TOTAL PARENTERAL-NUTRITION CONTAINING MEDIUM-CHAIN VS LONG-CHAIN TRIGLYCERIDE EMULSIONS ELEVATES PLASMA-CHOLESTEROL CONCENTRATIONS IN RATS

Male Fischer 344 rats (235-246 g) were fed for 6-14 d by intravenous o r intragastric infusion with total parenteral nutrition (TPN) solution s providing 40 or 65% of nonprotein energy as fat from long-chain trig lyceride (LCT) or a 3:1 admixture of medium-chain triglyceride (MCT) a nd LCT emulsions. In three separate experiments, plasma cholesterol co ncentrations were significantly greater (24-32%) with intravenous infu sion of TPN solutions containing MCT-LCT rather than LCT. Plasma chole sterol concentrations in rats were not significantly different with in tragastric infusion of TPN solutions containing MCT-LCT rather than LC T. Hepatic total lipid and triglyceride concentrations were not signif icantly different. Hepatic total cholesterol and esterified cholestero l concentrations were significantly lower in animals given 65% of ener gy from MCT-LCT rather than LCT emulsions (main effects, two-way ANOVA ). The concentration of individual hepatic acyl-CoA esters reflected t he fatty acid profiles of the lipid emulsions infused. Total hepatic a cyl-CoA concentrations suggested differences in utilization of acyl-Co A esters with intravenous infusion of MCT-LCT rather than LCT and were consistent with rapid oxidation of MCT. These data demonstrate that M CT-LCT elevates plasma cholesterol concentrations compared with LCT em ulsions with intravenous, but not with intragastric, infusion of TPN s olutions in rats.