A Multidimensional Framework for Integrated Toxicity Assessment and Prioritization of Naphthenic Acids in Marine Medaka (Oryzias melastigma): Neurotoxicity and Mechanistic Insights

Petroleum pollution poses a major challenge to global environmental health. Petroleum-derived naphthenic acids (NAs) are frequently detected in marine environments, yet their multidimensional toxicity and mechanisms remain poorly understood. Here, we developed an integrated toxicity framework combining bioassays, toxicity screening, computational simulations, transcriptomics, and bioinformatics to characterize NAs toxicity in marine medaka (Oryzias melastigma). A concentration gradient spanning environmentally detected levels to higher-effect concentrations (0.015–30 mg/L) revealed developmental defects, cardiac suppression, behavioral disruption, and metabolic dysfunction. CRITIC–AHP-based prioritization identified neurotoxicity as the predominant toxicity dimension, with cyclopentylpropionic acid (CPPA) and cyclohexylpropionic acid (CHPA) identified as major contributors. Mechanistically, these compounds were associated with distinct candidate pathways involving CXCR3-CXCL10 neuroinflammatory responses and DPP10-Kv4.2 ion homeostasis disruption. Their divergent toxicity profiles may be associated with differences in hydrophobicity and molecular flexibility. Rescue experiments supported these pathways, restoring swimming velocity by 60.32% and 62.09%, respectively. Furthermore, NAs induced neurobehavioral alterations and transcriptional signatures overlapping with Alzheimer’s disease-associated genes, with 14 and 12 candidate genes identified for CPPA and CHPA. Collectively, this study provides a cross-scale perspective linking physicochemical properties, toxicity pathways, and adverse outcomes of NAs, offering a conceptual approach for toxicity screening and mechanism elucidation of contaminants.