Renoprotective mechanisms of Grape seed proanthocyanidin extracts on diabetic rats

Objective To investigate the potential mechanisms of Grape seed proanthocyanidin extracts(GSPE) on inhibiting diabetic nephropathy.Methods Male Wistar rats were injected with 1% streptozotocin(STZ) through the tail vein to induce the diabetic rats.Then they were randomly divided into two groups: the diabetic group(the DM group) and the GSPE treatment group(the GSPE group,GSPE 250 mg/kg·d-1).Normal Wistar rats were enrolled as the control group(the C group). After 24 weeks,fasting plasma glucose(FPG),urea nitrogen(BUN),serum creatinine(SCr),glycosylated hemoglobin(HbA1c) and advanced glycation end products(AGEs) were determined,and the pathologic changes of renal tissues were observed.2-D difference gel electrophoresis and mass spectrometry were used to identify different expressions of renal proteins among the C,DM and GSPE groups.Results The levels of AGEs,BUN and SCr of the GSPE group were lower than those of the DM group(P0.05).The pathologic changes were ameliorated in the GSPE group.Twenty-five differentially expressed proteins were found in the renal tissues of the DM group.The protein with SSP No.1252 was identified as Glutathione S-transferase mu(GSTM) which was up-regulated in the kidneys of diabetic rats and back-regulated to normal levels after GSPE therapy.Conclusion GSPE may protect the kidney by decreasing the expression of GSTM.