小鼠大脑中动脉缺血再灌注后缺血区及周边区星形胶质细胞的变化

目的 探讨小鼠大脑中动脉缺血再灌注后脑梗死体积、星形胶质细胞(AS)病理形态及其蛋白表达的变化.方法 选取69只成年健康雄性KM小鼠,将小鼠随机分为脑缺血2h再灌注1、4、10、24、48、72 h模型组(n=9)以及假手术组(n=6,仅结扎右侧颈总动脉)和正常组(n=9).采用线栓法制备小鼠大脑中动脉局灶性脑缺血再灌注模型.应用2,3,5-氯化三苯基四氮唑(TTC)染色法观察脑梗死的部位与体积;免疫组化法观察脑缺血中心区与周边区不同再灌注时间点胶质纤维酸性蛋白(GFAP)的表达.结果 缺血再灌注1h开始出现脑梗死灶,且再灌注24 h时梗死体积最大,之后逐渐缩小(F=745.534,P=0.000).小鼠脑缺血再灌注后缺血中心区AS肿胀、肥大进而较快发生凋亡,其GFAP表达水平低于周边区(P＜0.05);而缺血周边区GFAP阳性表达的AS出现反应性活化,进而发生形态学改变;缺血周边区及对侧相应脑组织区域GFAP的表达量均随再灌注时间的延长呈现增加趋势(P＜0.05).结论 AS反应性活化可能是一种缺血后的全脑保护性防御机制,尤其是在缺血周边区,其活化程度影响脑组织的存活与修复,提示在脑缺血再灌注过程中AS反应性活化可能在脑损伤后可塑性形态及功能改变中发挥重要作用.

Changes of astrocytes in core zones and marginal areas of middle cerebral artery ischemia reperfusion in mice

Objective To investigate changes of the infarct volume,astrocyte (AS) morphology and the expression of glial fiber acidic protein (GFAP) in the cerebral ischemia reperfusion mice models.Methods Sixtynine male KM mice were selected and randomly divided into eight groups:1,4,10,24,48,72 h post reperfusion groups (n=9),the sham operation group (n=6,ligated the right common carotid artery) and the normal control group (n=9).The focal cerebral ischemia and reperfusion models in mice were established by suture method.2,3,5-triphenyltetrazolium chloride (TTC) staining was used to illustrate the location and volume of cerebral infarction,immunohistochemistry was used to detect the numbers and morphology of GFAP in core zones and marginal areas at different time points.Results The cerebral infarction started 1 hour after reperfusion.The largest infarct volume was achieved 24 h after reperfusion and then gradually reduced (F =745.534,P=0.000).Astrocytes appeared rapid apoptosis after the occurrence of cell swelling and hypertrophy in the core zone with a lower GFAP expression level than that of the marginal area (P＜0.05).Astrocytes expressing GFAP appeared reactive activation and then morphological changes in the marginal area.Moreover,the expression of GFAP in the marginal area and the contralateral brain tissue showed a trend of increase with the prolongation of reperfusion time (P＜0.05).Conclusions The reactive activation of astrocytes,especially in the marginal area of ischemia reperfusion,might be a cerebral protective defense mechanism,and the degree of the activation affected the survival and repair of brain tissue,suggesting that it might play an important role in the morphological and functional plasticity after brain damage in the process of cerebral ischemia and reperfusion.