Background Advanced glycation end products (AGEs) play a critical role in the development of diabeticnephropathy.Reactive oxygen species (ROS) may play a critical role in AGEs induced growth factor expression.In thisstudy,the effects of AGEs on transforming growth factor β1 (TGF-β1),connective tissue growth factor (CTGF) andfibronectin (Fn) mRNA expression and oxidative stress in cultured NRK-49F cells were examined.Methods NRK-49F cells were incubated with medium containing different doses of AGEs (50,100 or 200 μg/ml) for24 hours,or with AGEs 100 μg/ml for different times (0,12,24 or 48 hours).Cells in the serum-free medium or mediumcontaining 25 mmol/L glucose were controls.Cells were treated with 25 mmol/L glucose and 100 μg/ml AGEs for 24hours to determine the effects between AGEs and glucose.We clarified the role of antioxidant by pretreating cells withN-acetylcysteine (10 mmol/L),ginkgo biloba extract (50 or 100 mg/L) for 24 hours and with 100 μg/ml AGEs for further24 hours.Alamarblue dye assay was used to analyze cell growth;intracellular ROS generation was measured by flowcytometry;intracellular glutathione by fluorescence spectrophotometry;expressions of TGF-β1,CTGF and Fn mRNAby semiquantitative RT-PCR.Results AGEs significantly increased the expressions of TGF-β1,CTGF,Fn mRNA and intracellular ROS generationand decreased the glutathion level in NRK-49F cells in dose-and time-dependent manners.High glucose and AGEstogether significantly increased the expression of TGF-β1,CTGF and Fn mRNA,compared with AGEs and highglucose separately.Preincubation with N-acetylcysteine or ginkgo biloba extract increased GSH level,suppressedAGEs-induced oxidative stress and TGF-β1,CTGF and Fn mRNA overexpression.Conclusions AGEs can significantly increase expression of TGF-β1,CTGF,Fn mRNA in NRK-49F cells throughenhancement of oxidative stress.The accumulation of AGEs may play a pivotal role in the pathogenesis oftubulointerstitial fibrosis in diabetic nephropathy.Suppression of AGEs induced TGF-β1,CTGF and Fn mRNAoverexpression in renal fibroblasts through inhibition of oxidative stress may be a mechanism underlying effect ofginkgo biloba extract in diabetic nephropathy.In addition,antioxidant therapy may help prevent AGEs accumulationand its induced damage. Background Advanced glycation end products (AGEs) play a critical role in the development of diabetic nephropathy. Reactive oxygen species (ROS) may play a critical role in AGEs induced growth factor expression. In this study, the effects of AGEs on transforming growth factor β1 (TGF NRF-β1), connective tissue growth factor (CTGF) and fibronectin (Fn) mRNA expression and oxidative stress in cultured NRK-49F cells were examined. Methods NRK-49F cells were incubated with medium containing different doses of AGEs (50, 100 or 200 μg / ml ) for 24 hours, or with AGEs 100 μg / ml for different times (0, 12, 24 or 48 hours). Cells in the serum-free medium or mediumcontaining 25 mmol / L glucose were controls. Cells were treated with 25 mmol / L glucose and 100 μg / ml AGEs for 24hours to determine the effects between AGEs and glucose. We clarified the role of antioxidant by pretreating cells with N-acetylcysteine ​​(10 mmol / L), ginkgo biloba extract (50 or 100 mg / L) for 24 hours and with 100 μg / ml AGEs for further 24 hour s.Alamarblue dye assay was used to analyze cell growth; intracellular ROS generation was measured by flow cytometry; intracellular glutathione by fluorescence spectrophotometry; expressions of TGF-β1, CTGF and Fn mRNA by semiquantitative RT-PCR. Results AGEs significantly increased the expressions of TGF- β1, CTGF, Fn mRNA and intracellular ROS generation and decreased the glutathione level in NRK-49F cells in dose-and time-dependent manners. High glucose and AGEstogether significantly increased the expression of TGF-β1, CTGF and Fn mRNA, compared with AGEs and High density lipoprotein liposomes, highglucose separately. Preincubation with N-acetylcysteine ​​or ginkgo biloba extract increased GSH level, suppressedAGEs-induced oxidative stress and TGF-β1, CTGF and Fn mRNA overexpression.Conclusions AGEs can significantly increase expression of TGF-β1, CTGF, Fn mRNA in NRK- 49F cells throughenhancement of oxidative stress. The accumulation of AGEs may play a pivotal role in the pathogenesis of tubulointerstitial fibrosis in diabetic nephropath y.Suppression of AGEs induced TGF-β1, CTGF and Fn mRNAoverexpression in renal fibroblasts through inhibition of oxidative stress may be a mechanism underlying effect ofginkgo biloba extract in diabetic nephropathy.In addition, antioxidant therapy may help prevent AGEs accumulationand its induced damage.