EARLY LESION DEVELOPMENT IN THE AORTAS OF RABBITS FED LOW-FAT, CHOLESTEROL-FREE, SEMIPURIFIED CASEIN DIET

The initial endothelial morphological alterations and the development of raised, lipid-containing lesions in rabbit aortas were examined aft er 1 and 3 months on a casein-enriched, semipurified, cholesterol-free diet. The alterations were compared with those in rabbits fed soy-pro tein in the place of casein and with age-matched, chow-fed, control an imals. Using immunohistochemistry macrophages, T-lymphocytes, and smoo th muscle cells were identified in the lesions, and an expression of l eukocyte adhesion molecules, VCAM-1, ICAM-1 and, occasionally, E-selec tin was seen in sections of the aortas of casein-fed rabbits. The init ial alterations in the endothelium appear to include evidence of endot helial injury and white blood cell adhesion. No evidence of extracellu lar liposome formation was observed. This model of atherogenesis is co nsistent with endothelial injury being an important component of diet- induced atherogenesis and has similarities to human atherosclerosis.