阿司匹林对脑缺血炎症反应的抑制作用

目的探讨阿司匹林对脑缺血再灌注损伤炎症反应的影响及其机制.方法采用线栓法制备短暂性大脑中动脉缺血模型,用免疫组织化学染色观察脑组织中核转录因子-κB(NF-κB)活性、白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)的表达;HE染色观察中性粒细胞浸润.结果与对照组比较,小剂量阿司匹林组和大剂量阿司匹林组的NF-κB活性降低,以大剂量的阿司匹林作用更为明显;各阿司匹林组的IL-1β、TNF-α的表达明显降低,白细胞浸润明显减少.结论阿司匹林可抑制脑缺血再灌注损伤过程中的炎症反应;其机制可能与抑制NF-κB的激活和IL-1β、TNF-α表达有关.     

缺血性卒中与炎症反应

缺血性卒中存在着缺血性损伤和再灌流损伤,再灌流损伤的机制与缺血性卒中炎症反应有密切的关系。缺血性卒中的炎症反应是由多种细胞因子介导的链锁过程。阻止各种细胞因子的作用,干扰这一链锁的某些环节有可能成为缺血性卒中的有效治疗方法之一。     

活血化瘀汤对大鼠脑缺血-再灌注后免疫炎症反应的影响

目的 探讨活血化瘀汤对大鼠局灶脑缺血-再灌注免疫炎症反应的影响。方法 采用线栓法制备大鼠大脑中动脉阻塞(MCAO)模型。灌药组分别于术前胃灌注红花、桃仁、川芎、赤芍组成的活血化瘀汤,再灌注24 h后测定大鼠神经功能缺损程度;检测脑勺浆、血清C反应蛋白、补体、免疫球蛋白IgG及其病理电镜检查,并与对照组比较。结果 灌药组大鼠神经功能缺损程度较对照组轻(P<0.05);灌药组血清免疫球蛋白IgG,脑匀浆、血清C反应蛋白、补体比对照组低(P<0.05);病理损伤较对照组轻。高剂量灌药组中用药时间长组部分指标比用药时间短组低(P<0.05)。结论 活血化瘀汤可拮抗大鼠局灶脑缺血-再灌注后的炎症反应。     

雌激素抑制脑缺血再灌注损伤后炎症反应

目的：探讨雌激素对大鼠局灶性脑缺血再灌注损伤后炎症反应的影响。方法：大鼠分3组：对照组、双侧卵巢切除（OVX）组、OVX＋17β－E2组（200μg/kg，皮下注射每周1次，共4周）。4周后线检地建立右侧大脑中动脉闭塞（MCAO）1h,2h再灌注0，1，3，6，22，70h模型。在HE染色缺血半球选取10个高倍视野计算脑组织内浸润的中性粒细胞均数，免疫组化检测核转录因子－κB（NF－κB）表达。结果：外源性雌激素替代可以对抗OVX引起的NF－κB过分表达，减少脑实质内中性粒细胞浸润，减轻局部炎症反应。结论：雌激素能抑制脑缺血再灌注损伤后炎症反应。     

大鼠局灶性脑缺血再灌注后IL—6水平变化与神经元损害关系的探讨

目的 探讨大鼠局灶脑缺血再灌注后白细胞介素－6（IL－6）水平变化与神经元损害的关系。方法 将60只Wistar大鼠随机分为正常对照组、假手术组、缺血再灌注组。应用线栓法制作大鼠脑缺血再灌注损型,采用免疫组织化学方法检测大鼠脑组织IL－6的变化,用HE染色观察神经细胞损伤与白细胞浸润情况,并与正常对照组及假手术组大鼠比较。结果 IL－6在正常对照组大鼠神经元与胶质细胞仅有少量表达,缺血再灌注6小时时IL－6表达较正常神经元稍增多但无统计学意义（P＞0．05）,12小时开始在梗死周围区增高,第3天显著增强,以后逐渐下降。结论 IL－6在缺血性脑损伤中过量表达参与了脑组织的损伤过程。     

亚低温对大鼠脑缺血再灌注后炎症反应的作用研究

目的探讨亚低温对大鼠脑缺血再灌注后炎症反应的保护作用。方法雄性SD大鼠，线栓法建立脑缺血再灌注模型，随机分组．选择性头颅降温。结果(1)TNF—α、IL-1β、ICAM-1：缺血2h表达量即有不同程度增多，6～12h达高峰，再灌注组较持续缺血组增多更明显．降温组则明显减少；(2)多形核白细胞：缺血2h缺血区血管周围即可见白细胞浸润，6～12h后数量明显增加．再灌注组较持续缺血组多，降温组则明显减少；(3)脑梗死体积：降温持续缺血组和降温再灌注组的梗死体积均较相应常温组小．其中降温再灌注组的梗死体积更小，尤以降温再灌注12h组的梗死体积最小。结论本实验证实了大鼠脑缺血-再灌注后急性炎症反应的存在，亚低温对这种炎症级联反应的抑制可能是其发挥脑保护作用的重要机制之一。     

