Objective: To investigate the effect of insulin or (and) high glucose on the vascular endothelial growth factor (VEGF) expression in bovine retinal microvascular endothelial cells (BREC).
Methods: It was a experimental study. BREC were cultured with selective culture media. Passaged cells were cultured in normal (5 mmol/L) or high glucose (30 mmol/L) medium for 3 days. Equimolar mannitol was supplemented for osmotic controls. Cells were serum-deprived overnight in Dulbecco's modified Eagle's medium containing 0.2% w/v bovine serum albumin and then incubated in the absence or presence of 100 nmol/L insulin for 24 hrs. Cells were harvested and the expression of VEGF mRNA was analyzed by Real-time PCR. VEGF protein level was determined by HUVEC proliferation assay, immunofluorescence and western-blot
Results: Insulin or (and) high glucose significantly increased VEGF mRNA (F = 5.67, 9.04; P <0.05) and protein (F = 5.50, 5.57; P <0.05) expression. However, the combined effect of insulin and high glucose is weak in contrast to insulin or high glucose alone.
Conclusions: High glucose attenuated insulin-induced VEGF expression. Therefore, VEGF may be not the major factor that lead to transient worsening of diabetic retinopathy after acute insulin therapy in diabetes.