Effects of gender and social behavior on the development of coronary artery atherosclerosis in cynomolgus macaques.

This experiment involved examination of the effects of gender and social status ('competitive dominance') on the coronary artery atherosclerosis of cynomolgus monkeys. Thirty-two adult Macaca fascicularis (16 males, 16 females) were fed a diet containing a moderate amount of cholesterol (0.56 mg/cal) for 16 months. The monkeys were housed in groups of 4 animals of the same sex, and all groups were stable in composition for the entire experiment. After 1 year a'competitive dominance' score was determined for each monkey, based on feeding order in 9 trials involving a preferred food as incentive. At necropsy the coronary arteries were pressure perfused; 5 sections each were then taken from the left anterior descending, left circumflex and right coronary arteries. For each animal, the mean percent lumen stenosis calculated from theses 15 sections was used as the index of extent of coronary artery atherosclerosis. Males had significantly more extensive coronary artery atherosclerosis than did females. Further, among both males and females, submissive animals (low in competitiveness) had more extensive coronary artery stenosis than did their dominant (highly competitive) counterparts. A similar pattern was observed in the thoracic and abdominal portions of the aorta with respect to competitiveness, but not gender. In the iliac artery, females had less atherosclerosis than males but there was no competitiveness effect. The gender and social status effects on atherosclerosis were each statistically independent of variability in clinical-pathological measures (serum lipid concentrations and heart weight). The results indicated that: (a) gender and psychosocial stress independently affect the development of coronary artery atherosclerosis; (b) the mechanisms mediating these effects remain unknown; and (c) the cynomolgus macaque is a good model for the study of such phenomena.