Gpx4a-mediated ferroptosis underlines prothioconazole-induced ocular defects in early-life zebrafish

Prothioconazole (PTA), a commonly used triazolinthione fungicide, is often found as residue in aquatic environments and has shown toxicity and bioaccumulation potential in fish. Herein, we utilized zebrafish to assess the toxicity of PTA using in vitro , in silico and in vivo assays. Our findings indicated that PTA caused developmental impairments, such as a decrease in body length, eye diameter/body length ratio, melanin content, and light-visuomotor response, in the development of zebrafish larvae. The accumulation of PTA in zebrafish larvae gradually increased with the rise in PTA exposure concentration. PTA damaged the ocular structure of zebrafish larvae, including the RPE and IPL. Furthermore, it also decreased the expression of eye-development genes, such as mitfa , dct , otx2a , otx2b and sox10 , and disrupted the mitochondrial structure in the RPE region, resulting in reduced volume, increased membrane density, expanded cristae, and destruction of the outer mitochondrial membrane. RNA-seq also demonstrated that PTA affected the visual and sensory-related signaling pathways. Further mechanistic studies indicated that PTA triggered serious oxidative stress in the eyes of zebrafish larvae, which led to ferroptosis by directly inhibiting the expression of gpx4a. This, in turn, recruited macrophages to the ocular region and induced the expression of inflammatory factors. Conversely, supplementing with GSH and upregulating gpx4a expression in zebrafish larvae can mitigate oxidative stress induced by PTA, alleviate symptoms of microphthalmia, increase the expression of eye developmental genes, and inhibit the expression of inflammatory factors. This study reveals that PTA causes severe impairment of the visual system, highlighting the activation of ferroptosis triggered by the suppression of gpx4a as a contributing factor. • PTA causes severe ocular defects in zebrafish larvae. • PTA induces oxidative stress-mediated ferroptosis in the ocular region of zebrafish larvae. • Supplementation with GSH and over-expression of gpx4a in zebrafish can alleviate a series of adverse effects caused by PTA.