)和微血管面积密度(MVA);十湿重法检测脑含水量,透射电镜观察血脑屏障超微结构。结果:与假手术组相比,缺血再灌注组大鼠皮质微血管绝大部分闭合或僵直,MVD和MVA显著下降,脑含水量明显升高,电镜观察微血管腔狭窄,内皮细胞核固缩。丁苯酞组微血管形态好转,MVD和MVA升高,脑水肿和血脑屏障损伤程度均减轻。结论:丁苯酞可改善大鼠脑皮质微血管形态,减轻脑水肿和血脑屏障损伤,对脑缺血再灌注损伤有一定的预防性保护作用。     

胸腺素β4对局灶性大鼠脑缺血再灌注损伤的保护作用

目的研究胸腺素β4对大鼠局灶性脑缺血再灌注损伤的保护作用,并探讨其作用机制。方法线栓法制作大鼠大脑中动脉缺血再灌注模型。于缺血再灌注前30min给予胸腺素β4,缺血再灌注24h后进行神经功能评分,测定脑含水量、梗死面积、脑组织匀浆Caspase-3活性。结果胸腺素β4能显著降低神经功能评分,降低脑组织含水量,缩小脑梗死面积,降低缺血脑组织Caspase-3活性。结论胸腺素β4对于大鼠脑缺血再灌注损伤具有保护作用,其作用机制可能与抑制Caspase-3活性有关。     

DDR1蛋白在大鼠脑缺血再灌注损伤引起血脑屏障破坏中的作用及机制

目的:探讨盘状结构域受体酪氨酸激酶(discoidin domain recetor 1,DDR1)蛋白在局灶性脑缺血致血脑屏障损伤中的作用机制及其病理性意义。方法:成年雄性SD大鼠80只,体重280³20 g,采用随机数字表法,将其随机分为假手术组、缺血再灌注组、siRNA处理组和siRNA错配组,每组5只。采用大鼠大脑中动脉线栓法制备局灶性脑缺血再灌注模型,缺血120 min再灌注24 h时进行神经行为学评分,随后处死大鼠取脑,分别采用TTC(2,3,5-triphenyl tetrazolium chloride)染色法、干湿比重法、伊文思蓝法测定脑梗死体积、脑组织含水量及血脑屏障的通透性。结果:与假手术组比较,脑缺血再灌注组神经行为学评分降低(P<0.05),脑梗死体积百分比增加,缺血侧脑组织含水量增多(P<0.05),血脑屏障的通透性增大(P<0.01);与局灶性脑缺血再灌注组比较,DDR1-siRNA处理组神经行为学评分升高,脑梗死体积百分比减少,脑组织含水量减少(P<0.05),血脑屏障通透性降低(P<0.01)。结论:DDR1蛋白可能参与了脑缺血再灌注损伤后血脑屏障的破坏,抑制DDR1的表达可降低血脑屏障的通透性;另外,检测DDR1的表达可作为脑卒中早期诊断和判断预后的分子指标之一。     

局灶性脑缺血再灌注大鼠 Nogo-AmRNA的表达

为观察 Nogo-A m RNA在脑缺血再灌注后的动态变化 ,探索其在大脑皮质及纹状体神经元表达的意义及作用 ,应用原位杂交方法在大鼠局灶性大脑中动脉阻塞动物模型上观察脑缺血再灌注时大鼠 Nogo-A m RNA的表达。结果显示 :脑缺血再灌注大鼠缺血侧大脑皮质 Nogo-A m RNA的表达与假手术组比较明显增加 ,在 12 h内达高峰 (P<0 .0 1) ,2 4h时下降 ,48h时又升高 ,出现第二个高峰 ,然后逐渐降低 ,7～ 14 d降至基础水平 ;大脑纹状体脑缺血 1h后再灌流 ,2 h时 Nogo-A m RNA的表达明显增加 ,之后逐渐下降 ,到 2 4h时接近基础水平 ,48h时又升高 ,以后表达水平下降 ,3～ 14 d时 ,接近基础水平。结果提示 ,脑缺血后内源性 Nogo-A m RNA的表达呈动态性变化 ,参与了脑缺血后神经元的再生过程的调节。     

