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...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 DE83R 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 of X.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.展开更多
The developmental and reproductive effects of endocrine disruption on humans and wildlife rank among the most threatening of all environmental health concerns. Particularly vulnerable to chemical assaults are the hypo...The developmental and reproductive effects of endocrine disruption on humans and wildlife rank among the most threatening of all environmental health concerns. Particularly vulnerable to chemical assaults are the hypothalamic-pituitary-gonadal (HPG) axis and the hypothalamic-pituitary-thyroid (HPT) axis of the endocrine system. While the effects of endocrine disrupting chemicals (EDCs) on the HPG axis have been the subject of intense research efforts, with comprehensive elucidation, a lot remains to be clarified on the effects of EDCs on thyroid functions. For instance, there are no clear-cut biomarkers of exposure and effects of thyroid disrupting chemicals (TDCs) in intact organisms. Consequently, a number of in vitro assays have been developed, and are particularly useful for the identification and mechanistic characterization of potential TDCs considering the increasing number of EDCs that are being released into the environment. However, with the in vitro assays, studies suggest that a plausible major mode of action of TDCs, thyroid hormone receptor (THR) agonist activity, is not environmentally relevant. Here, we reviewed in vitro detection of TDCs activities in wastewater and surface waters. Data strongly suggest that cell lines may be responsible for the less frequent detection of THR agonist activity in wastewater and surface water. It was concluded that the development of reporter gene assays with thyroid hormone function related cell lines, is required.展开更多
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No. KZCX2-YW-420-3,KZCX2-YW-Q-02-05)the National Natural Science Foundation of China (No.20437020,20677074)
文摘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 DE83R 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 of X.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.
文摘The developmental and reproductive effects of endocrine disruption on humans and wildlife rank among the most threatening of all environmental health concerns. Particularly vulnerable to chemical assaults are the hypothalamic-pituitary-gonadal (HPG) axis and the hypothalamic-pituitary-thyroid (HPT) axis of the endocrine system. While the effects of endocrine disrupting chemicals (EDCs) on the HPG axis have been the subject of intense research efforts, with comprehensive elucidation, a lot remains to be clarified on the effects of EDCs on thyroid functions. For instance, there are no clear-cut biomarkers of exposure and effects of thyroid disrupting chemicals (TDCs) in intact organisms. Consequently, a number of in vitro assays have been developed, and are particularly useful for the identification and mechanistic characterization of potential TDCs considering the increasing number of EDCs that are being released into the environment. However, with the in vitro assays, studies suggest that a plausible major mode of action of TDCs, thyroid hormone receptor (THR) agonist activity, is not environmentally relevant. Here, we reviewed in vitro detection of TDCs activities in wastewater and surface waters. Data strongly suggest that cell lines may be responsible for the less frequent detection of THR agonist activity in wastewater and surface water. It was concluded that the development of reporter gene assays with thyroid hormone function related cell lines, is required.
