Warfarin is the most worldwide used
anticoagulant drug and
rodenticide. Since it crosses placental barrier it can induce
warfarin embryopathy (WE), a fetal mortality in neonates characterized by skeletal
deformities in addition to
brain hemorrhages. Although the effects of
warfarin exposure in aquatic off target species were already described, the particular molecular toxicological mechanisms during early development are still unclear. Here, we used zebrafish (Danio rerio) to describe and compare the developmental effects of
warfarin exposure (0, 15.13, 75.68 and 378.43 mM) on two distinct early developmental phases (embryos and eleuthero-embryos). Although exposure to both developmental phases induced fish mortality, only embryos exposed to the highest
warfarin level exhibited features mimicking mammalian WE, e.g. high mortality, higher incidence of
hemorrhages and altered skeletal development, among other effects. To gain insights into the toxic mechanisms underlying
warfarin exposure, the transcriptome of embryos exposed to
warfarin was explored through
RNA-Seq and compared to that of control embryos. 766 differentially expressed (564 up- and 202 down-regulated) genes were identified. Gene Ontology analysis revealed particular cellular components (cytoplasm, extracellular matrix, lysosome and vacuole), biological processes (mainly
amino acid and lipid metabolism and response to stimulus) and pathways (oxidative stress response and apoptosis signaling pathways) being significantly overrepresented in zebrafish embryos upon
warfarin exposure.
Protein-
protein interaction further evidenced an altered redox system, blood coagulation and vasculogenesis, visual phototransduction and
collagen formation upon
warfarin exposure. The present study not only describes for the first time the WE in zebrafish, it provides new insights for a better risk assessment, and highlights the need for programming the rat eradication actions outside the fish spawning season to avoid an impact on off target fish community. The urge for the development of more species-specific
anticoagulants for rodent pest control is also highlighted.