Institute of Geriatrics, Xiyuan Hospital, China Academy of Chinese Medical Sciences, 1 Xiyuan Caochang Road, Haidian District, Beijing, 100091, China.
School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, No. 11 North Third Ring Road East, Chaoyang District, Beijing, 100029, China.
J Ethnopharmacol. 2024 Jan 10;318(Pt B):116985. doi: 10.1016/j.jep.2023.116985. Epub 2023 Aug 1.
Huannao Yicong decoction (HYD) has been used in the study of AD for many years, which consists of Polygonum multiflorum Thunb., Panax ginseng C.A.Mey., Acorus gramineus Aiton, Coptis chinensis Franch., and Conioselinum acuminatum (Franch.) Lavrova. Previous studies have found that HYD could reduce β-Amyloid (Aβ) deposition and tau hyperphosphorylation which are the two critical pathological factors of AD. However, the mechanism of the neurotoxic interaction between Aβ and tau in AD remains unclear. Thus, the underlying mechanisms for HYD improving cognitive function of AD by interfering with the neurotoxic interaction between Aβ and tau remain to be explored.
The main objective of this study is to clarify the specific mechanisms of HYD on interfering with the neurotoxic interaction between Aβ and tau of AD both in vivo and in vitro.
APP/PS1/tau triple transgenic mice were randomly divided into 4 groups, namely model group, memantine group, HYD low-dose group (HYD-L), and HYD high-dose group (HYD-H) with 28 mice in each group, while 28 C57BL/6J mice as the control group. Gavage was applied to all the mice daily for 24 weeks. SH-SY5Y model cells overexpressing Aβ and tau proteins as the intervention object in vitro experiments. Morris water maze was used to observe the learning and memory ability of APP/PS1/tau mice. Aβ deposition was detected by immunohistochemistry, and the levels of Aβ and Aβ were detected by enzyme-linked immunosorbent assay (ELISA). Neurofibrillary tangles (NFTs) were observed by silver staining and the levels of phosphorylated tau proteins were detected by Western blot. The GSK-3β and CDK-5 mRNA expression were detected by real-time polymerase chain reaction (RT-PCR). Besides, the levels of PSD95, GluR1, NR2A, and NR2B were detected by Western blot. Meanwhile, cell experiments were performed to further verify the effect of HYD on tau phosphorylation related kinases (GSK-3β, CDK-5, and PP2A), which further to clarify the mechanism of HYD intervention on the neurotoxic interaction between Aβ and tau.
HYD improved the learning and memory ability of APP/PS1/tau mice. HYD decreased the levels of Aβ and Aβ inhibited tau hyperphosphorylation, which reduced Aβ deposition and NFTs forming. In addition, HYD inhibited the activity of kinases GSK-3β and CDK-5, and enhancing the activity of kinase PP2A. Moreover, HYD inhibited the overexpression of NR2A and NR2B, and increased the expression of GluR1 and postsynaptic density protein-95 (PSD95).
HYD can improve the cognitive deficits by interfering with the neurotoxic interaction between Aβ and tau. In addition, HYD can inhibit the overactivation of NMDARs and increase the levels of GluR1 and PSD95, which may play a role in alleviating neuronal excitotoxicity and improving synaptic function.
还脑益聪方（HYD）多年来一直用于 AD 的研究，它由何首乌、人参、菖蒲、黄连和苍耳组成。先前的研究发现，HYD 可以减少β-淀粉样蛋白（Aβ）沉积和 tau 过度磷酸化，这是 AD 的两个关键病理因素。然而，AD 中 Aβ和 tau 之间神经毒性相互作用的机制仍不清楚。因此，HYD 通过干扰 Aβ和 tau 之间的神经毒性相互作用来改善 AD 认知功能的潜在机制仍有待探索。
本研究的主要目的是阐明 HYD 体内、体外干预 AD 中 Aβ和 tau 之间神经毒性相互作用的具体机制。
APP/PS1/tau 三转基因小鼠随机分为 4 组，即模型组、美金刚组、HYD 低剂量组（HYD-L）和 HYD 高剂量组（HYD-H），每组 28 只，另设 28 只 C57BL/6J 小鼠为对照组。所有小鼠每日灌胃，共 24 周。体外实验以过表达 Aβ和 tau 蛋白的 SH-SY5Y 模型细胞为干预对象。Morris 水迷宫用于观察 APP/PS1/tau 小鼠的学习记忆能力。免疫组织化学法检测 Aβ 沉积，酶联免疫吸附试验（ELISA）检测 Aβ 和 Aβ。银染观察神经原纤维缠结（NFTs），Western blot 检测磷酸化 tau 蛋白水平。实时聚合酶链反应（RT-PCR）检测 GSK-3β 和 CDK-5 mRNA 表达。Western blot 检测 PSD95、GluR1、NR2A 和 NR2B 水平。同时，进行细胞实验进一步验证 HYD 对 tau 磷酸化相关激酶（GSK-3β、CDK-5 和 PP2A）的作用，进一步阐明 HYD 干预 Aβ 和 tau 之间神经毒性相互作用的机制。
HYD 改善了 APP/PS1/tau 小鼠的学习记忆能力。HYD 降低了 Aβ 和 Aβ 的水平，抑制了 tau 过度磷酸化，减少了 Aβ 沉积和 NFTs 的形成。此外，HYD 抑制了激酶 GSK-3β 和 CDK-5 的活性，增强了激酶 PP2A 的活性。此外，HYD 抑制了 NMDARs 的过度激活，增加了 GluR1 和突触后密度蛋白-95（PSD95）的表达。
HYD 可通过干扰 Aβ 和 tau 之间的神经毒性相互作用改善认知障碍。此外，HYD 可抑制 NMDARs 的过度激活，增加 GluR1 和 PSD95 的水平，从而可能减轻神经元兴奋性毒性和改善突触功能。
