OBJEVTIVE: To investigate the efficacy of Cyclocarya paliurus (C.paliurus) polysaccharides on streptozotocin-induced diabetic nephropathy in rats.METHODS: Rats were divided into 6 groups,including group of normal control,group of diabetic control,group of metformin treatment,low-dose group of C.paliurus polysaccharides treatment,middle-dose group of C.paliurus polysaccharides treatment and high-dose group of C.paliurus polysaccharides treatment.Histological analysis of kidney was analyzed using hematoxilin and eosin.Levels of blood glucose,creatinine,urea,uric acid were determined by spectrophotometry.Anti-oxidative enzymes were measured by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA).Advanced glycation end products (AGEs) and transforming growth factor-β1 (TGF-β1) level was measured by ELISA.RESULTS: Abnormal changes were observed in the group of diabetic control characterized by atrophy of the renal glomeruli with hypercellularity,congestion of glomerular tufts,dilation of the renal spaces,and degeneration of renal tubule.Compared with that of normal group,blood glucose,creatinine,urea,uric acid level was significantly increased in the group of diabetic control.Superoxide dismutase,catalase,glutathione peroxidase,glutathione reductase level was significantly decreased,but AGEs and TGF-β1 level was significantly increased.By contrast,administration of C.paliurus polysaccharides and metformin could reverse the above-mentioned results of the group of diabetic control,especially in the high-dose group of C.paliurus polysaccharides.CONCLUSION: Our findings suggest that C.paliurus polysaccharides may play a protecting role for nephropathy of diabetic rats by lowering glucose,creatinine,urea,uric acid level,enhancing the antioxidative ability,and reducing AGEs and TGF-β1 expression.