The frequent detection of progestins in various aquatic environments and their potential endocrine disruptive effects in fish have attracted increasing attention worldwide. However, data on their effects on thyroid function and neurotoxicity in fish are limited, and the underlying mechanisms remain unclear. Here, the effects of gestodene (GES, a common progestin) on the thyroid endocrine and nervous systems of mosquitofish (Gambusia affinis) were studied. Adult female fish were exposed to GES at environmentally relevant concentrations (4.4–378.7 ng/L) for 60 days. The results showed that exposure to 378.7 ng/L GES caused a significant decrease in fish growth compared with the control and a marked reduction in the total distance traveled (50.6%) and swimming velocity (40.1–61.9%). The triiodothyronine (T3) levels were significantly increased by GES in a dose-dependent manner, whereas those of tetraiodothyronine (T4) were significantly decreased only at the G500 concentration. The acetylcholinesterase (AChE) activity was decreased significantly in the 4.42 ng/L GES treatments, but increased significantly at 378.67 ng/L. In the brain, a strong increase in the transcriptional levels of bdnf, trh, and dio2 was observed in fish after the 378.7 ng/L treatment. In addition, chronic exposure to GES caused colloid depletion with a concentration-dependent manner in the thyroid, and angiectasis, congestion, and vacuolar necrosis in the brain. These findings provide a better understanding of the effects of GES and associated underlying mechanisms in G. affinis.

中文翻译：

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gestodene 对成年雌性蚊鱼 （Gambusia affinis） 的甲状腺内分泌干扰和神经毒性


在各种水生环境中频繁检测到孕激素及其对鱼类的潜在内分泌干扰作用，在世界范围内引起了越来越多的关注。然而，关于它们对鱼类甲状腺功能和神经毒性影响的数据有限，潜在机制仍不清楚。在这里，研究了 gestodene（GES，一种常见的孕激素）对蚊鱼 （Gambusia affinis） 甲状腺内分泌和神经系统的影响。成年雌鱼暴露于环境相关浓度 （4.4–378.7 ng/L） 的 GES 中 60 天。结果表明，与对照组相比，暴露于 378.7 ng/L GES 导致鱼类生长显着减少，总行进距离 （50.6%） 和游泳速度 （40.1-61.9%） 显着降低。GES 以剂量依赖性方式显着增加三碘甲状腺原氨酸 （T3） 水平，而四碘甲状腺原氨酸 （T4） 水平仅在 G500 浓度下显着降低。乙酰胆碱酯酶 （AChE） 活性在 4.42 ng/L GES 处理中显著降低，但在 378.67 ng/L 时显著增加。在大脑中，在 378.7 ng/L 处理后，在鱼中观察到 bdnf 、 trh 和 dio2 的转录水平强烈增加。此外，长期暴露于 GES 会导致甲状腺胶体耗竭呈浓度依赖性，以及大脑中的血管扩张、充血和空泡坏死。这些发现有助于更好地了解 GES 的影响及其在 G. affinis 中的相关潜在机制。