Trout oestrogen receptor sensitivity to xenobiotics as tested by different bioassays

A recombinant yeast system highly and stably expressing rainbow trout oestrogen receptor (rtER) was used in parallel with a more elaborated biological system, trout hepatocyte aggregate cultures to examine the oestrogenic potency of several chemicals commonly found in the environment. In hepatocyte cultures, the vitellogenin gene, whose expression is principally dependent upon oestradiol, was used as a biomarker. Moreover, competitive binding assays were performed to determine direct interaction between rtER and xenobiotics. This paper describes high specificity of our systems for screening potentially oestrogenic chemicals and determining the mode of action of trout ER with oestrogenic compounds. This work also demonstrates that it is important to combine bioassays with in vitro approaches to elucidate the mechanism of xenooestrogen actions. (C) 1999 Elsevier Science B.V. All rights reserved.