Environmental Engineering Post-Graduation Program, University of Blumenau, Blumenau, SC, Brazil.
Laboratory of Biomarkers of Aquatic Contamination and Immunochemistry, Department of Biochemistry, Federal University of Santa Catarina, UFSC, Florianópolis, SC, Brazil.
Environ Pollut. 2023 Apr 1;322:121159. doi: 10.1016/j.envpol.2023.121159. Epub 2023 Jan 27.
Thyroid hormones (TH) are essential for the metamorphosis of amphibians and their production can be influenced by environmental stressors, such as temperature fluctuations, and exposure to aquatic pollutants, such as herbicides. In the present study we evaluated the influence of different temperatures (25 and 32 °C) on the effects of the herbicide ametryn (AMT, 0 - control, 10, 50 and 200 ng.L) for 16 days on thyroidogenesis of bullfrog tadpoles. Higher temperature and AMT exposure caused a delay in the development of tadpoles, despite no differences were noted in weight gain and total length of the animals. Levels of triiodothyronine (T3) and thyroxine (T4) were not altered neither by AMT nor by temperature, but the highest temperature caused a decrease in total area and number of follicles in the thyroid gland. Transcript levels of thyroid hormone receptors alpha and beta (TRα and TRβ) and iodothyronine deiodinase 3 (DIO3) were lower at 32 °C, which is consistent with developmental delay at the higher temperature. Tadpoles exposed to 200 ng.L of AMT at 25 °C also presented delayed development, which was consistent with lower TRα and DIO3 transcript levels. Lower levels of estradiol were noted in tadpoles exposed to AMT at the higher temperature, being also possibly related to a developmental delay. This study demonstrates that higher temperature and AMT exposure impair thyroidgenesis in bullfrog tadpoles, disrupting metamorphosis.
甲状腺激素 (TH) 对两栖动物的变态发育至关重要，其产生可能受到环境胁迫的影响，如温度波动和暴露于水生污染物，如除草剂。在本研究中，我们评估了不同温度（25 和 32°C）对除草剂莠去津（AMT，0-对照，10、50 和 200ng.L）对牛蛙蝌蚪甲状腺发生的影响 16 天。尽管动物的体重增加和体长没有差异，但较高的温度和 AMT 暴露会导致蝌蚪发育延迟。三碘甲状腺原氨酸 (T3) 和甲状腺素 (T4) 的水平既不受 AMT 也不受温度的影响，但较高的温度会导致甲状腺滤泡的总面积和数量减少。甲状腺激素受体 alpha 和 beta (TRα 和 TRβ) 和碘甲状腺原氨酸脱碘酶 3 (DIO3) 的转录水平在 32°C 时降低，这与较高温度下的发育延迟一致。在 25°C 下暴露于 200ng.L AMT 的蝌蚪也表现出发育延迟，这与较低的 TRα 和 DIO3 转录水平一致。在较高温度下暴露于 AMT 的蝌蚪的雌二醇水平较低，这也可能与发育延迟有关。本研究表明，较高的温度和 AMT 暴露会损害牛蛙蝌蚪的甲状腺发生，扰乱变态发育。
