注射肿瘤坏死因子-α对大鼠脑缺血再灌注的影响

背景一些研究提示肿瘤坏死因子-α预注射对小鼠局灶性脑缺血可产生保护作用,脑缺血耐受与血浆肿瘤坏死因子-α水平增高有关.另一方面,肿瘤坏死因子-α是与脑卒中有关的一个有害细胞因子,抗肿瘤坏死因子-α循环抗体对再灌注损伤起保护作用.目的探讨脑缺血再灌注前、后不同时期注射肿瘤坏死因子-α对大鼠脑缺血灶的影响,是保护作用还是毒性作用.设计随机对照实验.单位哈尔滨医科大学附属第二医院神经科.材料实验于2002-01/2002-04在哈尔滨医科大学动物实验中心完成;选择健康雄性Wistar大鼠120只,随机将大鼠分为8组预注射肿瘤坏死因子-α 0.05,0.5,1.0μg及磷酸盐缓冲液对照组,后注射肿瘤坏死因子-α 0.05,0.5,1.0μg及磷酸盐缓冲液对照组,每组15只.方法制备大鼠大脑中动脉局灶性脑缺血模型.缺血前48 h或缺血2 h再灌注后,在大鼠小脑延髓池内分别注射不同剂量肿瘤坏死因子-α(0.05 μg,0.5 μg,1.0μg)或磷酸盐缓冲液.①各组取8只大鼠,于脑缺血2 h再灌注22 h,麻醉下处死取脑,制备TTC切片,用计算机图像分析系统测定每个脑片面积及梗死面积,然后计算梗死体积百分比.②各组取7只大鼠,于缺血2 h再灌注22 h后,麻醉下处死取脑,行HE、GFAP和ICAM-1免疫组化染色,用显微镜和计算机图像分析系统分析组织病理和免疫组化切片,计算胶质纤维酸性蛋白阳性细胞数目及每侧半球细胞内黏附分子-1阳性血管数.主要观察指标①各组大鼠脑梗死体积百分比.②各组大鼠脑组织病理学观察.③各组大鼠脑组织胶质纤维酸性蛋白和细胞间黏附分子-1蛋白表达情况.结果120只大鼠全部进入结果分析.①脑梗死体积百分比肿瘤坏死因子-α 0.5 μg预注射组及1.0μg预注射组脑梗死体积减小,0.5μg预注射组脑梗死体积百分比减小70.9%,1.0 μg预注射组减小66.5%;肿瘤坏死因子-α 0.5 μg后注射及1.0 μg后注射组脑梗死体积增加,0.5 μg后注射组脑梗死体积百分比增加22.3%,1.0 μg后注射组增加46.7%.肿瘤坏死因子-α 0.5 μg预注射组与1.0 μg预注射组间比较无显著差异(P＞0.05),肿瘤坏死因子-α 0.5 μg后注射组与1.0 μg后注射组间比较有显著差异(P＜0.05).②病理变化肿瘤坏死因子-α0.5 μg预注射组及1.0 μg预注射组脑组织变性坏死程度减轻;肿瘤坏死因子-α0.5 μg后注射及1.0 μg后注射组脑组织变性坏死程度加重.③胶质纤维酸性蛋白和细胞间黏附分子-1蛋白的表达肿瘤坏死因子-α0.5 μg预注射组及1.0 μg预注射组胶质纤维酸性蛋白和细胞间黏附分子-1蛋白表达减少(P均＜0.05);肿瘤坏死因子-α 0.5μg后注射及1.0 μg后注射组胶质纤维酸性蛋白和细胞间黏附分子-1蛋白表达增加(P均＜0.05);肿瘤坏死因子-α 0.5 μg预注射组与1.0 μg预注射组间比较无显著差异(P均＞0.05),肿瘤坏死因子-α 0.5 μg后注射组与1.0 μg后注射组间比较有显著差异(P均＜0.05).结论①肿瘤坏死因子-α预注射对脑缺血再灌注损伤有神经保护作用,该作用与星形胶质细胞的修复作用无关,而与细胞间黏附分子-1表达减少有关.②在脑缺血再灌注后给肿瘤坏死因子-α则加重脑缺血,该作用与细胞间黏附分子-1表达增加有关.③脑缺血前或脑缺血后给予肿瘤坏死因子-α决定了它的作用效果,这两种作用都有剂量依赖性.

