title: Neuroprotective effect of astaxanthin against glutamate-induced cytotoxicity in HT22 cells: Involvement of the Akt/GSK-3β pathway.
abstract: Oxidative stress (OS) mediated the pathogenesis of Alzheimer's disease (AD). Astaxanthin (ATX) has been reported to exert antioxidant activities as well as neuroprotective effects in vivo and in vitro. But it is still unknown whether the Akt/glycogen synthase kinase-3β (GSK-3β) signaling mediated the neuroprotective effect of ATX in HT22 cells. Flow cytometric analysis was used to evaluate reactive oxygen species (ROS) generation. Caspase and PARP activity was measured. The expressions of heme oxygenase-1 (HO-1), nuclear factor-E2-related factor 2 (Nrf2), Bcl-2, Bax, apoptosis-inducing factor (AIF), cytochrome-c (Cyto-c), p-Akt and p-GSK-3β were evaluated to elucidate the underlying mechanism. Our results showed that ATX significantly attenuated glutamate-induced cell viability loss and lactate dehydrogenase (LDH) release, decreased the expression of caspase-3/8/9 activity and cleaved PARP, and suppressed the intracellular accumulation of ROS in HT22 cells after exposure to glutamate. ATX also increased the mitochondrial expression of AIF, Cyto-c as well as Bax while decreased Bcl-2. Moreover, ATX also induced the HO-1 expression in a dose and time-dependent manner, increased the antioxidant-responsive element (ARE) activity and nuclear Nrf2 expression. Furthermore, treatment with ATX restored the p-Akt and p-GSK-3β (Ser9) as well as HO-1 expression reduced by glutamate. This protective effect was partially blocked by the inhibitors lithium chloride treatment in HT22, indicating the involvement of Akt/GSK-3β inactivation during the neuroprotective effect of ATX. Our results provide the first evidence that ATX can protect glutamate-induced cytotoxicity in HT22 via attenuating caspase activation and mitochondrial dysfunction and modulating the Akt/GSK-3β signaling, indicating ATX may be useful for the treatment of neurodegenerative disorders such as AD.
authors.affiliation: Department of Neurology, Guangzhou First Municipal People's Hospital, Guangzhou Medical University, Guangzhou-Birmingham University Brain and Cognition Center, No. 1 Panfu Road, Guangzhou 510180, China.
authors.forename: X
authors.initials: X
authors.lastname: Wen
authors.affiliation: State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China.
authors.forename: A
authors.initials: A
authors.lastname: Huang
authors.affiliation: Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.
authors.forename: J
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhong
authors.affiliation: Department of Neurology, the Sixth Affiliated Hospital Sun Yat-sen University, Guangzhou 510440, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Neurology, Guangzhou First Municipal People's Hospital, Guangzhou Medical University, Guangzhou-Birmingham University Brain and Cognition Center, No. 1 Panfu Road, Guangzhou 510180, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Neurology, Guangzhou First Municipal People's Hospital, Guangzhou Medical University, Guangzhou-Birmingham University Brain and Cognition Center, No. 1 Panfu Road, Guangzhou 510180, China. Electronic address: qpanxp@163.com.
authors.forename: X
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, China. Electronic address: Zhonglinliu@126.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D020169:Caspases / Q000378:metabolism; D002458:Cell Fractionation; D002461:Cell Line, Transformed; D003603:Cytotoxins / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000633:toxicity; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006624:Hippocampus / Q000166:cytology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D024341:Xanthophylls / Q000494:pharmacology
chemical_list: D003603:Cytotoxins; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D024341:Xanthophylls; D018698:Glutamic Acid; C005948:astaxanthine; D007770:L-Lactate Dehydrogenase; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D020169:Caspases
keywords: Akt; GSK-3β; Nrf2; astaxanthin; oxidative stress