Zebrafish Larvae as a Model Organism to Study Biotransformation

Abstract

The zebrafish larva is an increasingly used model organism in many fields of research, including drug development. Due to traits like their small size, rapid development, and high degree of genetic similarity with humans, they could likely represent a valuable model for investigating pharmacokinetic properties such as biotransformation in preclinical research. In this study, zebrafish larvae were used as a model system to investigate biotransformation of simvastatin, fluvastatin, and captopril using LC-MS/MS (ESI QQQ) for analysis. Zebrafish larvae were exposed to the drugs through aquatic exposure, and both the embryo water and the zebrafish larvae were analyzed for contents of drugs and selected metabolites. Procedures for sample preparation were established, and suitable LC-MS/MS methods were developed for the selected analytes. This study highlights that differences in developmental stages of the zebrafish larvae need to be considered when investigating biotransformation of drugs with this model system, since the maturation of several organs might affect the accumulation and elimination rates of the administered drugs. We encountered issues related to signal suppression and matrix effects when embryo water and homogenized zebrafish larvae were present in the samples. We also established that adsorption issues of hydrophobic drugs, like simvastatin, can contribute to poor signals or lack of detection when using plastic-based equipment for sample preparation. These considerations should be investigated further when using the zebrafish larva model. Despite these analytical reservations, metabolites of the administered drugs were detected in samples collected from zebrafish larvae, showing the value of zebrafish larvae as a model system in biotransformation studies. However, before the zebrafish larva can be appropriately validated as a model system to study biotransformation, further research is thus needed.