Simvastatin inhibits myointimal hyperplasia following carotid artery injury in cholesterol-fed rabbits

The effect of simvastatin, a potent inhibitor of 3-hydroxy 3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) was evaluated in an experimental model of myointimal hyperplasia in cholesterol-fed rabbits. Myointimal hyperplasia was induced by an air-drying injury of the left carotid artery followed by a 2%-cholesterol diet for 14 days. A 2-week oral treatment with simvastatin (6 mg/kg/day, p.o.) significantly lowered the circulating levels of cholesterol and triglycerides (41% and 49% inhibition respectively) as well as the low density lipoprotein (LDL)-cholesterol and high density lipoprotein (HDL)-cholesterol levels. Simvastatin also strongly affected the uptake of cholesterol in the arteries occurring as a consequence of vascular injury (44% inhibition, P < 0.001). Morphometric analysis revealed that both the intima and the media areas increased substantially 2 weeks after the lesion and showed a considerable smooth muscle cell accumulation in the neointima together with the presence of numerous foam cells. A 16-day oral treatment with simvastatin strongly reduced smooth muscle cells hyperplasia occurring in both the media and the intima following deendothelialization (19% and 60% inhibition respectively) suggesting that simvastatin may be a useful inhibitor of restenosis which occurs following vascular injury.