Bifenthrin (BF) and acetochlor (AT) are widely used as an insecticide and herbicide, respectively, which are introduced to the aquatic environment as a natural result. Although the thyroid active substances may coexist in the environment, their joint effects on fish have not been identified. We examined the joint toxicity of BF and AT in zebrafish (Danio rerio) in this study. An acute lethal toxicity test indicated that the median lethal concentration (LC₅₀) values of BF and AT under 96 h treatment were 0.40 and 4.56 µmol L⁻¹, respectively. The binary mixture of BF + AT displayed an antagonistic effect on the acute lethal toxicity. After 14 days post fertilization (dpf) with exposure to individual pesticides at sub-lethal concentrations of, no effects were observed on the catalase (CAT) and peroxidase (POD) activities, while the binary mixtures (except for the 7.2 × 10⁻³ µmol L⁻¹ BF + 1.2 × 10⁻² µmol L⁻¹ AT exposure group) significantly induced the CAT activity. The superoxide dismutase (SOD) activity and triiodothyronine (T3) level were significantly increased in all exposure groups. The thyroxine (T4) level remained unchanged after exposure to individual pesticides, but significantly increased in the 7.2 × 10⁻³ µmol L⁻¹ BF + 1.2 × 10⁻² µmol L⁻¹ AT group. The expressions of the genes Dio2, TRa, TSHβ and CRH in the thyroid hormone (TH) axis were significantly up-regulated in the 7.2 × 10⁻³ µmol L⁻¹ BF + 0.4 × 10⁻² µmol L⁻¹ AT group. Our data indicated that the binary mixture of BF + AT significantly altered the antioxidant enzyme activities and gene expressions in the hypothalamic–pituitary–thyroid (HPT) axis and changed the TH levels.

联苯菊酯（BF）和乙草胺（AT）分别广泛用作杀虫剂和除草剂，自然而然地将其引入水生环境。尽管甲状腺活性物质可能在环境中共存，但尚未确定它们对鱼类的共同作用。在这项研究中，我们检查了BF和AT对斑马鱼（Danio rerio）的联合毒性。急性致命毒性试验表明，在96 h处理后，BF和AT的平均致死浓度（LC ₅₀）值为0.40和4.56 µmol L ^-1， 分别。BF + AT的二元混合物对急性致死毒性具有拮抗作用。施肥（dpf）后14天暴露于亚致死浓度的单个农药后，对过氧化氢酶（CAT）和过氧化物酶（POD）的活性没有影响，而二元混合物（7.2×10 ^-3除外） µmol L ^-1 BF + 1.2×10 ^-2  µmol L ^-1 AT暴露组）显着诱导CAT活性。在所有暴露组中，超氧化物歧化酶（SOD）活性和三碘甲状腺素（T3）水平均显着增加。暴露于各种农药后，甲状腺素（T4）水平保持不变，但在7.2×10 ^-3  µmol L^-1 BF + 1.2×10 ^-2  µmol L ^-1 AT组。7.2×10 ^-3  µmol L ^-1 BF + 0.4×10 ^-2  µmol L ^-1 AT组的甲状腺激素（TH）轴上的Dio2，TRa，TSHβ和CRH基因的表达显着上调。我们的数据表明，BF + AT的二元混合物显着改变了下丘脑-垂体-甲状腺（HPT）轴的抗氧化酶活性和基因表达，并改变了TH水平。