Effect of tumor necrosis factor alpha treatment on cerebral ischemia-reperfusion injury in rats

BACKGROUND: Some studies suggest that pre-injection of tumor necrosis factor-α (TNF-α)can protect focal cerebral ischemia in mice. Cerebral ischemia tolerance is related to the increase of TNF-α level; on the other hand, TNF-α is an injurious cytokine associated with stroke. Circulating antibody against anti-TNF-α can protect reperfused injury.OBJECTIVE: To study the effects of TNF-α pretreatment and post-treatment on cerebral ischemia-reperfusion injury and explore possible mechanism.DESIGN: Randomized controlled study.SETTING: Neurological Department, the Second Hospital Affiliated to Harbin Medical University.MATERIALS: The experiment was conducted at the Animal Experiment Center of Harbin Medical University from January to April 2002. Totally 120 healthy adult male Wistar rats were randomly divided into the following 8 groups: TNF-α 0.05 μg, 0.5 μg and 1.0 μg pretreatment groups and PBS group, TNF-α 0.05 μg, 0.5 μg and 1.0 μg post-treatment groups and PBS group with 15 in each group.METHODS: The focal brain ischemia model of middle cerebral artery occlusion (MCAO) was made using inserting thread method. TNF-α of different doses (0.05 μg, 0.5 μg or 1.0 μg) or PBS was injected intracisternally and 22-hour reperfusion, 8 rats from each group were killed. Then the perhour reperfusion, 7 rats from each group were killed. Then pathological changes were observed, glial fibrillary acidic protein (GFAP) and intercellular adhesion molecule-1 (ICAM-1) expression were inspected by immunohistochemical method. Histopathological and immunohistochemical evaluation was made with the computer-assisted image analyzing system,and the number of GFAP positive cells and ICAM-1 positive vessels in each hemisphere was counted.riliary acidic protein and ICAM-1.infarct volume: TNF-α 0.5 μg and TNF-α 1.0 μg pretreatment groups showed reduced volume of lesion; infarct volume reduced by 70.9% in TNF-α 0.5 μg pretreatment rats and 66.5% in TNF-α 1.0 μg pretreatment rats. TNF-α 0.5 μg and TNF-α 1.0 μg post-treatment groups showed increased volume of lesion; infarct volume increased by 22.3% in TNF-α 0.5 μg post-treatment rats and 46.7% in TNF-α 1.0 μg post-treatment rats.TNF-α 0.05 μg and 1.0 μg pretreatment groups did not differ significantly (P ＞ 0.05), but there was an obvious difference between TNF-α 0.5 μg and pared with PBS pretreatment group, TNF-α 0.5 μg and 1.0 μg pretreatment groups showed lessened tissue damage and edema. Compared with PBS post-treatment group, TNF-α 0.5 μg and TNF-α 1.0 μg post-treatment fibriliary acidic protein and ICAM-1: TNF-α 0.5 μg and TNF-α 1.0 μg pretreatment groups showed reduced volume of glial fibriliary acidic protein and ICAM-1 (P ＜ 0.05); but TNF-α 0.5 μg and TNF-α 1.0 μg posttreatment groups showed increased volume of glial fibriliary acidic protein and ICAM-1 (P ＜ 0.05). TNF-α 0.05 μg and 1.0 μg pretreatment groups did not differ significantly (P ＞ 0.05); but there was an obvious difference between TNF-α 0.5 μg and 1.0 μg post-treatment groups (P ＜ 0.05).cerebral ischemia reperfusion injury. This effect is not related to the repair given after cerebral ischemia reperfusion, ischemia exacerbates, which is α are determined by whether TNF-αis given before or after cerebral ischemia in a dose-dependent manner.