title: Reduction of vitellogenin synthesis by an aryl hydrocarbon receptor agonist in the white sturgeon (Acipenser transmontamus).
abstract: Migrating white sturgeon (Acipenser transmontamus) may be subject to agricultural, municipal, and industrial wastewater effluents that likely contain different classes of endocrine-disrupting contaminants. Concern is mounting about the negative effects of environmental estrogens on fish reproduction; however, in environmental mixtures, the affects from estrogenic compounds may be suppressed by aryl hydrocarbon receptor (AhR) ligands. Indeed, reductions in 17beta-estradiol-induced (0.01 and 1 mg/kg) vitellogenin (VTG) levels were observed in white sturgeon coinjected with beta-naphthoflavone (BNF; 50 mg/kg), a model for contaminants that activate the AhR. Variation in the time of injection was used to attempt to correlate VTG inhibition to ethoxyresorufin-O-deethylase activity. No evidence was found to suggest that the inhibition of VTG is a direct result of enhanced estrogen metabolism by BNF-induced enzymes. Results of the present study are relevant for monitoring programs that measure VTG, because these results show that AhR-active environmental contaminants can repress VTG synthesis, which commonly is used as an indicator of estrogen-mimicking contaminants. Furthermore, suppression of natural estrogen signaling by AhR agonists may have significant effects on fish reproduction.
authors.affiliation: Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, California 95616, USA. ajpalumbo@ucdavis.edu
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Palumbo
authors.forename: Michael S
authors.initials: MS
authors.lastname: Denison
authors.forename: Serge I
authors.initials: SI
authors.lastname: Doroshov
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Tjeerdema
mesh_terms: D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D015536:Down-Regulation; D004958:Estradiol / Q000494:pharmacology*; D005399:Fishes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology*; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists*; D014819:Vitellogenins / Q000096:biosynthesis*
chemical_list: D010636:Phenols; D018336:Receptors, Aryl Hydrocarbon; D014819:Vitellogenins; D004958:Estradiol; C025256:nonylphenol; D019363:Cytochrome P-450 CYP1A1