大鼠局部脑缺血再灌流的实验研究

采用大鼠局部脑缺血再灌流模型，研究了大鼠脑缺血６ｈ、９ｈ和缺血６ｈ再灌流３ｈ脑梗塞体积，脑含水量，能量代谢，丙二醛（ＭＤＡ）和超氧化物歧化酶（ＳＯＤ）的变化。结果：脑缺血６ｈ、９ｈ可以造成严重的脑梗塞和脑水肿，ＡＴＰ含量和ＳＯＤ活性显著降低，乳酸和ＭＤＡ含量显著增加，和对照组相比均有显著差异（Ｐ＜０．０５或Ｐ＜０．００１）。再灌组和缺血两组比较，脑梗塞体积，脑水肿无明显差别（Ｐ＞０．０５），ＡＴＰ、乳酸、ＳＯＤ和ＭＤＡ均有不程度的改善。提示，大鼠局部脑缺血超过６ｈ可造成严重的脑损伤，并随缺血时间的再延长，脑损伤变化趋于平缓。再灌后，脑损伤未见明显加重。     

黄芪对大鼠脑缺血血脑屏障及脑血流的影响

利用大鼠局灶性脑缺血再灌流和全脑缺血再灌流损伤两种动物模型，观察黄芪注射液对脑缺血后再灌注期间血脑屏蔽及脑血流的保护作用。结果显示，与相庆对照组比较，不论是全脑缺血还是局灶性脑缺血１ｈ后再灌流３ｄ，应用黄芪的各组动物脑水肿明显减轻，血脑屏障通透性改善，大脑局部血流量显著增加。     

抗肿瘤坏死因子—α单克隆抗体对缺血再灌注大鼠脑损伤？…

目的 探讨ＴＮＦ－α－ｍＡｂ对缺血再灌注在脑损伤的影响。方法 用Ｚｅａ ｌｏｎｇａ报道的大白鼠局灶脑缺再灌注尼龙线栓塞模型,对６ｈ短暂脑缺血／再灌注大白鼠使用抗ＴＮＦ－αｍＡｂ／生理盐水后的脑梗塞体积、脑组织病理学变化及微血管内白细胞聚集及附壁现象进行了观察。结果 抗ＴＮＦ－α ｍＡｂ能减少脑梗塞体积,减轻脑组织变性坏死程度,减少白细胞在微血管内的聚集和粘附。结论 抗ＴＮＦ－αｍＡｂ能起到减轻脑缺     

抗肿瘤坏死因子-α单克隆抗体对缺血再灌注大鼠脑损伤影响的实验研究

目的　探讨 Ｔ Ｎ Ｆαｍ Ａｂ 对缺血再灌注大鼠脑损伤的影响。方法　用 Ｚｅａ ｌｏｎｇａ 报道的大白鼠局灶脑缺血再灌注尼龙线栓塞模型,对 ６ｈ 短暂脑缺血／再灌注大白鼠使用抗 Ｔ Ｎ Ｆαｍ Ａｂ／生理盐水后的脑梗塞体积、脑组织病理学变化及微血管内白细胞聚集及附壁现象进行了观察。结果　抗 Ｔ Ｎ Ｆαｍ Ａｂ 能减少脑梗塞体积,减轻脑组织变性坏死程度,减少白细胞在微血管内的聚集和粘附。结论　抗 Ｔ Ｎ Ｆαｍ Ａｂ 能起到减轻脑缺血／再灌注损伤作用。     

肿瘤坏死因子在局部脑缺血/再灌流中的表达

目的：为探讨局部脑缺血／再灌流中肿瘤坏死因子－α（ＴＮＦ－α）的动态变化及其与白细胞浸润的关系。方法;采用大鼠大脑中动脉梗死模型,分别用免疫组织化学方法检测ＴＮＦ－α、酶组化方法检测髓过氧化物酶（ＭＰＯ）的动态变化,用图像分析进行定量分析。结果：ＴＮＦ－α在缺血组（Ｉ）和缺血再灌流组（ＩＲ）０．５ｈ表达增多,１２ｈ达高峰,与对照组比较差异非常显著（Ｐ〈０．０１）,持续至１２ｈ;Ⅰ组１２ｈ、ＩＲ缄０     

