Neurotoxicity and aggressive behavior induced by anesthetic etomidate exposure in zebrafish: Insights from...

Etomidate (ETO), widely employed as a surgical anesthetic and more recently recognized as a drug of abuse, has been frequently detected in aquatic environment. However, the toxicity assessment of ETO is insufficient. Adult zebrafish were used to investigate toxicological effects of ETO. Four weeks ETO exposure could induced abnormal behaviors, including reduced anxiety, memory impairment, and heightened aggression. The increased aggression was quantitatively characterized using machine learning, which revealed significantly elevated instantaneous velocity and drastic changes in angular velocity. ETO was predominantly accumulated in the zebrafish brain, where it binds to GABA-A receptors, leading to a significant increase in GABA content. Furthermore, fluorescent staining of reactive oxygen species (ROS) in the brain revealed that ETO exposure significantly increased the oxidative stress level. This oxidative stress resulted in mitochondrial swelling, rupture, and damage to myelinated nerve fibers, ultimately causing cerebral injury in zebrafish. Multi-omics analysis further elucidated that ETO exposure down-regulated the MAPK signaling pathway, hyperactivated motor proteins, and induced metabolic disorders of lipids and amino acids. In summary, this study demonstrates that ETO induces neurotoxicity and behavioral alterations in zebrafish. These findings provide a critical insight into the mechanisms underlying ETO's neurotoxic effects and contribute to a more comprehensive understanding of its environmental and health risks.