原儿茶酸对β淀粉样蛋白_(1-42)诱导PC12细胞毒性的保护作用及机制

Effect of Protocatechuic Acid on Preventing PC12 Cells from Aamyloid Beta-Peptide-induced Toxicity and Its Mechanism

【目的】探讨原儿茶酸（PCA）在阿尔茨海默病（AD）细胞模型中的保护作用及机制。【方法】采用免疫荧光法鉴定β淀粉样蛋白（Aβ_（1-42））纤维聚体,将Aβ_（1-42）作用于PC12细胞,并于不同时间点（0、3、6、9、12、24 h）观察细胞形态,采用四甲基偶氮唑盐（MTT）法检测细胞存活率以确定造模条件,并用MTT法检测原儿茶酸对PC12细胞的毒性条件。采用预保护的给药方式,检测不同浓度的原儿茶酸对PC12细胞的干预作用。采用Western-blot法检测自噬相关标记蛋白Beclin1的表达水平,以探究原儿茶酸的保护作用机制。【结果】显微镜下观察到12、24 h时,Aβ_1-42白色团块聚集基本稳定,无明显差异,MTT检测细胞损伤率均达40%,由此确定12 h和24 h均可做为AD的造模条件。原儿茶酸在200~800μmol/L浓度作用24 h的条件下,细胞活力显著上升（P〈0.01）。Western-blot结果显示：原儿茶酸可显著增加Beclin1的表达水平。【结论】原儿茶酸有助于改善Aβ_（1-42）诱导的PC12细胞毒性,其机制可能与增加自噬水平有关。

Objective To investigate the protective effect of protocatechuic acid（PCA）on the PC12 cell model of Alzheimer＇s disease（AD）and to explore its mechanism. Methods Amyloid beta peptide1-42（Aβ1-42）fiber polymers were identified by immunofluorescence. After PC12 cells were stimulated with the Aβ1-42 fiber polymers, the cellular morphology was observed at different time points of hour 0, 3, 6, 9, 12, 24, and the cellular viability was tested by methyl thiazolyl tetrazolium（MTT）assay to monitor the modeling condition. The effect of PCA on PC12 cells was detected after PC12 cells were pretreated with the different contentions of PCA.Autophagy-related marker Beclin1 protein level was detected by Western blotting method to investigate the protective mechanism of PCA. Results Aggregated white Aβ1-42 mass was stable at hour 12 and 24,and showed no significant difference between the two time points,the cell damage rate being 40%. Therefore, we defined culturing time being 12 and 24 hours as the modeling condition of AD model. The cell viability was increased with 200- 800 μmol/L of PCA after culturing for 24 hours（P〈 0.01）,and the Western blotting results showed that the Beclin1 protein expression was up-regulated by PCA. Conclusion PCA prevents PC12 cells from Aβ1-42-induced toxicity,the mechanism being related with the increase of cellular autophagy.