The tissue-specific ferroptosis in zebrafish (Danio rerio) exposed to dibutyl phthalate at environmental-relevant concentrations

Dibutyl phthalate (DBP) is extensively contaminated in aquatic environment with severe threats to fishes, its toxic mechanisms and the susceptibility across different tissues require further investigations. In this study, zebrafish (Danio rerio) were used to investigate the histopathology with ferroptosis responses to DBP exposure through physiological and biochemical detection, histological examination, and transcript analyses. Following the chronic DBP exposure at environmental-relevant concentrations (0, 5, and 50 μg/L), the body weight, body length, condition factor, and gonadosomatic index of female zebrafish were decreased, along with a slightly increased hepatosomatic index and retarded development. Notably, the total iron content and distribution were elevated in the liver and brain, accompanied by increased lipid peroxidation and decreased glutathione peroxidase 4 (GPX4) and glutathione (GSH) levels, ultimately leading to histological impairments. Transcript analyses showed that DBP induced ferroptosis by down-regulating genes expression of system Xc⁻ and gpx4b, while up-regulating genes expression related to iron metabolism and lipid peroxidation in the liver. In the brain, similarly ferroptosis responses were observed, characterized by the downregulation of gpx4b and upregulation of iron metabolism-related genes and acsl4a expression. In contrast, the gill and ovary exhibited oxidative stress, lipid peroxidation, structural disruption or follicular retardation without pronounced ferroptosis response. Taken together, this study demonstrates that DBP exposure could induce ferroptosis in zebrafish in a tissue-specific manner, that contributes to an in-depth understanding of the biotoxicity and tolerance to chemical contamination.