Group Isolation and Atherosclerosis in Cholesterol-Fed Cockerels

Abstract

Group isolation, a highly unnatural environmental situation in cockerels, increases atherogenesis and decreases regression of previously induced atherosclerosis. This alteration occurs despite the absence of change in the hypercholesterolemic response to the diet in the induction experiments. It is accompanied by a reduction in weight gain despite food intake similar to the controls. Disturbing the social order by altering the pecking order in flocks of cockerels on a cholesterol-oil containing diet does not alter hypercholesterolemia and atherogenesis. However, it leads to increase in sex characteristics. Physical activity, with or without alterations in pecking order, causes a reduced weight gain even when food intakes are not altered. It is concluded that environmental factors can and do influence atherosclerosis. The types of environmental change which can produce this effect and the exact mechanisms involved require further study.