永久性大脑局灶缺血后angiopoietin-2和血管内皮生长因子在小鼠大脑皮层的表达

摘要

AIM: To study the expressions of vascular endothelial growth factor ( VEGF ), angiopoietin-1 ( Ang-1 ),angiopoietin-2 (Ang-2), Tie-l, and Tie-2 in C57BL/6mouse brain after permanent focal cerebral ischemia.METHODS: The mRNA levels of VEGF, Ang-1, Ang2, Tie-l, and Tie-2 were measured by semiquantitative reverse transcription polymerase chain reaction (RTPCR). The protein expressions of VEGF and Ang-2were determined by immunohistochemistry. RESULTS: Low mRNA levels of VEGF, Ang-1, Ang-2,Tie-l, and Tie-2 were constitutively expressed in the normal cortex of mouse. After middle cerebral artery occlusion (MCAO), the expressions of VEGF, Ang-2,and Tie-2 mRNA were dramatically increased in the infarcted cortex and the elevation was remained through 7 d of ischemia. However, the levels of Ang-1 and Tie1 mRNA were unchanged in the infarcted cortex.Immunoreactivities of Ang-2 or VEGF were hardly observed in the normal cortex. Ang-2 protein was evidently detected in the infarct core 8 h after MCAO and in the perifocal area 1 d after MCAO. Expression of VEGF protein was elevated in the infarct core 2 h after MCAO and in the perifocal area 1 d after MCAO.Immunoreaction was restricted to endothelial cells and glial-like cells within the infarct core and perifocal area.CONCLUSION: The expressions of Ang-2 and VEGF are induced after focal cerebral ischemia, which may contribute to the angiogenic response in the cortex of ischemic brain.%目的:研究永久性大脑局灶缺血后血管内皮生长因子(VEGF)、angiopoietin-1(Ang-1)、Ang-2、Tie-1和Tie-2在C57BL/6小鼠大脑皮层的表达.方法:采用半定量逆转录聚合酶链反应(RT-PCR)研究VEGF、Ang-1、Ang-2、Tie-1和Tie-2 mRNA表达的变化.采用免疫组织化学法研究VEGF和Ang-2蛋白的表达.结果:在正常小鼠大脑皮层VEGF、Ang-l、Ang-2、Tie-1和Tie-2 mRNA表达水平很低.当大脑中动脉阻断(MCAO)后,在梗塞皮层VEGF、Ang-2和Tie-2 mRNA表达显著增加,并且可维持到第7天.但Ang-1和Tie-1 mRNA表达在梗塞皮层无明显变化.在正常小鼠大脑皮层,几乎观察不到VEGF和Ang-2蛋白的表达.MCAO后8小时Ang-2蛋白表达在皮层梗塞区明显增加,l天后可在梗塞灶周边区看到Ang-2蛋白增加;而VEGF蛋白则在MCAO后2小时在皮层梗塞区即显著升高,1天后在梗塞灶周边区可观察到VEGF蛋白增加.不论在皮层梗塞区还是在梗塞灶周边区,Ang-2和VEGF免疫阳性都限于内皮细胞和胶质样细胞.结论:大脑局灶缺血后Ang-2和VEGF表达增加,可能有利于缺血大脑皮层的血管新生.