Fort Environmental Laboratories, Stillwater, Oklahoma 74074, USA.
Toxicol Sci. 2010 Feb;113(2):392-400. doi: 10.1093/toxsci/kfp280. Epub 2009 Nov 16.
Nieuwkoop and Faber stage 51 Xenopus laevis larvae were exposed for 21 days to four different concentrations of triclosan (TCS): <0.2 (control), 0.6, 1.5, 7.2, or 32.3 microg TCS/l. Primary endpoints were survival, hind limb length, body length (whole; snout to vent), developmental stage, wet whole body weight, and thyroid histology. Thyroid hormone (TH) concentrations were determined in whole thyroid and plasma samples from stage-matched exposure day 21 specimens. TH receptor-beta (TRbeta) expression was measured in stage-matched tail fin tissue samples collected at exposure days 0 and 21. Reduced larval growth occurred at exposure day 21 with 1.5 microg/l treatment. Larval developmental stage at exposure day 21 was not significantly different from controls based on observed parameters. Thyroid histology was not affected by TCS, and thyroxine (T4) levels in thyroid glands or plasma were not different from controls. A concentration-dependent increase in TRbeta expression in exposure day 21 larvae was not detected. However, increased expression was found in stage-matched larvae exposed to 1.5 or 7.2 microg TCS/l. Our study indicates that environmentally relevant TCS concentrations do not alter the normal course of thyroid-mediated metamorphosis in this standard anuran model.
荷兰胚胎学家纽沃克和法伯（Nieuwkoop and Faber）第 51 阶段的非洲爪蟾（Xenopus laevis）幼虫在 21 天内暴露于四种不同浓度的三氯生（TCS）中：<0.2（对照）、0.6、1.5、7.2 或 32.3μg TCS/L。主要终点是存活率、后肢长度、体长（全长；吻肛距）、发育阶段、湿体重和甲状腺组织学。在第 21 天的匹配暴露日，从整个甲状腺和血浆样本中测定甲状腺激素（TH）浓度。在第 0 天和第 21 天的匹配暴露日采集的尾鳍组织样本中测量了甲状腺激素受体-β（TRβ）的表达。1.5μg/L 处理时，21 天的幼虫生长受到抑制。根据观察到的参数，21 天的暴露日幼虫发育阶段与对照组无显著差异。TCS 未影响甲状腺组织学，甲状腺或血浆中的甲状腺素（T4）水平与对照组无差异。在第 21 天暴露的幼虫中未检测到 TRβ表达的浓度依赖性增加。然而，在暴露于 1.5 或 7.2μg TCS/L 的匹配幼虫中发现了表达增加。我们的研究表明，在这个标准的两栖动物模型中，环境相关浓度的 TCS 不会改变甲状腺介导的变态发育的正常过程。
