Journal of Lipid Research, Vol 31, 1413-1422, Copyright © 1990 by Lipid Research, Inc.
Effects of dietary cholesterol and fatty acids on plasma cholesterol level and hepatic lipoprotein metabolism
H Ohtani, K Hayashi, Y Hirata, S Dojo, K Nakashima, E Nishio, H Kurushima, M Saeki and G Kajiyama
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
The effects of dietary cholesterol and fatty acids on the plasma
cholesterol level and rates of very low density lipoprotein (VLDL)
cholesterol secretion and low density lipoprotein (LDL) transport through
LDL receptors in the liver of the hamster were investigated. Increases of
plasma VLDL- and LDL-cholesterol levels and VLDL- cholesterol secretion
from hepatocytes were observed in animals fed a diet enriched with 0.1%
cholesterol for 2 weeks in comparison with animals fed a control diet. The
addition of dietary palmitic acid accelerated the effect of dietary
cholesterol on plasma VLDL- and LDL- cholesterol levels and
VLDL-cholesterol secretion from hepatocytes. Dietary linoleic acid
accelerated the effect of dietary cholesterol on VLDL-cholesterol secretion
from hepatocytes and diminished the effect on the plasma LDL-cholesterol
level. Hepatic LDL receptor activity was considerably suppressed by a
control diet containing 0.05% cholesterol and a further small suppression
was induced by a diet enriched with 0.1% cholesterol with or without 5%
palmitic acid. However, dietary linoleic acid diminished the effect of
dietary cholesterol on the suppression of hepatic LDL receptor activity.
These results suggest that dietary palmitic acid augments the effect of
dietary cholesterol in elevating the plasma LDL-cholesterol level through
acceleration of VLDL-cholesterol secretion from the liver, and that dietary
linoleic acid diminishes the effect of dietary cholesterol in elevating the
plasma LDL-cholesterol level by preventing the suppression of hepatic LDL
receptor activity induced by cholesterol.