title: Effects of tetrabromobisphenol A on larval development and thyroid hormone-regulated biomarkers of the amphibian Xenopus laevis.
abstract: Effects of tetrabromobisphenol A (TBBA) on thyroid hormone (TH)-dependent morphological development and on TH-regulated biomarkers were investigated using the amphibian Xenopus laevis. Tadpoles were exposed in the Xenopus metamorphosis assay to different TBBA concentrations ranging from 2.5 to 500 microg/L for 21 days. Only the highest TBBA concentration inhibited larval development while the biomarker for negative feedback mechanism, TH receptor beta-mRNA, was not affected. Short-term exposures to TBBA, triiodothyronine (T3), and a combination of TBBA and T3 were performed to examine expression of TH-upregulated biomarkers. TBBA alone increased slightly the expression of TH receptor beta- and basic region leucin zipper transcription factor b/Zip-mRNA but inhibited their T3-induced elevation in a dose-dependent manner. Despite the fact that TBBA seems to cause only mild effects during long-term treatment on larval development, short-term exposure revealed indirect evidence that TBBA can function as a TH antagonist.
authors.affiliation: Department of Inland Fisheries, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin 12587, Germany.
authors.forename: Oana
authors.initials: O
authors.lastname: Jagnytsch
authors.forename: Robert
authors.initials: R
authors.lastname: Opitz
authors.forename: Ilka
authors.initials: I
authors.lastname: Lutz
authors.forename: Werner
authors.initials: W
authors.lastname: Kloas
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000633:toxicity*; D001681:Biological Assay; D015415:Biomarkers / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000187:drug effects*; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D013963:Thyroid Hormones / Q000494:pharmacology*; D014284:Triiodothyronine / Q000494:pharmacology; D015854:Up-Regulation; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D013956:Antithyroid Agents; D015415:Biomarkers; D011075:Polybrominated Biphenyls; D011988:Receptors, Thyroid Hormone; D013963:Thyroid Hormones; D014284:Triiodothyronine; C020806:tetrabromobisphenol A