Comparative Evaluation of Three Species of New World Monkeys for Studies of Dietary Factors, Tissue Lipids, and Atherogenesis

Abstract

Cebus (Cebus albifrons), woolly (Lagothrix lagotricha), and squirrel (Saimiri sciurea) monkeys were compared with respect to serum and other tissue cholesterol levels, serum β-lipoprotein concentrations, fatty acid distributions in various tissue lipids, and severity of aortic atherosclerosis. Monkeys individually caged and fed a semi-purified diet (basal) containing 16% of calories as corn oil were used. Assays of susceptibility to hypercholesterolemia and atherosclerosis were carried out using diets which supplied 45% of calories as corn oil or coconut oil with and without cholesterol. Cebus monkeys had the lowest mean serum cholesterol values of the 3 species studied with the basal diet. They also had the least spontaneous aortic sudanophilia. The responses of the serum cholesterol levels of the 3 species of monkeys to changes in dietary fat or the addition of cholesterol were similar. In the squirrel and woolly monkey the use of coconut oil (rather than corn oil) or the addition of cholesterol to either fat resulted in a marked increase in the serum cholesterol level and severity of atherosclerosis at 6 months; the cebus monkey had comparable serum cholesterol levels but little atherosclerosis with the high fat test diets. There was a high correlation in the squirrel and woolly monkey between the mean serum cholesterol levels with the test diets and extent of aortic sudanophilia, but the slopes of the regression lines of the cholesterol-sudanophilia plots for those 2 species were different. The susceptibility to diet-induced aortic sudanophilia was squirrel > woolly > cebus. Both diet and species affected cholesterol concentrations in several of the tissues studied.