GFAP与局灶性脑缺血(FCI)再灌注

脑血管疾病是一组严重害人类健康的疾病 ,目前已成为人类致残和死亡的重要原因之一。脑缺血再灌注损伤是脑缺血疾病临床治疗中的关键问题。星形胶质细胞 (AST)约占正常成人中枢神经系统细胞总数的 40 % ,对神经元有支持、保护、营养、修复作用 ,另外 ,AST在保持中枢神经系统离子浓度和pH值稳定 ,调节脑内葡萄糖水平中起着重要的作用 ;同时AST上还存在高亲和力谷氨酸转运体 ,能逆浓度摄取释放至细胞外液的谷氨酸 ,对维持细胞外液谷氨酸正常浓度也起着重要的作用[1 ] 。研究不同损伤条件下AST在时间、空间、形态 ,数目 ,功能状态等方面…     

甲磺酸加贝酯对脑缺血再灌注大鼠血脑屏障保护作用的研究

目的:研究甲磺酸加贝酯(GM)对脑缺血再灌注(I/R)大鼠模型血脑屏障(BBB)的保护作用,并初探其机制。方法:取180只成年雄性SD大鼠随机分为假手术组(sham组)、模型组(I/R组)、尼莫地平(NMP;2 mg·kg^-1·d^-1)组和GM(5、10和20 mg·kg^-1·d^-1)组,每组30只。采用线栓阻断大脑中动脉2 h的方法制备脑I/R大鼠模型,造模前10 min腹腔注射液给药。采用Longa评分法检测大鼠神经功能,伊文思蓝渗透法测定BBB通透性,干湿重法计算脑组织含水量,生化分析法测定超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性及丙二醛(MDA)含量,ELISA法测定肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)和IL-6的含量,RT-PCR法检测基质金属蛋白酶2(MMP-2)、MMP-9和核因子κB(NF-κB)的m RNA表达,Western blot法检测MMP-2、MMP-9和NF-κB蛋白表达。结果:与I/R组比较,经GM(10和20 mg·kg...     

抑制TRPV4通道减轻大鼠局灶性脑缺血再灌注损伤

目的建立大鼠脑缺血再灌注损伤模型,探讨应用瞬时受体电位通道香草酸亚型4(TRPV4通道)抑制剂是否能够减轻脑缺血再灌注损伤诱导的血脑屏障(blood brain barrier, BBB)开放和可能机制。方法制备大鼠局灶性脑缺血再灌注损伤模型;给予TRPV4抑制剂HC067047进行处理,Evans blue检测脑缺血再灌注后BBB通透性变化,Western bolt检测脑缺血组织中caveolin-1的表达水平。结果大鼠局灶性脑缺血再灌注后,BBB通透性和脑缺血组织中caveolin-1的表达水平明显增加,给予TRPV4抑制剂HC067047后,其BBB通透性和caveolin-1的表达水平明显减少。结论 TRPV4通道抑制减轻脑缺血再灌注诱发的BBB开放,与减少caveolin-1的表达水平相关。     

