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
Volume10
Pagination45-52
Date Published2016 12
ISSN2213-2317
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
Abstract

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.

DOI10.1016/j.redox.2016.09.010
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