Comparative primate atherosclerosis: I. Tissue Cholesterol Concentration and Pathologic Anatomy

Abstract

Stump-tailed macaques (Macaca arctoides), African green monkeys (Cercopithecus aethiops), squirrel monkeys (Saimiri sciureus), and woolly monkeys (Lagothrix lagothricha) were fed control, solid atherogenic (1 mg cholesterol/cal) or liquid diets containing 0, 0.5, or 1 mg cholesterol/cal.Stump-tailed macaques fed the solid atherogenic diet had the highest tissue and serum cholesterol concentration (about 700 mg/dl) and the most extensive atherosclerosis. These monkeys appeared to respond differently to diets containing 1 mg cholesterol/cal. Those animals fed the liquid diet had higher liver cholesterol concentration but lower serum cholesterol concentration than animals fed the solid diet. African green monkeys fed the solid atherogenic diet had serum cholesterol concentrations of about 450 mg/dl. A greater percentage of the abdominal aorta was covered by plaque than the thoracic aorta. Coronary artery atherosclerosis was focal with the largest plaques being found in the left main coronary artery. The microscopic appearance of these plaques was similar to that of plaques from people.Squirrel monkeys fed the atherogenic diet were the most variable group. The average serum cholesterol concentration averaged about 450 mg/dl (range: 291 to 716). The percentage of aorta covered by plaque ranged from 0 to 55% with more thoracic than abdominal aortic atherosclerosis. There were findings consistent with hemorrhage in plaques from two animals. These monkeys, like stump-tailed macaques but unlike African green monkeys had relatively high liver cholesterol concentrations.Woolly monkeys appeared to develop atherosclerosis when fed 1 mg cholesterol/cal but did not have greatly elevated serum cholesterol concentrations.