Exacerbation of spontaneously occurring arteriosclerosis in breeder rats following chronic treatment with cortisone

Male and female rats bred repeatedly develop arteriosclerosis spontaneously. Arteriosclerotic breeder rats and non-arteriosclerotic virgin rats were given chronic injections of cortisone. The arteriosclerotic animals showed the most significant catabolic effects due to overdose with steroid. Most importantly, the excess glucocorticoid caused an acceleration of the usual pattern of development of the arterial disease and increased severity of the pre-existing arteriosclerosis in breeder rats. Chronic injection of steroid did not induce arterial damage in previously non-arteriosclerotic virgin animals. It is believed that the increased activity of the hypothalamic-pituitary-adrenal axis in repeatedly bred rats leads to increased endogenous steroid levels which conditions the arterial wall towards derangement of connective tissue ground substance and elements and to the development of arteriosclerosis. Exogenous steroid treatment causes exacerbation of previously existing arterial lesions.