Effect Of Atorvastatin With Intravascular Ultrasound(IVUS) In Atherosclerotic Plaque In Rabbits

Objective:Except for the normal group the other groups were fed with high-fat diet combined with aortaventralis balloon-dilation injury to establish atherosclerotic rabbit model,The abdominal aortae were detected with IVUS to observe the abdominal aorta vascular wall and the formation of atherosclerotic plaques.Our objective was to explore the effect and mechanism of short-term different doses atorvastain on atheromatous plaque composion and stability in an atherosclerotic rabbit model.Methods:Except for the control group,the others established atherosclerotic model by combining a 8-week high fat diet feeding with aortaventralis balloon-dilation injury. Fourty male New Zealand White Rabbits were selected and randomly divided into four groups:the control group (n=10),model group (n=10),low-dosage atorvastain group (n=10) and high-dosage atorvastain group (n=10). Eight weeks later,the model group continued to give high fat diet,and the low or high dose atorvastain groups were given 2 weeks different doses drugs as 1mg/(kg·d)or 5mg/(kg·d) respectively. At the 10th week,all rabbits were sacrificed. Venous blood was drawn to measure serum lipid and hs-CRP.HE and Sirius red stain were used to evaluate the amount of collagenous fiber and the pathophysiological changes of abdominal aorta.IVUS was used to observe the abdominal aorta vascular wall and the formation of atherosclerotic plaques.The abdominal aortae were detected with IVUS to measure vascular external elastic membrane area (EEMA),plaque area (PA),lumen area narrowing (%) and lumen area (LA).Results:1. Serum lipid levels:comparing with the control group,serum lipid were significantly higher (P<0.01), Serum lipid in the two atorvastain groups were significantly lower than model group (P<0.05),and the reduce of high-dosage atorvastain group was much more obviously (P< 0.01)2. At the end of the study,comparing with the control group,hs-CRP were significantly higher (P<0.05), hs-CRP in the two atorvastain groups were significantly lower than model group (P<0.05),and the reduce of high-dosage atorvastain group was much more obviously (P<0.05).3. In control group vascular endothelial cells remain intact and arranged in neat rows. Internal elastic laminae intact,there were no obvious abnormalities.In model group, vascular endothelial cells fell off distinctly. Large number of macrophage-derived foam cells were accumulated under the intima.There was significant plaque with thin-cap fibroatheroma formation in the aortic. Comparaing with model group,the fibrous cap of vulnerable plaque thicken much in atrovastatin low-dose group. The degree of atheromatous in atrovastatin high-dose group was obviously decreased. A little part of endothelial cells fell off and foam cells under the intima were reduced. Medial membrane smooth muscle cells were arranged in order. Plaque had much more thicken-cap fibroatheroma than model group.4. In control group,internal elastic laminae intact,there were no plaque. Extra-elastic membranous atea(EEMA)、plaque area(PA)、lumen area stenosing(LAS%) in model group were significantly higher than in the two atorvastatin groups(P<0.05), there was no significant difference in lumen area between the model group and the twoatorvastatin groups(P>0.05)Conclusion:1.We have developed an animal model of vulnerable plaque in New Zealand white rabbit adominal aorta.Vulnerable plaque is successfully produced by fat-rich diet together with balloon-induced endothelial injury in the rabbit abdominal aorta.2. Atorvastatin is able to control the level of serum lipid and the level of hs-CRP observably and restrain inflammatory reaction with a dose-dependent manner.3.Atorvastatin is able to increase the content of collagen fiber, reduce the plaque and stabilize vulnerable plaque with a dose-dependent manner.