目的 探讨细胞外信号调节激酶/cAMP反应元件结合蛋白（ERK/CREB）信号通路在异菝葜皂苷元（SMI）促进β-淀粉样肽（Aβ）损伤SH-SY5Y细胞脑源性神经营养因子（BDNF）表达中的作用及其机制。方法 建立Aβ损伤SH-SY5Y细胞模型，采用RT-PCR法检测BDNF mRNA的表达，用Western blotting的方法检测pCREB和pERK的变化，最后通过阻断实验确认ERK/CREB信号通路在SMI促进BDNF mRNA表达中的作用。结果 SMI能促进Aβ损伤SH-SY5Y细胞BDNF mRNA的表达（P=0.000），并能上调信号分子CREB和ERK1/2的磷酸化水平（P=0.001，P=0.000）。用RNA干扰的方法阻断CREB的表达后，SMI促进BDNF mRNA表达的作用完全消失;用U0126阻断ERK1/2磷酸化后，SMI促进pCREB水平升高的作用完全消失。结论 SMI通过ERK/CREB通路促进Aβ损伤SH-SY5Y细胞BDNF mRNA的表达。

Objective To investigate the role of extracellular signal regulated kinase/cAMP response element binding protein (ERK/CREB) signaling pathway in promotion of brain derived neurotrophic factor (BDNF) expression in β-amyloid (Aβ) intoxicated SH-SY5Y cells by smilagenin (SMI) and relevant mechanisms. Methods The Aβ intoxicated cell model was built and RT-PCR assay was employed to detect the BDNF mRNA expression. Western blotting was used to detect changes in pCREB and pERK expressions. Finally, the role of ERK/CREB signaling pathway in the promotion of BDNF mRNA expression by SMI was confirmed by the use of blocking assay. Results SMI promoted the BDNF mRNA expression in Aβ intoxicated SH-SY5Y cells (P=0.000) and up-regulated the phosphorylation level of signal molecules CREB and ERK1/2 (P=0.001, P=0.000). After blocking the CREB expression by RNA interference, the effect of SMI on promoting the BDNF mRNA expression completely vanished. After blocking the ERK1/2 phosphorylation with U0126, the effect of SMI on promoting the increase in pCREB level completely vanished. Conclusion SMI promotes the BDNF mRNA expression in Aβ intoxicated SH-SY5Y cells through the ERK/CREB pathway.