The Effect Of Exogenous Advanced Glycation End Products On The Expression Of Vascular Endothelial Growth Factor In The Healthy Rats' Retina

ObjectiveDiabetic retinopathy (DR) is one of the most common and serious complication of diabetes mellitus, which has become one of the four blind diseases. Moreover, retinal neovascularization is the fundamental factor which leads to vitreous hemorrhage, retinal detachment and loss vision . Although massive and effective work on DR have been done, the mechanism is not completely clear. Some evidences have display the formation of advanced glycated end products ( AGEs ) has closed relation with the occurrence of retinal neovascularization and DR. Vascular endothelial growth factor ( VEGF) is the most potent angiogenic stimulator, which can stimulate vascular endothelial cell proliferation and migration and induce retinal neovascularization. Many studied showed that VEGF plays an important role in retinal neovascularization.Based on previous study , We infused AGEs to healthy rats , Observed whether AGEs have influence on the expression of VEGF of rats retina before the observation of retinal neovascularization. It may provide us a further recognition on DR.MethodAGEs - RSA were prepared by incubating rat serum albumin (RSA) with D- glucose for 8 weeks at 37 X,. The products ( AGEs - RSA) were identified by their characterized fluorescent spectrum.30 male healthy Wistar rats were divided into 3 groups at random , the normal control , RSA control , AGEs - RSA group. The rats were received intrap-eritoneal injection with sodium chloride, native RSA, AGEs - RSA respective-ly.The rats were euthanized and the eyes were removed. Immunohistochemical method was performed to detect the expression of VEGF with positive staining i-dentified by a brown precipitate. Selecting five fields at random to calculate the average gray value and performed semi - quantitive analysis with image analyzing system.ResultsAfter the incubation it becomes brown viscous products. The maximum excitation and emission wave length of AGEs - RSA were located at 370 nm and 440 nm respectively. Fluorescent value was 43. 27U/mg.The observation of HE staining;The constitution of retina is clear in the rats among the AGEs - RSA group. The cells of inner nuclear layer and ganglion cell layer loosened , intercellular space largened , cells amount decreased . The cells appearance has no obviously difference between AGEs - RSA group and normal control group.The brown precipitate, located in the inner nuclear layer and ganglion cell layer, indicates the presence of VEGF. Positive cells were significant increased in AGEs - RSA group . The averAGEs gray value of retina specimens staining for VEGF wasl45. 06 ± 2. 92, 144. 50 ± 3. 12, 111. 54 ± 3. 45 respectively. VEGF expression of AGEs - RSA group was significant higher than that of the two control groups ( P < 0. 01) .ConclusionAdvanced glycation end products plays an independent role in the pathological course of retina tissue. Advanced glycation end products can induced the higher expression of VEGF in the retina of healthy rats. Both have some relationship with the development of the diabetic retinopathy.