Toxicometabolomics
and biotransformation product (bioTP) elucidation
were carried out in single zebrafish (ZF) embryos exposed to carbamazepine
(CBZ). Exposures were conducted in 96-well plates containing six CBZ
concentrations ranging from 0.5 μg/L to 50 mg/L (
n
= 12 embryos per dose). In the 50 mg/L dose group, 33% of embryos
developed edema during the exposure (120 hpf), while hatching was
significantly delayed in three of the lower-dose groups (0.46, 3.85,
and 445 μg/L) compared to the control at 48 hpf. Toxicometabolomic
analysis together with random forest modeling revealed a total of
80 significantly affected metabolites (22 identified via targeted
lipidomics and 58 via nontarget analysis). The wide range of doses
enabled the observation of both monotonic and nonmonotonic dose responses
in the metabolome, which ultimately produced a unique and comprehensive
biochemical picture that aligns with existing knowledge on the mode
of action of CBZ. The combination of high dose exposures and apical
endpoint assessment in single embryos also enabled hypothesis generation
regarding the target organ for the morphologically altering insult.
In addition, two CBZ bioTPs were identified without additional exposure
experiments. Overall, this work showcases the potential of toxicometabolomics
and bioTP determination in single ZF embryos for rapid and comprehensive
chemical hazard assessment.