Neurotoxic potential of imatinib in aquatic vertebrates: Behavioral and biochemical disruptions in zebrafish.

Imatinib mesylate (IM), a first-generation tyrosine kinase inhibitor (TKI), remains a global standard in leukemia treatment. However, its environmental persistence and structural homology with conserved kinase domains in aquatic vertebrates raise concerns about potential off-target effects in non-target organisms. This study investigates, for the first time, the neurotoxic impact of IM on adult zebrafish (Danio rerio), employing a multidisciplinary approach that integrates behavioral assays, enzymatic analysis, oxidative stress biomarkers, and gene expression profiling. Exposure to IM induced a distinct anxiety-like behavioral phenotype in zebrafish, characterized by increased bottom-dwelling, heightened locomotor activity, and delayed exploration of upper tank zones in the Novel Tank Test. Concurrently, IM elicited a concentration-dependent inhibition of brain acetylcholinesterase (AChE) activity without classical active-site interaction, suggesting an indirect mechanism potentially linked to oxidative stress. Biochemical analyses confirmed increased lipid and protein oxidation, decreased antioxidant enzyme activities (SOD, CAT), and transcriptional upregulation of pro-apoptotic markers (bax, p53, casp3), alongside suppression of oxidative defense and energy-regulatory genes (nrf1, nrf2, prkaa1). The downregulation of prkaa1, encoding the catalytic subunit of AMP-activated protein kinase (AMPK), implicates disrupted metabolic adaptation and redox homeostasis as central features of IM-induced toxicity. Together, these findings suggest that IM provokes neurobehavioral disturbances in zebrafish through mitochondrial dysfunction, impaired AMPK signaling, oxidative stress, and secondary inhibition of AChE, ultimately leading to cholinergic dysregulation and anxiety-like responses.