Ezetimibe Inhibits Cholesterol Accumulation Via The PPARγ-dependent Pathway In Vascular Smooth Muscle Cells

AIM: To investigate the influence of ezetimibe on cholesterol accumulation in vascular smooth muscle cells induced by Chol:MβCD and the mechanism of ezetimibe.METHODS: VSMCs taken from rat aorta were respectively treated with different concentration of ezetimib(e0, 3, 10, 30μmol/L)for 24 hours or treated with 30μmol/L of ezetimibe for different time(0, 6, 12, 24, 48 hours). The concentration of total cholesterol and free cholesterol were detected by high performance liquid chromatography. Oil Red O dyeing experiment was used to show the cellular lipid droplets in lipid-loaded cells. The expression of caveolin-1, nSREBP-1, LXRα, ABCA1 and PPARγwere detected by western blotting, RT-PCR and Immunofluorescence methods respectively.Results: Chol:MβCD incubation with VSMCs increased cellular cholesterol accumulation, decreased the expression of caveolin-1, LXRαand ABCA1, and promoted nSREBP-1 expression. Ezetimibe treatment significantly inhibited the expression of nSREBP-1 in concentration-dependent manner. Reversely, ezetimibe enhanced the expressions of caveolin-1, LXRαand ABCA1 in a dose-dependent manner with the peak in 30μmol/ L. When VSMC were treated with 30μmol/ L ezetimibe for different time, the expression peaks of caveolin-1, LXRαand ABCA1 were at 24 hours. But the expression of nSREBP-1 was decreased. Interestingly, the mRNA level of PPARγhad no significant change. When VSMCs were transfected with pSliencer 2.1-U6 hygro-PPARγsiRNA, the level of cellular cholesterol was increased and the expression of caveolin-1, LXRαand ABCA1 were decreased.Conclusion: Ezetimibe inhibits Chol:MβCD-induced cholesterol accumulation of VSMCs via regulating the PPARγ-LXRα-ABCA1 pathway and PPARγ-SREBP 1/Caveolin-1 pathway.