Microplastics impair olfactory-mediated behaviors of goldfish Carassius auratus.

Recently, the ubiquitous presence of microplastics (MPs) has drawn worldwide concern over its potential threat to aquatic organisms. However, the effects of MPs on the olfactory ability of fish and the subsequent odorant evoked behaviors remain elusive. In the present study, we analyzed the potential olfactory toxicity of polystyrene (PS) MPs by assessing olfactory-driven behaviors of goldfish in response to odorants. Our results showed that the olfactory-driven behavioral responses of goldfish to L-cysteine and taurocholic acid were significantly hampered by a 28-day MP exposure. Further analysis demonstrated that exposure to MPs may suppress the expression of genes encoding olfactory G protein-coupled receptors, inhibit the enzyme activities of cation transport ATPases crucial for action potential generation, alter the in vivo contents of neurotransmitters as well as metabolites involved in the transduction of electrical signals, and cause olfactory bulb injury and neurotoxicity closely related to the processing of electrical signals. In conclusion, the results obtained in the present study suggest that MPs at environmentally relevant concentrations could impair the olfactory-mediated behavioral responses of goldfish, probably through hampering odorant identification, action potential generation, olfactory neural signal transduction, and olfactory information processing.