Potent upregulation of glutathione and NAD(P)H:quinone oxidoreductase 1 by alpha-lipoic acid in human neuroblastoma SH-SY5Y cells: protection against neurotoxicant-elicited cytotoxicity.
Alpha-lipoic acid (LA) has recently been reported to afford protective effects in neurodegenerative disorders. However, the mechanisms underlying LA-mediated neuroprotection remain to be investigated. This study was undertaken to determine whether LA treatment could increase endogenous antioxidants and phase 2 enzymes in cultured human neuroblastoma SH-SY5Y cells, and whether such increased cellular defenses could afford protection against cytotoxicity induced by neurotoxicants. Incubation of SH-SY5Y cells with micromolar concentrations of LA for 24 h resulted in a significant increase in the levels of reduced glutathione (GSH) and NAD(P)H:quinone oxidoreductase 1 (NQQ1) in a concentration-dependent fashion. Treatment of the cells with LA also led to an increased mRNA expression of gamma-glutamylcysteine ligase catalytic subunit (GCLC) and NQO1. To determine the protective effects of the LA-induced cellular defenses on neurotoxicant-elicitedl cell injury, SH-SY5Y cells were pretreated with LA for 24 h and then exposed to acrolein, 4-hydroxy-2-nonenal (HNE), H(2)O(2) and the peroxynitrite generator, 3-morpholinosydnonimine (SIN-1). We observed that LA pretreatment of SH-SY5Y cells led to a marked protection against acrolein, HNE, H(2)O(2 )and SIN-1-mediated cytotoxicity, as detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium reduction assay. Taken together, this study demonstrates for the first time that LA can induce GSH and NQO1 in cultured human neuroblastoma cells and LA-upregulated cellular defenses are accompanied by a markedly increased resistance to cytotoxicity induced by various neurotoxicants. The results of this study may have important implications for the neuroprotective effects of LA.
Jia
Zhenquan
Z
Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center, Research Building II, 1861 Pratt Drive, Blacksburg, VA 24060, USA.
Hallur
Seema
S
Zhu
Hong
H
Li
Yunbo
Y
Misra
Hara P
HP
D002374:Catalase / Q000378:metabolism; D045744:Cell Line, Tumor; D005978:Glutathione / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D009498:Neurotoxins / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism; D008063:Thioctic Acid / Q000494:pharmacology*
D009498:Neurotoxins; D012333:RNA, Messenger; D008063:Thioctic Acid; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D005978:Glutathione