肿瘤坏死因子α和缺血性脑损伤

缺血性脑损伤是由多种因素综合作用的结果,肿瘤坏死因子α是一种参与缺血性脑损伤病理生理过程的多功能细胞因子,具有双重、多样及网络性生物效应,在脑缺血的不同阶段产生不同甚至相反的综合性作用。本文对近年来脑缺血时肿瘤坏死因子α的表达变化、作用及相关机制的研究进展进行了综述。文中表明肿瘤坏死因子α在脑缺血后反应性增高,不仅可促进炎性坏死和细胞凋亡,而且还具有一定的神经保护作用。通过进一步研究其双向作用的机制,阻断它的神经毒性作用,充分发挥其神经保护作用,可为脑缺血损伤的有效治疗提供新思路。     

心肌缺血再灌注损伤模型大鼠心肌组织及血清肌钙蛋白Ⅰ表达和心肌肿瘤坏死因子α与重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白的干预**

背景：心肌缺血再灌注时生成大量的肿瘤坏死因子α直接造成心肌的收缩功能下降。 目的：观察药物重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白对大鼠缺血再灌注心肌损伤的影响。 方法：成年雄性Wistar大鼠建立心肌缺血再灌注模型。药物干预组在再灌注前注射重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白,模型组给予生理盐水,并设立不造模的假手术组。再灌注后立即测量心肌梗死面积,ELISA检测再灌注后的心肌肿瘤坏死因子α及血清肌钙蛋白Ⅰ的含量,实时PCR检测心肌肿瘤坏死因子α mRNA的表达。 结果与结论：与假手术组相比,模型组与药物干预组大鼠心肌肿瘤坏死因子α及其mRNA和肌钙蛋白的水平明显升高 (P < 0.05);与模型组相比,药物干预组心肌肿瘤坏死因子α及血清肌钙蛋白Ⅰ水平明显升高(P < 0. 05),心肌梗死体积与肿瘤坏死因子α mRNA的表达减少(P < 0. 05)。提示重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白能够减轻心肌缺血/再灌注损伤作用,改善大鼠的心功能。     

雪莲注射液对大鼠脑缺血/再灌注损伤后TNF-α、IL-1β和MMP-9含量的影响

目的探讨雪莲注射液对大鼠脑缺血/再灌注损伤的保护作用。方法采用SD大鼠大脑中动脉栓塞模型(MCAO),研究低、中和高剂量雪莲注射液对脑缺血/再灌注大鼠脑梗死体积及脑组织基底节区肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)和基质金属蛋白酶-9(MMP-9)蛋白表达的影响。结果雪莲注射液能够减少MACO脑梗死体积,降低脑组织中TNF-α、IL-1β和MMP-9的含量(P<0.01)。结论雪莲注射液对大鼠脑缺血再灌注损伤有一定保护作用,其作用机制与降低脑组织中TNF-α、IL-1β和MMP-9含量有关。     

缺血及再灌流时不同脑区磷脂酶A2活性的变化及作用探讨

本文利用大鼠４血管阻断法（４ＶＯ）建立脑缺血再灌模型，分别检测假手术组，缺血１５ｍｉｎ组，缺血１５ｍｉｎ后再灌流１ｈ，６ｈ，２４ｈ，７２ｈ和１６８ｈ各组不同脑区的磷脂酶Ａ２（ＰＬＡ２）活性变化。发现海马和皮质下脑皮ＰＬＡ２活性在再灌流早期显著升高，但随再灌流时间延长其活性反而低于假手术组；而皮质区ＰＬＡ２活性在再灌流早期虽然也升高，但很快接近假手术组，表明ＰＬＡ２活性改变有着区域性差别，参与并影响     

亚低温对局灶脑缺血再灌注损伤作用的实验研究

用改良Koizumi's局灶脑缺血模型,对比研究了常温、缺血期亚低温、再灌注期亚低温、缺血期加再灌注期亚低温对局部脑血流、血脑屏障及缺血梗塞灶体积影响。发现缺血期加再灌注期及单纯缺血期亚低温均有改善缺血周边区再灌注后急性高灌注和继发低灌流及核心区持续低灌流、减轻血脑屏障破坏、减少缺血梗塞灶体积的作用,该作用尤以前者为明显。     

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。     

Tumor necrosis factor alpha expression produces increased blood-brain barrier permeability following temporary focal cerebral ischemia in mice.

