Age and Dietary Polyunsaturated Fat Alter High Density Lipoprotein Subtraction Cholesterol Concentrations in a Pediatric Population of African Green Monkeys

African green monkeys were raised from birth to 60 months of age on diets containing cholesterol (0.8 mg/kcal) and enriched in polyunsaturated (polyunsaturated to saturated fat ratio [P:S]=2.5) or saturated (P:S=0J) fat Lipoproteins were isolated from plasma of a group of animals (#=123) and were separated by gel filtration chromatography at 9,14, 26,38, and 50 months of age, which covered a period through adolescence into young adulthood. Total plasma cholesterol (TPC) concentrations were 16% lower (p=0.01) in the polyunsaturated fat-fed group, and high density lipoprotein (HDL) cholesterol concentrations averaged 20% lower (p=0.008) in this group between 14 and 50 months of age, while plasma apolipoprotein A-I (apo A-I) averaged 7% lower (p=0.06) over this age interval in the animals. The HDL cholesterol to apo A-I ratio was found to be significantly lower (;?=0.006) in the animals fed the polyunsaturated fat diet This suggested that the HDL subtraction distribution might differ between groups. In a subset of animals (n=105, 64 male and 41 female), HDL was subfractionated by density gradient ultracentrifugation into six subtractions, HDL-I to HDL-VI, from lowest to highest density. The saturated fat-fed animals had significantly higher cholesterol concentrations in HDL-I and significantly lower cholesterol concentrations in HDL-III, HDL-IV, and HDL-V. These effects held across all ages studied; therefore, these diet effects were not age dependent In both diet groups, the HDL subtraction pattern changed with age such that the HDL-I and HDL-II cholesterol concentrations decreased, and those of HDL-IV, HDL-V, and HDL-VI increased as the animals matured. The decrease in HDL-I with age appeared to result primarily from a decrease in HDL-I in males, while the HDL-I cholesterol concentration in females did not change with age. We conclude that diet, age, and gender all affect HDL subtraction distribution and therefore can potentially modify the relative atherogenicity of the plasma HDL populations. It remains for future studies to demonstrate the effectiveness of each subtraction in promoting or preventing the cholesterol deposition of atherosclerosis. (Arteriosclerosis and Thrombosis 1991;ll:617-628)