Vascular endothelial growth factor is induced by long-term high glucose concentration and up-regulated by acute glucose deprivation in cultured bovine retinal pigmented epithelial cells.

Vascular endothelial growth factor (VEGF) is closely correlated to diabetic retinopathy. Its basal production in three types of cultured retinal cells (endothelial cells, pericytes and retinal pigment epithelial cells; RPE) was examined. RPE production of VEGF was markedly higher than the rest of the cells. VEGF production in RPE was significantly elevated by 10-day, but not by 1- or 3-day exposure to 16.5 mM glucose compared to a 5.5 mM glucose group. Transient deterioration of diabetic retinopathy is frequently observed during rapid correction of glycemic control. To determine whether VEGF is up-regulated following a sharp drop in the glucose concentration or not, we examined the changes in VEGF production in RPE before and after a sudden drop in the glucose concentration. VEGF production was significantly increased by a glucose concentration decrease from 5.5 to 0.5 mM, but not by a decrease from 33 or 16.5 to 5.5 mM. These findings suggest that up-regulation of VEGF may contribute to the development of diabetic retinopathy and its worsening by hypoglycemia.