Research Institute of Fish Culture and Hydrobiology, South Bohemian Research Centre of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia in Ceske Budejovice, Zatisi 728/II, CZ-38925 Vodnany, Czech Republic.
Department of Ecophysiology and Aquaculture, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Mueggelseedamm 310, D-12587 Berlin, Germany.
Aquat Toxicol. 2014 Sep;154:154-62. doi: 10.1016/j.aquatox.2014.05.008. Epub 2014 May 17.
The aim of the present study was to investigate the effects of the synthetic progestin levonorgestrel (LNG) on the reproductive endocrine system of a teleost fish, the roach (Rutilus rutilus). Pubertal roach were exposed for 28 days in a flow-through system to four concentrations of LNG (3, 31, 312, and 3124 ng/l). Both males and females treated with 3124 ng/l LNG exhibited the upregulated levels of vitellogenin and oestrogen receptor 1 mRNA in the liver. At the same concentration, LNG caused a significant upregulation of the mRNA expression of the gene encoding luteinising hormone β-subunit (lhβ) and the suppression of the mRNA expression of the gene encoding follicle-stimulating hormone β-subunit (fshβ) in the pituitary of both male and female roach. A lower LNG concentration (312 ng/l) suppressed mRNA expression of fshβ in males only. Females treated with 3124 ng/l LNG exhibited significantly lower plasma 11-ketotestosterone (11-KT) and oestradiol (E2) concentrations, whereas their testosterone (T) level was higher compared with the control. Females exposed to 312 ng/l LNG presented significantly lower plasma E2 concentrations. Males exposed to ≥31 ng/l LNG exhibited significantly reduced 11-KT levels. As determined through a histological analysis, the ovaries of females were not affected by LNG exposure, whereas the testes of males exposed to 31 and 312 ng/l LNG exhibited a significantly higher percentage of spermatogonia B compared with the control. The results of the present study demonstrate that LNG disrupts the reproductive system of pubertal roach by affecting the pituitary gonadotropin expression and the sex steroid levels. This disruption was determined to occur in males after exposure to an environmentally relevant concentration (31 ng/l). Moreover, the highest tested concentration of LNG (3124 ng/l) exerted an oestrogenic effect on fish of both sexes.
本研究旨在探讨合成孕激素左炔诺孕酮（LNG）对鱼类生殖内分泌系统的影响。幼龄罗非鱼（Rutilus rutilus）在流动系统中暴露于四种浓度的 LNG（3、31、312 和 3124ng/L）中 28 天。用 3124ng/L LNG 处理的雄性和雌性个体肝脏中的卵黄蛋白原和雌激素受体 1mRNA 水平均上调。在相同浓度下，LNG 导致雄性和雌性罗非鱼垂体中促黄体生成素β亚基（lhβ）编码基因的 mRNA 表达显著上调，并抑制促卵泡激素β亚基（fshβ）编码基因的 mRNA 表达。较低浓度的 LNG（312ng/L）仅抑制雄性个体的 fshβmRNA 表达。用 3124ng/L LNG 处理的雌性个体的血浆 11-酮睾酮（11-KT）和雌二醇（E2）浓度显著降低，而其睾酮（T）水平与对照组相比更高。暴露于 312ng/L LNG 的雌性个体血浆 E2 浓度显著降低。暴露于≥31ng/L LNG 的雄性个体 11-KT 水平显著降低。组织学分析结果表明，LNG 暴露未影响雌性个体的卵巢，而暴露于 31 和 312ng/L LNG 的雄性个体的精原细胞 B 比例显著高于对照组。本研究结果表明，LNG 通过影响垂体促性腺激素表达和性激素水平来破坏青春期罗非鱼的生殖系统。这种破坏在雄性个体中在接触环境相关浓度（31ng/L）后发生。此外，测试的最高 LNG 浓度（3124ng/L）对两性鱼类均表现出雌激素效应。
