Lipid droplets (LDs) are lipid-rich and dynamic organelles which undergo cycles of biogenesis (triacylglycerol synthesis, as well as LD growth, budding, and expansion) and degradation (lipophagy). Many studies have highlighted the causative role of abnormal LD accumulation in the development of non-alcoholic fatty liver disease (NAFLD). Furthermore, while the positive impact of physical activity on NAFLD has been widely studied, its effect on LD dynamics remains unclarified.
The aim of this study was to investigate the impact of moderate aerobic exercise on LDs in the context of preventing and improving NAFLD. To do so, NAFLD was induced in mice, which then underwent 15 weeks of regular treadmill exercise.
15 weeks of regular moderate treadmill exercise was found to alleviate obesity, insulin intolerance, hyperlipidaemia, and hyperglycaemia in mice fed a high-fat diet. Physical activity was also found to improve NAFLD-associated hepatic steatosis, inflammation, and ballooning. It also prevented fat deposition and liver injury.
Furthermore, exercise was found to regulate hepatic LD size and structure via the inhibition of abnormal LD expansion coupled with the restoration of its lipophagic activity. As such, physical activity seemed to regulate LDs’ dynamic periods of biogenesis and clearance, and thus restored the flexibility of lipid mobilisation and metabolism.