An Investigation of the Bioactivation Potential and Metabolism Profile of Zebrafish versus Human

The zebrafish model has been increasingly explored as an alternative model for toxicity screening of pharmaceutical drugs. However, little is understood about the bioactivation of drug to reactive metabolite and phase I and II metabolism of chemical in zebrafish as compared with human. The primary aim of our study was to establish the bioactivation potential of zebrafish using acetaminophen as a probe substrate. Our secondary aim was to perform metabolite profiling experiments on testosterone, a CYP3A probe substrate, in zebrafish and compare the metabolite profiles with that of human. The glutathione trapping assay of N-acetyl-p-benzoquinone imine demonstrated that zebrafish generates the same reactive metabolite as humans from the bioactivation of acetaminophen. Zebrafish possesses functional CYP3A4/5-like and UDP-glucuronosyltransferase metabolic activities on testosterone. Differential testosterone metabolism was observed among the two species. In silico docking studies suggested that the zebrafish CYP3A65 was responsible for the bioactivation of acetaminophen and phase I hydroxylation of testosterone. Our findings reinforce the need to further characterize the drug metabolism phenotype of zebrafish before the model can fully achieve its potential as an alternative toxicity screening model in drug research.