Social environment as a factor in diet-induced atherosclerosis.

Rabbits on a 2 percent cholesterol diet were individually petted, held, talked to, and played with on a regular basis. Measurements of aortic affinity for a Sudan stain, serum cholesterol levels, heart rate, and blood pressure were made at the end of the experimental period. Compared to control groups, which were given the same diet and normal laboratory animal care, the experimental groups showed more than a 60 percent reduction in the percentage of aortic surface area exhibiting sudanophilic lesions, even though serum cholesterol levels, heart rate, and blood pressure were comparable.