水通道蛋白9与血脑屏障通透性在大鼠缺血性脑水肿中的变化

Changes in Aquaporin-9 Expression and Blood-brain Barrier in the Brain of Rats after Focal Cerebral Ischemia

目的:探讨水通道蛋白9(AQP9)及血脑屏障(BBB)通透性在大鼠缺血性脑组织中的表达变化及其与脑水肿形成的关系。方法:SD大鼠60只,随机分为缺血组40只和假手术组20只。缺血组采用大脑中动脉栓塞法(MCAO)制备大鼠局灶性脑缺血模型,假手术组不造成缺血。在脑缺血6、12、24、48、72 h,通过光镜对缺血脑组织进行病理观察,检测脑缺血不同时程脑中伊文思蓝(EB)外渗的量,并应用免疫组化技术测定梗死区AQP9的分布及表达水平。结果:脑缺血后,光镜下可见神经元变性坏死,界限不清,核仁消失,血管内皮细胞肿胀,周围间质增大,部分细胞坏死,胶质细胞增生;脑缺血后6h,脑组织EB含量开始增加,并随缺血时间延长逐渐上升,在缺血后48 h达到高峰。在海马、透明隔、脉络丛、大脑皮质等发现AQP9于缺血后6 h开始上升,与EB含量的变化相似,48 h达到高峰,二者与假手术组相比差异有统计学意义(P<0.05);AQP9的表达变化与EB呈正相关(r>0.67,P<0.05)。结论:脑缺血后AQP9表达变化与血BBB的开放和脑水肿的形成密切相关,提示AQP9可能是缺血性脑水肿形成的重要参与因素。

Objective： To explore the changes in aquaporin-9（AQP9） expression and blood-brain bar- tier permeability in ischemia. Methods： Sixty SD rats were divided into ischemic group （n=40） and sham-operation group （n=20） randomly. The ischemic group was made by occluding unilateral middle cerebral artery with the suture method. And the sham-operation group was not caused ischemia. The morphology was observed with HE staining, the blood-brain barrier permeability was determined by Evans Bule （EB） extravasation method, and the expression of AQP9 was assessed by immunocyto- chemistry assay, at interval times of 6 h, 12 h, 24 h, 48 h, 72 h after cerebral ischemia, respectively. Results：Light microscopy showed neuronal degeneration and necrosis, swelling of the vascular en- dothelial cells, enlarged space around the neurons and peri-vascular space, and the increased number of gliosis. At 6 hours after cerebral ischemia, brain tissue EB content began to increase, and reached its peak at 48 hours. AQP9 expression rose 6h after ischemia in a similar manner to EB content. There was a positive correlation between expression of AQP9 and BBB penetrability （r〉0.67, P〈0.05）. Con- clusions：The up-regulation of AQP9 expression might imply that AQP9 would have a close relation to the formation of brain edema after cerebral ischemia.