Serum metabolomics reveals irreversible inhibition of fatty acid beta-oxidation through the suppression of PPARalpha activation as a contributing mechanism of acetaminophen-induced hepatotoxicity

Chem Res Toxicol. 2009 Apr;22(4):699-707. doi: 10.1021/tx800464q.


Metabolic bioactivation, glutathione depletion, and covalent binding are the early hallmark events after acetaminophen (APAP) overdose. However, the subsequent metabolic consequences contributing to APAP-induced hepatic necrosis and apoptosis have not been fully elucidated. In this study, serum metabolomes of control and APAP-treated wild-type and Cyp2e1-null mice were examined by liquid chromatography-mass spectrometry (LC-MS) and multivariate data analysis. A dose-response study showed that the accumulation of long-chain acylcarnitines in serum contributes to the separation of wild-type mice undergoing APAP-induced hepatotoxicity from other mouse groups in a multivariate model. This observation, in conjunction with the increase of triglycerides and free fatty acids in the serum of APAP-treated wild-type mice, suggested that APAP treatment can disrupt fatty acid beta-oxidation. A time-course study further indicated that both wild-type and Cyp2e1-null mice had their serum acylcarnitine levels markedly elevated within the early hours of APAP treatment. While remaining high in wild-type mice, serum acylcarnitine levels gradually returned to normal in Cyp2e1-null mice at the end of the 24 h treatment. Distinct from serum aminotransferase activity and hepatic glutathione levels, the pattern of serum acylcarnitine accumulation suggested that acylcarnitines can function as complementary biomarkers for monitoring the APAP-induced hepatotoxicity. An essential role for peroxisome proliferator-activated receptor alpha (PPARalpha) in the regulation of serum acylcarnitine levels was established by comparing the metabolomic responses of wild-type and Ppara-null mice to a fasting challenge. The upregulation of PPARalpha activity following APAP treatment was transient in wild-type mice but was much more prolonged in Cyp2e1-null mice. Overall, serum metabolomics of APAP-induced hepatotoxicity revealed that the CYP2E1-mediated metabolic activation and oxidative stress following APAP treatment can cause irreversible inhibition of fatty acid oxidation, potentially through suppression of PPARalpha-regulated pathways.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetaminophen / toxicity*
  • Animals
  • Carnitine / analogs & derivatives*
  • Carnitine / blood
  • Chemical and Drug Induced Liver Injury*
  • Chromatography, Liquid
  • Cytochrome P-450 CYP2E1 / deficiency
  • Cytochrome P-450 CYP2E1 / metabolism
  • Fatty Acids / metabolism
  • Glutathione / metabolism
  • Liver Diseases / metabolism
  • Liver Diseases / pathology
  • Mass Spectrometry
  • Metabolomics*
  • Mice
  • Mice, Knockout
  • PPAR alpha / antagonists & inhibitors*
  • PPAR alpha / metabolism
  • Time Factors


  • Fatty Acids
  • PPAR alpha
  • acylcarnitine
  • Acetaminophen
  • Cytochrome P-450 CYP2E1
  • Glutathione
  • Carnitine