Increasing evidence indicates that advanced glycation end products (AGEs) 
promote retinal alterations through oxidative stress. However, the pathways 
involved in AGE-induced generation of reactive oxygen species (ROS) in retinal 
cells are poorly defined. In the present study, we investigated the role of 
nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) oxidase in 
AGE-induced ROS intracellular generation and vascular endothelial growth factor 
(VEGF) expression in bovine retinal endothelial cells (BRECs). Incubation of 
BRECs with 100 microg/mL AGEs increased ROS generation and VEGF expression in 
these cells. Treatment of the cells with the NADPH oxidase inhibitors, apocynin 
and diphenylene iodonium, inhibited these effects. In retinal endothelial cells 
exposed to AGEs, translocation of protein kinase C (PKC)-beta2 and p47phox was 
observed. Inhibition of PKC by treatment of the cells with calphostin C, 
GF10923X, and LY379196 totally suppressed AGE-mediated p47phox translocation and 
ROS generation. Incubation of BRECs with gliclazide inhibited AGE-induced 
PKC-beta2 and p47phox translocation and totally abrogated AGE-mediated ROS 
generation and VEGF expression. Overall, these results demonstrate that AGEs 
induce intracellular ROS generation and VEGF expression in retinal endothelial 
cells through a PKC-dependent activation of NADPH oxidase. Inhibition of retinal 
NADPH oxidase expression and ROS generated by this system provides a new 
potential mechanism by which gliclazide may affect retinal VEGF expression and 
exert a beneficial effect on diabetic retinopathy.