In vivo triglyceride secretion and hepatic and plasma lipids in rats fed medium-chain triglycerides, tripelargonin, or corn oil

Abstract

The relationship between in vivo triglyceride secretion and the concentrations of cholesterol and triglycerides in liver and plasma was studied in fasted, male Sprague Dawley rats (150–170 g) fed 16% fat diets containing 8–16% medium chain triglycerides (68% C 8:0 and 24% C 10:0), 14% tripelargonate (C 9:0), or corn oil. Plasma and liver cholesterol concentrations were 10–20% lower ( P < 0.05), and hepatic activity of 3-hydroxymethyl-3-glutaryl Coenzyme A reductase was 44–66% lower ( P < 0.05) with ingestion of 14% medium chain triglycerides or tripelargonin than corn oil. Liver triglyceride concentrations were 19–44% lower ( P < 0.01) with ingestion of 14% medium chain triglycerides or tripelargonin than corn oil. Using the Triton WR-1339 technique, the rate of triglyceride secretion (mg/min × 100 g body wt), plasma triglyceride pool size, and the fractional rate constant for triglyceride secretion were not significantly different among treatment groups. This suggests that a greater rate of triglyceride secretion is not the primary factor associated with lower hepatic triglyceride levels in rats fed medium chain triglycerides. In summary, 10–20% lower plasma and liver cholesterol concentrations were noted with ingestion of saturated, medium-chain-length fatty acid triglycerides containing 8, 9, or 10 carbons compared to corn oil.