PARENT SESSION
1D Bioassays for specific hazards (estrogenic effects, genotoxicity, neurotoxicity, ...)
9:00 AM to 7:00 PM, Tuesday, 08 May 2001

(T/EH058) Antiestrogenic Effects of Aryl Hydrocarbon Receptor (AhR)-Ligands on Atlantic salmon .

Bemanian, Vahid¹, Male, Rune¹, ¹

ABSTRACT- In the fish liver the synthesis of egg yolk protein precursor vitellogenin (Vtg) and eggshell zona radiata proteins (Zrp) is under control of the estrogen receptor (ER). It has been shown that 17 - estradiol (E2) increases both the ER and Vtg gene transcriptional activity and mRNA stability. Environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are suspected to have antiestrogenic effects. The aryl hydrocarbon receptor (AhR) is the initial cellular target for TCDD and related compounds. The AhR is a ligand-activated transcription factor that stimulates gene expression when coupled with another structurally related protein, Ah receptor nuclear translocator (ARNT). The heterodimer binds specific DNA sequences, called xenobiotic response elements (XRE), and initiates transcription of various genes including those for xenobiotic metabolizing enzymes. In this study the effects of AhR-ligands on the expression of Vtg and ER have been under focus.

Key words: Atlantic salmon, Reproductive toxicity, Ah receptor, Dioxin