Biotransformation of two proteratogenic anti-epileptics in the zebrafish (Danio rerio) embryo

02:572 years ago

The zebrafish (Danio rerio) embryo has gained interest as an alternative model for developmental toxicity testing, which still mainly relies on in vivo mammalian models (e.g., rat, rabbit). However, cytochrome P450 (CYP)-mediated drug metabolism, which is critical for the bioactivation of several proteratogens, is still under debate for this model. Therefore, we investigated the potential capacity of zebrafish embryos/larvae to bioactivate two known mammalian proteratogens, carbamazepine (CBZ) and phenytoin (PHE) into their mammalian active metabolites, carbamazepine-10,11-epoxide (E-CBZ) and 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), respectively. Zebrafish embryos were exposed to three concentrations (31.25, 85, and 250 μM) of CBZ and PHE from 51⁄4 to 120 hours post fertilization (hpf) at 28.5°C under a 14/10 hour light/dark cycle. For species comparison, also adult zebrafish, rat, rabbit and human liver microsomes (200 μg/ml) were exposed to 100 μM of CBZ or PHE for 240 minutes at 28.5°C. Potential formation of the mammalian metabolites was assessed in the embryo medium (48, 96, and 120 hpf); pooled (n=20) whole embryos/larvae extracts (24 and 120 hpf); and in the microsomal reaction mixtures (at 5 and 240 minutes) by targeted investigation using a UPLC–Triple Quadrupole MS system with lamotrigine (0.39 μM) as internal standard. Our study showed that zebrafish embryos metabolize CBZ to E-CBZ, but only at the end of organogenesis (from 96 hpf onwards), and no biotransformation of PHE to HPPH occurred. In contrast, our in vitro drug metabolism assay showed that adult zebrafish metabolize both compounds into their active mammalian metabolites. However, significant differences in metabolic rate were observed among the investigated species. These results highlight the importance of including the zebrafish in the in vitro drug metabolism testing battery
for accurate species selection in toxicity studies.

Related

Cells4Thought: using iPSCs for neurodevelopmental health
Projects and initiatives
HealthToxicologyInnovationIn vitro

Cells4Thought: using iPSCs for neurodevelopmental health

The prevalence of neurodevelopmental disorders (NDDs), including cognitive impairments, is increasing worldwide with great impact on daily life quality. There is evidence that exposure to chemicals may contribute to the incidence of NDD. However, a causal link is lacking. Towards this goal, a human-relevant in vitro model system mimicking parts of brain development, such as neuronal network functioning, could be used for mechanistic research on how gene-environment interactions contribute to the development of NDD. This is going to be studied in the project Cells4Thought, using induced pluripotent stem cells form different individuals to study the effect of chemicals on neuronal differentiation.
02:3819 days ago
We all want a safer world for humanity, animals and the environment: Transition Animal-free Innovation
Projects and initiatives
HealthInnovationPolicy

We all want a safer world for humanity, animals and the environment: Transition Animal-free Innovation

Why is the transition to animal-free research so important? What are animal-free models? How does TPI (Transition Animal-Free Innovation) encourage their development and use? And who are we working with to make this happen? We explain this in our animation. More and more animal-free tests and research methods are becoming available, but not all research questions or safety tests can be answered in this way yet. In addition, the validation, qualification and acceptance of non-animal innovations still lags behind. Therefore, the Dutch Ministry of Agriculture, Nature and Food Quality (LNV) stimulates the development and application of animal-free innovations. This is done with the partner programme Transition Animal-free Innovation (TPI).
02:4855 days ago
New approaches for cancer hazard assessment
Innovation examples

New approaches for cancer hazard assessment

Chemical substances are subjected to assessment of genotoxic and carcinogenic effects before being marketed to protect man and the environment from health risks. For cancer hazard assessment, the long-term rodent carcinogenicity study is the current mainstay for the detection of nongenotoxic carcinogens. However, carcinogenicity studies are shown to have prominent weaknesses and are subject to ethical and scientific debate. A transition toward a mechanism-based weight of evidence approach is considered a requirement to enhance the prediction of carcinogenic potential for chemicals. At RIVM, we are working on this alternative approach for cancer hazard assessment, which makes optimal use of innovative (computational) tools and be less animal demanding. For more information, click on the link in the video or read on here (https://doi.org/10.1080/10408444.2020.1841732) and here (https://doi.org/10.1080/10408444.2018.1458818). Contact the expert (https://nl.linkedin.com/in/mirjamluijten)
03:142 months ago
Helpathon #10 – Can you help Jolanda and Elza?
Meeting videos
HelpathonsEducation

Helpathon #10 – Can you help Jolanda and Elza?

Jolanda van der Velden, Chair of Physiology, and Elza van Deel, Educator, from Amsterdam University Medical Center want to support PhDs in preparing for the animal-free transition. They are both looking for an implementation strategy and course design. Do you have an interest in animal-free education and education about animal-free research? Read more and register here (https://www.helpathonhotel.org/coming-up).
00:552 months ago