Alteration of blood-brain barrier (BBB) function occurs in both permanent and temporary cerebral ischemia. Studies in vivo and in vitro have shown that tumor necrosis factor-alpha (TNFalpha) is involved in changes of BBB permeability. However, the relationship between TNFalpha expression and BBB disruption during reperfusion is unclear. The aim of this study is to find the cell source of TNFalpha and to determine the relationship between TNFalpha expression and BBB disruption following temporary focal cerebral ischemia in mice. Adult CD-1 mice received 1 h middle cerebral artery occlusion (MCAO) followed by 2 h, 6 h, 12 h, 24 h, and 48 h of reperfusion. MCAO was achieved using an intraluminal suture technique and reperfusion was performed by the suture withdrawal. Neutralizing monoclonal anti-mouse TNFalpha antibody was administrated intraventricularly immediately after reperfusion. TNFalpha expression was determined by double labeling immunohistochemistry. BBB permeability was determined by albumin immunostaining. TNFalpha immunoreactivity (IR) was observed in the ipsilateral hemisphere from 1 h MCAO with 2 h reperfusion. TNFalpha positive cells included neurons, astrocytes, and ependymal cells. BBB disruption was detected beginning at 6 h reperfusion but was not present at 2 h of reperfusion. The areas of BBB disruption were significantly enlarged at 12 h reperfusion and plateaued at 24 h to 48 h reperfusion. BBB disruptions were significantly attenuated in the anti-TNFalpha antibody treated mice (p<0.05). Our results demonstrate that TNFalpha IR existed in neurons, astrocytes, and ependymal cells during reperfusion. TNFalpha IR following temporary focal cerebral ischemia precedes increased BBB permeability. Treatment with TNFalpha antibody reduces BBB disruption, suggesting TNFalpha may be an important mediator in altering BBB permeability during reperfusion.     

A standardisable model of focal cerebral ischaemia innormotensive rats

In this study various techniques with different periods of ischaemia have been used in order to describe a standardisable and reproducible model of reversible focal cerebral ischaemia in normotensive rats. Cerebral blood flow to the left hemisphere of the rats was temporarily interrupted by middle cerebral artery occlusion only in four rats of each group, by simultaneous middle cerebral artery and ipsilateral common carotid artery occlusion in six rats of each group, and by middle cerebral artery and bilateral common carotid artery occlusion in six rats of each group. Within each group temporary ischaemia lasted for 1, 2 or 3 h and animals survived for 24 h following reperfusion. An infarct of significant size with low standard deviation was observed after 3 h of distal middle cerebral artery and bilateral common carotid artery occlusion followed by 24 h of reperfusion. We have found that the ratio of the infarct volume to the supratentorial brain volume is a more reliable criterion (with less standard deviation) than infarct volume alone and could be used for comparison of results obtained in experimental studies.     

High-dose methylprednisolone treatment in experimental focal cerebral ischemia

Previous studies using steroids for experimental focal stroke have demonstrated conflicting results, possibly related to dose used or ischemic models employed. In this study we examined high-dose methylprednisolone treatment following permanent and temporary focal cerebral ischemia in the rat. Focal stroke was induced in spontaneously hypertensive rats by permanent right common carotid and either permanent or 3 h of temporary middle cerebral artery (MCA) occlusion. Methylprednisolone (105 mg/kg) was administered intra-arterially. Infarct volume was measured at 24 h after permanent and temporary MCA occlusion. Cerebral edema was determined by measuring right and left hemispheric volumes and water content 24 h after permanent MCA occlusion in one experiment. Methylprednisolone, whether administered in divided doses over 12 h (n = 15 in each group) or a single bolus (n = 9 per group), had no effect on infarct volume after permanent MCA occlusion. Methylprednisolone treatment also had no influence on cerebral edema (n = 9 per group). In two different experiments, methylprednisolone given in divided doses over 12 h (n = 11, n = 25) after temporary MCA occlusion decreased infarct volume (P < 0.05) by 20% compared with saline controls (n = 10, n = 25). High dose methylprednisolone decreased infarct volume following temporary, but not permanent, focal ischemia. The benefit suggests that high dose methylprednisolone may prove useful clinically if reperfusion can be established with thrombolytic agents. Furthermore, the differential treatment effect in the setting of comparable ischemic insults implies that different modifiable biochemical processes may be present during temporary but not permanent focal ischemia, thus providing indirect evidence for reperfusion injury.     

