Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
J Environ Sci (China). 2012;24(5):949-55. doi: 10.1016/s1001-0742(11)60819-x.
Ioxynil, a phenolic herbicide, is known to exert thyroid hormone (TH) disrupting activity by interfering with TH-binding to plasma proteins and a step of the cellular TH-signaling pathway in restricted animal species. However, comparative studies are still lacking on the TH disruption. We investigated the interaction of [125I]ioxynil with serum proteins from rainbow trout, bullfrog, chicken, pig, rat, and mouse, using native polyacrylamide gel electrophoresis. Candidate ioxynil-binding proteins, which included lipoproteins, albumin and transthyretin (TTR), differed among the vertebrates tested. Rainbow trout and bullfrog tadpole serum had the lowest binding activity for ioxynil, whereas the eutherian serum had the highest binding activity. The cellular uptake of, and response to, ioxynil were suppressed by rat serum greater than by tadpole serum. The cellular uptake of [125I]ioxynil competed strongly with phenols with a single ring, but not with THs. Our results suggested that ioxynil interferes with TH homeostasis in plasma and with a step of cellular TH-signaling pathway other than TH-uptake system, in a species-specific manner.
碘硝酚是一种酚类除草剂，已知通过干扰甲状腺激素（TH）与血浆蛋白的结合以及细胞 TH 信号通路的一个步骤，在特定动物物种中发挥甲状腺激素干扰活性。然而，关于 TH 破坏的比较研究仍然缺乏。我们使用天然聚丙烯酰胺凝胶电泳研究了[125I]碘硝酚与来自虹鳟鱼、牛蛙、鸡、猪、大鼠和小鼠的血清蛋白的相互作用。候选碘硝酚结合蛋白包括脂蛋白、白蛋白和转甲状腺素（TTR），在测试的脊椎动物中有所不同。虹鳟鱼和牛蛙蝌蚪血清对碘硝酚的结合活性最低，而真兽类血清的结合活性最高。大鼠血清比蝌蚪血清更能抑制碘硝酚的细胞摄取和对碘硝酚的反应。[125I]碘硝酚的细胞摄取与具有单个环的酚类物质强烈竞争，但与 TH 不竞争。我们的结果表明，碘硝酚以种特异性方式干扰血浆中的 TH 动态平衡和细胞 TH 信号通路的一个步骤，而不是 TH 摄取系统。
