Department of Physiology, College of Medicine, The Catholic University of Korea.
Biol Pharm Bull. 2013;36(3):331-8. doi: 10.1248/bpb.b12-00263.
Various effects of acorn extract have been reported including antioxidant activity, cytotoxicity against cancer cells, and the levels of acetylcholine and its related enzyme activities in the dementia mouse models. However, it is unclear whether acorn extract inhibits glutamate-induced calcium signaling in hippocampal neurons. This study was an investigation into the effect of acorn extract on intracellular free Ca concentrations ([Ca]) in cultured rat hippocampal neurons using fura-2-based digital calcium imaging and photometry. Hippocampal neurons were used between 10 and 14 d in culture from embryonic day-18 rats. Treatment with acorn extract (1 µg/mL to 1 mg/mL) for 30 min inhibited glutamate (100 µM)-induced [Ca] increases in a dose-dependent manner (IC=46.9 µg/mL). After depletion of intracellular Ca stores by treatment with the inhibitor endoplasmic reticulum Ca-ATPase, thapsigargin (1 µM), treatment with acorn extract (50 µg/mL) for 30 min decreased the subsequent glutamate-induced [Ca] increases. Acorn extract significantly inhibited (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) (30 µM)-induced [Ca] increases. In addition, acorn extract inhibited the AMPA-induced [Ca] responses in the presence of 1 µM nimodipine. Acorn extract also significantly inhibited N-methyl-D-aspartate (100 µM)-induced [Ca] increases. Acorn extract significantly inhibited 50 mM KCl -induced [Ca] increases. Acorn extract significantly inhibited (S)-3,5-dihydroxyphenylglycine-induced [Ca] responses. Moreover, acorn extract almost completely blocked synaptically mediated [Ca] spikes induced by decreasing extracellular Mg concentration to 0.1 mM. These results suggest that acorn extract inhibits synaptically induced frequent [Ca] spikes through multiple pathways such as ionotropic glutamate receptors, voltage-gated Ca channels and metabotropic glutamate receptors in cultured rat hippocampal neurons.
橡实提取物具有抗氧化活性、抑制癌细胞活力、增加痴呆症小鼠模型中乙酰胆碱及其相关酶活性等多种作用。然而，橡实提取物是否能抑制谷氨酸诱导的海马神经元内钙离子信号尚不清楚。本研究采用基于 fura-2 的数字钙成像和分光光度法，观察橡实提取物对培养的大鼠海马神经元细胞内游离 Ca 浓度([Ca])的影响。采用 18 日龄大鼠胚胎培养 10-14 天的海马神经元进行实验。橡实提取物（1μg/mL 至 1mg/mL）处理 30min 可剂量依赖性抑制谷氨酸（100μM）诱导的[Ca]增加（IC=46.9μg/mL）。用内质网 Ca-ATP 酶抑制剂 thapsigargin（1μM）耗尽细胞内 Ca 库后，橡实提取物（50μg/mL）处理 30min 可降低随后谷氨酸诱导的[Ca]增加。橡实提取物显著抑制（S）-α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）（30μM）诱导的[Ca]增加。此外，橡实提取物在 1μM 尼莫地平存在下也抑制 AMPA 诱导的[Ca]反应。橡实提取物还显著抑制 N-甲基-D-天冬氨酸（100μM）诱导的[Ca]增加。橡实提取物显著抑制 50mM KCl 诱导的[Ca]增加。橡实提取物显著抑制（S）-3,5-二羟基苯甘氨酸诱导的[Ca]反应。此外，橡实提取物几乎完全阻断了通过降低细胞外 Mg 浓度至 0.1mM 诱导的突触介导的[Ca]尖峰。这些结果表明，橡实提取物通过离子型谷氨酸受体、电压门控 Ca 通道和代谢型谷氨酸受体等多种途径抑制培养的大鼠海马神经元中突触诱导的频繁[Ca]尖峰。