Tumor necrosis factor-alpha neutralization reduced cerebral edema through inhibition of matrix metalloproteinase production after transient focal cerebral ischemia.

After focal cerebral ischemia, tumor necrosis factor-alpha deteriorates cerebral edema and survival rate. Therefore, tumor necrosis factor-alpha neutralization could reduce cerebral microvascular permeability in acute cerebral ischemia. Left middle cerebral artery occlusion for 120 mins followed by reperfusion was performed with the thread method under halothane anesthesia in Sprague-Dawley rats. Antirat tumor necrosis factor-alpha neutralizing monoclonal antibody with a rat IgG Fc portion (15 mg/kg) was infused intravenously right after reperfusion. Stroke index score, infarct volume, cerebral specific gravity, and the endogenous expression of tumor necrosis factor-alpha, matrix metalloproteinase (MMP)-2, MMP-9, and membrane type 1-MMP in the brain tissue were quantified in the ischemic and matched contralateral nonischemic hemisphere. In the antitumor necrosis factor-alpha neutralizing antibody-treated rats, infarct volume was significantly reduced (P=0.014, n=7; respectively), and cerebral specific gravity was dramatically increased in the cortex and caudate putamen (P<0.001, n=7; respectively) in association with a reduction in MMP-9 and membrane type 1-MMP upregulation. Tumor necrosis factor-alpha in the brain tissue was significantly elevated in the ischemic hemisphere 6 h after reperfusion in the nonspecific IgG-treated rats (P=0.021, n=7) and was decreased in the antitumor necrosis factor-alpha neutralizing antibody-treated rats (P=0.001, n=7). Postreperfusion treatment with antirat tumor necrosis factor-alpha neutralizing antibody reduced brain infarct volume and cerebral edema, which is likely mediated by a reduction in MMP upregulation.     

Mild hypothermia reduces infarct size resulting from temporary but not permanent focal ischemia in rats.

BACKGROUND AND PURPOSE: Mild hypothermia (32-35 degrees C) has been repeatedly shown in laboratory models to reduce damage resulting from global cerebral ischemic insults. Little information is available, however, regarding the protective potential of mild hypothermia against focal ischemia. We designed the present study to determine whether mild hypothermia influences outcome from either temporary or permanent middle cerebral artery occlusion in the rat. METHODS: In experiment 1 (permanent occlusion), mechanically ventilated, halothane-anesthetized spontaneously hypertensive rats underwent permanent ligation of the middle cerebral artery. Pericranial temperature was maintained at either 37 degrees C (n = 11) or 33 degrees C (n = 11) during the first 2 hours of occlusion. In experiment 2 (temporary occlusion), the vessel was occluded for 1 hour only. Pericranial temperature was controlled at either 37 degrees C (n = 12) or 33 degrees C (n = 14) during ischemia and for 1 hour after reperfusion. In both experiments, the rats were allowed to recover, with neurological function scored at 24 and 96 hours after onset of ischemia. Cerebral infarct volume (as determined by nitro blue tetrazolium staining) was planimetrically evaluated 96 hours after onset of ischemia. RESULTS: No difference in infarct volume was observed between groups undergoing permanent occlusion (177 +/- 53 mm3 for 37 degrees C rats, 167 +/- 71 mm3 for 33 degrees C rats [mean +/- SD]). Although neurologic function correlated with infarct volume at 96 hours (all animals in experiment 1 combined; p less than 0.01), we were unable to demonstrate an intergroup difference in function. In animals undergoing temporary occlusion, mean +/- SD infarct volume was 48% less in the hypothermic group (89 +/- 54 mm3 for 37 degrees C, 46 +/- 31 mm3 for 33 degrees C; p less than 0.03). Neurological function again correlated with infarct size (p less than 0.02), but improvement in function approached significance for the hypothermic group (p less than 0.06) at 24 hours after reperfusion only. CONCLUSIONS: Benefits from mild hypothermia may be obtained under conditions of temporary but not permanent middle cerebral artery occlusion in the rat.     

