Effects of atrazine on CYP19 gene expression and aromatase activity in testes and on plasma sex steroid concentrations of male African clawed frogs (Xenopus laevis)

Markus Hecker, June Woo Park, Margaret B. Murphy, Paul D. Jones, Keith R. Solomon, Glen Van Der Kraak, James A. Carr, Ernest E. Smith, Louis du Preez, Ronald J. Kendall, John P. Giesy

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Some investigators have suggested that the triazine herbicide atrazine can cause demasculinization of male amphibians via upregulation of the enzyme aromatase. Male adult African clawed frogs (Xenopus laevis) were exposed to three nominal concentrations of atrazine (1, 25, or 250μg atrazine/l) for 36 days, and testicular aromatase activity and CYP19 gene expression, as well as concentrations of the plasma sex steroids testosterone (T) and 17β-estradiol (E2), and gonad size (GSI) were measured. There were no effects on any of the parameters measured, with the exception of plasma T concentrations. Plasma T concentrations in X. laevis exposed to the greatest concentration of atrazine were significantly less (p = 0.034) than those in untreated frogs. Both CYP19 gene expression and aromatase activities were low regardless of treatment, and neither parameter correlated with the other. We conclude that aromatase enzyme activity and gene expression were at basal levels in X. laevis from all treatments, and that the tested concentrations of atrazine did not interfere with steroidogenesis through an aromatase-mediated mechanism of action.

Original languageEnglish
Pages (from-to)273-280
Number of pages8
JournalToxicological Sciences
Volume86
Issue number2
DOIs
StatePublished - Aug 2005

Keywords

  • Amphibians
  • Aromatase
  • Endocrine modulation
  • Estrogen synthesis
  • Gene expression
  • Q-RT-PCR

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