Xiao Chen, Liu Zidong, Li Dapeng, Refaey Mohamed M, Tang Rong, Li Li, Zhang Xi
College of Fisheries, Huazhong Agricultural University, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan, 430070, PR China; Department of Animal Production, Faculty of Agriculture, Mansoura University, Al-Mansoura 35516, Egypt.
College of Fisheries, Huazhong Agricultural University, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan, 430070, PR China.
Chemosphere. 2017 Nov;186:798-804. doi: 10.1016/j.chemosphere.2017.07.119. Epub 2017 Aug 8.
Nitrite has the potential to disturb thyroid hormone homeostasis, but little is known about the underlying mechanisms. In the present study, juvenile grass carp (Ctenopharyngodon idellus) were exposed to various concentrations of nitrite (0, 0.5, 1, 4, and 16 mg/L, respectively). Serum concentrations of triiodothyronine (T), thyroxine (T), free triiodothyronine (FT), free thyroxine (FT), 3,3,5'-triiodothyronine (rT), thyroid-stimulating hormone (TSH), and the activity of iodothyronine deiodinases were assayed at 0, 12, 24, 48, and 96 h after exposure. It was found that acute nitrite exposure significantly altered the TH levels and iodothyronine deiodinase activities. The rT levels were significantly increased in the treatment groups, whereas the concentrations of T, FT, FT, and TSH decreased significantly. The concentration of T was elevated in the lower-dose exposure group, but was reduced in the higher-dose exposure group. Increases in type I iodothyronine deiodinase (ID1) and type III iodothyronine deiodinase (ID3) activities were observed in the exposure groups. The activity of type II iodothyronine deiodinase (ID2) decreased at 12 and 24 h after exposure. A decrease of colloid in the thyroid follicles was observed in the exposure group. The results indicate that acute nitrite exposure has the potential to disturb the homeostasis of thyroid hormone metabolism, leading to a hypothyroidism state in the juvenile grass carp.
亚硝酸盐有可能扰乱甲状腺激素稳态，但其潜在机制却鲜为人知。在本研究中，将幼草鱼（草鱼）暴露于不同浓度的亚硝酸盐（分别为0、0.5、1、4和16毫克/升）中。在暴露后的0、12、24、48和96小时，测定血清中三碘甲状腺原氨酸（T）、甲状腺素（T）、游离三碘甲状腺原氨酸（FT）、游离甲状腺素（FT）、3,3,5'-三碘甲状腺原氨酸（rT）、促甲状腺激素（TSH）的浓度以及碘甲状腺原氨酸脱碘酶的活性。结果发现，急性亚硝酸盐暴露显著改变了甲状腺激素水平和碘甲状腺原氨酸脱碘酶活性。各处理组的rT水平显著升高，而T、FT、FT和TSH的浓度显著降低。低剂量暴露组的T浓度升高，但高剂量暴露组的T浓度降低。暴露组中观察到I型碘甲状腺原氨酸脱碘酶（ID1）和III型碘甲状腺原氨酸脱碘酶（ID3）活性增加。暴露后12和24小时，II型碘甲状腺原氨酸脱碘酶（ID2）的活性降低。暴露组甲状腺滤泡中的胶体减少。结果表明，急性亚硝酸盐暴露有可能扰乱甲状腺激素代谢的稳态，导致幼草鱼出现甲状腺功能减退状态。