神经节苷脂对大鼠脑缺血再灌注损伤的脑保护作用

目的探讨神经节苷脂对大鼠脑缺血再灌注损伤的脑保护作用。方法采用线栓法制作缺血再灌注大鼠模型,分别用神经节苷脂(治疗组)和生理盐水(对照组)腹腔注射。观察两组大鼠缺血90min、缺血90min再灌注24h的脑梗死面积、神经功能缺损程度、细胞凋亡数、细胞凋亡率。结果治疗组大鼠于相同时间点脑梗死面积较对照组明显减小,仅表现轻度的神经功能缺损,且神经细胞的凋亡数较对照组显著减少(均P<0.01)。结论神经节苷脂能明显减小大鼠实验性脑缺血的脑梗死面积,减轻脑缺血再灌注后神经功能缺损程度,显著减轻缺血区神经元损害,具有显著的脑保护作用。     

The effect of the NMDA receptor antagonist MK-801 on cerebral blood flow and infarct volume in experimental focal stroke

The non-competitive N-methyl-D-aspartate receptor/channel antagonist dizocilipine maleate (MK-801) has been reported to reduce infarct volume in a variety of focal stroke models. We examined the effect of MK-801 on infarct volume and cerebral blood flow in temporary and permanent focal ischemia in rats. In Wistar rats exposed to permanent right common carotid artery and 2 h of transient right middle cerebral and left common carotid artery occlusion followed by 22 h of reperfusion, MK-801 reduced infarct volume by 73% (P less than 0.05) and significantly increased cerebral blood flow to the ischemic core throughout the 2-h period of ischemia. In spontaneously hypertensive rats (SHRs) exposed to permanent right common carotid artery occlusion and 2 h of transient right middle cerebral artery occlusion followed by 22 h of reperfusion, MK-801 decreased infarct volume by 13% (P greater than 0.05) and increased cerebral blood flow to the penumbral region. In SHRs subjected to permanent right common carotid and middle cerebral artery occlusion MK-801 reduced infarct volume by 18% at 3 h (P greater than 0.05), by 25% at 6 h (P less than 0.01) and by 18% at 24 h (P less than 0.05). MK-801-treated SHRs had no difference in cerebral blood flow to the ischemic core, but increased cerebral blood flow to penumbral zones as compared with untreated SHRs. These results suggest that the protective effect of MK-801, at least in part, relates to improved cerebral blood flow.     

电针预处理对脑缺血再灌注后SOD_2的表达影响

目的观察电针预处理对脑缺血再灌注后锰超氧化物歧化酶表达的影响。方法成年雄性C57小鼠随机分为假手术组(sham)、电针预处理组(EA)、大脑中动脉栓塞组(MCAO)、电针加大脑中动脉栓塞组(EA+MCAO),采用MCAO法诱导小鼠局灶性脑缺血再灌注模型。再灌2 h应用Western blot以及免疫荧光组织化学染色技术检测SOD2表达,再灌24 h评估神经行为学、测量脑梗死容积和神经细胞凋亡。结果脑缺血再灌注2 h,SOD2表达显著降低,而电针预处理可上调SOD2的表达,增加SOD2在神经元的免疫荧光强度。同时电针预处理可改善缺血再灌注后的神经功能障碍,减轻脑梗死容积率,减少末端脱氧核苷酸转移酶介导的生物素脱氧尿嘧啶核苷酸缺口末端标记法(TUNEL)阳性细胞数目。结论电针预处理可上调脑缺血再灌注后SOD2表达,可能参与其诱导的脑保护作用。