Due to run-off and rain events, agrochemicals can enter water catchments, exerting endocrine disruption effects and toxicity to aquatic organisms. Linuron is a phenylurea herbicide used to control a wide variety of vegetative weeds in agriculture in addition to residential applications. However, there are few studies that quantify its toxicity to early developmental stages of fish. The objectives of this study were to assess the acute toxicity of linuron to zebrafish embryos/larvae by measuring mortality, morphological deformities, oxidative respiration, gene expression, and locomotor activity via the Visual Motor Response test. Zebrafish embryos at ~6-h post-fertilization (hpf) were exposed to either embryo rearing medium (ERM), or one dose of 0.625, 1.25, 2.5, 5, and 10 μM linuron for up to 7 days post-fertilization (dpf) depending on the assay. Zebrafish larvae exposed to linuron displayed pericardial edema, yolk sac edema, and spinal curvature. Oxidative respiration assessments in embryos using the Agilent XF^e24 Flux Analyzer revealed that linuron decreased mean basal respiration and oligomycin-induced ATP-linked respiration in 30 hpf embryos at 20 μM after a 24-hour exposure. In 7 dpf larvae, transcript abundance was determined for 6 transcripts that have a role in oxidative respiration (atp06, cox1, cox4-1, cox5a1, cytb, and nd1); the relative abundance of these transcripts was not altered with linuron treatment. A Visual Motor Response test was conducted on 7 dpf larvae to determine whether linuron (0.625 to 5 μM) impaired locomotor activity. Larval activity in the dark period decreased in a dose dependent manner and there were indications of hypoactivity as low as 1.25 μM. Transcript abundance was thus determined for tyrosine hydroxylase (th1) and glutamic acid decarboxylase 67 (gad1b), two rate limiting enzymes that control the production of dopamine and gamma-aminobutyric acid respectively. The mRNA levels of gad1b (p = 0.019) were reduced with increasing concentrations of linuron while th1 (p = 0.056) showed a similar decreasing trend, suggesting that neurotransmitter biosynthesis may be altered with exposure to linuron. This study improves knowledge related to the toxicity mechanisms for linuron and is the first to demonstrate that this anti-androgenic chemical impairs oxidative respiration and exerts neurotoxic effects associated with neurotransmitter biosynthesis during early development. These data are significant for environmental risk assessment of agrochemicals.

由于径流和降雨事件，农用化学品可以进入集水区，对水生生物产生内分泌干扰和毒性。Linuron 是一种苯脲类除草剂，除住宅应用外，还用于控制农业中的多种植物性杂草。然而，很少有研究量化其对鱼类早期发育阶段的毒性。本研究的目的是通过视觉运动反应测试测量死亡率、形态畸形、氧化呼吸、基因表达和运动活性，评估 linuron 对斑马鱼胚胎/幼虫的急性毒性。受精后约 6 小时 (hpf) 的斑马鱼胚胎暴露于胚胎培养培养基 (ERM) 或一剂 0.625、1.25、2.5、5 和 10 μM linuron，最多 7 天后受精 (dpf ) 取决于检测。暴露于 linuron 的斑马鱼幼虫表现出心包水肿、卵黄囊水肿和脊柱弯曲。使用安捷伦 XF 评估胚胎的氧化呼吸^e 24 Flux Analyzer 显示，在 24 小时暴露后，20 μM 的 linuron 降低了 30 hpf 胚胎的平均基础呼吸和寡霉素诱导的 ATP 相关呼吸。在 7 dpf 幼虫中，测定了 6 个在氧化呼吸中起作用的转录本（atp06、cox1、cox4-1、cox5a1、cytb和nd1 ）的转录本丰度。); 这些转录本的相对丰度没有随着 linuron 处理而改变。对 7 dpf 幼虫进行了视觉运动反应测试，以确定 linuron（0.625 至 5 μM）是否会损害运动活动。黑暗时期的幼虫活动以剂量依赖性方式降低，并且有低至 1.25 μM 的低活动迹象。因此确定了酪氨酸羟化酶 ( th1 ) 和谷氨酸脱羧酶 67 ( gad1b ) 的转录丰度，这两种限速酶分别控制多巴胺和 γ-氨基丁酸的产生。gad1b ( p  = 0.019)的 mRNA 水平随着linuron浓度的增加而降低，而th1 ( p = 0.056) 显示出类似的下降趋势，表明神经递质生物合成可能会随着暴露于利奴隆而改变。这项研究提高了与 linuron 毒性机制相关的知识，并首次证明这种抗雄激素化学物质会损害氧化呼吸，并在早期发育过程中发挥与神经递质生物合成相关的神经毒性作用。这些数据对于农用化学品的环境风险评估具有重要意义。