INFLUENCE OF XENOBIOTICS ON RAINBOW-TROUT LIVER ESTROGEN-RECEPTOR ANDVITELLOGENIN GENE-EXPRESSION

Rainbow trout hepatocyte primary culture was used to test the influenc e of some xenobiotics on the expression of two genes implicated in rep roduction, those for the estrogen receptor (ER) and vitellogenin (Vg). We showed that chlordecone, nonylphenol, a polychlorobiphenol (PCB) m ixture (Aroclor 1245) and lindane were able to induce ER and Vg mRNA a ccumulation. Antiestrogens, 4-hydroxytamoxifen and ICI 164,384, preven ted the effects of the xenobiotics, indicating that the induction of g ene expression is mediated by the ER. Among these four xenobiotics, on ly chlordecone and nonylphenol were able to displace the binding of [H -3]estradiol to ER-enriched COS-1 extracts, and to activate an estroge n-dependent reporter gene (ERE-TK-CAT) cotransfected with an expressio n vector containing ER cDNA. The results suggest that chlordecone and nonylphenol are direct inducers of rainbow trout ER and Vg gene expres sion, whereas PCBs and lindane act through their hepatic metabolites. Moreover, pentachlorophenol acts as an antagonist of the induction by estradiol of rainbow trout ER and Vg gene expression.