Lipid metabolic adaption to long-term ambient PM2.5 exposure in mice
2021
Emerging evidence has demonstrated that exposure to fine particulate matter (PM₂.₅) is a risk factor for lipid metabolic disorders in the liver. However, the effects of PM₂.₅ exposure time duration on hepatic lipid metabolism remain unknown. In this study, C57BL/6 mice were randomly divided into ambient PM₂.₅ (PM) or filtered air (FA) exposure chamber for short-term (4 weeks) or long-term (24 weeks) exposure via a whole body exposure system. We measured hepatic triglyceride and free fatty acid levels and analyzed the alteration of lipometabolism-related molecules in the liver. We found that triglyceride levels were significantly elevated in both short-term and long-term PM₂.₅-exposed mice and free fatty acid levels were increased after long-term PM₂.₅ exposure. Besides, enzymes for lipolysis and fatty acid oxidation in the liver were inhibited after short-term PM₂.₅ exposure but adaptively enhanced after long-term PM₂.₅ exposure. Furthermore, molecules for fatty acid uptake were down-regulated in the short-term PM₂.₅-exposed mice whereas molecules for lipid export were induced after long-term PM₂.₅ exposure. Therefore, ambient PM₂.₅ exposure disturbed hepatic lipid metabolism and the effects varied in different exposure duration. These findings in mice provide new insight into the biological basis of PM₂.₅-induced human metabolic dysfunction and specific strategies may be applied based on different exposure time periods.
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