Toxic effects of enrofloxacin on grass carp (Ctenopharyngodon idellus): an ecological risk assessment based on cross-system regulatory mechanisms and network toxicology

Enrofloxacin (ENR), a fluoroquinolone antibiotic commonly utilized in aquaculture, poses significant risks to human health due to its residues bioaccumulating in aquatic species and subsequently entering the food chain. Consequently, elucidating the toxicological mechanisms of ENR in cultured fish species and its associated health implications for humans is imperative. Grass carp (Ctenopharyngodon idellus) were exposed to varying concentrations of ENR for 14 days, followed by a 14-day depuration period. The results demonstrated that elevated ENR concentrations induced oxidative stress in gut tissues, resulting in histopathological damage. Concurrently, significant alterations in neurochemical and immune-related biomarkers were observed, correlating strongly with gut oxidative stress. These findings suggest that ENR triggers gut injury, concomitant with neurotoxicity and immunotoxicity mediated via the gut-brain and gut-liver axes. Given that ENR residues in grass carp may enter the human body through the food chain, a network toxicology approach was utilized to investigate its potential human toxicity. Four core target proteins were identified, and molecular docking revealed interactions between ENR and these targets. Thus, ENR may interact with gut injury-associated core proteins, leading to gut injury and contributing to subsequent neurotoxicity and immunotoxicity. This study investigated the toxicological effects of ENR on fish and explored its potential toxicity to humans, providing a scientific basis for the safe use of ENR and ensuring food safety in aquatic fish.