Effect of High NEFA Concentration on Lipid Metabolism Disorders in Hepatocytes Based on lipidomics

Fatty liver is a common nutritional metabolic disease in periparturient dairy cows, which seriously affects their reproductive performance. During periparturient period, dairy cows are in a state of negative energy balance because they cannot meet the nutritional requirements for maintenance and lactation. As a result, non-esterified fatty acids (NEFA) are mobilized from adipose tissue, leading to an increase in NEFA concentration in the blood. When the rate of NEFA esterification into triglycerides (TAG) exceeds the rate of NEFA processing, fatty liver will form. Existing studies suggest that NEFA is closely associated with lipid metabolism disorders in hepatocytes, but it is not clear through which metabolites or metabolic pathways NEFA affects lipid metabolism disorders in hepatocytes. Therefore, the aim of this study was to investigate the effect of high concentration of NEFA on lipid metabolism in hepatocytes through the lipidomic approach and molecular biology techniques. Here, we found that NEFA (0.6-2.4 mM) significantly reduced the cell viability in a concentration-dependent manner, indicating that high concentrations of NEFA have lipotoxicity on hepatocytes. In addition, NEFA promoted TAG accumulation, increased the mRNA expression of the lipogenic molecules SREBP and FASN, and decreased the mRNA expression of lipolytic molecules CPT1A and HSL in hepatocytes. Mechanistically, the results of lipidomics analysis further showed that NEFA induced lipid metabolism disorders in hepatocytes by regulating metabolic pathways such as glycerol phospholipid metabolism, glycosyl phosphatidylinositol anchored biosynthesis, triglyceride metabolism, sphingolipid metabolism, and inositol phosphate metabolism.