Effect of atorvastatin on expression of macrophage and smooth muscle actin in carotid atherosclerotic plaques in rabbits

AIM: To observe inflammatory macrophages and smooth muscle actin in carotid atherosclerotic plaques in rabbits and the effects of atorvastatin on them and to explore whether statins could stabilize carotid plaques and its possible mechanism. METHODS: Twenty-four rabbits were randomly divided into three groups: control group (n=8) and hypercholesterolemia group (n=16). The hypercholesterolemia group was fed a hypercholesterol diet for 2 weeks and then catheter-induced arterial wall injury was made. Rabbits in hypercholesterolemia and aortic injury group were randomized into model group (n=8) and atorvastatin group 5 mg/(kg·day) for 10 weeks (n=8). Carotid arteries were isolated and paraffin-embedded slices were obtained. Blood lipids and lipoproteins were detected and the development of atherosclerotic plaques was evaluated by light microscopy. The levels of macrophages and smooth muscle actin in the common carotid artery were measured by immunohistochemical analysis. RESULTS: Serum concentrations of TC and LDL-C in atorvastatin group were lower than those in hypercholesterolemia model group (P<0.01). The intimal-medial thickness ［(0.49±0.072)mm vs.(0.66±0.079)mm, P<0.05］ in atorvastatin group was significantly less than that in hypercholesterolemia model group. Immunohistochemical analysis showed much less stain in macrophages in atorvastatin group compared with that in hypercholesterolemia model group. More smooth muscle actin was observed in atherosclerotic plaque than that in atorvastatin group. CONCLUSIONS: Atorvastatin may decrease the level of macrophages in atherosclerotic plaque and increase the development of smooth muscle actin, thus prohibiting the formation and development of atherosclerosis.