Effect of feeding diets of varying fatty acid composition on apolipoprotein expression in newborn swine.

The purpose of this study was to determine the effect of chronic (1 wk) feeding of dietary triacylglycerol (TG) of varying fatty acid composition on small intestinal and hepatic apolipoprotein expression, as well as serum lipid and apolipoprotein concentrations, in newborn swine. Two-day-old female swine were fed one of three diets by gavage with the following lipid composition: medium-chain TG (MCT; MCT oil), intermediate-chain saturated TG (ICST; coconut oil), and long-chain polyunsaturated TG (LCPUT; safflower oil) at 753 kJ . kg-1 . day-1 with 51% of energy from fat. After 1 wk, serum lipids and apolipoprotein concentrations were measured, and jejunal apolipoprotein B (apo B) and apo A-I mass and apo B, apo A-I, apo A-IV, and apo C-III synthesis were measured. Liver was processed for determination of apo B and apo A-I mass and apo B, apo A-I, apo C-III, and beta-actin mRNA abundance by slot blot hybridization. Compared with the MCT and LCPUT groups, the ICST group had higher total serum cholesterol, TG, high-density lipoprotein (HDL)-cholesterol, and apo A-I concentrations. There were no differences among the three groups for intestinal apolipoprotein mass or synthesis. In liver, apo A-I mass was highest in the ICST group. Liver apo A-I and apo C-III mRNA abundance was highest in the ICST group. Among all three groups, hepatic apo A-I mass correlated significantly with plasma HDL-cholesterol concentrations, and serum TG concentrations correlated with hepatic apo C-III mRNA abundance. In conclusion, we found that in the newborn piglet, chronic feeding of ICST increases serum total cholesterol, TG, HDL-cholesterol, and apo A-I concentrations and hepatic expression of apo A-I and apo C-III mRNA, compared with feeding of MCT or LCPUT. We speculate that increased hepatic apo A-I expression may contribute to the higher serum HDL and apo A-I concentrations in the ICST animals. Increased hepatic expression of apo C-III with ICST feeding may contribute to the higher serum TG concentrations by apo C-III-mediated inhibition of the catabolism of triacylglycerol-rich lipoproteins.