Abstract
Introduction: The atherosclerotic effect of hypercholesterolemia on the vascular function is well-known. However, limited studies were done on the effect of hypercholesterolemia without atherosclerotic lesion on the vascular compliance. The aim of this study was to investigate the effects of hyperlipidemia induced by cholesterol rich diet on vessel function in isolated rat aorta in the absence of atherosclerotic lesion. Methods: Male wistar rats were randomly divided into 3 groups of 6 animals in each. The rats in normal control group were fed a standard laboratory diet and two other groups were fed a high fat diet for 36 days. A group of high fat fed rats was treated orally with Lovastatin started at day of 16 and continued for last 20 days of the experimental period. At the end of the experiment, inferior vena cava blood was collected to measure the lipid levels and the thoracic aorta was excised and used for isolated vessel preparation and histological study. Results: The results of this study indicated that high-cholesterol diet significantly increased total cholesterol and LDL levels in serum (p<0.001). The increase in the serum levels of cholesterol was associated with a profound reduction of endothelium dependent vasodilatation of the thoracic aorta. However, in histopathological study no atherosclerotic lesion was observed. Short-term treatment by Lovastatin (10 mg/kg/day) produced a significant reduction (p<0.05) in the level of total cholesterol and LDL. The endothelium-dependent vasodilatation was improved significantly (P<0.01) by Lovastatin as an anti-hyperlipidemic drug. Conclusion: Hypercholesterolemia is associated with endothelial dysfunction in aorta, despite the absence of atherosclerotic lesions.