敲除let-7a减轻脑缺血再灌注后炎症反应和神经损伤

目的研究微小RNA let-7a在脑缺血再灌注后神经损伤中的作用及机制。方法将大鼠分为假手术组、对照组、anti-let-7a组和GFP组,每组各12只大鼠,假手术组大鼠为假手术组。对照组、anti-let-7a组和GFP组分别经尾静脉给予生理盐水、表达anti-let-7a的AAV-9质粒或者对照空质粒实验,然后通过线栓法建立脑缺血再灌注大鼠模型。模型建立24 h后,TTC法检测梗死体积,tunel法检测细胞凋亡,Western blot检测caspase-3表达,ELISA和qRT-PCR检测脑组织中TNF-α和IL-6的表达。并通过Western blot、qRT-PCR和荧光报告基因验证let-7a对MKP1表达的调控。结果 anti-let-7a组大鼠脑梗死体积明显小于GFP组和对照组,脑组织内凋亡细胞数、caspase-3、TNF-α和IL-6的表达明显低于GFP组和对照组。let-7a可与MKP1 mRNA 3’UTR端结合,下调MKP1在PC12细胞中的蛋白表达。结论敲除let-7a可通过调控MKP1表达,抑制MAPK信号通路的激活从而减轻脑缺血再灌注后的炎症反应和细胞凋亡发挥神经保护作用。     

丁咯地尔对大鼠脑缺血再灌注损伤后炎症反应的干预

近年来，缺血性脑损伤后多形核白细胞(polymorphonuclear cells，PMN)浸润现象受到研究人员的重视，其通过多种途径介导脑缺血再灌注损伤。盐酸丁咯地尔是临床常用的治疗缺血性脑血管病的药物，具有改善微循环，抑制血小板聚集的作用，有实验提示盐酸丁咯地尔还具有抗炎的作用。我们通过观察PMNs浸润过程中核因子     

Detrimental effects of post-treatment with fatty acids on brain injury in ischemic rats

Studies have illustrated that fatty acids, especially polyunsaturated fatty acids (PUFA), have a role in regulating oxidative stress via the enhancement of antioxidative defense capacity or the augmentation of oxidative burden. Elevated oxidative stress has been implicated in the pathogenesis of brain injury associated with cerebral ischemia/reperfusion (I/R). The objective of this study was to assess whether treatment with fatty acids after focal cerebral I/R induced by occlusion of the common carotid arteries and the middle cerebral artery has effects on brain injury in a rat model. PUFA, including arachidonic acid (AA) and docosahexaenoic acid (DHA), and the saturated fatty acid, stearic acid (SA), were administrated 60 min after reperfusion via intraperitoneal injection. AA and DHA aggravated cerebral ischemic injury, which manifested as enlargement of areas of cerebral infarction and increased impairment of motor activity, in a concentration-dependent manner. However, there were no remarkable differences in post-ischemic alterations between the SA and saline groups. The post-ischemic augmentation of injury in AA and DHA treatment groups was accompanied by increases in the permeability of the blood-brain barrier (BBB), brain edema, metalloproteinase (MMP) activity, inflammatory cell infiltration, cyclooxygenase 2 (COX-2) expression, caspase 3 activity, and malondialdehyde (MDA) production, and by a decrease in the brain glutathione (GSH) content. Furthermore, we found that either AA or DHA alone had little effect on free radical generation in neuroglia, but they greatly increased the hydrogen peroxide-induced oxidative burden. Taken together, these findings demonstrate the detrimental effect of PUFA such as AA and DHA in post-ischemic progression and brain injury after cerebral I/R is associated with augmentation of cerebral I/R-induced alterations, including oxidative changes.     

