缺血后大鼠脑内神经血管单元病理损害的研究

Research on pathological lesion of neurovascular unit in rat brain after chronic cerebral ischemia

目的观察慢性缺血后大鼠脑内神经血管单元的病理损害。方法将30只Wistar大鼠随机分为假手术组5只和缺血组25只。缺血组大鼠分别在缺血3、7、14 d、1、3个月时间段,各取5只灌注取脑,采用HE染色观察大鼠神经细胞的病理改变;免疫组织化学半定量检测胶质纤维酸性蛋白(GFAP)、血管内皮生长因子(VEGF)和层黏连蛋白(Laminin)的含量,观察其动态变化规律。结果缺血早期神经元皱缩、肿胀,后期嗜酸性变和坏死。星形胶质细胞早期肿胀、断裂,随着缺血时间的延长胶质细胞开始增生,形成瘢痕组织,同时伴有血管新生。与假手术组比较,缺血组大鼠5个时间段GFAP表达进行性增加;缺血3 d VEGF表达开始增加,7、14 d增加明显(P<0.05),1、3个月VEGF表达虽有减少但仍高于假手术组(P<0.05)。缺血3 d Laminin明显减少,7 d减少更明显,14 d、1、3个月表达逐渐增加(P<0.05)。结论慢性脑缺血后在不同时间段,神经元、GFAP、VEGF、Laminin呈规律变化。脑部缺血后不仅是神经元的变化,还有胶质细胞、血管内皮细胞及基底膜的变化。

Objective To observe pathological lesion of neurovascular unit in rat brain after chronic cerebral ischemia. Methods Thirty Wistar rats were randomly divided into sham operation group （five） and ischemia group（twenty-five）. After the rats were in ischemia for 3, 7, 14 d, 1,3 months,five rats from ischemia group were sacrificed at each time period and brains were taken. HE staining was used to examine the pathological changes in nerve cell, immunohistochemical method was used to examine the contents of glial fibrillary acidic protein（GFAP）, vascular endothelial growth factor（VEGF） and laminin and observe the regularity of dynamic changes. Results Neurons at the early ischemic stage shrank, swelled,later became acidophilic and necrotic. Astrocytes at early stage swelled and fractured;with prolongation of ischemia time,glial cells began to proliferate and formed scar tissue, accompanied by angiogenesis. Compared with sham group, GFAP expression in ischemia group increased progressively in 5 time periods. After ischemia for 3 d,VEGF expression began to increase,and increased significantly on d 7 and d 14 of ischemia,in 1,3 months,although the VEGF expression decreased, but still higher than sham group. After 3 d of ischemia,laminin reduced significantly and more significantly after 7 d, but gradually increased after 14 d, 1,3 months （P 〈 0.05）. Conclusion The neuron, GFAP, VEGF and laminin show regular changes after chronic cerebral ischemia. After brain ischemia, not only the neurons change, but also glial cells, vascular endothelium and basement membrane show regular changes.