Dietary Fats Differentially Modulate the Expression of Lecithin:Cholesterol Acyltransferase, Apoprotein-A1 and Scavenger Receptor B1 in Rats

Abstract

In the present study the effects of dietary fat with defined fatty acids on lecithin:cholesterol acyltransferase (LCAT) and apoA-1, the two components of HDL that play a major role in reverse cholesterol transport (RCT), were examined. In addition, the expression of scavenger receptor B1 (SR-B1), the receptor involved in the uptake of HDL core lipids, was also determined under the same conditions in rats fed semisynthetic diets supplemented with triolein (TO), tripalmitin (TP) or menhaden oil (MO). Serum LCAT activity [ micro mol CE/(L.h)] was significantly (P < 0.05) higher in rats fed TO (33 +/- 4) compared with those fed TP (23 +/- 3) or MO (21 +/- 1). The levels of hepatic LCAT mRNA and hepatic SR-B1 receptor protein did not differ between rats fed TP and MO. The triolein diet, on the other hand, increased the induction of hepatic LCAT mRNA and hepatic SR-B1 receptor protein 1.5- to 2-fold. Serum HDL cholesterol concentrations differed among all groups and were 1.30 +/- 0.08, 1.17 +/- 0.10 and 0.91 +/- 0.06 mmol/L for TO-, TP- and MO-fed rats, respectively. Serum apoA-1 levels were significantly higher in TO-fed rats than in the other two groups. The data indicate that TO increases the secretion of HDL and its components (apoA-1 and LCAT), and stimulates the production of hepatic SR-B1 receptor protein. Overall, these results suggest that triolein may promote RCT and thus retard the development of atherosclerosis.