Combined effects of a high-fat diet and polyethylene microplastic exposure induce impaired lipid metabolism and locomotor behavior in larvae and adult zebrafish.

Microplastics (MP), tiny plastic particles, can be ingested by fish through their habitat or contaminated food sources. When combined with a high-fat diet (HFD), MP exposure may lead to increased MP accumulation in fish and negative impacts on their health. However, the underlying mechanisms of how MP and HFD interact to promote fat accumulation in fish remain poorly understood. In this study, we aimed to evaluate the combined effect of HFD and polyethylene MP (PE-MP) in the zebrafish model (Danio rerio) and decipher its molecular mechanisms. Adult zebrafish exposed to the combined HFD and PE-MP showed elevated lipid accumulation, total cholesterol, triglycerides, and abnormal swimming behavior compared to HFD-fed fish. Histological and gene expression analysis revealed severe hepatic inflammation and injury, resembling nonalcoholic fatty liver disease (NAFLD) in the HFD + PE-MP exposed zebrafish. Moreover, HFD and PE-MP exposure upregulated genes related to lipogenesis (SREBP1, FAS, and C/EBPα) and inflammation (tnfα, il1β, and il-6) in the liver. These findings underscore the interactive effect of environmental pollutants and fish diet, emphasizing the importance of improving fish culture practices to safeguard fish health and human consumers from microplastic contamination through the food chain. This research sheds light on the complex interactions between microplastics and diet, providing valuable insights into the potential risks of microplastic pollution in aquatic ecosystems and the implications for human health. Understanding the underlying molecular mechanisms will contribute to international research efforts to mitigate the adverse effects of microplastics on both environmental and public health.