High sensitivity of Nrf2 knockout mice to acetaminophen hepatotoxicity associated with decreased expression of ARE-regulated drug metabolizing enzymes and antioxidant genes

Akiko Enomoto, Ken Itoh, Eiko Nagayoshi, Junko Haruta, Toyoe Kimura, Tania O'Connor, Takanori Harada, Masayuki Yamamoto

Research output: Contribution to journalArticlepeer-review

582 Citations (Scopus)

Abstract

Nrf2, which belongs to the basic leucine zipper (bZip) transcription factor family, has been implicated as a key molecule involved in antioxidant-responsive element (ARE)-mediated gene expression. In order to examine the role of Nrf2 in protection against xenobiotic toxicity, the sensitivity of nrf2 knockout mice to acetaminophen (N-acetyl-4-aminophenol (APAP)) was analyzed. The saturation of detoxification pathways after high levels of exposure to APAP is known to induce hepatotoxicity. Two factors important in its detoxification are UDP-glucuronosyltransferase (UDP-GT), an ARE-regulated phase-II drug-metabolizing enzyme, and glutathione (GSH), an antioxidant molecule whose synthesis depends on ARE-regulated γ-glutamylcysteine synthetase (γGCS). Two- to 4-month-old male mice were orally administered a single dose of APAP at 0, 150, 300, or 600 mg/kg. Doses of 300 mg/kg APAP or greater caused death in the homozygous knockout mice only, and those that survived showed a greater severity in hepatic damage than the wild-type mice, as demonstrated by increased plasma alanine aminotransferase activity, decreased hepatic non-protein sulfhydryl (NPSH) content, and centrilobular hepatocellular necrosis. The high sensitivity of Nrf2-deficient mice was confirmed from observations made at 0, 2, 8, and 24 h after dosing with 300 mg/kg APAP; increased anti-APAP immunoreactivity was also noted in their livers at 2 h. Untreated homozygous knockout mice showed both a lower UDP-GT activity and NPSH content, which corresponded to decreased mRNA levels of UDP-GT (Ugt1a6) and the heavy chain of γGCS, respectively. These results show that Nrf2 plays a protective role against APAP hepatotoxicity by regulating both drug metabolizing enzymes and antioxidant genes through the ARE.

Original languageEnglish
Pages (from-to)169-177
Number of pages9
JournalToxicological Sciences
Volume59
Issue number1
DOIs
Publication statusPublished - 2001
Externally publishedYes

Keywords

  • ARE
  • Acetaminophen
  • Eletrophile
  • Glutathione
  • Hepatotoxicity
  • Knockout mice
  • Nrf2
  • Oxidative stress
  • UDP-Glucuronosyltransferase
  • γ-glutamylcysteine synthetase

ASJC Scopus subject areas

  • Toxicology

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