TitleGlutathione maintenance mitigates age-related susceptibility to redox cycling agents.
Publication TypeJournal Article
Year of Publication2016
AuthorsThomas NO, Shay KP, Kelley AR, Butler JA, Hagen TM
JournalRedox Biol
Date Published2016 12
KeywordsAcetylcysteine, Aging, Animals, Gene Expression Regulation, Developmental, Glutathione, Glutathione Peroxidase, Hepatocytes, Lipid Peroxidation, Male, NAD(P)H Dehydrogenase (Quinone), Oxidation-Reduction, Rats, Rats, Inbred F344, Vitamin K 3

Isolated hepatocytes from young (4-6mo) and old (24-26mo) F344 rats were exposed to increasing concentrations of menadione, a vitamin K derivative and redox cycling agent, to determine whether the age-related decline in Nrf2-mediated detoxification defenses resulted in heightened susceptibility to xenobiotic insult. An LC for each age group was established, which showed that aging resulted in a nearly 2-fold increase in susceptibility to menadione (LC for young: 405μM; LC for old: 275μM). Examination of the known Nrf2-regulated pathways associated with menadione detoxification revealed, surprisingly, that NAD(P)H: quinone oxido-reductase 1 (NQO1) protein levels and activity were induced 9-fold and 4-fold with age, respectively (p=0.0019 and p=0.018; N=3), but glutathione peroxidase 4 (GPX4) declined by 70% (p=0.0043; N=3). These results indicate toxicity may stem from vulnerability to lipid peroxidation instead of inadequate reduction of menadione semi-quinone. Lipid peroxidation was 2-fold higher, and GSH declined by a 3-fold greater margin in old versus young rat cells given 300µM menadione (p<0.05 and p≤0.01 respectively; N=3). We therefore provided 400µMN-acetyl-cysteine (NAC) to hepatocytes from old rats before menadione exposure to alleviate limits in cysteine substrate availability for GSH synthesis during challenge. NAC pretreatment resulted in a >2-fold reduction in cell death, suggesting that the age-related increase in menadione susceptibility likely stems from attenuated GSH-dependent defenses. This data identifies cellular targets for intervention in order to limit age-related toxicological insults to menadione and potentially other redox cycling compounds.

Alternate JournalRedox Biol
PubMed ID27687220
PubMed Central IDPMC5040638
Grant ListP01 AT002034 / AT / NCCIH NIH HHS / United States
R01 AG017141 / AG / NIA NIH HHS / United States