Microplastic exposure induces muscle growth but reduces meat quality and muscle physiological function in chickens.

Microplastic (MP) pollution has become one of the global environmental concerns, but the contamination and effect of MP on chicken skeletal muscle are scarcely researched. Here, we found MP contamination in the chicken skeletal muscles, which were directly collected from a large-scale chicken farm. Using Pyrolysis-Gas Chromatography-Mass Spectrometry and Agilent 8700 laser direct infrared imaging spectrometer, we found that polystyrene (PS) and polyamide are the significant type of MPs detected in chicken skeletal muscle. Constant PS-MP oral feeding for >21 days increases the content of MP deposited in chicken breast muscle, but the MP content in the leg muscle was gradually decreased. Surprisingly, the chicken's body and skeletal muscle weight was increased after constant PS-MP feeding. Physiological results showed that PS-MP exposure inhibited energy and lipid metabolism, induced oxidative stress, and potential for neurotoxicity in the skeletal muscle. Metabolomic analysis of the liquid chromatography-tandem mass spectrometry and gas chromatography coupled with the mass spectrometer results showed that PS-MP exposure changed the metabolomic profile and reduced meat quality. In vitro, experimental results showed that PS-MP exposure induced chicken primary myoblasts proliferation and apoptosis but decreased myoblasts differentiation. Transcriptome analysis of the skeletal muscle indicates that PS-MP exposure affects skeletal muscle function by regulating genes involved in neural function and muscle development. Considering that chicken is one of the most important meat foods in the world, this study will provide an essential reference for protecting meat food safety.