Biomedical Engineering Reference
In-Depth Information
Chapter
9
Whole Zebrafish Cytochrome
P450 Assay for Assessing
Drug Metabolism and Safety
Chunqi Li, Liqing Luo, Jessica Awerman, and Patricia McGrath
Phylonix, Cambridge, MA, USA
9.1 INTRODUCTION
Cytochrome P450 (CYP) enzymes catalyze the majority of known drug metabolizing
reactions and many clinically relevant drug-drug interactions are associated with CYP
inhibition or induction. Because of their genetic and physiological similarity to
humans, zebrafish show promise as a predictive animal model for assessing drug
metabolism and safety. Several zebrafish CYP genes that either have high homology to
human genes or cause catalyzing reactions similar to those in mammals, including
CYP3A65, CYP1A1, A19, B19, 2K6, 3C1, 2J1, and CYP26D1, have been cloned and
characterized. Zebrafish CYP3A65 has been confirmed as a CYP3A ortholog. In this
research, using a commercially available human CYP3A4-specific substrate, we
developed a microplate-based whole zebrafish CYP3A4 functional activity assay.
Specificity of the assaywas initially confirmed using azamulin, amammalianCYP3A4
inhibitor, dexamethasone and rifampicin, CYP3A4 inducers, and
-naphthoflavone
(ANF), a non-CYP3A4 inhibitor/inducer. We further validated the zebrafish model by
assessing five additional mammalian CYP3A4 inhibitors, disopyramide, erythromy-
cin, fluvoxamine, omeprazole, and cimetidine, and six mammalian CYP3A4 inducers,
carbamazepine, hydrocortisone, prednisone, pregnenolone-16
a
-carbonitrile, lovastat-
in, and phenytoin. Overall successful prediction rate was 87% (13/15): 100% for
inhibition (6/6) and 75% for induction (6/8). These results demonstrate that zebrafish
exhibit comparable CYPmetabolism profiles as mammals supporting use of thewhole
zebrafish microplate assay as a preliminary screen for assessing drug safety.
a
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