title: In Vitro Biotransformation of Two Human CYP3A Probe Substrates and Their Inhibition during Early Zebrafish Development.
abstract: At present, the zebrafish embryo is increasingly used as an alternative animal model to screen for developmental toxicity after exposure to xenobiotics. Since zebrafish embryos depend on their own drug-metabolizing capacity, knowledge of their intrinsic biotransformation is pivotal in order to correctly interpret the outcome of teratogenicity assays. Therefore, the aim of this in vitro study was to assess the activity of cytochrome P450 (CYP)-a group of drug-metabolizing enzymes-in microsomes from whole zebrafish embryos (ZEM) of 5, 24, 48, 72, 96 and 120 h post-fertilization (hpf) by means of a mammalian CYP substrate, i.e., benzyloxy-methyl-resorufin (BOMR). The same CYP activity assays were performed in adult zebrafish liver microsomes (ZLM) to serve as a reference for the embryos. In addition, activity assays with the human CYP3A4-specific Luciferin isopropyl acetal (Luciferin-IPA) as well as inhibition studies with ketoconazole and CYP3cide were carried out to identify CYP activity in ZLM. In the present study, biotransformation of BOMR was detected at 72 and 96 hpf; however, metabolite formation was low compared with ZLM. Furthermore, Luciferin-IPA was not metabolized by the zebrafish. In conclusion, the capacity of intrinsic biotransformation in zebrafish embryos appears to be lacking during a major part of organogenesis.
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. evy.verbueken@uantwerpen.be.
authors.forename: Evy
authors.initials: E
authors.lastname: Verbueken
authors.affiliation: Wilson Tox Lab, Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada. derekrxr@gmail.com.
authors.forename: Derek
authors.initials: D
authors.lastname: Alsop
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. moayad.saad@student.uantwerpen.be.
authors.forename: Moayad A
authors.initials: MA
authors.lastname: Saad
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. casper.pype@uantwerpen.be.
authors.forename: Casper
authors.initials: C
authors.lastname: Pype
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. els.vanpeer@uantwerpen.be.
authors.forename: Els M
authors.initials: EM
authors.lastname: Van Peer
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. Christophe.Casteleyn@UGent.be.
authors.forename: Christophe R
authors.initials: CR
authors.lastname: Casteleyn
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. chris.vanginneken@uantwerpen.be.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Van Ginneken
authors.affiliation: Wilson Tox Lab, Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada. wilsojo@mcmaster.ca.
authors.forename: Joanna
authors.initials: J
authors.lastname: Wilson
authors.affiliation: Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Antwerp, Belgium. steven.vancruchten@uantwerpen.be.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Van Cruchten
mesh_terms: D000818:Animals; D001711:Biotransformation / Q000187:drug effects; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D049454:Firefly Luciferin / Q000378:metabolism; D006801:Humans; D007654:Ketoconazole / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D015335:Molecular Probes / Q000378:metabolism*; D010078:Oxazines / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics; D013379:Substrate Specificity / Q000187:drug effects; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism*
chemical_list: D015335:Molecular Probes; D010078:Oxazines; C076580:7-methoxyresorufin; D049454:Firefly Luciferin; D051544:Cytochrome P-450 CYP3A; D007654:Ketoconazole
keywords: activity; and biotransformation; cytochrome P450; development; embryo; in vitro; zebrafish