Extensive studies have shown that oxidative stress is a crucial pathogenic factor in Alzheimer’s disease (AD). Nuclear factor E2-related factor 2 (Nrf2) is a master cytoprotective regulator against oxidative stress, and thus represents an attractive therapeutic target in AD. The goal of our study is to investigate the contribution of Nrf2 in Rhynchophylline (Rhy)-induced neuroprotection in AD. The data showed that intraperitoneal administration of Rhy (10 or 20 mg/kg) could ameliorate Aβ_1–42-induced cognitive impairment, evidenced by performance improvement in memory tests. The result of Antioxidant response element (ARE)-luciferase activity assay indicated that Rhy treatment improved ARE promoter activity. The results of reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) assessment in the frontal cortex and hippocampus showed that Rhy treatment could attenuate Aβ_1–42-induced oxidative stress to some extent, evidenced by reversion of these cytokines compared to Aβ_1–42 + Veh group. Rhy treatment also restored expression of Nrf2 and its downstream protein heme oxygenase-1 (HO-1), NAD(P)H/quinone oxidoreductase 1 (NOQ1), and recombinant glutamate cysteine ligase, modifier subunit (GCLM) in the frontal cortex and hippocampus of Aβ_1–42-treated mice. In addition, to investigate whether activation of Nrf2-mediated pathway is responsible for the neuroprotection of Rhy, Nrf2 siRNA was used in human neuroblastoma cells (SH-SY5Y). Interestingly, the results showed that the protective effects of Rhy, including anti-oxidative, anti-apoptosis and elevation of Nrf2 and its downstream proteins, were abolished in Nrf2 siRNA-transfected cells. These findings indicate that Rhynchophylline is protective against Aβ_1–42-induced neurotoxicity via Nrf2–ARE activation, and suggest that Rhy may serve as a potential candidate and promising Nrf2 activator for management of AD.

大量研究表明，氧化应激是阿尔茨海默病（AD）的关键致病因素。核因子 E2 相关因子 2 (Nrf2) 是对抗氧化应激的主要细胞保护调节因子，因此代表了 AD 中有吸引力的治疗靶点。我们研究的目的是调查 Nrf2 在钩藤碱 (Rhy) 诱导的 AD 神经保护中的作用。数据显示，腹腔注射 Rhy（10 或 20 mg/kg）可以改善 Aβ _1-42诱导的认知障碍，记忆测试中的表现改善就证明了这一点。抗氧化反应元件（ARE）-荧光素酶活性测定结果表明，Rhy处理提高了ARE启动子活性。额叶皮层和海马的活性氧（ROS）、丙二醛（MDA）和谷胱甘肽（GSH）评估结果表明，Rhy 治疗可以在一定程度上减轻 Aβ _1-42诱导的氧化应激，这通过这些细胞因子的逆转得到证明。与 Aβ _1–42 + Veh 组相比。 Rhy 治疗还恢复了额叶皮质中 Nrf2 及其下游蛋白血红素加氧酶-1 (HO-1)、NAD(P)H/醌氧化还原酶 1 (NOQ1) 和重组谷氨酸半胱氨酸连接酶修饰亚基 (GCLM) 的表达。 Aβ _1-42处理小鼠的海马体。此外，为了研究 Nrf2 介导的通路激活是否与 Rhy 的神经保护有关，在人神经母细胞瘤细胞 (SH-SY5Y) 中使用了 Nrf2 siRNA。有趣的是，结果表明，Rhy 的保护作用，包括抗氧化、抗凋亡和 Nrf2 及其下游蛋白的升高，在 Nrf2 siRNA 转染的细胞中被消除。 这些发现表明钩藤碱可通过 Nrf2-ARE 激活来预防 Aβ _1-42诱导的神经毒性，并表明 Rhy 可以作为治疗 AD 的潜在候选者和有前景的 Nrf2 激活剂。