星形胶质细胞的缝隙连接蛋白43参与冷冻伤后脑水肿的形成

目的:探讨脑水肿后星形胶质细胞缝隙连接蛋白43(Cx43)的表达及其在脑水肿的发生发展过程中所起的作用。方法:采用颅骨外液氮冷冻法建立大鼠右侧顶叶皮层脑水肿模型。实验分为假手术组、脑水肿模型组和脑水肿模型+缝隙连接阻断剂(carbenoxolone或octanol)干预组。干湿重法测定冷冻伤后的脑含水量;甲酰胺法测定大鼠血脑屏障通透性的改变;HE染色观察冷冻伤脑组织的病理变化;Western blot法和免疫组化检测Cx43蛋白的表达情况。结果:冷冻伤可引起大鼠损伤脑皮层区的含水量增加,在冷冻伤后24 h脑水肿发展到高峰。冷冻伤引起损伤脑皮层区域的血脑屏障通透性增加,范围大于直接冷冻损伤区。HE染色观察显示冷冻伤中心区细胞坏死明显,而冷冻伤周围区域出现水肿。脑冷冻伤引起冷冻伤周围皮层区域的Cx43蛋白表达增加,但冷冻伤中心区的Cx43蛋白表达降低。Carbenoxolone或octanol阻断Cx43的功能,降低了冷冻伤皮层区的含水量和血屏障通透性。结论:脑水肿时星形胶质细胞上的Cx43表达上调,功能增强;阻断Cx43的功能可在一定程度上减轻脑水肿。

Astrocytic connexin 43 is involved in development of cryoinjury-induced cerebral edema

ATM: To discuss the change of astrocytic connexin 43 (Cx43) expression in cerebral edema and the potential roles of Cx43 in the development of cerebral edema. METHODS: Cryoinjury-induced cerebral edema model was established in the right parietal lobe cortex in the rats. The animals were divided into sham group, cryoinjury-induced cerebral edema model group, and cryoinjury-induced cerebral edema model injected with carbenoxolone (or octanol) group. Dry and wet weight method was used to measure the content of brain water. Methanamide method was used to evaluate the permeability of blood-brain barrier (BBB) after cryoinjury. HE staining showed the physiological changes in injured brain cortex. The protein expression of Cx43 was detected by Western blot and immunohistochemical staining. RESULTS: The brain water content in the injured cortex of rats was increased and cerebral edema developed to the peak at 24 h after cryoinjury. The permeability of BBB was increased in the injured cortex of the rats, and the area where BBB was damaged was larger than injured area. HE staining showed that many cells were dead in the central area of cryoinjury, and at the same time cerebral edema was appeared obviously in the surrounding area of injured brain cortex. The protein expression of Cx43 was up-regulated in the surrounding area of injured brain cortex, while Cx43 expression decreased in the injured cortex at different periods after cryoinjury. Both the content of brain water in the injured cortex and the permeability of BBB at 24 h after cryoinjury were reduced after injecting carbenoxolone or octanol intraperitoneally to block Cx43. CONCLUSION: The cerebral edema up-regulates the expression of Cx43 and also strengthens its function. Once Cx43 is blocked, the degree of cerebral edema in rats is attenuated.