Aim To investigate the effects of rosiglitazone on the expression of angiotensin Ⅱ(AngⅡ)type 1 receptor(AT1R)and AngⅡ type 2 receptor(AT2R)in AngⅡ-induced vascular smooth muscle cells(VSMC)and possible molecular mechanisms of anti-atherosclerosis.Methods VSMC of mice were cultured by the explant-attachment method.Using semi-quantitative reverse transcription polymerase-chain reaction(RT-PCR)and immunochemistry,we measured the dose and time dependent effects of rosiglitazone on AT1R and AT2R mRNA and protein in AngⅡ-induced mice VSMC.Results Slight expressions of AT1R and AT2R were observed in cultured VSMC in vitro.AngⅡmarkedly upregulated the expression of AT1R mRNA and protein(p<0.01).Meanwhile,AngⅡdownregulated the expression of AT2R mRNA and protein(p<0.01 and 0.05).Twelve hours post different concentration rosiglitazone(20,30,50 μmol/L)treatment,the expression of AT1R mRNA and protein of VSMC were significantly attenuated(p<0.01,vs AngⅡ group).However,the expression of AT2R mRNA and protein of VSMC were markedly upregulated(p<0.01,vs AngⅡ group).At 6 hours post 30 μmol/L rosiglitazone treatment,the expression of AT1R mRNA and protein decreased,and then the expression of AT2R mRNA and protein increased,reaching a maximum at 24 h post treatment(p<0.01).Conclusions Rosiglitazone can not only downregulate the expression of AT1R mRNA and protein,but also upregulate the expression of AT2R mRNA and protein in AngⅡ-induced VSMC in concentration-dependent and time-dependent manners.Above effects may be crucial mechanisms of the anti-inflammation and anti-atherosclerosis of peroxisome proliferator-activated receptor-γ agonists.