Testing Strategies for Metabolite-Mediated Neurotoxicity

Area of Science:

• Toxicology
• Developmental Neurotoxicity
• In Vitro Assays

Background:

• Metabolism-dependent toxicity challenges current non-animal new approach methods (NAMs) in risk assessment.
• Existing NAMs often lack metabolic activity, potentially leading to false negative predictions for human health hazards.
• Assessing metabolite-mediated toxicity is crucial for accurate developmental neurotoxicity (DNT) evaluations.

Purpose of the Study:

• To develop and evaluate strategies for integrating metabolic activity into DNT NAMs.
• To identify suitable positive controls for metabolite-related neurotoxicity.
• To enhance the predictive capacity of NAMs for accurately assessing chemical risks.

Main Methods:

• Utilized hepatic post-mitochondrial fractions (S9) to generate metabolite mixtures.
• Applied metabolite mixtures to NAMs, including the MitoMet (UKN4b) and cMINC (UKN2) assays.
• Assessed the toxic potency of metabolites compared to parent compounds on neuronal health.

Main Results:

• Demonstrated that some metabolites exhibit higher neurotoxic potency than their parent compounds.
• Successfully integrated a "metabolisation module" using S9 fractions into DNT NAMs.
• Showcased the applicability and transferability of the integrated approach across different NAMs.

Conclusions:

• The developed strategy effectively addresses metabolite-mediated toxicity in DNT NAMs.
• Integrating metabolic capability into NAMs is essential for robust next-generation risk assessment (NGRA).
• Further discussion is needed for broader implementation of this approach in regulatory science.