Spontaneous Arteriosclerosis of the Mesenteric, Renal, and Peripheral Arteries of Repeatedly Bred Rats

Abstract

Repeatedly bred male and female rats develop arteriosclerosis spontaneously. The arteriosclerosis appears to be accelerated by breeding because virgin rats of comparable age do not develop arterial disease. The arterial lesions begin in the abdominal aorta and consist of subendothelial swelling, mucopolysaccharide accumulation and eventual fibrosis. With continued, active breeding, the arterial lesions continue to increase in severity in the abdominal aorta, becoming grossly visible in the female breeder and of microscopic proportions in the male breeder. Concomitant with the increasing severity of arteriosclerosis in the abdominal aorta, the mesenteric arteries and the visceral branches also show increasing numbers of arterial lesions. The lesions in the mesenteric and visceral branches are of varied morphology. The main renal artery, for example, shows fibromuscular dysplasia, its hilar portion displays intimal basophilia and elastosis and the intrarenal branches develop intimal cushions. The male breeder develops severe, grossly visible lesions in the proximal portions of the iliac arteries, the lesions becoming less complex distally. The female breeder shows no grossly visible lesions in the iliac arteries but arteriosclerosis is severe throughout the length of the arteries to the extremities, the severity of these lesions being proportional to the arteriosclerosis in the abdominal aorta and its branches.