From menarche to menopause: coronary artery atherosclerosis and protection in cynomolgus monkeys

The effects on atherogenesis of stress, pregnancy, and oral contraceptive therapy were studied in a nonhuman primate model. The stress of social subordination was associated with ovarian dysfunction, unfavorable lipoprotein changes, and increased coronary artery atherosclerosis compared with nonstressed (socially dominant) or normal monkeys. Although pregnant animals exhibited lower high-density lipoprotein cholesterol concentrations, they had only one half as much diet-induced coronary artery atherosclerosis as their nonpregnant counterparts. Monkeys treated with an Ovral-like regimen also exhibited adverse lipoprotein changes. Nevertheless, prevalence and extent of coronary artery plaques decreased. We conclude that estrogen is an important factor in the animals' "female protection" against diet-induced atherosclerosis. We also suggest that the lowering of high-density lipoproteins by the progestin component of higher-dose contraceptives is not necessarily atherogenic if a sufficiently potent exogenous estrogen is administered concomitantly.