J. Biol. Chem., Vol. 262, Issue 15, 7014-7020, May, 1987
In vivo regulation of hepatic LDL receptor mRNA in the baboon. Differential effects of saturated and unsaturated fat
JC Fox, HC McGill Jr, KD Carey and GS Getz
The effects of diets enriched with cholesterol and different fats upon
plasma lipoproteins and hepatic low density lipoprotein (LDL) receptor mRNA
levels were studied in a group of 18 normal baboons. Animals were fed diets
containing 1% cholesterol and 25% fat as either coconut oil, peanut oil, or
olive oil for a period of 20 weeks. Plasma total cholesterol, high density
lipoprotein (HDL) cholesterol, beta- lipoprotein (LDL + very low density
lipoprotein) cholesterol, apolipoprotein B and apolipoprotein A-I were
measured in samples obtained at 4-week intervals. All three diet groups
demonstrated a statistically significant increase in plasma cholesterol as
compared to base line throughout the experiment. Hepatic LDL receptor
(LDL-R) mRNA levels were quantified by dot blot hybridization in serial
liver biopsies. Animals fed saturated fat sustained a significant reduction
in hepatic LDL-R mRNA as compared to those fed either monounsaturated or
polyunsaturated fat. A strong negative correlation between LDL-R mRNA and
plasma total cholesterol (r = -0.71), HDL cholesterol (r = - 0.76), and
plasma apo A-I (r = -0.77) was observed only in those animals fed coconut
oil. Weak negative correlations between LDL-R mRNA and other plasma
parameters did not achieve statistical significance. We conclude that
saturated and unsaturated oils may influence plasma cholesterol levels in
part through differential effects on LDL receptor biosynthesis in baboons.