The effects of environmentally relevant concentrations of enrofloxacin on growth performance, oxidative stress, and mRNA expression of apoptotic enzymes (caspase-3, caspase-8)/pro-inflammatory cytokines (IL-1β, TNF-β, and IL-6) in gills of Oreochromis niloticus.

Aquatic habitats that include antibiotic residues pose the risk of causing antibiotic resistance as well as negative health impacts on human and non-target species. To assess the effects of enrofloxacin at environmentally relevant concentrations on Oreochromis niloticus, growth performance of O. niloticus, oxidative stress, and the transcriptional gene expressions of apoptotic enzymes and pro-inflammatory cytokines were determined in the gills. Environmentally relevant concentrations of enrofloxacin (1-10-100 µg/L) were exposed to fish for periods of 7 days and 21 days. The results demonstrated that enrofloxacin negatively affected growth performance at high applied concentrations in O. niloticus in the long-term effect. Furthermore, enrofloxacin disrupts the GSH-dependent antioxidant system in the gills, leading to oxidative stress through increased lipid peroxidation. Short-term exposure to low and medium concentrations of enrofloxacin increased the mRNA expression of apoptotic enzymes (caspase-3, caspase-8) and pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) in the gills. Considering the research findings, environmentally relevant concentrations of enrofloxacin negatively impact growth performance in O. niloticus and induce toxicity through the induction of inflammation and apoptosis, coupled with oxidative stress in the gills. In conclusion, the ecotoxicological impact of enrofloxacin necessitates careful consideration due to its potential to negatively affect non-target organisms.