摘要
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-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 medium containing 25 mmol/L glucose were controls. Cells were treated with 25 mmol/L glucose and 100 μg/ml AGEs for 24 hours 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 hours. 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 glutathion level in NRK-49F cells in dose- and time-dependent manners. High glucose and AGEs together significantly increased the expression of TGF-β1, CTGF and Fn mRNA, compared with AGEs and high glucose separately. Preincubation with N-acetylcysteine or ginkgo biloba extract increased GSH level, suppressed AGEs-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 through enhancement of oxidative stress. The accumulation of AGEs may play a pivotal role in the pathogenesis of tubulointerstitial fibrosis in diabetic nephropathy. Suppression of AGEs induced TGF-β1, CTGF and Fn mRNA overexpression in renal fibroblasts through inhibition of oxidative stress may be a mechanism underlying effect of ginkgo biloba extract in diabetic nephropathy. In addition, antioxidant therapy may help prevent AGEs accumulation and 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-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 medium containing 25 mmol/L glucose were controls. Cells were treated with 25 mmol/L glucose and 100 μg/ml AGEs for 24 hours 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 hours. 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 glutathion level in NRK-49F cells in dose- and time-dependent manners. High glucose and AGEs together significantly increased the expression of TGF-β1, CTGF and Fn mRNA, compared with AGEs and high glucose separately. Preincubation with N-acetylcysteine or ginkgo biloba extract increased GSH level, suppressed AGEs-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 through enhancement of oxidative stress. The accumulation of AGEs may play a pivotal role in the pathogenesis of tubulointerstitial fibrosis in diabetic nephropathy. Suppression of AGEs induced TGF-β1, CTGF and Fn mRNA overexpression in renal fibroblasts through inhibition of oxidative stress may be a mechanism underlying effect of ginkgo biloba extract in diabetic nephropathy. In addition, antioxidant therapy may help prevent AGEs accumulation and its induced damage.
