Transcriptomic analysis of Bama pig's liver in various nutritional states reveals a metabolic difference of fatty acids.

Both fasting and treatment with a high-fat diet (HFD) can dramatically change fat metabolism in the liver and, thus, are commonly used methods to investigate hepatic fat metabolism and related diseases. Here, the gene expression profiles of pig liver under both conditions were investigated and changes in hepatic triacylglycerol (TG) levels under different diet conditions were determined. In this study, both fasting and HFD conditions significantly increased hepatic TG levels and serum levels of cholesterol, TG, high-density lipoprotein, low-density lipoprotein, and apolipoprotein B. Transcriptome sequencing analysis identified 580 differentially expressed genes (DEGs) between the fasting group and the control group (F/C group) and 613 between the HFD group and the control group (H/C group). Kyoto Encyclopedia of Genes and Genomes enrichment analysis found that the DEGs of the F/C group were mainly enriched in the synthesis pathways of fatty acids (FAs) with less than 16 carbons, while the DEGs of the H/C group were mainly enriched in the synthesis pathways of FAs with more than 16 carbons. In order to verify whether changes in the expression levels of the DEGs caused changes in FA metabolism, the composition and saturation of the FAs in liver TG were analyzed, which showed that under fasting conditions, the contents of monounsaturated and polyunsaturated FAs had increased, while the proportion of saturated FAs had decreased. However, the content of polyunsaturated FAs decreased, while the contents of monounsaturated and saturated FAs increased under HFD conditions. These results will help clarify the differences in FA metabolism in the liver under different nutritional states and indicate that the proportion of unsaturated FAs had increased in hepatic fat under fasting conditions.