National Food Institute, Technical University of Denmark, Division of Toxicology and Risk Assessment, Søborg, Denmark.
Food Chem Toxicol. 2013 Sep;59:534-40. doi: 10.1016/j.fct.2013.06.050. Epub 2013 Jul 4.
Thyroid disrupting chemicals can potentially disrupt brain development. Two studies investigating the effect of the antibacterial compound triclosan on thyroxine (T₄) levels in rats are reported. In the first, Wistar rat dams were gavaged with 75, 150 or 300 mg triclosan/kg bw/day throughout gestation and lactation. Total T₄ serum levels were measured in dams and offspring, and all doses of triclosan significantly lowered T₄ in dams, but no significant effects on T₄ levels were seen in the offspring at the end of the lactation period. Since this lack of effect could be due to minimal exposure through maternal milk, a second study using direct per oral pup exposure from postnatal day 3-16 to 50 or 150 mg triclosan/kg bw/day was performed. This exposure pointed to significant T₄ reductions in 16 day old offspring in both dose groups. These results corroborate previous studies showing that in rats lactational transfer of triclosan seems limited. Since an optimal study design for testing potential developmental neurotoxicants in rats, should include exposure during both the pre- and postnatal periods of brain development, we suggest that in the case of triclosan, direct dosing of pups may be the best way to obtain that goal.
甲状腺干扰化学品可能会干扰大脑发育。有两项研究报告了调查抗菌化合物三氯生对大鼠甲状腺素 (T₄) 水平影响的结果。在第一项研究中，Wistar 大鼠母体在整个妊娠期和哺乳期每天通过灌胃给予 75、150 或 300mg/kg bw 的三氯生。测量了母体和后代的总 T₄ 血清水平，所有剂量的三氯生均显著降低了母体的 T₄，但在哺乳期结束时，后代的 T₄ 水平没有显著影响。由于这种缺乏影响可能是由于通过母乳的最小暴露，因此进行了第二项研究，使用从出生后第 3 天到 16 天的直接经口幼仔暴露，每天给予 50 或 150mg/kg bw 的三氯生。这种暴露导致两个剂量组的 16 天大的后代 T₄ 明显减少。这些结果证实了先前的研究结果，表明在大鼠中，三氯生的哺乳期转移似乎是有限的。由于测试潜在发育神经毒性剂的最佳大鼠研究设计应包括在大脑发育的产前和产后期间进行暴露，因此我们建议，在三氯生的情况下，直接对幼仔进行给药可能是实现这一目标的最佳方式。
