Metabolism of low- and high-density-lipoprotein-free cholesterol in rats fed high-fat diets.
The regulating process of cholesterol in the liver was studied in relation to its exogenous contribution in the rats fed high-fat (28%) high-cholesterol (1.2%) diets rich in saturated (S) fat (lard) or polyunsaturated (PU) fat (corn oil). Accordingly, the fate of 14C free cholesterol originating from high- or low-density lipoproteins (LDL) was examined in the biliary, hepatic and plasmatic lipids, as well as the activity of two key enzymes in the metabolism of lipoproteins: lipoprotein lipase (LPL) and lecithin cholesterol acyl transferase (LCAT). The LPL activity increased in the S diet, in comparison to the PU diet or to a low fat (6%) control (C) diet and the LCAT activity increased but not significantly in the PU diet. In bile the secretion of 14C-cholesterol and 14C-bile salts originating from 14C-cholesterol-HDL increased in the S diet compared to the PU diet and a C diet [previous results]. S and PU diets increased to the same extent the hepatic storage of 14C-esterified cholesterol originating from LDL, compared to the C diet. This cholesterol would contribute to a greater extent to the hepatic synthesis of the lipoproteins destined for the plasma in the case of the S diet than that of PU diet. These results may be explained by the adaptation of hepatic acyl cholesterol acyl transferase and cholesterolesterase to both high-fat-diet enzymes acting simultaneously on the two free and esterified cholesterol compartments. It resulted in an important redistribution of the cholesterol of these two compartments between plasma, bile and liver.
Chanussot
F
F
INSERM Unité 130, Marseille, France.
Esnault-Dupuy
C
C
Martigne
M
M
Portugal
H
H
Lairon
D
D
Quignard
A
A
Alcindor
L G
LG
Pauli
A M
AM
Lafont
H
H
Hauton
J C
JC
D000818:Animals; D001646:Bile / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000378:metabolism; D008076:Cholesterol, HDL / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000032:analysis*; D008077:Lipoproteins, LDL / Q000032:analysis*; D008081:Liposomes / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D002791:Cholesterol, Dietary; D008076:Cholesterol, HDL; D004041:Dietary Fats; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008081:Liposomes; D002784:Cholesterol; D007862:Phosphatidylcholine-Sterol O-Acyltransferase; D008071:Lipoprotein Lipase