Abstract:

Objective：Angiopoietin-1(Ang-1), angiopoietin-2(Ang-2) and their receptor Tie-2 play crucial roles in regulating angiogenesis and vascular integrity. Advanced glycation end-poducts (AGEs) is involved in diabetic nephropathy. In the present study we investigated effects of AGEs on the expressions of Ang-1, Ang-2 and Tie-2 in cultured NRK-49F cells and the possible underlying mechanism. Methodology： NRK-49F cells were treated with 400μg/ml AGEs or with 25mmol/L glucose for 24h. The cells in the serum-free medium were regarded as controls. These cells were pretreated with medium containing ginkgo biloba extract (50 mg/L) for 24 hours, and then treated with 100μg/ml AGEs or 25mmol/L glucose for another 24 hours respectively. The expressions of Ang-1, Ang-2, Tie-2, NF-κB and I-κB were performed by realtime-PCR and westernblot techniques. Intracellular reactive oxygen species (ROS) generation was measured by flowcytometry and fluorescence inverse microscope. The role of antioxidant was also observed. Results Compared with control, AGEs significantly increased intracellular ROS generation and expressions of Ang-1, but not Ang-2 and Tie-2. AGEs also significantly increased NF-κB expression and decreased I-κB expression in NRK-49F cells. These effects could be significantly attenuated by preincubation with ginkgo biloba extract. Conclusions：Our data demonstrate that AGEs can significantly increase expression of Ang-1 expression in NRK-49F cells through enhance of oxidative stress and NF-κB pathway. The accumulation of AGEs may play a pivotal role in the pathogenesis of abnormal angiogenesis in diabetic nephropathy. Ginkgo biloba extract may have a well prospect in prevention of AGEs-induced microvascular lesions