Effects of low dosage rapamycin on expression of the vascular endothelial growth factor in diabetic nephropathy rats

Objective To investigate the expression of vascular endothelial growth factor(VEGF) in the renal tissue of diabetic rats and the effects of rapamycin on their expression.Methods SD rats were randomly divided into control group(group A,n=8),diabetic nephropathy group(group B,n=8) and rapamycin group(group C,n=8).We induced diabetic rat model by a single intraperitoneal injection of streptozotocin(STZ,60 mg/kg).The rats were sacrificed at 8 weeks,the urine sample in the last 24 hours was collected for analysis of albuminuria and creatinine.The expressions of VEGF in the renal tissue were assessed using reverse transcription polymerase chain reaction(RT-PCR) and Western blot.Urine albumin/creatinine ratio(ACR),kidney weight index(KWI) and mean glomerular volume(GV) were observed.Results The expression of VEGF increased in the renal cortex in group B and group C compared to group A(P0.05),and the expression of VEGF in group C was lower significantly than that in group B.The expression of VEGF was correlated positively with urine albumin/creatinine ratio and mean glomerular volume(P0.05).Conclusions VEGF plays an important role in the development of early diabetic nephropathy.Rapamycin may exert a renal protection on diabetic nephropathy,which mechanism may be possibly partly through the reduction of expression of VEGF in kidney.