Effect of the A_(2A) adenosine receptor on the expression of vascular endothelial growth factor under high glucose conditions in human retinal pigment epithelium cells

Objective To study the effect of the A2A adenosine receptor on the expression of vascular endothelial growth factor(VEGF) under high glucose conditions in human retinal pigment epithelium(RPE) cells.Methods For cultured human RPE cells:immunohistochemistry was used to detect the A2A adenosine receptor in human RPE cells;cultured human RPE cells were treated with high glucose(33 mM)+adenosine deaminase(ADA,2 U/ml),high glucose+ADA+adenosine A2A receptor agonist(CGS21680,50 μM),high glucose +ADA +CGS21680 +adenosine A2A receptor antagonists(SCH58261,100 μM) for 24 h.After treatment,total RNA was extracted and cell culture medium was collected,real-time PCR and ELISA were used to measure the expression of VEGF mRNA and protein in human RPE by adenosine A2A receptor under high glucose conditions.Results A2A adenosine receptor expression as found in cultured RPE.The labeling was largely in the cytosol and membrane,but not in the nucleus.Under high glucose conditions,the adenosine A2A receptor agonist CGS(50 μM) stimulates an increase in the expression of VEGF mRNA(2.7 fold) and protein(1.5 fold),while for the adenosine A2A receptor antagonist SCH(100 μM) in RPE cells,VEGF mRNA decreased by about 40% and protein levels decreased by about 60%.Conclusion Under high glucose conditions,the adenosine A2A receptor can stimulate the synthesis of VEGF.Therefore the adenosine A2A receptor may be involved in the formation of diabetic retinopathy neovascularization.