摘要目的 探讨大鼠脑缺血后血管内皮生长因子(VEGF)和血管生成素(angiopoietin,Ang)的表达变化及其在血管生成和血管通透性变化中的作用.方法 选择160只雄性SD大鼠,采用随机区组法分为假手术组,缺血2h、6h、12h、1d、3d、7d和14d组,用线栓法制作大脑中动脉阻塞脑缺血损伤模型,分别于脑缺血后不同时间点处死大鼠.通过逆转录聚合酶链反应(RT-PCR)、Western blot及免疫组织化学方法检测大鼠脑缺血后不同时间点VEGF、Ang-1及Ang-2 mRNA和蛋白的表达变化.CD31标记鼠脑缺血后不同时间点的血管数量.Evans blue检测血脑屏障通透性.结果 大鼠脑缺血后VEGF mRNA表达逐渐增高,12 h达第一个高峰(0.7249 ±0.1933,P＜0.01),7d达第二个高峰(0.5264±0.1519,P＜0.01)；VEGF蛋白表达也逐渐增高,于12 h达高峰(1.1017±0.1302,P＜0.01).Ang-2 mRNA和蛋白在脑缺血组织也逐渐增高,均12 h达高峰(0.6747±0.2416,P＜0.01；1.1197±0.1780,P＜0.01).与之相反,Ang-1 mRNA和蛋白表达逐渐降低,分别于3 d(0.3220±0.1427,P＜0.01)和1 d(0.1298±0.0293,P＜0.01)达最低水平,这些因子在脑缺血后的表达促进血管生成.脑缺血后血管通透性逐渐增加,EB含量在缺血1d达高峰[(6.219±0.887) μg/g,P＜0.01].结论 大鼠脑缺血后VEGF、Ang-1和Ang-2共同协调作用促进血管生成,在组织损伤修复过程中发挥着重要的作用.

abstractsObjective To examine the temporal and spatial expression of vascular endothelial growth factor (VEGF) and angiopoietins (Ang) in rat brain after cerebral ischemia,and to elucidate the roles they played in angiogenesis and vascular permeability.Methods Rats were subjected to either middle cerebral artery occlusion (MCAO) or sham operation.Reverse transcriptase-polymerase chain reaction,Western blotting,and immunohistochemistry were used to detect the expression of VEGF,Ang-1 and Ang-2 at different time points after ischemia.CD31 was used to label endothelial cells after MCAO.Vascular permeability was determined by Evans blue.Results VEGF was markedly increased at 2 h,had an initial peak at 12 h (0.7249 ±0.1933,P＜0.01),and a second peak at 7 days(0.5264 ±0.1519,P ＜0.01).Ang-2 mRNA and protein significantly increased after MCAO,both of them peaked at 12 h (0.6747 ±0.2416,P ＜ 0.01 ; 1.1197 ± 0.1780,P ＜ 0.01 ).In contrast,Ang-1 mRNA and protein gradually decreased after MCAO,respectively reaching a minimum at 3 d (0.3220 ± 0.1427,P ＜ 0.01 ) and 1 d(0.1298 ±0.0293,P ＜0.01 ).Changes in the expression of these factors correlated with the progress of angiogenesis and vascular permeability.Evans blue test revealed that the vascular permeability gradually increased,and peaked at day 1 afterischemia [(6.219±0.887) μg/g,P＜0.01].Conclusion Dynamic temporal changes in VEGF,Ang-1 and Ang-2 expression stimulate the cerebral angiogenesis after focal cerebral ischemia.