DIFFERENTIAL EFFECT OF DIETARY-FAT SATURATION AND CHOLESTEROL ON HEPATIC APOLIPOPROTEIN GENE-EXPRESSION IN RATS

The effects of dietary cholesterol and fat saturation on hepatic apoli poprotein A-I, A-II, A-IV, B, C-I, C-III, E and LDL receptor mRNA leve ls were studied in male rats. Animals were maintained for 2 months on a high fat diet (40%, w/w) containing 0.1% cholesterol. Two groups of control animals received either chow diet or chow plus 0.1%, cholester ol, while experimental groups received as their fat supplement coconut , corn or olive oil. Olive oil fed animals had higher levels of hepati c apo A-I than the control cholesterol group (1.6 +/- 0.3 vs. 0.8 +/- 0.2). Apo E mRNA levels were 50% and 72% higher in animals consuming t he saturated (coconut) and unsaturated (corn and olive) fat diet than the control cholesterol group. Apo B and apo C-I mRNA levels were not affected by the experimental conditions. Apo A-IV mRNA increased betwe en 66% and 127% in groups in which cholesterol was present. LDL recept or mRNA increased 2 times in the corn fed group compared with the cont rol groups. These results indicate that the expression of genes coding for products involved in lipoprotein metabolism have a differential s usceptibility to dietary fat saturation and cholesterol.