[Effect of niclosamide on thyroid endocrine system of larval zebrafish].

To examine the effect of niclosamide on thyroid endocrine disruption in larval zebrafish.Zebrafish embryos (2 hours post-fertilization) were exposed to niclosamide at concentrations of 0, 5, 10, 20, 40 μg/L and 80 μg/L until 120 hours post-fertilization, and the body weight, hatching rate, malformation rate and survival rate of zebrafish embryos/larvae were measured. In addition, the triiodothyronine (T3) and thyroxin (T4) activities were determined in zebrafish, and the expression of tshβ and ttr genes that were associated with the regulation of thyroid hormones was quantified using a quantitative real-time PCR (qPCR) assay.Following exposure to niclosamide, there was no concentration-dependent hatching rate (F = 0.947, P = 0.924) or body weight of larval zebrafish (F = 1.042, P = 0.409); however, there were concentration-dependent survival rate (F = 9.309, P = 0.005) and malformation rate (F = 14.900, P = 0.001). As compared to controls, exposure to niclosamide at concentrations of 40 μg/L and 80 μg/L resulted in a significant reduction in the survival rate (both P values < 0.05), and a marked rise in the malformation rate of larval zebrafish (both P values < 0.05). In addition, the T4 activity increased (R2 = 0.927, F = 6.858, P = 0.003) and T3 activity decreased (R2 = 0.925, F = 8.212, P = 0.001) in larval zebrafish with the concentration of niclosamide. qPCR assay determined up-regulation of tshβ gene expression (R2 = 0.840, F = 9.032, P = 0.002) and down-regulation of ttr gene expression (R2 = 0.952, F = 9.130, P = 0.002).Niclosamide exposure at environmental related concentrations may cause thyroid endocrine disruption of larval zebrafish.［摘要］目的 研究灭螺药氯硝柳胺对斑马鱼幼鱼甲状腺内分泌系统的干扰效应。方法 将受精2 h内的斑马鱼胚胎分别暴露于浓度为0、5、10、20、40 μg/L和80 μg/L的氯硝柳胺120 h, 观察不同暴露浓度下斑马鱼胚胎/幼鱼体重、胚胎孵化率、畸形率和存活率等指标; 同时检测鱼体内四碘甲状腺原氨酸 (T4) 和三碘甲状腺原氨酸 (T3) 水平, 并采用荧光定量PCR法检测与甲状腺激素调节相关的两个重要基因tshβ 和ttr 表达情况。结果 暴露于不同浓度氯硝柳胺后, 各组斑马鱼幼鱼孵化率 (F = 0.947, P = 0.924) 和体重 (F = 1.042, P = 0.409) 差异无统计学意义, 存活率 (F = 9.309, P = 0.005) 和畸形率 (F = 14.900, P = 0.001) 差异有统计学意义; 与对照组相比, 较高浓度的氯硝柳胺暴露(40 μg/L和80 μg/L)可显著降低斑马鱼幼鱼存活率 (P 均< 0.05), 并显著增加斑马鱼幼鱼畸形率 (P 均< 0.05) 。随着氯硝柳胺暴露浓度的增加, 斑马鱼幼鱼体内T4含量增加 (R2 = 0.927, F = 6.858, P = 0.003) 、T3含量减少 (R2 = 0.925, F = 8.212, P = 0.001), tshβ 基因表达水平上调 (R2 = 0.840, F = 9.032, P = 0.002) 、ttr 基因表达水平下调 (R2 = 0.952, F = 9.130, P = 0.002) 。结论 环境相关浓度的氯硝柳胺暴露可对斑马鱼幼鱼甲状腺内分泌系统造成干扰。.