Jianjie Chen, Wenjuan Xue, Jinling Cao, Jie Song, Ruhui Jia, Meiyan Li
State Key Laboratory of Ecological Animal Husbandry and Environmental Veterinary Medicine, College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu 030801, Shanxi, China.
State Key Laboratory of Ecological Animal Husbandry and Environmental Veterinary Medicine, College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu 030801, Shanxi, China.
Aquat Toxicol. 2016 Feb;171:48-58. doi: 10.1016/j.aquatox.2015.12.010. Epub 2015 Dec 24.
Excessive fluoride in natural water ecosystem has the potential to detrimentally affect thyroid endocrine system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of fluoride on growth performance, thyroid histopathology, thyroid hormone levels, and gene expressions in the HPT axis in male zebrafish (Danio rerio) exposed to different determined concentrations of 0.1, 0.9, 2.0 and 4.1 M of fluoride to investigate the effects of fluoride on thyroid endocrine system and the potential toxic mechanisms caused by fluoride. The results indicated that the growth of the male zebrafish used in the experiments was significantly inhibited, the thyroid microtrastructure was changed, and the levels of T3 and T4 were disturbed in fluoride-exposed male fish. In addition, the expressional profiles of genes in HPT axis displayed alteration. The expressions of all studied genes were significantly increased in all fluoride-exposed male fish after exposure for 45 days. The transcriptional levels of corticotrophin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroglobulin (TG), sodium iodide symporter (NIS), iodothyronine I (DIO1), and thyroid hormone receptor alpha (TRα) were also elevated in all fluoride-exposed male fish after 90 days of exposure, while the inconsistent expressions were found in the mRNA of iodothyronineⅡ (DIO2), UDP glucuronosyltransferase 1 family a, b (UGT1ab), transthyretin (TTR), and thyroid hormone receptor beta (TRβ). These results demonstrated that fluoride could notably inhibit the growth of zebrafish, and significantly affect thyroid endocrine system by changing the microtrastructure of thyroid, altering thyroid hormone levels and endocrine-related gene expressions in male zebrafish. All above indicated that fluoride could pose a great threat to thyroid endocrine system, thus detrimentally affected the normal function of thyroid of male zebrafish.
天然水生态系统中过量的氟化物有可能对甲状腺内分泌系统产生不利影响，但对于鱼类的此类影响或潜在机制知之甚少。在本研究中，我们评估了氟化物对暴露于0.1、0.9、2.0和4.1 M不同测定浓度氟化物的雄性斑马鱼（Danio rerio）生长性能、甲状腺组织病理学、甲状腺激素水平以及HPT轴基因表达的影响，以研究氟化物对甲状腺内分泌系统的影响以及氟化物引起的潜在毒性机制。结果表明，实验中使用的雄性斑马鱼的生长受到显著抑制，甲状腺微观结构发生变化，暴露于氟化物的雄性鱼体内T3和T4水平受到干扰。此外，HPT轴基因的表达谱也发生了改变。暴露45天后，所有暴露于氟化物的雄性鱼中所有研究基因的表达均显著增加。暴露90天后，所有暴露于氟化物的雄性鱼中促肾上腺皮质激素释放激素（CRH）、促甲状腺激素（TSH）、甲状腺球蛋白（TG）、钠碘同向转运体（NIS）、碘甲状腺原氨酸I（DIO1）和甲状腺激素受体α（TRα）的转录水平也升高，而碘甲状腺原氨酸Ⅱ（DIO2）、UDP葡萄糖醛酸基转移酶1家族a、b（UGT1ab）、转甲状腺素蛋白（TTR）和甲状腺激素受体β（TRβ）的mRNA表达则不一致。这些结果表明，氟化物可显著抑制斑马鱼的生长，并通过改变甲状腺微观结构、改变甲状腺激素水平和内分泌相关基因表达，显著影响雄性斑马鱼的甲状腺内分泌系统。以上所有表明，氟化物可能对甲状腺内分泌系统构成巨大威胁，从而不利地影响雄性斑马鱼甲状腺的正常功能。
