创伤性脑损伤后AQP4表达与血脑屏障通透性的关系

【目的】研究创伤性脑损伤（TBI）后水通道蛋白04（AQP4）的表达变化与血脑屏障（BBB）通透性之间的关系。方法】健康成年Wistar大鼠，随机分成TBI组和假手术（S0）组。自由落体硬膜外撞击方法致重度脑创伤模型。S0组除不予以撞击外，其余操作与TBI组相同。分时段取脑，观察以下指标：①测创伤脑组织中伊文氏蓝（EB）外渗量；②透射电镜下观察创伤后BBB和细胞的超微病理改变；③免疫组化和原位杂交检测AQP4蛋白及其mRNA的表达变化；④氯化三苯四唑染色后，用图像分析软件测定每张脑片的面积和坏死区面积。【结果]BBB通透性、超微病理变化和坏死区体积百分比在s0组中变化不大。脑损伤后，BBB通透性增加，其增加有两个高峰，分别在TBI后12h和TBI后3d，以后者更明显。透射电镜下可见血管及其周围神经元、胶质细胞的超微结构有明显改变，在TBI后3d改变最明显。脑损伤后脑组织坏死区体积百分比增加，最大值也在TBI后3d。免疫组化和原位杂交显示，脑损伤后AQP4在脑组织中的表达逐渐上调，1d达高峰，持续至3d后下降，7d接近S0组水平。【结论】大鼠TBI后BBB通透性的增加与脑水肿的形成密切相关；TBI后BBB通透性增加，可能与AQP4表达上调有关，两者的变化影响TBI后脑水肿的发生、发展。

Relationship Between AQP4 Expression and Blood-brain Barrier Permeability after Traumatic Brain Injury

Objective]To investigate the relationship between the expression of Aquaporin-4（AQP4） and the permeability of blood-brain barrier （BBB） after traumatic brain injury （TBI）. Methods] Healthy Wistar rats were randomly divided into TBI group and sham operation（SO） group. The TBI group was subjected to traumatic brain injury by the Feeney＇s method. In the SO group/ only a skull hole was open with no brain im- pact. The brains of the animals were taken out at 4h, 8h, 12h, ld, 3d, 5d and 7d after TBI. The following procedures were performed： （1）The BBB permeability of traumatic brain was determined by EB extravasation method; （2） The pathological changes of the ultrastructure of BBB and the neurocytes were observed under the TEM; （3） The expressions of AQP4 and its mRNA were detected with IHC and ISH. （4） The area of the trau- matic tissue and the whole brain were analyzed with the computer imaging software after TTC staining. Results] The permeability of BBB, the ratio of traumatic tissue volume, the ultrastructure of the vessels and the neuroeytes had no significant changes in the SO group. The permeability of BBB increased after TBI. The in- creasing permeability formed two peaks at 12h and 3d after TBI respectively, and the latter was higher. The ratio of traumatic tissue volume increased after TBI, and the largest ratio reached 3d after TBI. The expression of AQP4 was positive in the cytoplasm and cytomembrane. After TBI, the expression of AQP4 up regulated and finally reached a peak at l~3d after TBI. Under TEM, the ultrastructure of the vessels and the neuro- cytes had a great change and reached a peak at 1-3d after TBI. Conclusion]The permeability of BBB increa ses after TBI, which implies that the damage of BBB is critical to the formation of brain edema after TBI. The increasing may be induced by the up-regulated expression of AQP4. The changes of BBB permeability and AQP4 expression would be involved in the formation of brain edema after TBI.