Ovariectomy, social status, and atherosclerosis in cynomolgus monkeys

Abstract

Evidence is contradictory regarding the effects of natural or surgical menopause on "female protection" against coronary artery atherosclerosis. We evaluated atherosclerosis, plasma lipids, blood pressure, and carbohydrate tolerance in 21 ovariectomized and 23 intact female cynomolgus macaques fed a moderately atherogenic diet for 30 months. We also evaluated the influence of social dominance status, with particular emphasis on a possible relationship with ovarian endocrine function. Atherosclerosis was two to 10 times as extensive in coronary, carotid, and iliaco-femoral arteries of the ovariectomized females; this could be explained, in part, by 15% to 20% increases in total plasma and LDL cholesterol concentrations. Socially dominant intact females were protected against advanced atherosclerotic lesions (plaques) of the coronary arteries, while subordinate females and ovariectomized females were not. Increased susceptibility to advanced coronary artery atherosclerosis in subordinate intact females may have been related in some way to chronic ovarian dysfunction observed in seven of 12 of these individuals. As a group, subordinate intact females also had enlarged adrenal glands, suggestive of mechanisms that may influence atherogenesis independently. The results indicate that, in this species, ovariectomy and chronic ovarian dysfunction related to subordinate social status are associated with a more atherogenic plasma lipid pattern and abolish "female protection" against coronary artery atherosclerosis.