目的: 利用小鼠低氧预适应模型,探究Notch信号通路在调控低氧预适应条件下神经再生的可能作用。方法: ICR小鼠侧脑室注射γ-分泌酶抑制剂DAPT后建立低氧预适应模型,根据低氧暴露次数随机分为常氧组(C组)、低氧组(H组)、低氧预适应组(HPC组)、常氧＋二甲基亚砜对照组(DMSO组)、常氧＋DAPT组(C＋DAPT组)、低氧组＋DAPT组(H＋DAPT组)及低氧预适应组＋DAPT组(HPC＋DAPT组),应用Western-blot、RT-PCR检测海马组织内Notch1及其下游效应因子Hes1 mRNA和蛋白的表达变化,应用免疫荧光技术检测小鼠海马齿状回的细胞增殖情况。结果: 与C组和H组比较,经过低氧预适应处理7 d后,Notch1的mRNA和蛋白水平均升高(P＜0.05),Hes1的蛋白表达增加(P＜0.05);与H组相比,HPC组Brdu阳性细胞数量降低(P＜0.05);与DMSO组相比,各DAPT注射组Notch1 mRNA和蛋白水平均降低(P＜0.05),Hes1蛋白表达升高被逆转。结论: 低氧预适应可能激活Notch信号通路,调节小鼠海马区的神经元再生。
Objective: To explore the possible role of Notch signaling pathway in regulating nerve regeneration under hypoxic preconditioning conditions by using a mouse hypoxic preconditioning model. Methods: The hypoxic preconditioning model was established by intracerebroventricular injection of γ-secretase inhibitor DAPT in ICR mice. According to the number of hypoxic exposures, the mice were randomly divided into normoxic group (C group), hypoxic group (H group), hypoxic preconditioning group (HPC group), normoxic+dimethyl sulfoxide control group (DMSO group), normoxic+DAPT group (C+DAPT group), hypoxic+DAPT group (H+DAPT group) and hypoxic preconditioning+DAPT group (HPC+DAPT group). The expression of Notch1 and its downstream effector Hes1 mRNA and protein in hippocampus were detected by Western-blot and RT-PCR. The cell proliferation of hippocampal dentate gyrus was detected by immunofluorescence. Results: Compared with group C and group H, after 7 days of hypoxic preconditioning, the mRNA and protein levels of Notch1 increased (P＜0.05), and the protein expression of Hes1 increased (P＜0.05). Compared with H group, the number of Brdu positive cells in HPC group was decreased (P＜0.05). Compared with DMSO group, the mRNA and protein levels of Notch1 in each DAPT injection group were decreased (P＜0.05), and the increase of Hes1 protein expression was reversed. Conclusion: Hypoxic preconditioning may activate the Notch signaling pathway and regulate neuronal regeneration in the hippocampus of mice.
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