title: Thyroid disruption by technical decabromodiphenyl ether (DE-83R) at low concentrations in Xenopus laevis.
abstract: Decabromodiphenyl ether (decaBDE), as a flame retardant, is widely produced and used. To study the thyroid disruption by technical decaBDE at low concentrations, Xenopus laevis tadpoles were exposed to technical decaBDE mixture DE-83R (1-1000 ng/L) in water from stage 46/47 (free swimming larvae, system of Nieuwkoop and Faber) to stage 62. DE-83R at concentration of 1000 ng/L significantly delayed the time to metamorphosis (presented by forelimb emergence, FLE). Histological examination showed that DE-83R at all tested concentrations caused histological alterations - multilayer follicular epithelial cell and markedly increased follicle size accompanied by partial colloid depletion and increase in the peripheral colloid vacuolation, in thyroid glands. All tested concentrations of DE-83R also induced a down-regulation of thyroid receptor mRNA expression. These results demonstrated that technical decaBDE disrupted the thyroid system in X. laevis tadpoles. Analysis of polybrominated diphenyl ethers (PBDEs) (sum of 39 congeners) in X. laevis indicated that mean concentrations of total PBDEs in X. laevis exposed to 1, 10, 100, 1000 ng/L were 11.0, 128.1, 412.1, 1400.2 ng/g wet weight, respectively. Considering that PBDEs burden ofX. laevis tadpoles was close to PBDEs levels in amphibians as reported in previous studies, our study has raised new concerns for thyroid disruption in amphibians of technical decaBDE at environmentally relevant concentrations.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. xiaofeiqin@163.com
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Qin
authors.forename: Xijuan
authors.initials: X
authors.lastname: Xia
authors.forename: Zhongzhi
authors.initials: Z
authors.lastname: Yang
authors.forename: Shishuai
authors.initials: S
authors.lastname: Yan
authors.forename: Yaxian
authors.initials: Y
authors.lastname: Zhao
authors.forename: Rongguo
authors.initials: R
authors.lastname: Wei
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Mi
authors.initials: M
authors.lastname: Tian
authors.forename: Xingru
authors.initials: X
authors.lastname: Zhao
authors.forename: Zhanfen
authors.initials: Z
authors.lastname: Qin
authors.forename: Xiaobai
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D001822:Body Burden; D005786:Gene Expression Regulation / Q000187:drug effects; D055768:Halogenated Diphenyl Ethers / Q000633:toxicity*; D008675:Metamorphosis, Biological / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016019:Survival Analysis; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology*; D037042:Thyroid Hormone Receptors beta / Q000235:genetics / Q000378:metabolism; D014867:Water / Q000737:chemistry; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D055768:Halogenated Diphenyl Ethers; D012333:RNA, Messenger; D037042:Thyroid Hormone Receptors beta; D014867:Water; C010902:decabromobiphenyl ether