Wadsworth Center, New York State Department of Health, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, USA.
Arch Environ Contam Toxicol. 2011 Jul;61(1):151-8. doi: 10.1007/s00244-011-9677-8. Epub 2011 May 15.
Perchlorate can perturb thyroid hormone (TH) homeostasis by competitive inhibition of iodide uptake by the thyroid gland. Until recently, the effects of perchlorate on TH homeostasis were examined by measuring serum concentrations of THs by immunoassay (IA) methods. IA methods are sensitive, but for TH analysis they are compromised by lack of adequate specificity. In this study, we determined the concentrations of six THs: L-thyroxine (T₄), 3,3',5-triiodo-L-thyronine (T₃), 3,3',5'-triiodo-L-thyronine (rT₃), 3,5-diiodo-L-thyronine, 3,3'-diiodo-L-thyronine, and 3-iodo-L-thyronine in the serum of rats administered perchlorate by isotope (¹³C₆-T₄)-dilution liquid chromatography-tandem mass spectrometry. The method recoveries for THs spiked into a serum matrix were between 97.0% and 115%, with a coefficient of variation of 2.1% to 9.4%. Rats were placed on an iodide-deficient or iodide-sufficient diet for 2.5 months, and for the last 2 weeks of that period they were provided drinking water either without or with perchlorate (10 mg/kg body weight/day). No significant differences in serum concentrations of T₃ and T₄ were observed between rats given iodide-deficient and iodide-sufficient diets for 2 or 2.5 months. After 24 h of perchlorate exposure, significantly lower concentrations of T₃ and T₄ were found in the serum of rats administered the iodide-deficient diet but not in rats administered the iodide-sufficient diet. However, after 2 weeks of perchlorate exposure, TH levels in rats fed the iodide-sufficient diet were also significantly lower than those in control rats. Our results suggest that perchlorate affects TH homeostasis and that such effects are more pronounced under iodide-deficient nutrition.
高氯酸盐可通过竞争性抑制甲状腺摄取碘来扰乱甲状腺激素 (TH) 稳态。直到最近，人们一直通过免疫测定 (IA) 方法测量血清 TH 浓度来检查高氯酸盐对 TH 稳态的影响。IA 方法具有较高的灵敏度，但用于 TH 分析时，其特异性不足。在这项研究中，我们通过同位素（¹³C₆-T₄）-稀释液相色谱-串联质谱法测定了给予高氯酸盐的大鼠血清中六种 TH 的浓度：L-甲状腺素 (T₄)、3,3',5-三碘-L-甲状腺素 (T₃)、3,3',5'-三碘-L-甲状腺素 (rT₃)、3,5-二碘-L-甲状腺素、3,3'-二碘-L-甲状腺素和 3-碘-L-甲状腺素。TH 加入血清基质的回收率在 97.0%到 115%之间，变异系数在 2.1%到 9.4%之间。大鼠接受碘缺乏或碘充足饮食 2.5 个月，在此期间的最后 2 周，给予不含或含高氯酸盐（10mg/kg 体重/天）的饮用水。给予碘缺乏或碘充足饮食 2 或 2.5 个月的大鼠血清 T₃ 和 T₄ 浓度无显著差异。暴露于高氯酸盐 24 h 后，给予碘缺乏饮食的大鼠血清中 T₃ 和 T₄ 浓度显著降低，但给予碘充足饮食的大鼠则无此现象。然而，暴露于高氯酸盐 2 周后，给予碘充足饮食的大鼠的 TH 水平也明显低于对照组大鼠。我们的研究结果表明，高氯酸盐影响 TH 稳态，在碘缺乏营养条件下，这种影响更为明显。
