Yang Liang, Lu Xiangqi, Pan Dongliang, Zhang Yusong, Zheng Yi, Mei He, Yang Bo, Sun Da, Li Qiong, Lin Jian, Chen Jiangfei
Wenzhou Municipal Key Laboratory of Neurodevelopmental Pathology and Physiology, the Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325035, China; School of Public health, Wenzhou Medical University, Wenzhou 325035, China.
School of Public health, Wenzhou Medical University, Wenzhou 325035, China.
Ecotoxicol Environ Saf. 2025 Jul 15;300:118456. doi: 10.1016/j.ecoenv.2025.118456. Epub 2025 Jun 2.
The ecological risks of tire antioxidant 6PPD and its transformed metabolite 6PPD-quinone (6PPDQ) have received high attention. The present study evaluated the developmental neurotoxicity and potential mechanisms under 6PPD or 6PPDQ embryonic exposures in zebrafish. Our findings revealed that embryonic exposure to both compounds suppressed larval locomotion during dark periods, while only 6PPD significantly reduced the larval light stimulus sensitivity and phototactic response. Following recovery to juvenile stages, pretreated fish exhibited heightened anxiety and reduced sociability for both chemicals, aggression was exclusively occurred in 6PPDQ, shoaling pattern was tighter in 6PPDQ but looser in 6PPD. Both compounds elevated larval cell death and oxidative stress while inhibiting cranial development, with 6PPD increasing and 6PPDQ decreasing inter-ocular distance. Transgenic strain analyses demonstrated that 6PPD markedly activated Gfap and Olig2 expression in the eye-brain axis region, whereas 6PPDQ specifically enhanced Olig2 expression in brain region. Retinal müller cells (labeled by Gfap) and cone cell patterns were disrupted exclusively by 6PPD, as was the fan-like lens arrangement visualized via Cms1 mitochondrial labeling. Molecular analyses aligned with these observations that both compounds altered neural development genes (sox2, nrxn2a, rab33a), while 6PPD specifically dysregulated ocular development genes (cyp26a, rlbp1b, rdh5). Conversely, 6PPDQ exhibited stronger activation of xenobiotic metabolism and redox activity genes (cyp1a, gstp1, prdx1, p4ha1a) and uniquely upregulated intestinal immune (ccr9a) and potassium channel (kcnj1a.3) genes expression. In silico affinity analysis corroborated these distinctions, showing 6PPD's preferential binding to CYP26A and 6PPDQ's stronger interaction with CYP1A. These findings collectively suggest that 6PPD and 6PPDQ induce divergent neurotoxicity pathways of eye-brain axis disruption and gut-brain communication perturbation, respectively, which likely drive their compound-specific behavioral effects.
轮胎抗氧化剂6PPD及其转化代谢产物6PPD-醌（6PPDQ）的生态风险已受到高度关注。本研究评估了斑马鱼胚胎暴露于6PPD或6PPDQ下的发育神经毒性及潜在机制。我们的研究结果表明，胚胎暴露于这两种化合物均会抑制幼鱼在黑暗时期的运动，而只有6PPD显著降低幼鱼对光刺激的敏感性和趋光反应。恢复到幼鱼阶段后，经预处理的鱼对这两种化学物质均表现出焦虑加剧和社交性降低的情况，攻击性仅在6PPDQ处理组出现，6PPDQ处理组的集群模式更紧密，而6PPD处理组则更松散。两种化合物均会增加幼鱼的细胞死亡和氧化应激，同时抑制头部发育，6PPD会增加眼间距，而6PPDQ会减小眼间距。转基因品系分析表明，6PPD显著激活眼-脑轴区域的Gfap和Olig2表达，而6PPDQ则特异性增强脑区域的Olig2表达。视网膜穆勒细胞（由Gfap标记）和视锥细胞模式仅被6PPD破坏，通过Cms1线粒体标记可视化的扇形晶状体排列也是如此。分子分析与这些观察结果一致，即两种化合物均会改变神经发育基因（sox2、nrxn2a、rab33a），而6PPD则特异性失调眼部发育基因（cyp26a、rlbp1b、rdh5）。相反，6PPDQ对外源生物代谢和氧化还原活性基因（cyp1a、gstp1、prdx1、p4ha1a）的激活更强，并且独特地上调肠道免疫（ccr9a）和钾通道（kcnj1a.3）基因的表达。计算机模拟亲和力分析证实了这些差异，表明6PPD优先与CYP26A结合，而6PPDQ与CYP1A的相互作用更强。这些研究结果共同表明，6PPD和6PPDQ分别诱导眼-脑轴破坏和肠-脑通讯扰动这两种不同的神经毒性途径，这可能导致它们产生化合物特异性的行为效应。
