You are here:
ASSESSMENT OF A FATHEAD MINNOW REPRODUCTION ASSAY FOR IDENTIFYING ENDOCRINE-DISRUPTING CHEMICALS WITH DIVERSE MODES OF ACTION
Citation:
Korte, J J., M. W. Hornung, Jensen, M D. Kahl, E A. Makynen, AND G T. Ankley. ASSESSMENT OF A FATHEAD MINNOW REPRODUCTION ASSAY FOR IDENTIFYING ENDOCRINE-DISRUPTING CHEMICALS WITH DIVERSE MODES OF ACTION. Presented at Joint Regional SETAC/SOT Annual Meetings, USEPA, Duluth, MN, April 9-10, 2002.
Description:
The US EPA has developed a short-term reproduction test with the fathead minnow to identify potential endocrine disrupting chemicals (EDCs). The assay is initiated by collecting baseline spawning data from reproductively-active adult fathead minnows for 21 d, followed by a 21 d exposure to sublethal concentrations of test material. Measurements are made of fecundity, fertility, hatch success, secondary sex characteristics, gonadal condition (e.g. histopathology), plasma vitellogenin, and plasma sex steroids (estradiol, testosterone, and 11-ketotestosterone). To evaluate performance of the assay, we have conducted tests with several chemicals representative of major modes of action of concern from an EDC perspective. Chemicals tested have included methoxychlor (metabolites are estrogen receptor agonists); flutamide and vinclozolin (androgen receptor antagonists); and fadrozole (cytochrome P450 aromatase [CYP19] inhibitor). Reductions in fecundity were clearly evident in exposures to methoxychlor, methyltestosterone, trenbolone, flutamide and fadrozole. These reproductive effects were accompanied by changes in other parameters reflective of the expected mode of action. For example, in the fadrozole test, estradiol and vitellogenin levels were accompanied by changes in other parameters reflective of the expected mode of action. For example, in the fadrozole test, estradiol and vitellogenin levels were decreased in females, as would be predicted if CYP19 was inhibited. Likewise exposure to the androgen receptor agonists caused masculinization in females, while estrogenic chemicals produced feminization in males. This assessment of the test method shows the utility of the assay to provide guidance in identifying diverse modes of action of potential EDCs. This abstract does not necessarily reflect EPA policy.