5-LO通路活化对大鼠脑缺血再灌注损伤致血脑屏障破坏的影响

为了研究大鼠局灶性脑缺血再灌注损伤(CIRI)后血脑屏障(BBB)通透性的改变,观察5-脂氧酶(5-LO)、白三烯(LTs)、核因子-κB(NF-κB)、基质金属蛋白酶-9(MMP-9)的表达变化,探讨5-LO通路活化参与BBB破坏的可能机制,本实验采用线栓法制备大鼠大脑中动脉闭塞2h/再灌注24h模型。伊文氏蓝示踪剂检测BBB的通透性;RT-PCR检测损伤侧脑组织5-LO mRNA、半胱氨酰白三烯受体1(CysLTR1)mRNA的表达;ELISA检测血清LTB4的含量;免疫组织化学法检测损伤侧脑组织5-LO、NF-κB、MMP-9蛋白的表达情况。结果显示:局灶性脑缺血2h/再灌注24h后,大鼠BBB的通透性明显增高,5-LO mRNA、CysLTR1 mRNA的表达以及血清LTB4的含量均增高;5-LO、NF-κB、MMP-9蛋白在脑组织内的表达亦显著增多。本研究结果提示,CIRI后5-LO通路活化可经CysLTR1、LTB4、NF-κB、MMP-9介导BBB破坏,继而引发级联反应,加重脑损伤。     

大豆异黄酮对局灶性脑缺血再灌注损伤大鼠血脑屏障通透性的影响及其机制

目的 探讨大豆异黄酮(SI)对局灶性脑缺血再灌注大鼠的血脑屏障(BBB)通透性的影响及相关机制。方法 72只健康成年SD大鼠均分为假手术组(Sham组)、缺血再灌注组(I/R组)和SI预处理组(SI组),每组各24只。SI组每天按120 mg/kg体质量给予12 mg/mL SI灌胃1次,Sham组和I/R组每天用等体积生理盐水灌胃1次,均连续灌胃21 d。在实验第22天,I/R组和SI组大鼠用线栓阻断右侧大脑中动脉血流制作大脑中动脉缺血再灌注动物模型;Sham组不插入线栓,未阻断血流,其余手术操作与I/R和SI组一致。I/R组和SI组大鼠缺血2 h后,拔出阻塞的线栓恢复血流,再灌注24 h。根据Zea longa评分,选择造模成功的大鼠。采用2,3,5-氯化三苯基四氮唑(TTC)检测大鼠脑梗死体积,干湿重法检测脑组织含水量,伊文思蓝(EB)示踪法检测BBB通透性,Western blot检测脑组织MMP-9、TIMP-1蛋白表达。比较三组大鼠的测量数据,分析SI预处理对以上观测指标的影响。结果 SI组和I/R组大鼠的神经功能评分、脑梗死体积、脑组织含水量和脑组织内EB含量均高于Sham组,而SI组低于I/R组,分别为(1.50±1.13)、(2.33±0.82)和(0.00±0.00)分,12.5%±2.34%、37.50%±2.28%和0.07%±0.03%,81.75%±0.86%、84.17%±0.54%和78.24%±0.41%,(46.50±1.41)、(55.44±1.37)和(3.83±1.49)μg/g,差异均有统计学意义(P值均＜0.01)。SI组和I/R组MMP-9、TIMP-1表达均明显高于Sham组,分别为0.81±0.23、1.15±0.14、1.15±0.14和2.31±0.20、1.62±0.21、1.62±0.21,差异均有统计学意义(P值均<0.01);与I/R组相比,SI组MMP-9表达减少、TIMP-1表达增加,差异均有统计学意义(P值均＜0.01)。结论 SI可能通过下调缺血再灌注后脑组织MMP-9蛋白表达和上调TIMP-1蛋白表达,降低BBB的通透性,减轻缺血再灌注后脑水肿的程度和脑组织EB的含量。     

Effects of endothelin-1 on blood-brain barrier permeability during focal cerebral ischemia in rats

