Spontaneous arteriosclerosis in old, male, virgin Sprague--Dawley rats.

Virgin, male, Sprague--Dawley rats were observed from 3 to 34 months of age. Systolic blood pressure rose progressively with age, reaching abnormally elevated levels in some, becoming abnormally low in others. The old virgin males gained and then lost weight progressively with age, their pituitary and adrenal glands were heavier than young rats, and their thymi were greatly involuted. The old virgin rats manifested fatty infiltration of the liver and islet beta cell degranulation concomitant with hyperlipidemia, hyperglycemia, and elevated circulating corticosterone levels. Spontaneous arteriosclerosis, identical to that found in younger breeder rats was found in these old virgin males. Therefore, the vascular and other degenerative changes found in young breeder rats in considered to be an example of accelerated arterial disease.