The AhR/ROS-mediated lipid peroxidation pathway contributes to 6PPDQ-induced intestine-specific injury in zebrafish...

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPDQ), an emerging environmental contaminant derived from tire rubber, has been reported to accumulate at higher levels in the intestine than in other tissues of zebrafish, raising concerns regarding intestinal susceptibility. However, its potential developmental toxicity toward the intestine during embryonic development remains largely unclear. Here, zebrafish embryos exposed to 6PPDQ (0.2-2000 μg/L) exhibited pronounced intestinal injury characterized by intestinal redness and swelling, mucosal damage, and excessive inflammation. Mechanistically, 6PPDQ initially activated the aryl hydrocarbon receptor (AhR) signaling, which mediated excessive production of reactive oxygen species (ROS). In support of this finding, both AhR antagonist CH-223191 and ROS scavenger N-acetylcysteine effectively alleviated 6PPDQ-induced intestinal injury, thereby supporting the critical role of 6PPDQ-triggered AhR/ROS signaling in the event. Moreover, 6PPDQ suppressed the SLC7A11-GSH-GPX4 antioxidant defense system and elevated malondialdehyde levels, while these oxidative imbalances induced by 6PPDQ were effectively reversed by CH-223191, suggesting that AhR/ROS-mediated lipid peroxidation contributed to 6PPDQ-induced intestinal injury. This notion was further reinforced by findings that lipid peroxidation inhibitors, liproxstatin-1 and ferrostatin-1, successfully ameliorated 6PPDQ-induced intestinal injury phenotypes. In summary, our results revealed that the AhR/ROS-mediated lipid peroxidation pathway contributes to the 6PPDQ-caused intestinal injury in zebrafish during embryonic development. These findings provide novel insights into the intestinal susceptibility of 6PPDQ and highlight its potential risks to the embryonic development of fish.