Lipid deposition in the aorta of adjuvant arthritic rats with hypercholesterolemia

This study offers findings which should aid in the development of a convenient animal model of atherosclerosis. Inbred Fisher strain rats were fed an atherogenic diet containing 1.5% cholesterol and 0.5% cholic acid and given a single subcutaneous injection of adjuvant (Mycobacterium butyricum) into the base of the tail. The animals were maintained for 8 weeks. Rats given the atherogenic diet showed markedly increased serum cholesterol levels, and all of those given the adjuvant injection developed severe polyarthritis. Cholesterol feeding tended to delay the onset of arthritis and remarkably suppressed the inflammatory response, particularly in the early stage of development. This may have been due to the lowered lipid peroxide levels in the serum of rats fed the atherogenic diet. Adjuvant arthritis together with cholesterol feeding markedly increased the cholesterol content of the aorta, whereas either treatment alone had little effect. The amounts of the connective tissue components and minerals in the aorta were not changed by both treatments. These results show that early atherosclerosis could be produced under the conditions used and that chronic inflammation and hypercholesterolemia are principal factors in the pathogenesis.