# Neurotoxicity-Based Toxicometabolomics of N‑Ethyl Pentedrone Using Zebrafish as an In Vivo Model

## TL;DR

This study explores the neurotoxic effects of N-ethyl pentedrone using zebrafish, revealing how it affects brain chemistry and metabolism.

## Contribution

The study provides novel insights into the metabolism and neurotoxic mechanisms of N-ethyl pentedrone using a zebrafish in vivo model.

## Key findings

- NEP metabolism involves N-dealkylation, β-ketone reduction, hydroxylation, and O-glucuronidation.
- NEP exposure alters metabolite levels linked to neurotransmitter function, energy metabolism, and oxidative stress.
- Zebrafish model effectively identifies neurochemical disruptions caused by NEP exposure.

## Abstract

New psychoactive
substances (NPS), particularly synthetic cathinones,
have gained increasing attention due to their widespread recreational
use and associated public health risks. Within this class, N-ethyl pentedrone (NEP) has been linked to cases of severe
intoxication; however, its metabolism and neurobiological effects
have remained poorly characterized. This study aimed to investigate
the metabolism and neurotoxicological effects of NEP using the Zebrafish
Water Tank protocol, an established alternative model for evaluating
the toxicological properties of psychoactive substances. Liquid chromatography-high-resolution
mass spectrometry (LC-HRMS) was employed to characterize NEP metabolites
in exposure water and zebrafish brain tissue, complemented by a toxicometabolomic
approach to elucidate adverse events triggered in the central nervous
system. The analysis revealed metabolic processes of NEP primarily
through N-dealkylation, β-ketone reduction,
hydroxylation, and O-glucuronidation. Metabolites
were identified in exposure water (n = 3) and in
brain tissue (n = 7). Untargeted toxicometabolomics
revealed six statistically significant differentially expressed metabolites
between the exposed and control animals. Four annotated metabolites
were found upregulated in NEP-exposed zebrafish: propionylcarnitine
(p = 0.001, fold change (FC) = 2.2), l-kynurenine
(p = 0.024, FC = 2.9), adenylyl(3′–5′)­cytidine
(p = 0.027, FC = 2.1), and cytidine (p = 0.028, FC = 2.5), whereas two were downregulated: putatively PI­(19:1­(9Z)/0:0)
(p = 0.032, FC = 0.2) and an identified compound
(p = 0.034, FC = 0.3). Altogether, these findings
suggest neurochemical alterations induced by NEP exposure involving
disruptions in neurotransmitter biosynthesis and function, energy
metabolism, and oxidative stress responses. Furthermore, changes in
lipid metabolism and mitochondrial function highlight the potential
mechanisms underlying the observed neurotoxicity. Overall, our findings
provide new insights into the metabolism and neurobiological effects
of NEP, underscoring its potential neurotoxicity and associated mechanisms.
Additionally, this study reinforces the utility of zebrafish as a
model for investigating the pharmacokinetics and toxicodynamics of
NPS.