Anoxic depolarization determines ischemic brain injury

Abstract

To clarify the role of anoxic depolarization (AD) in ischemic brain injury, we examined the correlation between AD and ischemia-induced neuronal injury. Twenty-eight rats underwent transient forebrain ischemia with lowering of blood pressure and bilateral carotid occlusion while direct current shiftslelectrocorticogram, and cortical blood flow (COBF) were epidurally recorded from the right parietal cortex. One week later the right parietal cortex was studied histopathologically. AD appeared 0.5-3.0 min after carotid occlusion in 21 of28 animals. Circulation was reinitiated 75 min afterAD onset in 77 rats (group A) and 10 min after onset in 70 rats (group B). AD did not develop during 20 min of ischemia in 7 rats (group C). All 72 rats (6 from group A and 6 from group B) in which CoBF decreased below 9.5% of control flow exhibited AD. Histopathologic examination disclosed massive neuronal necrosis in 5 of the 6 group A animals with marked flow reduction but in none from group B. CoBF fell between 9.5% and 20% in 74 rats, among these, AD appeared in 9 (5 from group A and 4 from group B) but not in 5 (group C). Massive neuronal necrosis was demonstrated in 3 of5 rats from group A. Ischemic neuronal changes were absent or minimal in only 7/5 ofgroup A animals, a much lower fraction than in group B (4/4, p<0.05) or in group.C (5/5/, p<0.05). When CoBF remained above 20% of control flow during ischemia (2 rats) no AD or irreversible injury occurred. The present study suggests that AD is a more reliable determinant of irreversible brain injury than degree of CBF reduction, and also demonstrates that 75 min is the critical duration of AD for irreversible brain injury at brain temperatures around 37° C. [Neural Res 1998; 20: 343-348]     

DWI动态评价大鼠脑缺血—再灌注损伤区的组织学特征

目的本研究运用磁共振弥散加权成像(DWI)技术动态评价大鼠脑缺血—再灌注损伤后不同时间脑损伤区DWI信号强度(SI)及表观扩散系数(ADC)的变化,结合组织学检测,分析损伤区组织学特征。方法健康成年SD雄性大鼠(n=80)随机分成8组,分别为脑缺血—再灌注1h、3h、6h、12h、1d、3d、7d组和假手术组,采用线栓法制作大鼠右侧大脑中动脉缺血—再灌注(MCAO/R)模型,Zea Longa评分评价神经功能损伤程度,Philips Achieva 3.0T MR扫描仪对假手术组和缺血—再灌注后不同时间点大鼠脑部行冠状位DWI扫描,在工作站上重建ADC图,测量基底核层面梗死灶DWI-SI和ADC值,计算相对ADC值(r ADC)和相对DWI-SI(r DWI-SI)值。2,3,5-氯化三苯基四氮唑(TTC)染色评价梗死体积的变化。苏木精—伊红染色观察组织形态学变化。结果假手术组动物麻醉苏醒后未见神经功能缺损,脑缺血—再灌注1h大鼠出现神经损伤,3h~1d时症状逐渐加重,3~7d时症状改善。假手术组DWI及ADC图均未见异常信号;MCAO/R后1h DWI上右侧纹状体及周围部分皮质区域出现高信号,相应部位ADC值降低,1h~1d DWI高信号范围随时间推移逐渐增大,信号强度逐渐增高,3~7d时开始降低;r ADC值随时间先降低后升高,6h达到最低,12h开始回升,1d时r ADC值较12h稍降低(P0.05),3d时r ADC升高,7d时与假手术组无明显差异(P0.05);1h~1d r DWI-SI持续升高,1d达最高峰,3~7d开始下降,7d时仍明显高于假手术组。苏木精—伊红染色显示假手术组右侧海马及皮质区结构未见明显异常;缺血—再灌注12h缺血侧海马区及皮质区出现可见部分浓染细胞和胞浆空泡形成,核固缩,但细胞排列尚好;1d时缺血侧神经元缺血损伤加重,细胞排列紊乱,细胞间隙增宽,出现大量胞浆空泡化,核固缩显著;3d时缺血侧海马区空泡化有所减轻。假手术组TTC染色未见梗死区域;脑缺血—再灌注1h可见右侧纹状体及周围少许皮质梗死;1h~1d梗死体积逐渐增大,1~3d时达到峰值,7d时梗死体积减小。1h~1d缺血侧脑水肿体积随时间持续增加,1d达到高峰,3d时开始下降,7d明显减轻。模型组各时间点神经功能评分与相应时间点基底核区梗死灶r DWI-SI呈显著性正相关(r=0.503,P=0.000);相应时间点脑梗死体积、水肿体积与r DWI-SI均呈显著性正相关(r=0.542,P=0.001;r=0.740,P=0.000)。结论磁共振弥散加权成像获得的DWI-SI及ADC值,对评价脑缺血再灌注损伤组织学特征具有高度的敏感性和特异性,对脑缺血—再灌注损伤后缺血区的动态改变具有直观的价值。     

Neuroprotective effect of an antioxidant in ischemic brain injury

The production of reactive oxygen species (ROS) has been implicated in reperfusion injury after cerebral ischemia, and antioxidant enzymes are believed to be among the major mechanisms by which the cells counteract the deleterious effect of ROS after cerebral ischemia. ROS also mediate the mitochondrial signaling pathway that may lead to apoptosis following cerebral ischemia. The recent development and availability of transgenic and knockout mutant rodents that either overexpress or are deficient in antioxidant genes have provided powerful tools for dissecting the molecular and cellular mechanisms of signaling pathways, direct oxidative damage, or both that are involved in ischemic brain injury. This article focuses on the contribution of ROS or an antioxidant system to the molecular pathway of postischemic apoptosis following transient focal cerebral ischemia by using transgenic mice that overexpress the cytosolic antioxidant copper/zinc superoxide dismutase.     

