Cerium oxide nanoparticles (CeO₂-NP) have already been detected in the aquatic compartment, however, the evaluation of potential ecotoxicological effects on biota are scarce. The present study aimed to assess the toxic effects of CeO₂-NP in Oncorhynchus mykiss in different organs/tissues (gills, liver and kidney) after acute exposure (96 h) to three concentrations: 0.25, 2.5 and 25 mg/L. Oxidative stress response (catalase - CAT; glutathione S-transferases - GSTs), lipid peroxidation (thiobarbituric acid reactive substances - TBARS), Na⁺/K⁺-ATPase activity, genotoxicity (genetic damage index - GDI) and histopathology (organ's pathological indices) were evaluated. CAT activity was increased in gills and decreased in liver of fish exposed to the highest CeO₂–NPs concentration tested. However, GSTs and Na⁺/K⁺-ATPase activities and TBARS levels were not significantly altered in analysed organs. CeO₂–NP caused marked changes in the gills (aneurysms, blood capillary congestion, lamellar hypertrophy and hyperplasia, secondary lamella fusion and epithelial lifting), in liver (pyknotic nucleus, hyperemia, enlargement of sinusoids and leucocyte infiltration) and kidney (shrinkage of the glomeruli, enlargement of the Bowman space, tubular degeneration and nuclear hypertrophy). Moreover, a semi-quantitative histopathological scoring system (pathological index) confirmed significant alterations in the three organs of all exposed fish. Furthermore, a significant increase of GDI indices observed in gills and liver, for all tested concentrations, indicated a dose-dependent effect. The present study suggests that the release of CeO₂-NP into the aquatic environment promotes biochemical, genotoxic and histopathological damages in fish. However, the mechanisms underlying the occurrence of such effects require further investigation.

氧化铈纳米颗粒（CeO ₂ -NP）已经在水生隔室中被检测到，但是，对生物区系的潜在生态毒理作用的评估却很少。本研究旨在评估CeO ₂ -NP在急性暴露（96 h）三种浓度（0.25、2.5和25 mg / L）后对不同器官/组织（腮，肝和肾）的Mycorhynchus mykiss的毒性作用。氧化应激反应（过氧化氢酶-CAT；谷胱甘肽S-转移酶-GSTs），脂质过氧化（硫代巴比妥酸反应性物质-TBARS），Na ⁺ / K ⁺评估了ATP酶活性，遗传毒性（遗传损伤指数-GDI）和组织病理学（器官的病理指数）。暴露于最高CeO ₂ -NPs浓度的鱼类中，g的CAT活性增加，而肝脏的CAT活性降低。然而，GSTs和Na ⁺ / K ⁺ -ATPase活性以及TBARS水平在被分析的器官中并没有显着改变。铈₂–NP引起肝脏（py状核，充血，正弦波和白细胞浸润的增大）和肾脏（肾小球收缩）的the（动脉瘤，毛细血管充血，板层肥大和增生，继发性椎板融合和上皮抬高）明显改变。 ，鲍曼空间的扩大，肾小管变性和核肥大）。此外，半定量组织病理学评分系统（病理指数）证实了所有裸露鱼类的三个器官的显着变化。此外，对于所有测试浓度，在g和肝脏中观察到的GDI指数均显着增加，表明其呈剂量依赖性。本研究表明CeO ₂的释放-NP进入水生环境会促进鱼类的生化，遗传毒性和组织病理学损害。但是，这种影响发生的机制还需要进一步研究。