Antiatherogenic Effect Of Pioglitazone: Potential Role And Molecular Basis

Objective:To investigate the effects and mechanism of peroxisome proliferators-activated receptorγagonist pioglitazone on leptin-induced proliferation of rat aortic vascular smooth muscle cells (VSMCs).Methods:(1)Primary rat aortic vascular smooth muscle cells were cultured with the adherent method of tissue explants.VSMCs were observed and verified by inverted phase contrast microscope and transmission electron microscope.(2)VSMCs were stimulated with leptin at different concentrations(12.5,25.0,50.0,100.0ng/ml)for 24,48 and 72 hours,the proliferation of which was determined by Methyl thiazolyl tetrazolium(MTT)assay.(3)After induction with 100.0ng/ml leptin for 72 hours,VSMCs were treated by pioglitazone at different concentrations (1.0,10.0,100.0μmol/L),the proliferation of which was observed by MTT.(4)Total RNA and protein were extracted and the expression of PCNA and OB-R at mRNA level as well as protein level were measured by Reverse transcription-polymerase chain reaction(RT-PCR)and Western blot,respectively.Results:(1)Compared with controls,leptin (12.5,25.0,50.0,100.0ng/ml)stimulated VSMCs proliferation,of which 50.0 ng/ml and 100.0ng/ml were statistically significant(P＜0.05).The effect was also time and dose-dependent,reaching optimal proliferation rate(22.4%)at 100.0ng/ml for 72h.(2)Pioglitazone antagonized leptin-induced VSMCs proliferation,with the strongest effect at 100μmol/L(P＜0.01).(3)Leptin treatment(100.0ng/ml)for 72h significantly promoted PCNA and OB-R expression of VSMCs at both mRNA and protein levels(P＜0.05).(4)Compared with leptin only group, pioglitazone at different concentrations(1.0,10.0,100.0μmol/l)for 24 hours attenuated the increase of PCNA and OB-R expression in VSMCs induced by leptin,especially at 100μmol/L(P＜0.01).Conclusion: Hyperleptinemia was related to the pathogenesis of atherosclerosis. Pioglitazone may suppress leptin-stimulated VSMCs proliferation and influence the phenotypic change of VSMCs by reducing OB-R and PCNA expression,which may be beneficial for cardiovascular system.