何首乌苷通过激活BDNF/TrkB信号通路拮抗H2O2诱导的大鼠海马神经元氧化损伤

探讨脑源性神经营养因子/酪氨酸激酶受体B(BDNF/TrkB)信号通路激活参与何首乌苷(PMG)对过氧化氢(H2O2)诱导神经元氧化应激损伤的保护作用。实验采用神经元原代培养,建立大鼠乳鼠海马神经元氧化应激损伤模型。实验结果显示高浓度的H2O2与MTT测定的细胞存活率降低相关,选择细胞存活率在40%~50%之间的200μmol/LH2O2浓度作为氧化应激损伤的实验浓度。与模型组相比,PMG预处理组(200μmol/L)可抑制H2O2诱导的神经元损伤(P<0.001)。TUNEL和β-微管蛋白III荧光染色显示PMG保护H2O2诱导的神经细胞损伤,明显降低细胞凋亡率(P<0.001),细胞骨架形态恢复正常。与PMG+H2O2预处理组相比较,当加入BDNF/TrkB信号转导通路阻断剂K252a后,PMG+H2O2+K252a组神经元细胞存活率大幅度下降(P<0.01),细胞骨架形态呈损伤状态。同时,我们发现PMG预处理恢复H2O2诱导的BDNF和P-TrkB的低表达水平,并且用K252a阻断BDNF/TrkB信号传导抑制了PMG对BDNF和P-TrkB表达水平的影响(P<0.01)。综上所述,何首乌苷可能通过激活BDNF/TrkB信号转导通路及维护神经元骨架的完整,实现对大鼠海马神经元氧化应激损伤的拮抗作用。

PMG antagonizes H2O2-induced oxidative damage in rat hippocampal neurons via activating BDNF/TrkB signaling pathway

This study focuses on the protective role of Polygonum multiflorum glycosides (PMG) on hydrogen peroxide (H2O2)-induced neuronal injury and the involvement of brain-derived neurotrophic factor/tyrosine kinase receptor B (BDNF/TrkB) signaling pathway.Oxidative stress injury model of neonatal rat hippocampal neurons was used.The results showed that the high concentration of H2O2 is associated with the lower the cell viability with MTT assay and 200 μmol/L H 2O 2,resulting in cell viability between 40% and 50%,was chosen for inducing oxidative stress.PMG pretreatment group (200 μmol/L) inhibited H2O2-induced neuronal damage comparing to model group ( P <0.001).TUNEL and β-tubulin III fluorescence staining showed PMG protected H2O2 induced damage of neuronal cells,the apoptosis rate ( P <0.001),and the damaged cytoskeleton morphology.Comparing with the PMG+H2O2 pretreatment group,inclusion of K252a,a BDNF/TrkB signal transduction pathway blocker,decreased the neuronal survival rate ( P <0.01) and maintained an abnormal state of cytoskeletal morphology.Finally,we found that PMG pretreatment restored H2O2 induced lower expression level of BDNF and P-TrkB and blocking BDNF/TrkB signaling with K252a inhibit the PMG effect on BDNF and P-TrkB expression level.In summary,PMG has a protective effect on H2O2-induced oxidative stress in neonatal rat hippocampal neurons,potentially through activation of BDNF/TrkB signal transduction pathway to maintain normal morphology of neuronal skeleton.