Effect of Red Grain Sorghum Whole Kernel Surface Lipid, Wax, and Oil Fractions on Saturated Fat Diet Induced Changes on Hepatic Metabolic and Energy Homeostasis in Hamsters

The surface lipid extracted from tannin-containing red grain sorghum whole kernel (R-GS-WK), and its two fractions, oil and wax, possess cholesterol-lowering properties when supplemented to a moderately fat diet rich in saturated fat. However, it is yet unknown how these sorghum lipid supplements affect hepatic cellular energy metabolism and metabolic flexibility when the latter is under the chronic influence of saturated fatty acid rich diet. To further understand the effects of these R-GS-WK lipid supplements, the objective of this research was to determine the effects and possible mechanisms of R-GS-WK surface lipid, wax and oil on hepatic cellular central carbon metabolism of a hamster model fed with moderately fat diet rich in saturated fatty acids, and to identify the components responsible for these effects. Three hamster studies were conducted to investigate the effects of these R-GS-WK lipid supplements. In each study, fifty-five 9-wk-old male hamsters were randomly assigned to five diet groups (n=11), including a 5% (wt:wt) fat diet [control diet (C)], a 15% (wt:wt) moderately fat diet [diet rich in saturated fat (HSF), which accounted for 70% of the total fatty acids], or HSF supplemented with either 1%, 3% or 5% (wt:wt) of R-GS-WK lipid supplement for 4 wks. Liver samples were analyzed via metabolic profiling and top-down proteomics to determine the effects on intermediates involved in the central carbon and energy metabolic pathways. The addition of surface lipid, wax and oil effectively upregulated hepatic lipogenesis and bile acid biosynthesis to reduce hepatic fat load and relieve mitochondrial stress, maintained mitochondrial oxidative machinery through upregulating glycolysis and amino acid degradation. Characterization of the three lipid supplements elucidated components that contributed to these modulating effects. However, the addition of sorghum lipid supplementation does not solve the fundamental problem of energy surplus, nor does it relief the redox misbalance. The hamsters also showed early signs of hepatic steatosis and were possibly pre-diabetic