这篇综述总结了有关甲状腺激素产生的生理学和控制的知识现状,化学物质干扰其合成和释放的影响导致甲状腺癌。它没有考虑低甲状腺激素的潜在神经发育后果。有许多已知的分子启动事件(MIE)影响哺乳动物中的甲状腺激素合成,并且许多化学物质能够同时激活多个MIE。对啮齿动物中化学诱导的甲状腺癌的AOP分析已经确定了易患啮齿动物癌症发展的关键事件,其中许多事件将在适当的条件下在人类中发挥作用。如果他们暴露在足够高浓度的影响化学品中。然而,有条件,至少,将表明人类对这些影响的敏感性存在显著的数量差异,由于生物学上的差异,啮齿动物对甲状腺的影响更加敏感,这些物种中甲状腺激素的运输和控制,而人类的营业额明显较低,并且T4/T3的血清运输与啮齿动物的运输不同。关于啮齿动物和人类甲状腺生理学之间声称的质量差异存在激烈的争论,和重大保留,科学和监管,在关键时间窗内,低甲状腺激素水平对神经发育的潜在影响仍然存在。相比之下,甲状腺癌的化学诱导情况,通过对甲状腺激素产生和释放的影响,在理论上都不那么模棱两可,和实际数据,在啮齿动物中显示出与化学诱发甲状腺癌相关的关键事件的明确剂量相关阈值。此外,运输的质的差异,和半衰期的数量差异,甲状腺激素的分解代谢和周转,存在,在人类的正常情况下不会运作。
This
review summarises the current state of knowledge regarding the physiology and control of production of thyroid hormones, the effects of chemicals in perturbing their synthesis and release that result in thyroid cancer. It does not consider the potential neurodevelopmental consequences of low thyroid hormones. There are a number of known molecular initiating events (MIEs) that affect thyroid hormone synthesis in mammals and many chemicals are able to activate multiple MIEs simultaneously. AOP analysis of chemical-induced thyroid cancer in rodents has defined the key events that predispose to the development of rodent cancer and many of these will operate in humans under appropriate conditions, if they were exposed to high enough concentrations of the affecting chemicals. There are conditions however that, at the very least, would indicate significant quantitative differences in the sensitivity of humans to these effects, with rodents being considerably more sensitive to thyroid effects by virtue of differences in the biology, transport and control of thyroid hormones in these species as opposed to humans where turnover is appreciably lower and where serum transport of T4/T3 is different to that operating in rodents. There is heated debate around claimed qualitative differences between the rodent and human thyroid physiology, and significant reservations, both scientific and regulatory, still exist in terms of the potential neurodevelopmental consequences of low thyroid hormone levels at critical windows of time. In contrast, the situation for the chemical induction of thyroid cancer, through effects on thyroid hormone production and release, is less ambiguous with both theoretical, and actual data, showing clear dose-related thresholds for the key events predisposing to chemically induced thyroid cancer in rodents. In addition, qualitative differences in transport, and quantitative differences in half life, catabolism and turnover of thyroid hormones, exist that would not operate under normal situations in humans.