Pioglitazone reduces smooth muscle cell density of rat carotid arterial intima induced by balloon catheterization.

The effect of pioglitazone on balloon catheterization-induced carotid arterial intimal thickening lesion of male Wistar fatty rats and its littermates (Wistar lean rats) was investigated. Pioglitazone was administered via gastric tube at 10 mg/kg/day to 12-week-old rats for 7 days. Age-matched rats without pioglitazone were used as respective controls. Each rat was catheterized using a balloon catheter inserted from the left femoral artery to the left common carotid artery, and the endothelium in the left common carotid artery was denuded. Rats were then treated with pioglitazone for 14 days post catheterization and the left common carotid artery was removed and stained with Elastica-Masson and anti-alpha-smooth muscle actin antibody. In addition, for smooth muscle cell (SMC) culture, pioglitazone was administered at 10 mg/kg/day for 28 days to a separate group of 12-week-old rats, and the aortic medial outgrowth rate of their SMCs was measured. Age-matched rats without pioglitazone were prepared as respective controls. In comparison with the area ratio of the thickened intima/media of fatty rats without treatment, those of fatty rats with treatment and lean rats without treatment were significantly decreased by approximately 60%, and also that of lean rats with treatment to 27%. With anti-alpha-smooth muscle actin antibody staining, almost all cells present in intimal thickening were positive. Treatment with pioglitazone reduced the amount of anti-alpha-smooth muscle actin antibody-staining cells. In addition, the outgrowth rate of SMCs at day 10 compared to that in fatty rats without treatment decreased to 42% in fatty rats with treatment, 29% in lean rats without treatment and 23% in lean rats with treatment, respectively. Therefore, pioglitazone has an inhibitory effect on the growth of SMCs, and consequently suppressed carotid intimal thickening. Furthermore, this inhibitory effect was enhanced in diabetes.