BDNF及其受体Trk B在低氧预适应小鼠中的表达变化和作用

The expression and function of BDNF and its receptor TrkB in hypoxic preconditioned mice

目的探究BDNF、TrkB受体及BDNF/TrkB信号通路在急性低氧与低氧预适应小鼠中的表达变化及作用,进一步完善低氧预适应神经保护的分子机制,为低氧预适应的临床应用提供理论依据。方法以ICR小鼠为对象,分别构建急性低氧与低氧预适应小鼠模型,模型构建完成0～4 d后,通过Western blot、real-time PCR技术,检测小鼠海马脑区BDNF、TrkB受体在早期相和晚期相的表达及BDNF/TrkB信号通路活性的变化。结果研究发现随着小鼠低氧次数的增加,耐受时间明显增加(P<0. 05);较对照组,急性低氧和低氧预适应组BDNF及全长型TrkB受体表达有增加的趋势,在低氧预适应早期相BDNF蛋白水平表达显著增加(P<0. 05)。较对照组,截短型TrkB受体表达则有降低的趋势,在低氧预适应中、晚期相其mRNA表达显著降低(P<0. 05);较对照组,急性低氧组BDNF/TrkB信号通路活性被抑制,而低氧预适应组BDNF/TrkB信号通路活性有增加的趋势,且在晚期相差异有显著性(P<0. 05)。结论低氧预适应可能是通过上调BDNF表达并增加其与TrkB受体的结合,以及下调截短型TrkB受体表达,减少异二聚体形成,从而共同激活BDNF/TrkB信号通路,最终对小鼠产生神经保护作用。

Objective To explore the expression and mechanism of BDNF and TrkB receptors under acute hypoxia and hypoxic preconditioning,and to provide a reference for the study and clinical application of hypoxic preconditioning.Methods A model of acute hypoxia and hypoxic preconditioning was generated in ICR mice.After 0-4 days,the hippocampus was isolated from the brains of hypoxic mice,and the protein and gene expressions of BDNF and its receptor TrkB were detected by Western blot and real-time PCR.Results The study found that the tolerance time was increased significantly with the increased amount of hypoxia in mice(P<0.05).Compared with the control group,the expression of BDNF and the full-length TrkB receptor in the hypoxia group was increased,and the expression of BDNF protein was significantly increased in the early phase of hypoxic preconditioning(P<0.05).Compared with the control group,the expression of the truncated TrkB receptor was decreased,and the expression of mRNA was significantly decreased in the middle and late phase of hypoxic preconditioning(P<0.05).Compared with the control group,the activity of the BDNF/TrkB signaling pathway was inhibited in the acute hypoxia group and increased in the hypoxic preconditioning group.The activity of the BDNF/TrkB signaling pathway was significantly increased in the late phase(P<0.05).Conclusions Hypoxic preconditioning may be mediated by upregulating the binding between BDNF and TrkB,downregulating the expression of truncated TrkB,reducing the formation of heterodimers,and co-activating the BDNF/TrkB signaling pathway,which ultimately has a neuroprotective effect in mice.