Comparison between the hypercholesterolaemia in rabbits induced by semipurified diets containing either cholesterol...

Rabbits were fed a semipurified diet containing soy protein for 4 weeks and subsequently transferred to a semipurified diet containing soy protein plus cholesterol (2 g/kg), or a semipurified diet containing casein as protein source. One group of rabbits was fed the soy protein diet throughout the entire experimental period. Blood samples from the animals were taken after an overnight fast. The rabbits transferred to the soy plus cholesterol diet and to the casein diet showed a significant increase in serum cholesterol concentration after 1 and 3 days, respectively. The cholesterol and protein content of the LDL1 (1.019 less than p20 less than 1.040) fraction was markedly increased after 3 days on the casein and soy plus cholesterol diets. Thereafter the cholesterol, but not the protein concentration increased in the IDL1 (1.006 less than p20 less than 1.012) and VLDL (p20 less than 1.006) fractions, the effect being earlier and more pronounced in the soy plus cholesterol-fed animals. When compared to the soy-fed animals, the casein and soy plus cholesterol-fed animals showed a marked increase in the apoprotein E content of their VLDL and IDL fractions. It is concluded that cholesterol- and casein-induced hypercholesterolaemia in rabbits develop in a similar manner. In both hypercholesterolaemias the cholesterol concentration increases first in the LDL fraction and subsequently in the IDL and VLDL fractions.