title: Dietary exposure to polybrominated diphenyl ether 47 (BDE-47) inhibits development and alters thyroid hormone-related gene expression in the brain of Xenopus laevis tadpoles.
abstract: Few studies have investigated the thyroid-disrupting effects of polybrominated diphenyl ethers (PBDEs) across multiple levels of biological organization in anurans, despite their suitability for the screening of thyroid disruptors. Therefore, the present study evaluated the effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on development, thyroid histology and thyroid hormone-related gene expression in Xenopus laevis exposed to 0 (control), 50 (low), 500 (medium) or 5000μg BDE-47/g food (high) for 21days. Only the high dose of BDE-47 hindered growth and development; however, thyroid hormone-associated gene expression was downregulated in the brains of tadpoles regardless of dose. These results show that BDE-47 disrupts thyroid hormone signaling at the molecular and whole-organism levels and suggest that gene expression in the brain is a more sensitive endpoint than metamorphosis. Furthermore, the altered gene expression patterns among BDE-47-exposed tadpoles provide insight into the mechanisms of PBDE-induced thyroid disruption and highlight the potential for PBDEs to act as neurodevelopmental toxicants.
authors.affiliation: Department of Biology, Texas Christian University, Fort Worth, TX, 76129, USA.
authors.forename: Alexandra T
authors.initials: AT
authors.lastname: Yost
authors.affiliation: Department of Biology, Texas Christian University, Fort Worth, TX, 76129, USA.
authors.forename: Leah M
authors.initials: LM
authors.lastname: Thornton
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX, 76203, USA.
authors.forename: Barney J
authors.initials: BJ
authors.lastname: Venables
authors.affiliation: Department of Biology, Texas Christian University, Fort Worth, TX, 76129, USA. Electronic address: m.jeffries@tcu.edu.
authors.forename: Marlo K
authors.initials: MK
authors.lastname: Sellin Jeffries
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000633:toxicity*; D015870:Gene Expression / Q000187:drug effects*; D055768:Halogenated Diphenyl Ethers / Q000633:toxicity*; D007814:Larva / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000235:genetics; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013963:Thyroid Hormones / Q000235:genetics*; D014982:Xenopus laevis
chemical_list: D052244:Endocrine Disruptors; D055768:Halogenated Diphenyl Ethers; D011988:Receptors, Thyroid Hormone; D013963:Thyroid Hormones; C511295:2,2',4,4'-tetrabromodiphenyl ether
keywords: Amphibian; Development; Endocrine disruption; Gene expression; Metamorphosis; Polybrominated diphenyl ether; Thyroid function; Xenopus