Abstract： Objective To explore the effect of high glucose and SB203580 on the expression of pigment epithelium-derived factor(PEDF)in cultured glomerular mesangial cells(GMC).Methods Cultured HBZY-1 rat GMC were divided into 7 groups(glucose was used as a stimulating factor,SB203580 as an intervenor):normol glucose(5.6mmol/L)group,high glucose-treated group(10,20,30mmol/L),mannitol-treated group,therapy(SB203580)group,drug-solvent control group.We measured the expression of PEDF of each glomerular mesangial cells group by real time quantitative PCR.Results 1.Normol glucose group showed the higher expression of PEDF than did the high glucose group.The expression of PEDF mRNA of group of normol glucose was 5.3,11.3,27.9 times elevated above high glucose groups(all P<0.05).2.The expression of PEDF mRNA was higher in therapy group than in high glucose group.The expression of PEDF mRNA in therapy group was 31.8 times that of high glucose group(P<0.05).Conclusions High glucose can decrease significantly the expression of PEDF in cultured mesangial cells,which is independent of the osmotic pressure.Downregulated expression of PEDF induced by high glucose is related with P38MAPK signal transduction pathways