Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong 518055, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong 518055, China.
Phytomedicine. 2023 Sep;118:154962. doi: 10.1016/j.phymed.2023.154962. Epub 2023 Jul 17.
Berberine (BBR) is a natural alkaloid extracted from the herb Coptis chinensis. This compound has the ability to penetrate the blood-brain barrier (BBB) and exhibit neuroprotective value in the treatment of Alzheimer's disease (AD). AD is a neurodegenerative disease characterized by β-amyloid (Aβ) deposition, hyperphosphorylated tau and other characters. Iron accumulation and ferroptosis were also detected in AD brain, which can result in neuronal damage. However, it is still unclear whether BBR can suppress ferroptosis in AD and alleviate its underlying pathology.
This study investigated whether BBR may affect ferroptosis and related signaling pathways in triple transgenic AD (3 × Tg-AD) mice.
Four-month-old 3 × Tg-AD mice received oral administration of BBR at a dose of 50 mg/kg for 7.5 months. Cognitive function and anxiety levels in mice were assessed using the morris water maze test, open field test, and novel object recognition test. Western blot, immunohistochemistry, and ICP-MS were employed to assess the pathology of AD, brain iron metabolism, and ferroptosis signaling pathways. Transmission electron microscopy was used to detect mitochondrial changes. The synergistic effects of BBR combined with Nrf2 were investigated using molecular docking programs and surface plasmon resonance technology. Co-inmunoprecipitation assay was used to examine the effect of BBR on the binding ability of Nrf2 and Keap1.
The results indicated that chronic treatment of BBR mitigated cognitive disorders in 3 × Tg-AD model mice. Reductions in Aβ plaque, hyperphosphorylated tau protein, neuronal loss, and ferroptosis in the brains of 3 × Tg-AD mice suggested that BBR could alleviate brain injury. In addition, BBR treatment attenuated ferroptosis, as evidenced by decreased levels of iron, MDA, and ROS, while enhancing SOD, GSH, GPX4, and SLC7A11. Consistent with the in vivo assay, BBR inhibited RSL3-induced ferroptosis in N2a-sw cells. BBR increased the expression levels of GPX4, FPN1 and SLC7A11 by regulating Nrf2 transcription levels, thereby inhibiting ferroptosis. Molecular docking programs and surface plasmon resonance technology demonstrated the direct combination of BBR with Nrf2. Co-inmunoprecipitation analysis showed that BBR inhibited the interaction between Keap1 and Nrf2.
For the first time, these results showed that BBR could inhibit iron levels and ferroptosis in the brains of 3 × Tg-AD model mice and partially protect against RSL3-induced ferroptosis via the activation of Nrf2 signaling.
小檗碱（BBR）是从黄连中提取的一种天然生物碱。该化合物能够穿透血脑屏障（BBB），并在治疗阿尔茨海默病（AD）方面表现出神经保护作用。AD 是一种神经退行性疾病，其特征是β-淀粉样蛋白（Aβ）沉积、过度磷酸化的 tau 等。AD 大脑中也检测到铁积累和铁死亡，这会导致神经元损伤。然而，目前尚不清楚 BBR 是否能抑制 AD 中的铁死亡并减轻其潜在的病理学。
本研究旨在探讨 BBR 是否会影响 3 重转基因 AD（3×Tg-AD）小鼠中的铁死亡和相关信号通路。
4 月龄 3×Tg-AD 小鼠给予 BBR 口服，剂量为 50mg/kg，持续 7.5 个月。采用 Morris 水迷宫测试、旷场测试和新物体识别测试评估小鼠的认知功能和焦虑水平。采用 Western blot、免疫组织化学和 ICP-MS 评估 AD 病理学、脑铁代谢和铁死亡信号通路。采用透射电子显微镜观察线粒体变化。采用分子对接程序和表面等离子体共振技术研究 BBR 与 Nrf2 的协同作用。采用共免疫沉淀检测 BBR 对 Nrf2 与 Keap1 结合能力的影响。
结果表明，BBR 慢性治疗可改善 3×Tg-AD 模型小鼠的认知障碍。减少 3×Tg-AD 小鼠大脑中的 Aβ斑块、过度磷酸化的 tau 蛋白、神经元丢失和铁死亡表明 BBR 可减轻脑损伤。此外，BBR 处理可降低铁、MDA 和 ROS 水平，同时增加 SOD、GSH、GPX4 和 SLC7A11 水平，从而减轻铁死亡。与体内实验一致，BBR 抑制 RSL3 诱导的 N2a-sw 细胞铁死亡。BBR 通过调节 Nrf2 转录水平增加 GPX4、FPN1 和 SLC7A11 的表达水平，从而抑制铁死亡。分子对接程序和表面等离子体共振技术表明 BBR 与 Nrf2 直接结合。共免疫沉淀分析表明，BBR 抑制 Keap1 与 Nrf2 的相互作用。
这些结果首次表明，BBR 可抑制 3×Tg-AD 模型小鼠大脑中的铁水平和铁死亡，并通过激活 Nrf2 信号部分保护 RSL3 诱导的铁死亡。
