Molecular and behavioral assessment in larval zebrafish (Danio rerio) following exposure to environmentally relevant levels of the antineoplastic cyclophosphamide

Antineoplastics treat cancers and enter aquatic ecosystems through wastewater and hospital effluent. Risks associated with antineoplastics are not well characterized in aquatic organisms. We conducted zebrafish embryo/ larvae toxicity assays to evaluate responses to cyclophosphamide (0.01-50 mu M). Zebrafish survival was affected by 5 mu M cyclophosphamide and deformities were noted at > 1 mu M. Oxidative respiration remained unchanged in embryos with exposure up to 200 mu M. Reactive oxygen species were not increased by 50 mu M cyclophosphamide exposure. More than 15 oxidative stress and immune-related transcripts were measured. Superoxide dismutase 2 and heat shock protein 70 and 90a were induced in larvae by cyclophosphamide. Immune-related transcripts were assessed due to immunosuppressive properties of cyclophosphamide, and mmp9 and myd88 levels were altered in expression. Hyperactivity of larvae was noted following 5 mu M cyclophosphamide exposure. There was no change in anxiety-related endpoints (light-dark preference). Risks for larval fish exposed to cyclophosphamide in the environment may be low.