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Interaction of nonylphenol and hepatic CYP1A in rats

Authors
  • Lee, Ping C.
  • Chakraborty Patra, Sharmistha
  • Stelloh, Cary T.
  • Lee, Winnie
  • Struve, Mark
Type
Published Article
Journal
Biochemical Pharmacology
Publisher
Elsevier
Publication Date
Jan 01, 1996
Accepted Date
Apr 16, 1996
Volume
52
Issue
6
Pages
885–889
Identifiers
DOI: 10.1016/0006-2952(96)00409-1
Source
Elsevier
Keywords
License
Unknown

Abstract

Both estradiol and nonylphenol (NP) inhibited hepatic microsomal 7-ethoxyresorufin O-deethylase (EROD) activity of β-naphthoflavone-treated rats. Enzyme kinetic analyses (Lineweaver-Burk plots) using different estradiol and NP concentrations with graded increases in the concentrations of the substrate, ethoxyresorufin, showed that the inhibition was of a competitive nature at all concentrations of estradiol or NP used. Thus, the mechanism by which NP inhibits EROD activity is similar to that of estradiol. NP, however, was much less potent than estradiol. Young rats treated in vivo with 80 mg/kg body weight of NP demonstrated a slight but significant decrease in their hepatic microsomal EROD activity and CYP1A protein as measured by western blot analysis. In addition, treatment with NP led to a decrease in the steady-state levels of hepatic CYP1A mRNA in rats, suggesting that NP acted at the pre-translational level. The competitive nature of inhibition by NP on hepatic microsomal EROD activity indirectly suggests that this compound is a possible substrate of the CYP1A enzyme. Furthermore, NP had a moderate modulating effect on the expression of CYP1A in rat liver. BiocHEM pharmacol 52;6:885-889, 1996.

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