大鼠实验性脑创伤挫伤灶内皮屏障抗原和Ⅳ型水通道蛋白免疫反应性的动态改变

目的研究实验性脑创伤中内皮细胞屏障的损伤修复以及与位于星形细胞足突的Ⅳ型水通道的关系。方法成年雄性SD大鼠32只,随机分入对照组,伤后1h组,4h组,1d组,3d组,6d组和11d组。在大鼠重度冲击加速性伤模型中,应用免疫组化法观察脑创伤灶中内皮屏障抗原(EBA)和Ⅳ型水通道蛋白(AQP4)免疫反应性在不同时点的动态改变。采用图像分析技术对挫伤病灶免疫反应性进行定量分析。结果在血脑屏障损伤的皮质挫伤灶,伤后1dAQP4和EBA免疫反应性明显消失,AQP4阴性反应区面积明显大于EBA阴性反应区(P<0.05)。伤后3d,EBA表达重新出现。伤后6d,EBA表达延伸至挫伤中心区,AQP4表达始见于边缘。伤后11d,二者免疫反应性基本恢复。结论挫伤灶血管源性水肿形成同时伴有内皮屏障功能和星形细胞足突水通道的改变。同一创伤强度下,星形细胞足突AQP4损伤范围较内皮EBA大,恢复较慢。

Dynamic Changes in Immuno-reactivity of Endothelial Barrier Antigen and Aquaporin-4 in Contused Focus in Rats with Brain Injury

Objective To investigate the mechanism of damage to blood-brain barrier (BBB), correlating with the changes of water channel localized at the peri-vascular foot processes of astrocytes in the rats with experimental head injury. Method Thirty-two adult male SD rats were divided randomly into the designated groups, i.e. 1 hour, 4 hours, 1 day, 3 days, 6 days, and 11 days after the injury and control groups. A reported impact-acceleration head injury model was used. The immunoreactivity of endothelial barrier antigen (EBA) and aquaporin-4 (AQP4) in injured brains were assessed by immunohistochemistry. Image analysis was also used to quantify the negative reaction area in the contused focus. Results Loss of immunoreactivity of EBA and AQP4 were observed in the contused focal cortex with damage to BBB 1 day after the injury. The negative reaction area of AQP4 in the core of contusion was significantly larger than that of EBA in 1 day group, when exposed to the same intensity of injury (P<0.05). EBA re-expression in the contused focus started from the third day after the injury. However, re-expression of AQP4 began from the 6th day onwards. Conclusion Development of vasogenic edema in focal contusion is associated with the changes in both EBA and AQP4. Damage to the water channel at the foot processes of astrocytes is significantly more severe than that to the endothelial barrier function.