Activation of NRF2/ARE by isosilybin alleviates Aβ25-35-induced oxidative stress injury in HT-22 cells

• Published in: Neuroscience letters Vol. 632; pp. 92 - 97
• Main Authors: Zhou, Jing, Chao, Gao, Li, YuLei, Wu, Min, Zhong, ShuZhi, Feng, ZunYong
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 06.10.2016
• Subjects: Amyloid beta-Peptides - pharmacology; Animals; Antioxidant Response Elements - drug effects; Antioxidants - pharmacology; Cell Line; Cell Survival - drug effects; Hippocampus - drug effects; Hippocampus - metabolism; HT-22 cell; Isosilybin; L-Lactate Dehydrogenase - metabolism; Malondialdehyde - metabolism; Mice; NF-E2-Related Factor 2 - metabolism; Oxidative stress; Oxidative Stress - drug effects; Peptide Fragments - pharmacology; Reactive oxygen species; Silymarin - analogs & derivatives; Silymarin - pharmacology; Oxidative stress; Reactive oxygen species; Isosilybin; HT-22 cell
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2016.08.043

•Isosilybin alleviates HT-22 cell oxidative stress injury induced by Aβ25-35.•Isosilybin inhibits the accumulation of ROS in HT-22 cells.•Isosilybin activates the NRF2-ARE signalling to eliminates the accumulation of ROS in HT-22 cells. Aβ-mediated oxidative stress damage is considered a direct cause of Alzheimer’s disease (AD). Therefore, drugs that have been developed to block oxidative stress are considered effective for AD treatment. Isosilybin is a flavonoid compound extracted from Silybum marianum, and it has been confirmed to have many pharmacological activities. This study aimed to verify that isosilybin could alleviate the Aβ25–35-induced oxidative stress damage in HT-22 hippocampal cells and to investigate the specific targets of isosilybin. A non-toxic dose of isosilybin significantly inhibited the production of reactive oxygen species (ROS), the release of malondialdehyde (MDA) and lactate dehydrogenase (LDH), and the Aβ25–35-stimulated reduction in total antioxidant capacity (T-AOC). Subsequent studies showed that isosilybin significantly increased the protein and mRNA expression of antioxidases, including heme oxygenase-1 (HO-1), glutathione S-transferase (GST), and aldo-keto reductases 1C1 and 1C2 (AKR1C2). Moreover, isosilybin stimulated the activity of an antioxidant-response element (ARE)-driven luciferase reporter gene. Further studies showed that isosilybin induced the expression of NFR-2 in a time- and dose-dependent manner and promoted its translocation to the nucleus. This result indicated that the antioxidant function of isosilybin might be achieved through the activation of NRF2/ARE signalling. Subsequent studies showed that the NRF2-specific agonist t-BHQ effectively inhibited ROS, MDA and LDH release and T-AOC reduction under Aβ25–35 stimulation. In addition, t-BHQ induced the expression of HO-1, GST, and AKR1C2, as well as the activity of ARE luciferase reporter plasmids. NRF2 siRNA blocked the antioxidative stress damage function of isosilybin. Therefore, NRF2 is likely to be a key mediator of isosilybin’s anti-Aβ25–35-mediated oxidative stress damage function. Overall, our results confirmed that isosilybin regulates the expression of HO-1, GST, and AKR1C2 through the activation of NRF2/ARE signalling, inhibiting ROS accumulation and ultimately alleviating Aβ25–35-induced oxidative stress damage in HT-22 cells.