Adverse outcome pathway-based analysis of vanillic acid-induced neurodevelopmental toxicity and cellular senescence in zebrafish.

Vanillic acid (VA), widely used in industrial and therapeutic applications, also presents potential ecological and biological risks. This study systematically investigated the developmental and neurotoxic effects of VA in zebrafish and explored its mechanistic pathways within an Adverse Outcome Pathway (AOP) framework. VA exposure resulted in concentration-dependent toxicity, with an LC50 of 638.3 μM. High VA concentrations induced developmental abnormalities, including malformations of the eyes, otic vesicles, craniofacial structures, and tails. Behavioral assessments revealed a significant reduction in larval locomotor activity, indicating disruption of neural development. At the molecular level, VA exposure affected the expression of multiple key genes involved in nervous system, sensory organ development and cellular senescence, such as gfap, pomca, bdnf, s100b, insm1a, mbpa, p21, and telom. Notably, VA exhibited a biphasic effect on cellular senescence, with lower concentrations inhibiting and higher concentrations promoting it. Molecular docking analysis suggested potential binding interactions of VA with neural, sensory organ and senescence-related proteins (Telom, Gnat2, Gnat1, Col2a1a, and Sox9b). The AOP framework delineated the mechanistic sequence of VA-induced toxicity from molecular perturbations to organism-level outcomes, including abnormal behavior and increased early-life mortality. Ecological risk assessment further predicted moderate acute toxicity of VA to green algae, highlighting its potential environmental hazard. Overall, these findings provided comprehensive insights into the molecular mechanisms underlying VA-induced neurodevelopmental and cellular senescence, highlighting its potential implications for aquatic ecosystem health and human environmental safety.