Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA.
Biochem Biophys Res Commun. 2014 Feb 28;445(1):218-24. doi: 10.1016/j.bbrc.2014.01.166. Epub 2014 Feb 4.
Delivery of optimal amounts of brain-derived neurotrophic factor (BDNF) to regions of the brain affected by neurodegenerative diseases is a daunting task. Using natural products with neuroprotective properties, such as green tea polyphenols, would be a highly useful complementary approach for inexpensive long-term treatment of these diseases. In this study, we used PC12(TrkB) cells which ectopically express TrkB, a high affinity receptor for BDNF. They differentiate and induce neurite outgrowth in response to BDNF. Using this model, we show for the first time that treatment with extremely low concentrations (<0.1 μg/ml) of unfractionated green tea polyphenols (GTPP) and low concentrations (<0.5 μM) of their active ingredient, epigallocatechin-3-gallate (EGCG), potentiated the neuritogenic ability of a low concentration (2 ng/ml) of BDNF. A synergistic interaction was observed between GTPP constituents, where epigallocatechin and epicatechin, both individually lacking this activity, promoted the action of EGCG. GTPP-induced potentiation of BDNF action required the cell-surface associated 67 kDa laminin receptor (67LR) to which EGCG binds with high affinity. A cell-permeable catalase abolished GTPP/EGCG-induced potentiation of BDNF action, suggesting the possible involvement of H2O2 in the potentiation. Consistently, exogenous sublethal concentrations of H2O2, added as a bolus dose (5 μM) or more effectively through a steady-state generation (1 μM), potentiated BDNF action. Collectively, these results suggest that EGCG, dependent on 67 LR and H2O2, potentiates the neuritogenic action of BDNF. Intriguingly, this effect requires only submicromolar concentrations of EGCG. This is significant as extremely low concentrations of polyphenols are believed to reach the brain after drinking green tea.
将足够量的脑源性神经营养因子（BDNF）递送到受神经退行性疾病影响的大脑区域是一项艰巨的任务。使用具有神经保护特性的天然产物，如绿茶多酚，将是一种非常有用的补充方法，可以廉价地长期治疗这些疾病。在这项研究中，我们使用了 PC12（TrkB）细胞，这些细胞异位表达 TrkB，这是 BDNF 的高亲和力受体。它们分化并响应 BDNF 诱导神经突生长。使用这种模型，我们首次表明，极低浓度（<0.1μg/ml）的未分级绿茶多酚（GTPP）和其有效成分表没食子儿茶素-3-没食子酸酯（EGCG）的低浓度（<0.5μM）处理增强了低浓度（2ng/ml）BDNF 的神经突生成能力。观察到 GTPP 成分之间存在协同相互作用，其中表没食子儿茶素和表儿茶素单独缺乏这种活性，但促进了 EGCG 的作用。GTPP 诱导的 BDNF 作用增强需要细胞表面相关的 67kDa 层粘连蛋白受体（67LR），EGCG 与该受体具有高亲和力结合。细胞通透性过氧化氢酶消除了 GTPP/EGCG 诱导的 BDNF 作用增强，表明 H2O2 可能参与了增强作用。一致地，外源性亚致死浓度的 H2O2，作为单次剂量（5μM）添加，或通过稳态产生（1μM）更有效地添加，增强了 BDNF 的作用。总的来说，这些结果表明 EGCG 依赖于 67LR 和 H2O2 增强 BDNF 的神经突生成作用。有趣的是，这种作用只需要亚毫摩尔浓度的 EGCG。这很重要，因为饮用绿茶后，相信极少量的多酚可以到达大脑。
