Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, South Korea.
National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KIRBB), Cheongju 28116, South Korea.
Neuroscience. 2020 Jan 21;428:38-49. doi: 10.1016/j.neuroscience.2019.11.043. Epub 2019 Dec 23.
Quercetin is a bioactive flavonoid which abundantly exists in vegetables and fruits. Quercetin exerts a neuroprotective effect against cerebral ischemia. Thioredoxin acts as antioxidant by regulating redox signaling. This study investigated whether quercetin regulates thioredoxin expression in focal cerebral ischemia and glutamate-induced neuronal cell death. Male Sprague Dawley rats (210-230 g) were intraperitoneally injected with vehicle or quercetin (10 mg/kg) 1 h prior to middle cerebral artery occlusion (MCAO). Cerebral cortex was collected 24 h after MCAO. MCAO led to neurological movement deficits, brain edema, and serious histopathological damages in cerebral cortex, and quercetin alleviated these damages following MCAO. We observed the change of thioredoxin expression in MCAO animals with quercetin using proteomic approach, reverse-transcription PCR, and Western blot analyses. Thioredoxin expression decreased in vehicle-treated MCAO animals, while quercetin attenuated this decrease. Moreover, quercetin treatment alleviated the decrease in the number of thioredoxin-positive cells in cerebral cortex of MCAO animals. Furthermore, immunoprecipitation analysis demonstrated that interaction of apoptosis signal-regulating kinase 1 (ASK1) and thioredoxin was decreased in MCAO animals with vehicle, while quercetin prevented MCAO-induced decrease in these binding. In addition, quercetin also alleviated the reduction of cell viability and the decrease in thioredoxin expression in glutamate-treated hippocampal cell line and primary cultures of cortical neurons. However in thioredoxin-silenced cortical neuron, anti-apoptotic effect of quercetin was decreased. Thus, changes of thioredoxin expression by quercetin may contribute to the neuroprotective effect of quercetin in focal cerebral ischemia. Our findings suggest that quercetin mediates its neuroprotective function by regulation of thioredoxin expression and maintenance of interaction between ASK1 and thioredoxin.
槲皮素是一种生物活性类黄酮，广泛存在于蔬菜和水果中。槲皮素对脑缺血具有神经保护作用。硫氧还蛋白作为一种抗氧化剂，通过调节氧化还原信号发挥作用。本研究旨在探讨槲皮素是否调节局灶性脑缺血和谷氨酸诱导的神经元细胞死亡过程中的硫氧还蛋白表达。雄性 Sprague Dawley 大鼠（210-230g）在大脑中动脉闭塞（MCAO）前 1 小时腹腔注射载体或槲皮素（10mg/kg）。MCAO 后 24 小时收集大脑皮质。MCAO 导致神经运动缺陷、脑水肿和大脑皮质严重的组织病理学损伤，而槲皮素减轻了 MCAO 后的这些损伤。我们使用蛋白质组学方法、逆转录 PCR 和 Western blot 分析观察了 MCAO 动物给予槲皮素后硫氧还蛋白表达的变化。与对照组相比，MCAO 动物的硫氧还蛋白表达减少，而槲皮素可减轻这种减少。此外，槲皮素治疗减轻了 MCAO 动物大脑皮质中硫氧还蛋白阳性细胞数量的减少。此外，免疫沉淀分析表明，与对照组相比，在给予载体的 MCAO 动物中，凋亡信号调节激酶 1（ASK1）和硫氧还蛋白之间的相互作用减少，而槲皮素可防止 MCAO 诱导的这种结合减少。此外，槲皮素还减轻了谷氨酸处理的海马细胞系和皮质神经元原代培养物中细胞活力的降低和硫氧还蛋白表达的降低。然而，在硫氧还蛋白沉默的皮质神经元中，槲皮素的抗凋亡作用降低。因此，槲皮素对硫氧还蛋白表达的改变可能有助于槲皮素在局灶性脑缺血中的神经保护作用。我们的研究结果表明，槲皮素通过调节硫氧还蛋白表达和维持 ASK1 与硫氧还蛋白之间的相互作用来介导其神经保护功能。