The purpose of this study was to determine whether the transport of small hydrophilic molecules across the blood-brain barrier (BBB) during focal cerebral ischemia could be altered by a topical application of endothelin-1 (ET-1) in the ischemic cortex (IC). Forty minutes after middle cerebral artery (MCA) occlusion, patches of 10 nM ET-1 (low-endothelin group), 100 nM ET-1 (high-endothelin group), or normal saline (control group) were placed on the IC of rats for a 20-min period. One hour after MCA occlusion, transfer coefficient (Ki) of [14C-alpha-]aminoisobutyric acid (14C-AIB) or regional cerebral blood flow (rCBF) was determined. Vital signs were not significantly different among the experimental groups. In the control group (n=8), the Ki of the IC was significantly higher than that of the contralateral cortex (CC; 11.9+/-5.8 vs 5.0+/-1.9 microl/g per minute). In the low-endothelin group (n=8), the Ki of the IC was still significantly higher than that of the CC (9.4+/-5.2 vs 5.3+/-2.5 microl/g per minute). However, in the High-endothelin group (n=8), the Ki of the IC was not different from that of the CC (6.9+/-2.1 vs 5.6+/-2.3 microl/g per minute) and 42% lower than that of the control group. The rCBF was not affected by 100 nM of ET-1 [control (n=6): IC 53+/-18 ml/100 g per minute, CC 94+/-23 ml/100 g per minute; high-endothelin (n=6): IC 49+/-15 ml/100 g per minute, CC 98+/-24 ml/100 g per minute]. Our data suggest that the application of endothelin-1 in the IC could reduce the transfer coefficient of small hydrophilic molecules across the BBB during focal ischemia.     

Effects of zileuton,a new 5-lipoxygenase inhibitor,in experimentally induced colitis in rats

Intravenous injection of platelet-activating factor (PAF) (0.36 mol/kg b.w.) in mice induced severe hemoconcentration, leucopenia, thrombocytopenia and finally the death of 85% of the tested animals. Combined inhibition of histamine and serotonin by promethazine and chlorpromazine, 6.24 and 3.12 mg/kg b.w. subcutaneously, protected the mice from PAF in part, reducing the death rate to 43%. These drugs did not protect the mice against the PAF-induced hemoconcentration, leucopenia and thrombocytopenia. Sulfinpyrazone (100 mg/kg b.w.) intravenously was the most effective both in protecting mice from PAF-induced death, reducing the death rate to 17%, and from thrombocytopenia, although hemoconcentration persisted. These results indicated that an important component of the PAF-induced systemic effects is mediated by reactions which can be inhibited by sulfinpyrazone. Furthermore, PAF-induced thrombocytopenia is not a direct PAF effect since it can be inhibited by sulfinpyrazone.     

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。     

Reduction of the multiple organ injury and dysfunction caused by endotoxemia in 5-lipoxygenase knockout mice and by the 5-lipoxygenase inhibitor zileuton

The role of 5-lipoxygenase (5-LOX) in the pathophysiology of the organ injury/dysfunction caused by endotoxin is not known. Here, we investigate the effects of treatment with 5-LOX inhibitor zileuton in rats and targeted disruption of the 5-LOX gene in mice (5-LOX(-/-)) on multiple organ injury/dysfunction caused by severe endotoxemia. We also investigate the expression of beta2-integrins CD11a/CD18 and CD11b/CD18 on rat leukocytes by flow cytometry. Zileuton [3 mg/kg intravenously (i.v.)] or vehicle (10% dimethyl sulfoxide) was administered to rats 15 min prior to lipopolysaccharide (LPS; Escherichia coli, 6 mg/kg i.v.) or vehicle (saline). 5-LOX(-/-) mice and wild-type littermate controls were treated with LPS (E. coli, 20 mg/kg intraperitoneally) or vehicle (saline). Endotoxemia for 6 h in rats or 16 h in mice resulted in liver injury/dysfunction (increase in the serum levels of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, bilirubin), renal dysfunction (creatinine), and pancreatic injury (lipase, amylase). Absence of functional 5-LOX (zileuton treatment or targeted disruption of the 5-LOX gene) reduced the multiple organ injury/dysfunction caused by endotoxemia. Polymorphonuclear leukocyte infiltration (myeloperoxidase activity) in the lung and ileum as well as pulmonary injury (histology) were markedly reduced in 5-LOX(-/-) mice. Zileuton also reduced the LPS-induced expression of CD11b/CD18 on rat leukocytes. We propose that endogenous 5-LOX metabolites enhance the degree of multiple organ injury/dysfunction caused by severe endotoxemia by promoting the expression of the adhesion molecule CD11b/CD18 and that inhibitors of 5-LOX may be useful in the therapy of the organ injury/dysfunction associated with endotoxic shock.     

