Tebuthiuron is a phenylurea herbicide widely used in agriculture that can reach the aquatic environments, possibly posing negative effects to the aquatic biota. Phenylurea herbicides, such as diuron, are known to cause estrogenic and anti-androgenic effects in fish, but no such effects were yet reported for tebuthiuron exposure. Thus, the aim of this study was to evaluate if tebuthiuron, at environmentally relevant concentrations (100 and 200 ng/L) and after 25 days of exposure have estrogenic and/or anti-androgenic effects on male of Nile tilapia (Oreochromis niloticus), through the evaluation of plasmatic testosterone (T) and estradiol (E₂) levels, brain aromatase (CYP19) levels (western-blot), and by evaluating the histology of the testicles. When compared to the control group, plasmatic T levels decreased about 76% in the animals exposed to 200 ng/L of tebuthiuron, while E₂ levels increased about 94%, which could be related to a significant increase (77%) in CYP19A1 levels, an enzyme that catalyzes the conversion of androgens into estrogens. Histological analyses of the testicles also demonstrated that tebuthiuron at both tested concentrations caused a decrease in the diameter of the seminiferous tubules and in the diameter of the lumen. Therefore, the gonadosomatic index (GSI) was reduced by 36% % in the animals exposed 200 ng/L to tebuthiuron. Indeed, the relative frequency of spermatocytes and spermatids increased respectively 73% (200 ng/L) and 61% (100 ng/L) in the tebuthiuron exposed animals, possibly due to the impairment of sperm release into the lumen, that was decreased 93% (200 ng/L) in the treated animals compared to the control. These results confirm that tebuthiuron causes estrogenic and anti-androgenic effects in Nile tilapias at environmentally relevant concentrations.

Tebuthiuron是一种苯脲类除草剂，广泛用于农业中，可以到达水生环境，可能对水生生物造成负面影响。苯脲类除草剂（例如杜隆）已知会在鱼类中引起雌激素和抗雄激素作用，但尚未见到丁苯磺隆暴露有此类作用。因此，本研究的目的是评估在环境相关浓度（100和200 ng / L）且暴露25天后替丁硫龙对尼罗罗非鱼（Oreochromis niloticus）的雄性有雌激素和/或抗雄激素作用，通过评估血浆睾丸激素（T）和雌二醇（E ₂）水平，脑芳香化酶（CYP19）水平（western印迹），以及评估睾丸的组织学特征。与对照组相比，暴露于200 ng / L替丁硫龙的动物的血浆T水平降低约76％，而E ₂水平升高约94％，这可能与CYP19A1的显着增加（77％）有关水平，一种催化雄激素转化为雌激素的酶。睾丸的组织学分析还表明，两种测试浓度的丁苯磺隆都会导致生精小管的直径和管腔的直径减小。因此，在暴露于200 ng / L的丁丁硫龙的动物中，性腺体指数（GSI）降低了36％。实际上，在暴露于丁丁硫龙的动物中，精子细胞和精子的相对频率分别增加了73％（200 ng / L）和61％（100 ng / L），这可能是由于精子释放入管腔的损伤减少了93与对照组相比，治疗动物的％（200 ng / L）。这些结果证实替丁硫龙在环境相关浓度下会在尼罗罗非鱼中引起雌激素和抗雄激素作用。