Behavioral profiling of zebrafish embryos exposed to a panel of 60 water-soluble compounds

The zebrafish is a powerful whole animal model which is complementary to in vitro and mammalian models. It has been shown to be applicable to the high-throughput behavioral screening of compound libraries. We have analysed 60 water-soluble toxic compounds covering a range of common drugs, toxins and chemicals, and representing various pharmacological mechanisms. Wild-type zebrafish larvae were cultured individually in defined buffer in 96 well plates. They were exposed for a 96 h period starting at 24 h post fertilization (hpf). A logarithmic concentration series was used for range-finding, followed by a narrower geometric series for LC50 determination. LC50 values were determined at 24 h intervals and behavioral testing was carried out on day 5. We used the visual motor response test, in which movement of individual larvae was analysed using automated video-tracking. For all compounds, LC50 values were found to decrease as the embryo developed. The majority of compounds (57/60) produced an effect in both the basal (lights on) and challenge phases (lights off) of the behavioral assay. These effects were either (i) suppression of locomotor activity (monotonic concentration-response); (ii) stimulation then suppression (biphasic response); (iii) stimulation (monotonic response). We conclude that behavioral assays with zebrafish embryos could be useful for pharmaceutical efficacy and toxicity screening. The precise phenotypic outcome obtained with behavioral assay varies with compound class.

► The high-throughput behavioral-based assay with zebrafish embryos.
► The precise readout obtained varies with compound class.
► Our assay is sensitive not only to toxins but also to useful drugs.
► This assay uses sub-lethal doses and more sensitive than mortality-based assays.
► Our assay is for detecting biological activities, with unique behavioral signature.