全反式维甲酸通过作用于JNK/P38 MAPK信号通路减轻大鼠脑缺血再灌注引起的血脑屏障损伤

目的:观察全反式维甲酸(all-trans retinoic acid,ATRA)对脑缺血再灌注(cerebral ischemia-reperfusion,CIR)损伤大鼠血脑屏障的影响,并探讨其可能的作用机制。方法:将SD雄性大鼠随机分组为假手术(sham)组、模型(CIR)组及CIR+ATRA(10、30和90 mg/kg)组。采用MCAO线栓法建立大鼠CIR损伤模型,缺血1. 5 h,再灌注24 h后,进行神经功能行为学评分及脑梗死体积、脑含水量和伊文思蓝含量的测定;明胶酶谱法检测基质金属蛋白酶9(MMP-9)的活性; Western blot法检测脑组织中紧密连接蛋白(claudin-5、occludin和ZO-1)、JNK、p-JNK、P38、p-P38和MMP-9的蛋白水平。结果:与CIR模型组相比,ATRA(30 mg/kg)可明显改善大鼠神经功能,减少脑梗死体积,降低脑含水量和伊文思蓝含量,降低缺血区紧密连接蛋白的降解(P 0. 01),降低缺血脑组织中MMP-9的活性及蛋白的表达(P 0. 01),抑制JNK/P38 MAPK通路中JNK和P38的磷酸化并减少p-JNK和p-P38的蛋白水平(P 0. 01)。结论:ATRA能够减轻CIR对大鼠脑组织的损伤和血脑屏障的破坏,其保护作用可能与抑制JNK/P38 MAPK信号通路和MMP-9的激活有关。     

颈淋巴阻滞对大鼠血脑屏障通透性的影响

目的: 探讨大鼠颈淋巴阻滞后血脑屏障(BBB)通透性的变化。方法: 手术组大鼠采用Casley-Smith法阻滞颈淋巴,对照组大鼠不摘除颈淋巴结和不结扎淋巴管,只将它们分离暴露。每组于术后1、3、5、7、14、21 d,通过观察血清中S-100B的浓度、电镜观察镧离子示踪剂和BBB超微结构变化来确定BBB通透性的改变。结果: 各组血清中S100B浓度变化无显著差异,提示BBB没有破坏;电镜观察:对照组与手术组的超微结构变化相同,各组术后各时点血管腔外没有发现镧离子。结论: 颈淋巴阻滞对BBB通透性没有显著影响。     

The effect of a selective 5-lipoxygenase inhibitor,zileuton, on tissue damage in acute colonic inflammation in rats

Though the mechanism of tissue damage induced by colonic inflammation in ulcerative colitis is unknown, it has been established that the inflammatory mediator and potent neutrophil (PMN) chemotaxin, leukotriene B4(LTB₄), is present in elevated amounts in the inflamed mucosa. The unique role of 5-lipoxygenase in the production of leukotrienes has made it a target for inhibition. This study used a rat model of acute colonic inflammation induced by a single IP injection of Mitomycin-C to test the efficacy of a specific and potent 5-lipoxygenase inhibitor zileuton in the treatment of colonic inflammation. We hypothesized that after inducing colitis in rats with mitomycin-C, the administration of oral zileuton would inhibit leukotriene production, thus preventing PMN infiltration and subsequent tissue damage. Zileuton decreased colonic tissue damage as measured by Histological score. However, zileuton did not significantly decrease neutrophil infiltration measured by mucosal PMN or myeloperoxidase (MPO) levels. Although zileuton was successful in significantly decreasing the frequency of severe colitis in our model, the fact that the decrease in PMN count and MPO level was not statistically significant suggests that another mechanism may be involved in its anti-inflammatory effect.