水通道蛋白-4在大鼠急性脑缺血再灌注脑组织中的表达

Expression of aquaporin-4 in rats brain tissues after acute cerebral ischemia and reperfusion

目的:探讨水通道蛋白-4(AQP4)在急性脑缺血再灌注脑组织中的表达规律。方法:线栓法建立右侧大脑中动脉栓塞(MCAO)模型,分为假手术组、栓塞组和再灌注组。对脑组织病理观察、TTC染色,免疫组织化学、原位杂交组织化学、荧光定量PCR和免疫印迹检测。结果:栓塞组在右侧基底节区见细胞器肿胀、细胞体积增大,但细胞膜和血脑屏障结构完整,TTC染色缺血面积明显增加。所有再灌注组右侧基底节区的细胞肿胀减轻,再灌注早期组可见轻度血管源性水肿,TTC染色缺血面积逐渐缩小。AQP4基因和蛋白的表达量明显下降,分别与栓塞组比较均存在显著性差异。再灌注后各组AQP4基因和蛋白表达明显下降,但均高于假手术组。结论:无论是脑缺血或是再灌注,AQP4的表达均与细胞内水肿的程度一致,再灌注早期可出现血管源性水肿,再灌注越早脑细胞越容易恢复正常。

Objective： To investigate the rule of aquaporin-4 （AQP4） expression in rat brain tissue following the acute cerebral ischemia and reperfusion. Methods： 70 Wistar rats were randomly divided into 7 groups, including control group（A） and occluded and reperfusion groups. In the occluded groups, the right middle cerebral artery of rats was unilaterally occluded （MCAO） at an interval of 30 min （B）, 60 min （C）, and after that, the reperfusion was performed at an interval of 30 min （D, E）, 60 min （F, G） （n=10）. All rats were sacrificed and perfused with the mixture solution of TTC. The acute cerebral ischemic tissues were examined with light microscope （LM）, transmission electron microscope （TEM）, immunohistochemistry （IC）, in situ hybridization （ISH）, real-time fluorescent quantitative PCR and Western blotting. Results： The ischemic areas detected by TTC staining became larger over time. Simultaneously, the expression of AQP4 in Group B and C increased significantly compared with that in Group A. However, after reperfusion, the cell organs became less swollen. At the right basal ganglia of Groups D, E, F and G, vasogenic brain edema was observed, the ischemic areas detected by TTC staining was reduced, and the expression of AQP4 decreased significantly. There was significant difference between occluded groups （B, C） and reperfusion groups （D, E, F, G）. The significant decrease of AQP4 expression was indicated in all reperfusion groups, but the expression was higher than that in the control group. Conclusion： Both in cerebral ischemia and reperfusion groups, the change of AQP4 expression was coincided with the extent of the intracellular brain edema. Vasogenic brain edema was exhibited in the early stage of reperfusion. The earlier reperfusion operates the better recovery of the neurons shape, which lays an experimental basis of the clinic gene therapy for brain infarction.