Increased susceptibility of Nrf2-null mice to 1-bromopropane-induced hepatotoxicity

Toxicol Sci. 2010 Jun;115(2):596-606. doi: 10.1093/toxsci/kfq075. Epub 2010 Mar 8.

Abstract

1-Bromopropane (1-BP) was introduced as an alternative to ozone-depleting solvents. However, it was found to exhibit neurotoxicity, reproductive toxicity, and hepatotoxicity in rodents and neurotoxicity in human. However, the mechanisms underlying the toxicities of 1-BP remain elusive. The present study investigated the role of oxidative stress in 1-BP-induced hepatotoxicity using nuclear factor erythroid 2-related factor 2 (Nrf2)-null mice. Groups of 24 male Nrf2-null mice and 24 male wild-type (WT) C57BL/6J mice were each divided into three groups of eight and exposed to 1-BP at 0, 100, or 300 ppm for 8 h/day for 28 days by inhalation. Liver histopathology showed significantly larger area of necrosis in Nrf2-null mice relative to WT mice at the same exposure level. Nrf2-null mice also had greater malondialdehyde (MDA) levels, higher ratio of oxidized glutathione/reduced form of glutathione, and lower total glutathione content. The constitutive level and the increase in ratio per exposure level of glutathione S-transferase (GST) activity were lower in the liver of Nrf2-null mice than WT mice. Exposure to 1-BP at 300 ppm increased the messenger RNA levels of heme oxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GcLm), glutamate-cysteine synthetase (GcLc), glutathione reductase, and NAD(P)H: quinone oxidoreductase 1 (NQO1) in WT mice but not in Nrf2-null mice except for GST Yc2. Nrf2-null mice were more susceptible to 1-BP-induced hepatotoxicity. That oxidative stress plays a role in 1-BP hepatotoxicity is deduced from the low expression levels and activities of antioxidant enzymes and high MDA levels in Nrf2-null mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Animals
  • Chemical and Drug Induced Liver Injury / etiology
  • Chemical and Drug Induced Liver Injury / genetics
  • Chemical and Drug Induced Liver Injury / metabolism*
  • Enzymes / genetics
  • Enzymes / metabolism
  • Gene Expression Regulation, Enzymologic / drug effects
  • Genetic Predisposition to Disease
  • Hydrocarbons, Brominated / toxicity
  • Inhalation Exposure
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NF-E2-Related Factor 2 / physiology*
  • Oxidative Stress / drug effects
  • Solvents / toxicity*

Substances

  • Enzymes
  • Hydrocarbons, Brominated
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, mouse
  • Solvents
  • 1-bromopropane