过刊浏览

人参皂甙Rb1减轻冈田酸诱导的大鼠海马神经元Tau蛋白过度磷酸化

李永坤, 陈晓春, 朱元贵, 彭小松, 曾育琦, 沈杰, 黄天文

福建医科大学附属协和医院,福建省老年医学研究所.福建,福州 350001

摘要

为研究人参皂甙Rb1(ginsenoside Rb1)对冈田酸(okadaic acid,OA)诱导的大鼠海马神经元Tau蛋白过度磷酸化的影响及其可能机制,实验随机分为正常组、溶媒对照组、OA模型组和Rb1预处理组。正常组不作任何处理;Rb1预处理组大鼠分别用5、10、20 mg/kg的Rb1预处理,每天一次,共14 d,于d13向海马背侧注射1.5#mu#l OA[0.483#mu#l,溶于10%二甲基亚砜(dimethysulphoxide,DMSO)];OA模型组大鼠于第13天时海马背侧注射OA,溶媒对照组则注射等体积的生理盐水。各组均于第15天收取标本。通过Bieschowski's染色、免疫组化和Western blot,分别观察大鼠海马神经元胞体和突起内神经原纤维的改变和磷酸化Tau蛋白的表达水平,同时检测蛋白磷酸酯酶2A(protein phosphatase--2A,PP2A)活性以探讨其作用机制。结果显示:(1)OA模型组与溶媒对照组及正常组比较,海马神经元胞体和突起着色较深,染色不均匀;神经元中Thr~(231)和Ser~(396)位点磷酸化的Tau蛋白和总Tau含量增多;PP2A活性则明显下降({sl P}<0.01);(2)Rb1预处理组大鼠海马神经元胞体和突起染色均匀,神经原纤维走行规则;海马神经元中Thr~(231)和Ser~(396)位点磷酸化的Tau蛋白和总Tau含量较OA模型组减少,而PP2A活性明显增高({sl P}<0.01)。以上观察结果表明,人参皂甙Rb1可以减轻OA诱导的大鼠海马神经元Tau蛋白过度磷酸化,其机制可能与提高PP2A活性有关。

关键词： 人参皂甙Rb1; 阿尔茨海默病; 冈田酸; Tau蛋白; 磷酸化; 蛋白磷酸酯酶2A

Ginsenoside Rb1 attenuates okadaic acid--induced Tau protein hyperphosphorylation in rat hippocampal neurons

Li Yongkun, Chen Xiaochun, Zhu Yuangui, Peng Xiaosong, Zeng Yuqi, Shen Jie, Huang Tianwen

The Affiliated Union Hospital of Fujian Medical University, Fujian Institute of Geriatrics.Fuzhou 350001,Fujian

Abstract

The present study was aimed to investigate the effects of ginsenoside Rb1 on okadaic acid (OA)-induced Tau hyperphosphorylation in Sparague Dawley rat hippocampal neurons and to explore its possible mechanism. Animals were randomly divided into four groups. Group 1 received dimethysulphoxide (DMSO) injection (Vehicle group), Group 2 only received OA injection (OA group), Group 3 was pretreated with Rb1 and then received OA injection (Rb1 pretreatment group), and the Group 4 was an intact control group. The animals in Group 3 were injected intraperitoneally with various doses of Rb1 at 5, 10, or 20 mg/kg (once a day for 14 days). On the thirteen day of pretreatment, animals in Rb1 pretreatment group as well as animals in OA group received a bolus injection of 0.483 #mu#g of OA (1.5 #mu#l of solution in DMSO) at right dorsal aspect of hippocampus to induce Tau hyperphosphrylation. The brains were harvested one day after the last treatment. In all groups, the morphology of neurofibrils, phosphorylation of Tau protein, and the activity of phosphatase 2A (PP2A) were investigated. In OA group, the Bielschowski's assay revealed darkened and uneven neurofibrils staining in the hippocampus. The immunohistochemistry results showed a significant increase in Thr~(231) phosphorylation of Tau protein in OA group relative to the control group (P<0.01). OA injection also markedly decreased PP2A activity (P<0.01). Western blot confirmed Thr~(231) phosphorylation of Tau protein and it also detected phosphorylation of Ser~(396) of Tau protein. The animals with Rb1 pretreatment displayed even staining of neurofibrils and normal pattern of fiber organization. Rb1 pretreatment also attenuated Thr~(231) and Ser~(396) hyperphosphorylations of Tau protein, and restored PP2A activity compared to the OA group (P<0.01). These results indicate that OA-induced hyperphosphorylation of Tau protein in rat hippocampal neurons can be attenuated by the pretreatment of ginsenoside Rb1. These data also implicate that Rb1 has potential neuroprotective effects on Tau-related neuropathology.

Key words: Ginsenoside Rb1;Alzheimer disease;Okadaic acid;Tau proteins;Phosphorylation;Protein Phosphatase-2A

收稿日期：　　录用日期：

通讯作者：　　E-mail:

引用本文：

李永坤, 陈晓春, 朱元贵, 彭小松, 曾育琦, 沈杰, 黄天文. 人参皂甙Rb1减轻冈田酸诱导的大鼠海马神经元Tau蛋白过度磷酸化[J]. 生理学报 2005; 57 (2): .

Li Yongkun, Chen Xiaochun, Zhu Yuangui, Peng Xiaosong, Zeng Yuqi, Shen Jie, Huang Tianwen. Ginsenoside Rb1 attenuates okadaic acid--induced Tau protein hyperphosphorylation in rat hippocampal neurons. Acta Physiol Sin 2005; 57 (2): (in Chinese with English abstract).