Carotid artery atherosclerosis in cholesterol-fed female cynomolgus monkeys. Effects of oral contraceptive treatment, social factors, and regional adiposity.

Female cynomolgus monkeys, a previously established model of carotid and coronary artery atherosclerosis, were used to study the relationships between potential risk factors and carotid artery atherosclerosis. Over a 24-month treatment period, one-third of the monkeys (n = 25) were given the oral contraceptive Ovral, one-third of the monkeys (n = 26) were given the oral contraceptive Demulen, and the remaining monkeys constituted a control group (n = 26). At necropsy, the atherosclerosis extent was measured in the left and right common carotid arteries and the left and right carotid bifurcations. Plasma lipid concentrations, regional adiposity, and social status were related to carotid artery atherosclerosis extent. The relationships between regional adiposity and social status and carotid artery atherosclerosis were accounted for, at least in part, by plasma lipid concentrations. Oral contraceptives had an adverse effect on plasma cholesterol concentrations and a protective effect against carotid artery atherosclerosis after adjusting for their effect on plasma lipids. The net result of these effects was little or no change in atherosclerosis extent in the carotid arteries due to oral contraceptive treatment.