Dynamics in zebrafish development define transcriptomic specificity after angiogenesis inhibitor exposure

Chemical exposure during embryonic development can pose significant risks potentially leading to birth defects. Testing of chemicals regarding their developmental toxicity potential requires huge efforts, animals, and costs. For reduction of those, the zebrafish embryo might be applied, however, suitability of the respective OECD test with regard to specificity needs to be confirmed. The OECD TG 236 Fish Embryo Acute Toxicity Test recommends testing within the 0-96 hours post-fertilization (hpf) window. Although this timeframe captures critical stages of organogenesis and vascular development, a more time resolved exposure scenario is needed to elucidate the dynamic influence of developmental toxicants. In this study, we investigated the effects on the zebrafish transcriptome after exposure to putative vascular disruptor compounds, the tyrosine kinase inhibitors, sorafenib and SU4312, and the putative vascular disruptor compound Rotenone. We used an early (0 hpf) and a late (24 hpf) exposure start to determine specificity and sensitivity of the developing zebrafish embryo model. In both exposure scenarios we measured changes on the zebrafish transcriptome at multiple time points and developed an analysis pipeline for the detection and evaluation of differentially expressed genes (DEGs) in this time series data based on generalized additive models (GAMs). We observed mainly unspecific developmental toxicity in the early exposure scenario, while a specific repression of vascular related genes was only partially observed. In contrast, differential expression of vascular-related genes could be identified clearly during with the late exposure scenario. Finally, we compared the toxicodynamic responses with the toxicokinetics of the compounds and show the influence of the internal dose kinetics on the gene expression patterns in zebrafish embryo.