大鼠脑出血后水通道蛋白4的表达与血脑屏障超微结构变化的相关性研究

Correlation between aquaporin-4 expression and the change of blood-brain barrier ultramicrostructure after cerebral hemorrhage in rats

目的观察脑出血后水通道蛋白4(AQP4)和血脑屏障(BBB)超微结构在脑水肿形成中的不同时间点的变化特征,探讨二者在脑水肿形成中的作用机制。方法采用自体非抗凝血注入尾状核制做脑出血模型,免疫组化法检测脑出血后血肿周围组织AQP4的表达,伊文思蓝检测BBB的通透性,干湿重法检测脑水肿含水量,电镜观察BBB超微结构的变化。结果与对照组相比较,脑出血组在脑出血后6h脑含水量、AQP4表达和伊文思蓝含量开始增加,差异有显著性(P<0.05),72h达到最高峰(P<0.05),之后开始下降,到第7天仍高于正常。AQP4表达与BBB通透性呈显著正相关(r=0.726,P<0.05);AQP4表达与脑含水量的变化规律也趋于一致(r=0.793,P<0.05)。BBB电镜观察:脑出血后6h脑微血管内皮细胞吞饮小泡增多、线粒体堆积。72h胶质细胞足突内线粒体逐渐肿胀、模糊,细胞充满大量空泡,基膜断裂。7d内皮细胞回缩,毛细血管基底膜形态开始恢复。结论脑出血后AQP4表达和BBB的通透性有显著相关性,提示脑出血后可能通过提高AQP4的表达水平,增加BBB的通透性,参与脑水肿的形成。

Objective To examine the changes of aquaporin-4 （AQP4） expression and blood-brain barrier （BBB） ultramicrostructure after cerebral hemorrhage in rats and their roles in the development of brain edema. Methods The cerebral hemorrhage models were prepared by stereotaxic injection of auto-non-anticoagulant artery blood into the caudate nucleus. AQP4 expression was detected by im- munityhistochemistry. BBB permeability was detected by Evans blue method. Brain water contents were measured by dry-wet weigh method. BBB uhramicrostructure was observed under a byelectron microscope. Results Compared with the normal control group, AQP4 expression, BBB permeability and brain water content increased in the cerebral hemorrhage group at 6 hrs （ P 〈 0.05 ）, reached a peak at 72 hrs （ P 〈 0.01 ）, then decreased gradually, but remained higher at 7 days after hemorrhage. AQP4 expression was positive correlated with BBB permeability （ r = O. 726, P 〈 O. 05 ） and brain water content （ r = O. 793, P 〈 0.05 ）. Pinocytosis bullule in- creased and chondrosomes were piled up in vascular endothelial cells 6 hrs after cerebral hemorrhage. Chondrosomes in the foot process of gliacyte was swollen and dim and basal lamina was disrupted at 72 hrs. Endothelial ceils and capillary basement membranes were gradually recovered 7 days after hemorrhage. Conclusions There is a positive correlateion beween AQP4 expression and BBB permea- bility in rats with cerebral hemorrhage. This suggests that cerebral edema may be developed through the up-regulation of AQP4 expres- sion and the increase of BBB permeability after cerebral hemorrhage.