大鼠弥漫性轴索损伤后大脑皮层rab10的表达及意义

Expression and significance of rab10 in the cerebral cortex of rats after diffuse axonal injury

目的研究大鼠弥漫性轴索损伤（diffuse axonal injury,DAI）后小G蛋白rab10在大脑皮层的表达变化规律,探讨DAI后rab10在神经修复中的作用及意义。方法采用头颅瞬间旋转损伤装置建立大鼠DAI模型,随机分为1d、3d、7d组及对照组。采用Gless嗜银染色和TUNEL染色分别观察DAI后神经轴索形态和凋亡变化;采用Western blot、免疫组化等方法检测大鼠大脑皮层rab10的分布及表达,并采用免疫荧光双标染色分析大脑皮层神经元内rab10的表达变化。结果嗜银染色显示DAI后1d神经轴索形态损伤最严重,3～7d时损伤逐渐减轻;TUNEL染色显示DAI后1d凋亡细胞数开始升高,3～7d时凋亡数量更高,呈迟发性改变。Western blot及免疫组化结果均提示DAI后1d大脑皮层rab10的表达显著增加,3d后稍降低,7d后明显降低,但仍高于正常（P〈0.05）;免疫荧光双标染色提示正常神经元内几乎不表达rab10,DAI后神经元内rab10表达在1～3d较高,7d时较前降低。结论大鼠DAI后大脑皮层rab10表达水平先增加,随后降低;神经元内rab10的表达变化可能与DAI后神经轴索修复有关。

Objective To explore the dynamic expression of rabl0 in rat cerebral cortex after diffuse axonal injury （DAI） and its role in DAI. Methods Rat DAI models were established by a facility developed to let the rats＇ heads spin 90 degrees at the moment to cause shearing injury. Rats were randomly divided into 4 subgroups （sham-operation group and 1, 3 and 7 d groups）. The morphological changes of neural and axonal injury were observcd under microscopy by Gless＇ silver impregnation technique. Apoptosis of neurons was observed by TUNEL. Western blot and immunohistochemistry staining were used to determine the expression of tab10 in cerebral cortex after DAI. The expression and co-localization of tab10 and neuN in rats after DAI were evaluated by double-labeling immunofluorescence staining at different time points. Results The morphological damage was most obvious at 1 d after DAI, and the damage gradually lessened from 3 d to 7 d. TUNEL staining showed that the number of apoptotic cells began to rise at 1 d after DAI, and the number of apoptosis was higher at 3 d and 7 d. The expression of rab10 increased significantly at 1 d after DAI, declined slightly after 3 d, and declined significantly at 7 d （P〈0.05）. The co-localization of rabl0 and neuN revealed that rab10 in neurons increased during 1 and 3 d after DAI and then gradually decreased. Oonclusion Rabl0 expression significantly increases and then gradually deceases in cerebral cortex of rats after DAI. Changes of rabl0 expression in neurons might be related to the repair of axonal morphology after DAI.