The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China.
Department of Hematology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China.
ACS Chem Neurosci. 2021 Apr 7;12(7):1100-1111. doi: 10.1021/acschemneuro.0c00544. Epub 2021 Mar 16.
Recently, combination therapy has proven to be an effective strategy for treating polygenic/multifactorial/complex disorder such as Parkinson's disease (PD). Here, we hypothesized that dual up-regulation of glutamate cysteine ligase (GCL) catalytic subunit (GCLc) and GCL modifier subunit (GCLm) via nuclear factor E2-related factor (Nrf2) contribute to the antioxidant effect of paeoniflorin (PF) synergistically with glycyrrhetinic acid (GA) (henceforth called PF/GA) in the context of MPP/MPTP neurotoxicity. Expectedly, CompuSyn synergism/antagonism analysis showed that PF/GA exerts synergistic neuroprotection. Moreover, the antioxidant effect of PF was significantly enhanced by the combined administration of GA, although GA alone did not confer the effect. Mechanistically, PF triggered extracellular signal-regulated kinase (ERK1/2) phosphorylation, resulting in Nrf2 nuclear translocation from cytoplasmic pool via de novo synthesis in MPP-challenged SH-SY5Y cells. Concomitantly, GA activates Akt which in turn induces nuclear accumulation of Nrf2. Especially, PF/GA up-regulated glutamate-cysteine ligase catalytic subunit (Gclc) and glutamate-cysteine ligase modifier subunit (Gclm) are formed via two separate pathways. Furthermore, these results were confirmed through pathway blockade assays using PD98059 (ERK1/2 inhibitor), LY294002 (phosphatidylinositol-3-kinase inhibitor), and shRNA-induced Nrf2 knockdown. Additionally, using a mouse MPTP-induced model of PD, we demonstrated that PF/GA synergistically ameliorates both motor deficits and oxidative stress in the ventral midbrain. In parallel, PF/GA also up-regulated both GCLc and GCLm expression at levels of transcription and translation. Conversely, antiparkinsonism and antioxidant effects of PF/GA were not observed in Nrf2-knockout MPTP-mice. Collectively, these results show that ERK1/2 and Akt activation contribute to the synergistic antioxidant effect of PF/GA. Hence, PF/GA regimen warrants further preclinical and possible clinical study for PD.
最近，联合治疗已被证明是治疗多基因/多因素/复杂疾病（如帕金森病）的有效策略。在这里，我们假设通过核因子 E2 相关因子 (Nrf2) 双重上调谷氨酸胱氨酸连接酶 (GCL) 催化亚基 (GCLc) 和 GCL 修饰亚基 (GCLm)，与甘草次酸 (GA) 一起协同作用，对 MPP/MPTP 神经毒性具有抗氧化作用（以下简称 PF/GA）。不出所料，CompuSyn 协同/拮抗分析表明 PF/GA 发挥协同神经保护作用。此外，GA 联合给药可显著增强 PF 的抗氧化作用，尽管 GA 单独给药无此作用。从机制上讲，PF 触发细胞外信号调节激酶 (ERK1/2) 磷酸化，导致 Nrf2 通过从头合成从细胞质池向 SH-SY5Y 细胞中的核内易位，在 MPP 挑战的情况下。同时，GA 激活 Akt，进而诱导 Nrf2 的核内积累。特别是，PF/GA 通过两条独立的途径上调谷氨酸胱氨酸连接酶催化亚基 (Gclc) 和谷氨酸胱氨酸连接酶修饰亚基 (Gclm)。此外，通过使用 PD98059（ERK1/2 抑制剂）、LY294002（磷脂酰肌醇 3-激酶抑制剂）和 shRNA 诱导的 Nrf2 敲低的通路阻断测定来证实这些结果。此外，使用小鼠 MPTP 诱导的 PD 模型，我们证明 PF/GA 协同改善中脑腹侧的运动缺陷和氧化应激。同时，PF/GA 还在转录和翻译水平上调 GCLc 和 GCLm 的表达。相反，在 Nrf2 敲除的 MPTP 小鼠中，PF/GA 没有观察到抗帕金森病和抗氧化作用。总之，这些结果表明 ERK1/2 和 Akt 激活有助于 PF/GA 的协同抗氧化作用。因此，PF/GA 方案值得进一步进行临床前和可能的临床研究。
