依达拉奉对脑缺血大鼠大脑皮质Notch-1表达的影响

The effects of Edaravone on the expression of Notch-1 in rat cortex after focal cerebral ischemia

目的:探讨依达拉奉对脑缺血大鼠大脑皮质Notch-1表达的影响。方法:应用微创开颅法复制大鼠大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)模型。将SD大鼠随机分为假手术组(Sham组)、模型组(MCAO组)和依达拉奉组(E组)。应用TTC染色测定大鼠MCAO后梗死体积,免疫组化单标、荧光双标、Realtime PCR和Western Blot技术检测大鼠MCAO后不同时间点大脑皮质Notch-1的表达变化。结果:(1)TTC染色显示依达拉奉治疗组大鼠脑缺血梗死区域明显缩小,梗死体积与MCAO组比较有显著差异(P<0.05);(2)免疫组化单标染色显示Sham组大鼠大脑皮层未见Notch-1阳性细胞表达,MCAO组于1 d、3 d及7 d在缺血半暗区可见大量Notch-1阳性细胞,依达拉奉可减少大鼠大脑皮层Notch-1阳性细胞数(P<0.05);(3)荧光双标染色显示缺血半暗区见大量呈激活状态的小胶质细胞和Notch-1阳性细胞,小胶质细胞有Notch-1表达,依达拉奉可降低Notch-1在小胶质细胞中的表达;(4)RT-PCR和Western Blot结果显示依达拉奉可明显降低MCAO大鼠Notch-1的mRNA和蛋白表达(P<0.05)。结论:大鼠脑缺血后小胶质细胞大量激活并表达Notch-1信号;依达拉奉可能通过Notch-1信号通路抑制小胶质细胞的激活,对缺血后脑组织发挥保护作用。

Objective： This study aimed to investigate the expression of Notch-1 in the cerebral cortex after middle cerebral artery occlusion （MCAO） in rats. Methods： The focal cerebral ischemia model of MCAO in rats was established following a minimal invasive craniotomy. Sprague Dawley rats were randomly divided into sham operation group （sham）, MCAO group and Edaravone （E） group. TI＇C staining was used to measure infarct volume after focal cerebral ischemia. Expression of Notch-1 in the ischemic cerebral tissue after MCAO with or without treatment was assessed by immunohisto- chemistry, Real-time PCR and Western Blot analysis. Results： （ 1 ） The results of TI＇C staining showed the infarct vol- ume in Edaravone group was significantly reduced （ P 〈 0.05 ） ; （ 2 ） Immunohistochemical staining showed that there were no obvious Notch-1 positive cells in cerebral cortex of sham group. A large number of Notch-1 positive cells were observed in MCAO group at 1 d, 3 d and 7 d. Edaravone could decrease the number of Notch-1 positive cells （P 〈 0.05） ; （3） Double immunofluorescence staining showed there were a large number of activated microglia and Notch-1 positive cells in the penumbral zones of MCAO rats. Some activated microglia expressed Notch-1. Edaravone could decrease the expression of Notch-1 in activated microglia; （4） The results of Real-time PCR and Western Blot showed that Edaravoue could significantly decrease the expression of Notch-1 mRNA and protein （P 〈 O. 05 ）. Conclusion ： Microglia were activated and expressed Notch-1 after MCAO, Edaravone may inhibit the activation of microglia via Notch-1 signal pathway and play a neuroprotective role in cerebral isehemia rat.