The effect of various diets on atherogenesis in rhesus monkeys

Abstract

The present study compares the production of lesions induced by different dietary regimens. Eighteen male rhesus monkeys were divided into three groups and fed according to varying dietary patterns for 12 months. Although a wide spectrum of lesions was observed in each dietary group, plaques with characteristics specific for each diet were predominant. The first group was fed a diet containing 25% fat as a 1 : 1 mixture of butterfat and coconut oil and 2% cholesterol. For the second group, the same ratio was alternated at 2-month intervals with a cholesterol-free diet containing 25% corn oil. Animals in the third group were fed a diet consisting of 2% cholesterol and 25% peanut oil. The latter group was subdivided into two subgroups of 3 animals each; one subgroup received peanut oil “contaminated” with aflatoxin. All diets produced hyperlipemia and hyperlipoproteinemia. The highest levels of serum cholesterol were recorded in animals fed a diet enriched by a mixture of butterfat, coconut oil and cholesterol continuously. Peanut oil-induced lesions were fibrocellular with minimal intracellular lipid deposition, while the coconut oil-butterfat feeding resulted in abundant, predominantly intracellular lipid accumulation, mostly in foam cells. Animals fed the alternating diets developed only mild intimal lesions with minimal lipid deposition. Lipid closely associated with the internal elastic membrane was observed in this latter group, a pattern similar to that reported by us previously in regressing lesions. Lesions in the coronary arteries closely resembled those in the aortas in each group. Densitometric analysis of serum samples fractionated by electrophoresis provided semi-quantitative data for estimating α- and β-lipoproteins. The rations of α to β were such as to indicate a marked rise in β-lipoprotein in both groups fed the high cholesterol ration. This was accompanied by an actual depression of a in the peanut oil-fed animals and a relatively slight increase in a concentration in the coconut—buffer-fed monkeys.