AimTo investigate the effect of extractive of pericarpium trichosanthis (EPT) on cell cycle of rat vascular smooth muscle (VSMC) proliferation induced by platelet-derived growth factor-BB (PDGF-BB) and to probe especially into its mechanism.MethodsVSMC from the thoracic aorta of SD rats were cultured by tissue explant method.Effect of EPT (10, 20 and 30 mg/L) on PDGF-BB-induced VSMC proliferation was assessed by ³H-TdR method, the cell cycle was analyzed by flow cytometry, expression of c-fos and c-myc mRNA in VSMC were detected by real-time quantitative reverse transcription-polymerase chain reaction (real-time RT-PCR).ResultsPDGF-BB could significantly increase the rate of ³H-TdR incorporation (p<0.01) and the percentage of S phase cells, and degrade the G0/G1 phase cell percentage in the cell cycle (p<0.01).At the same time, PDGF-BB could up-regulate c-fos and c-myc mRNA expression (p<0.01).Addition of EPT (10, 20 and 30 mg/L) markedly inhibited the PDGF-BB-induced proliferation of the VSMC (p<0.01), decreased the S phase cell percentage and upgraded the G0/G1 phase cell percentage in the cell cycle, EPT could also depress the elevated expression of c-fos and c-myc mRNA indcued by PDGF-BB.ConclusionsEPT could inhibit the VSMC proliferation induced by PDGF-BB through preventing the transformation of the G0/G1 phase cell to S phase cell in the cell cycle.The mechanism may be related to its down-regulatory effect on c-fos and c-myc mRNA expressions.