The effect of high dose endotoxin on CYP3A2 expression in the rat

Pharm Res. 1998 Oct;15(10):1603-8. doi: 10.1023/a:1011915402914.


Purpose: The purpose of our research was two-fold: 1) to further characterize the downregulation of CYP3A2 mRNA, protein, and activity during an acute phase response (APR); 2) most importantly, to relate the time-dependent activation of nuclear proteins to putative DNA binding sequences within the CYP3A2 5'-flanking region, with the loss in CYP3A2 expression.

Methods: Rats were injected (2.0 mg/animal, i.p.) with LPS and sacrificed at 1, 2, 4, 6, 8, 24, 48, and 72 hours. Hepatic nuclear protein was isolated and analyzed for binding activity to AP-1, NFkappaB, and NF-IL6 consensus sequences. Hepatic CYP3A2 mRNA levels were determined by solution hybridization and CYP3A2 protein, CYP3A2 activity, and total P450 were measured in hepatic microsomes.

Results: Computer analysis of the 5'-flanking region of CYP3A2 revealed the presence of 5 NF-IL6 and 4 AP-1 putative DNA binding sites. The strongest increase in AP-1 binding activity occurred between 6 and 24 hr, and the alteration in binding complexes to an NF-IL6 oligonucleotide occurred between 4 and 24 hr. Maximum loss in CYP3A2 mRNA occurred at 8 hr post-LPS injection and remained lowered at the 24 hr timepoint. CYP3A2 protein was significantly decreased at 24, 48, and 72 hours post-LPS treatment with corresponding decreases in CYP3A2 activity and total P450.

Conclusions: The changes in NF-IL6 and AP-1 binding after LPS treatment, which appears to correlate with the changes in CYP3A2 mRNA, combined with the presence of putative NF-IL6 and AP-1 sites located in the CYP3A25'-flanking region, may indicate a potential role for NF-IL6 and AP-1 in CYP3A2 downregulation during an APR.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acute-Phase Reaction / metabolism
  • Animals
  • CCAAT-Enhancer-Binding Proteins
  • Cytochrome P-450 Enzyme System / drug effects*
  • Cytochrome P-450 Enzyme System / genetics
  • Cytochrome P-450 Enzyme System / metabolism
  • DNA-Binding Proteins / metabolism
  • Down-Regulation
  • Enzyme-Linked Immunosorbent Assay
  • Lipopolysaccharides / pharmacology*
  • Male
  • NF-kappa B / metabolism
  • Nuclear Proteins / metabolism
  • RNA, Messenger / analysis
  • Rats
  • Rats, Sprague-Dawley
  • Steroid Hydroxylases / drug effects*
  • Steroid Hydroxylases / genetics
  • Steroid Hydroxylases / metabolism
  • Transcription Factor AP-1 / metabolism


  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Lipopolysaccharides
  • NF-kappa B
  • Nuclear Proteins
  • RNA, Messenger
  • Transcription Factor AP-1
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • steroid hormone 6-beta-hydroxylase