Effects of High Cholesterol and Saturated Fat Diet on the Aortic Wall Structure of New Zealand White Male Rabbits

There has been increased attention focused on atherosclerosis, with a rise in the number of investigations exploring its pathogenesis and ways of diagnosing and treating the disease. During the progression and development of atherosclerosis, the mechanical properties of the arterial wall have been extensively studied using animals fed a diet of high cholesterol and saturated fat. One view held is that the arterial wall becomes hardened, while others hold the opposite view. From the standpoints of diagnosis and treatment, dimensional and morphological changes in the arterial wall during the development of atherosclerosis are considered to play important roles. However, the dimensional and morphological changes in the arterial wall of animals fed a high cholesterol and saturated fat diet have not been well documented. Therefore, in this study, rabbits were fed a diet containing 0.5% cholesterol plus 0.5% olive oil for periods of 4, 8, and 12 weeks, and the cholesterol concentration of blood plasma, and the dimensional and morphological changes in the rabbit’s arterial wall were examined following each cholesterol feeding period. We found that the cholesterol concentration of blood plasma significantly increased throughout the cholesterol feeding period. In cholesterolfed rabbits, the arterial wall had a tendency to thicken; the ratio of wall thickness to radius of aortic ring specimens, measured immediately after procurement of the specimen, was significantly increased compared with normal-fed rabbits. Morphological examination revealed a marked increase in thickness of the intima, smooth muscle proliferation, and connective tissue formation; lipid-laden cells were observed near the basement of the lesion. The tunica media underlying plaques showed marked disruption of elastin, collagen, smooth muscle cells, and a focal loss of normal media architecture. These changes were noted to be more prominent in thoracic aortae than in abdominal aortae.