Environmentally relevant concentrations of fluconazole alter the embryonic development, oxidative status, and gene expression of NRF1, NRF2, WNT3A, WNT8A, NRD1, and NRD2 of Danio rerio embryos

Up to date, there is little information published concerning fluconazole (FCZ) toxicity at environmentally relevant concentrations. Bearing in mind the above background of FCZ, we aimed to evaluate the embryotoxic effects environmentally relevant concentrations of FCZ (800-1000 ng/L) may induce in Danio rerio. Moreover, we also wanted to prove whether these FCZ concentrations could generate oxidative stress and alter the expression of several genes related to the antioxidant mechanisms, sterol and retinol biosynthesis, and embryogenesis. Our findings demonstrate that FCZ, at all concentrations, induced pericardial edema, yolk sac deformation, scoliosis, and tail malformation in embryos. Moreover, we also demonstrated this drug altered the redox equilibrium of fish, promoting the production of lipoperoxidation level, hydroperoxide content, and protein carbonyl content in a concentration-dependent manner. Concerning gene expression, FCZ downregulated wingless-type MMTV integration site family member 3a (WNT3A), wingless-type MMTV integration site family member 8a (WNT8A), N-arginine dibasic convertase 1 (NRD1), and N-arginine dibasic convertase 2 (NRD2) and upregulated cytochrome P450 family 26 subfamily a member 1 (CYP26A1), cytochrome P450 family 26 subfamily a member 1B (CYP261B), nuclear respiratory factor 1 (NRF1), and nuclear respiratory factor 2 (NRF2) in D. rerio larvae. Collectively, our results point out that FCZ, at low concentrations, may alter the embryogenesis, oxidative status, and expression of several genes in D. rerio embryos via an impairment in sterol and retinol biosynthesis. Thus, our results provide some of the first evidence that FCZ, even at environmentally relevant concentrations, is harmful to aquatic species.