Toxicity assessment of VX in zebrafish: multi-organ toxicity evaluation and tissue distribution visualization using DESI-MSI.

As a chemical warfare agent posing a persistent threat, VX's potential hazards in military and terrorist scenarios underscore the urgency of investigating its multi-organ toxicity and bioaccumulative properties. In this study, first of all, zebrafish larvae were first used as a model to evaluate the toxic effects of VX, and the median lethal concentration (LC50) and maximum non-lethal concentration (MNLC) of acute exposure was determined to be 409.98 μg/L, and the MNLC was 77.43 μg/L. Subsequent multi-organ toxicity evaluations at MNLC-based exposure concentrations revealed distinct pathological phenotypes in VX-exposed zebrafish larvae, including microphthalmia, pericardial edema, hepatic degeneration, renal edema, and delayed yolk sac resorption, concomitant with significant dose-dependent impairment of burst-swimming capacity and spontaneous movement frequency. Histological examinations revealed that VX induced multi-organ damage in adult zebrafish, involving the spinal cord, brain, gills, kidneys, and liver. Finally, a DESI-MSI-driven analytical framework was established to achieve micrometer-resolution mapping of VX and its metabolites, delineating spatiotemporal accumulation of VX in multiple organ systems. DESI-MSI spatial mapping revealed VX and EMPA biodistribution across nine anatomically defined zebrafish organs (eye, brain, gill, heart, liver, kidney, spinal cord, gonad, muscle), while LC-MS/MS validation confirmed the semi-quantitative reliability of DESI-MSI data. The bioaccumulation factor (BCF) analysis revealed gender-specific accumulation of VX in zebrafish (females: 30.86 ± 2.35; males: 4.28 ± 0.47, after VX exposure for 4 days), demonstrating pronounced bioaccumulation potential with a 7.2-fold sex disparity. This study pioneers the evaluation of VX-induced multi-organ toxicity and delineates its spatiotemporal biodistribution in zebrafish, providing critical evidence for mechanistic investigations of organ-specific damage and establishing a methodological foundation for comparative toxicological research and risk mitigation strategies related to chemical warfare agents.