大鼠急性脑缺血再灌注损伤精氨酸加压素变化和脑水肿实验研究

应用大鼠急性脑缺血再灌注动物模型，观察精氨酸加压素（ＡＶＰ）在急性脑缺血再灌注损伤中的变化及与脑水肿关系，结果表明丘脑下部ＡＶＰ含量在脑缺血３０ｍｉｎ明显增加，再灌注６０ｍｉｎ后进一步增加，且与大脑皮层水含量是显著相关性。提示，ＡＶＰ参与急性脑缺血再灌注损伤，丘脑下部ＡＶＰ含量增高，可加重或促进脑缺血再灌注后脑水肿形成。     

神经调节素在脑缺血再灌注损伤中的抗炎作用机制研究

目的研究神经调节素-1β（NRG-1β）对小鼠脑缺血再灌注损伤后炎症反应的抑制作用和机制。方法应用线栓法建立小鼠大脑中动脉闭塞再灌注（MCAO／R）模型,经颈内动脉微量注射NRG．1B（2μg／kg）干预治疗,氯化三苯基四氮唑（TTC）染色观察脑梗死体积,免疫荧光染色检测神经细胞凋亡,免疫组织化学检测酪氨酸激酶受体（ErbB-4）和基质金属蛋白酶-9（MMP-9）的表达。结果脑缺血再灌注损伤后,神经细胞凋亡数量明显增多,并诱导ErbB-4和胶质细胞MMP-9表达增强。应用NRG-1β干预治疗后,缺血脑组织梗死体积和细胞凋亡数量较对照组显著减小,ErbB-4受体表达增强,而胶质细胞MMP-9表达下调（P〈0．05）。结论NRG—1β可能通过下调脑缺血再灌注损伤诱导的胶质细胞MMP-9表达和抑制细胞凋亡,而发挥其抗炎作用。     

缺血性脑损伤诱导大鼠巢蛋白表达的实验研究

目的探讨缺血性脑损伤对内源性神经干细胞增殖、迁移的影响。方法选用健康雄性SD大鼠62只，随机分为正常组（6只）、脑缺血10min再灌流1、3、5、7、10、15、20d组（简称手术组，每时间点6只）、假手术对照组（14只，每时间点2只），参照Pulsinelli—Brierley方法制作短暂性全脑缺血动物模型：用SABC免疫组化法显示巢蛋白（nestin）阳性细胞；光镜下观察nestin阳性细胞的形态学变化并计数，半定量分析脑缺血损伤后内源性神经干细胞增殖、迁移的变化过程。结果手术组的nestin阳性细胞在缺血再灌流24h后表达增多，7～10d到高峰，15d时仍有显著表达；在室管膜下区的nestin阳性细胞有向皮质、海马迁移的迹象。结论缺血性脑损伤能诱导内源性神经干细胞增殖，这可能对脑损伤后的修复发挥作用。     

局灶性脑缺血再灌注损伤大鼠脑、肝中IGF-1的动态表达及其意义

目的 探讨胰岛素样生长因子-1(IGF-1)在局灶性脑缺血再灌注损伤大鼠脑、肝中的表达变化及其意义.方法 采用线栓法制备大鼠局灶性脑缺血再灌注模型,应用免疫组化染色方法检测大鼠脑缺血再灌注后2h、1d、3d、7d时脑、肝标本中IGF-1蛋白的含量.结果 正常脑组织有低水平的IGF-1表达,脑缺血再灌注后2h后表达即有明显升高,1d时持续升高,至3d时达高峰,7d时又有所回落,其表达主要位于大脑皮质区.经方差分析,脑组织中IGF-1蛋白含量脑缺血再灌注组与对应各时间点假手术组比较差异均有统计学意义(P<0.05);假手术组各时间点比较差异无统计学意义(P>0.05);脑缺血再灌注组1d和7d间比较差异无统计学意义(P>0.05),其余脑缺血再灌注组各时间点间比较差异均有统计学意义(P<0.05).正常肝组织中有极低水平IGF-1表达,脑缺血再灌注2h、1d、3d后肝组织中IGF-1蛋白含量与假手术组各对应时间点比较差异无统计学意义(p>0.05),脑缺血再灌注7d时与脑缺血再灌注组其余各时间点及假手术组对应时间点比较差异均有统计学意义(P<0.05).结论 脑缺血再灌注损伤后大鼠脑、肝中内源性IGF-1水平有明显变化,提示IGF-1的变化与脑缺血再灌注损伤有关联.