Vascular Endothelial Growth Factor (VEGF) and Advanced Glycation End Products (AGEs) Overexpression in the Retina and Serum and Lens Opacities of Streptozotocin-induced Diabetic Rats

Abstract

Background: Vascular Endothelial Growth Factor (VEGF) and Advanced Glycation End products (AGEs) have been implicated in the development of diabetic retinopathy. In this study, we examined the expression of VEGF and AGEs in the retina and serum, apoptosis in the retina, and lens opacities in streptozotocin (STZ)-induced diabetic rats. Methods: The localization of VEGF and AGEs in the retina of STZ-induced diabetic rats was determined by immunohistochemical analysis, and apoptotic cell death was assessed using the TUNEL assay. In the serum, STZ-induced diabetic rats were assayed for VEGF and AGEs by ELISA. Lenses were also isolated to detect the opacity. Results: Expression of VEGF and accumulation of AGEs were significantly increased in the retinal ganglion cell layers (GCL) and nuclear cell layers (NCL) of STZ-induced diabetic rats compared to normal control rats. In addition to cellular expression, serum VEGF and AGEs levels were also increased significantly in STZ-diabetic rats compared to normal rats (both P < 0.001) and there was a significant correlation between the serum VEGF and AGEs levels (r = 0.504). The lens opaque density of STZ-induced diabetic rats were significantly higher than in normal rats (P < 0.001). Conclusions: AGEs could be involved in the development of diabetic retinopat hy through the induction of VEGF. One could possibly correlate this lens opaque formation with elevation of AGE induced VEGF level. Thus, this study should be considered as a basic research for studying pathology of the retina and lens in diabetic experimental models. (KOREAN DIABETES J 32:44~52, 2008)