Cholesteryl Ester Species Differently Elevate Plasma Cholesterol in Hamsters

This study was to examine the effect of free cholesterol (C) and individual cholesteryl ester (CE) species, namely cholesteryl palmitate (CP), cholesteryl stearate (CS), cholesteryl oleate (CO), and cholesteryl linoleate (CL) on plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), non-HDL-C, and triacylglycerols (TG) in hamsters. Results showed that addition of dietary CE species into diet at 0.1% differently raised plasma TC concentrations, with CO elevating plasma TC to 331 mg/dL, while CS raised plasma TC only to 220 mg/dL. It was found that CS was a poor substrate of pancreatic cholesterol esterase, while CO was a good substrate. The fecal analysis showed CS-fed hamsters had the highest fecal cholesterol concentration, while RT-PCR analysis found CS feeding was associated with down-regulations of intestinal Niemann-Pick C1 like 1 (NPC1L1) and acyl-CoA: cholesterol acyltransferase 2 (ACAT2) as well as microsomal triacylglycerol transport protein (MTP). It was therefore concluded that the plasma cholesterol-raising activity of CE species was partially governed by their hydrolysis rates in the intestine, and the relative low raising activity associated with CS was mediated by down-regulation of intestinal NPC1L1, ACAT2, and MTP.