Chronic exposure to areca alkaloids at environmentally relevant concentrations alters neurobehavior, gut microbiota...

Trace-level neuroactive contaminants in aquatic environments are increasingly recognized as ecological hazards, yet the neurotoxic potential of areca alkaloids remains largely unexplored. In this study, adult zebrafish were chronically exposed to arecoline or arecaidine for 90 days to investigate long-term neurobehavioral toxicity and associated biological alterations. Behavioral assessments revealed persistent impairments in social interaction, reduced aggression, and altered exploratory activity following alkaloid exposure. Concomitantly, areca alkaloids induced intestinal injury characterized by villus atrophy, goblet cell depletion, epithelial alterations, and increased macrophage infiltration. Gut microbiota profiling revealed compositional shifts, with significant enrichment of inflammation-associated genera, including Acinetobacter, Pseudomonas and Rhodococcus, and depletion of several commensal taxa. At the central level, brain histopathology revealed neuronal damage and increased expression of apoptosis-associated markers. Brain metabolomic analysis further revealed extensive alterations in amino acid- and neurotransmitter-related metabolism, highlighted by alterations in glutamate, glycine, serine, N-acetyl-L-aspartic acid, and citrate, as well as enrichment of pathways related to alanine, aspartate and glutamate metabolism and aminoacyl-tRNA biosynthesis. Integrated correlation analyses revealed associations among altered gut bacterial genera, brain metabolic pathways, and behavioral endpoints, suggesting potential links among gut microbial alterations, brain metabolic changes, and behavioral outcomes following areca alkaloid exposure. In summary, these findings reveal that long-term exposure to areca alkaloids at environmental concentrations elicits neurobehavioral and neurotoxic effects in adult zebrafish accompanied by alterations in gut microbiota and brain metabolism, highlighting the potential of areca alkaloids as environmental neurotoxicants relevant to aquatic health risk assessment.