There are many concerns about the impacts of Endocrine-Disrupting Chemicals on both wildlife and human populations. A plethora of chemicals have been shown to interfere with the Hypothalamic–Pituitary–Thyroid (HPT) axis in vertebrates. Disruption of the HPT axis is one of main endocrine criteria considered for the regulation of chemicals, along with the estrogen axis, androgen axis and steroidogenesis (EATS). In response to these concerns, the Organization for Economic Cooperation and Development (OECD) initiated the validation of test guidelines (TGs) covering the EATS modalities. Regarding thyroid activity and/or disruption assessment, three OECD TGs are validated, all of them using amphibians. To date, no OECD TGs based on fish are available for the detection of Thyroid Active Chemicals (TACs). To fill this gap, we developed a new test for the detection of TACs, the TETHYS assay (Transgenic Eleuthero-embryonic THYroid-Specific assay). This assay uses a medaka (Oryzias latipes) transgenic line Tg(tg:eGFP) expressing Green Fluorescent Protein in the thyroid follicles, under the control of the thyroglobulin promoter. This assay is performed at eleuthero-embryonic life-stages with an exposure length of 72 h. In the present study, the following reference chemicals with known thyroid hormone system mechanism of action have been tested: methimazole, sodium perchlorate, sodium tetrafluoroborate, diclofenac, iopanoic acid, sobetirome, NH-3 and 1–850. Except for the thyroid receptor antagonists, all chemicals tested were identified as thyroid active, modifying the total fluorescence and the size of the thyroid follicles. To investigate the test specificity, we tested three chemicals presumed to be inert on the HPT axis: cefuroxime, abamectin and 17α-ethinylestradiol. All were found to be inactive in the TETHYS assay. This promising New Approach Methodology can serve as a foundation for the development of a new OECD TG in the frame of regulatory assessment of chemicals for thyroid activity.

中文翻译：

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测试青鳉转基因刺五加胚胎 THYroid 特异性测定 （TETHYS） 对不同作用机制的敏感性


关于内分泌干扰化学品对野生动物和人类的影响，人们有很多担忧。大量的化学物质已被证明会干扰脊椎动物的下丘脑-垂体-甲状腺 （HPT） 轴。HPT 轴的破坏是考虑调节化学物质的主要内分泌标准之一，还有雌激素轴、雄激素轴和类固醇生成 （EATS）。为了回应这些担忧，经济合作与发展组织 （OECD） 启动了涵盖 EATS 模式的测试指南 （TG） 的验证。关于甲状腺活性和/或破坏评估，验证了三种 OECD TG，它们都使用两栖动物。迄今为止，尚无基于鱼类的 OECD TG 可用于检测甲状腺活性化学物质 （TAC）。为了填补这一空白，我们开发了一种用于检测 TAC 的新测试，即 TETHYS 检测（转基因刺五加胚胎 THYroid 特异性检测）。该测定使用在甲状腺球蛋白启动子的控制下在甲状腺滤泡中表达绿色荧光蛋白的青鳉 （Oryzias latipes） 转基因系 Tg（tg：eGFP）。该测定在刺五加胚胎生命阶段进行，暴露时间为 72 小时。在本研究中，已经测试了以下具有已知甲状腺激素系统作用机制的参考化学品：甲巯咪唑、高氯酸钠、四氟硼酸钠、双氯芬酸、碘帕诺酸、索贝替罗、NH-3 和 1-850。除甲状腺受体拮抗剂外，所有测试的化学物质均被鉴定为甲状腺活性物质，改变了总荧光和甲状腺滤泡的大小。为了研究测试特异性，我们测试了三种被认为在 HPT 轴上呈惰性的化学物质：头孢呋辛、阿维菌素和 17α-炔雌二醇。 在 TETHYS 测定中发现所有 ALL 均无活性。这种有前途的新方法方法可以作为在甲状腺活性化学物质的监管评估框架内开发新的 OECD TG 的基础。