Nutritional effects on blood lipid and HDL cholesterol concentrations in two subspecies of African green monkeys...

The African green monkey has previously been found to be a promising model for the study of atherosclerosis. We have compared the plasma and HDL cholesterol response to dietary manipulation in the two subspecies of African green monkeys (vervets and grivets) most often imported for biomedical research purposes. Twenty vervets and 20 grivets were fed, in succession, diets containing safflower oil, butter, or lard as the principal dietary fat at a level of 40% of calories. Ten animals of each subspecies were fed the diets without added cholesterol (control groups) and 10 were fed diets with either added crystalline cholesterol (safflower oil and butter diets) or egg yolk (lard diet) to raise the diet cholesterol level at least five-fold. The effect of the type of dietary fat was that total plasma cholesterol (TPC) and HDL cholesterol concentrations were lowest while the safflower oil diet was fed, were significantly higher when butter fat diets were fed, and were highest when the egg yolk-lard based diets were fed. In addition, a significant effect of the elevated level of dietary cholesterol, independent of the type of dietary fat, was seen: a statistically significant negative correlation between TPC and HDL cholesterol concentrations was induced. In contrast, a positive correlation between TPC and HDL cholesterol concentrations was found at the lower dietary cholesterol level. Thus, the different factors (type of fat versus cholesterol) influenced lipoprotein metabolism in distinct yet related ways. Although average values for both plasma and HDL cholesterol concentrations were significantly higher in the grivet subspecies than in the vervet subspecies, the data for both subspecies fit the same regression lines. This outcome suggested that the subspecies differed in the magnitude of response rather than in the mechanism of response.