Micro/nanoplastics impair the feeding of goldfish by disrupting the complicated peripheral and central regulation of appetite

The ubiquitous presence of plastic particles in water bodies poses a potential threat to aquatic species. Although numerous adverse effects of microplastics (MPs) and nanoplastics (NPs) have been documented, their effects on fish feeding, one of the most important behaviors of animals, are far from being fully understood. In this study, the effects of MPs and NPs (at environmentally realistic levels) on fish food consumption and feeding behavior were assessed using goldfish (Carassius auratus) and polystyrene (PS) particles as representatives. In addition, to reveal the potential mechanisms, the effects of MPs and NPs on peripheral and central regulation of appetite were evaluated by examining appetite-regulation related intestinal, serous, and hypothalamic parameters. The results obtained indicated that the 28-day MP- and NP-exposure significantly impaired goldfish feeding by disrupting peripheral and central appetite regulation. Based on differences observed in their effects on the abovementioned behavioral, histological, and physiological parameters, MPs and NPs may interfere with appetite regulation in a size-dependent manner. Blocking the gastrointestinal tract and causing histopathological and functional damage to inner organs may be the main routes through which MPs and NPs disrupt appetite regulation. Our findings suggested that plastic particles exposure may have far-reaching effects on fish species through impaired feeding, which warrants further attention.