血管内皮生长因子及其磷酸化受体系统在背景型糖尿病视网膜病变大鼠中的表达

Expression of vascular endothelial growth factor/vascular endothelial growth factor receptor system in experimental backgroud diabetic retinopathy

目的 血管内皮生长因子 (VEGF)是糖尿病诱发的视网膜新生血管形成的主要媒介。为探讨VEGF及其高亲和力酪氨酸激酶受体 (VEGFR :Flt 1、Flk 1)是否参与了背景型糖尿病视网膜病变 (BDR)的发生。方法 采用斑点杂交和免疫组织化学技术检测了链脲菌素诱导的糖尿病大鼠模型中视网膜VEGFmRNA和蛋白表达的丰度及分布。免疫沉淀和免疫印迹分析了Wistar鼠视网膜血管磷酸化Flt 1和Flk 1表达情况。消化铺片和电镜定量分析评估DR。结果 形态观察显示病程 6月的糖尿病动物视网膜病变尚未突破内界膜 ,其血管床无细胞性毛细血管数目仅较正常对照组轻微上升 ,而深层毛细血管基底膜异常则较对照组显著为高 (P <0 .0 5 )。虽然糖尿病视网膜VEGF蛋白表达分布与对照组无异 ,但在血管壁、内核层、外丛状层糖尿病大鼠VEGF表达上调 ,糖尿病组视网膜VEGFmRNA水平也较对照组显著升高 (1.4 2± 0 .0 8任意光密度单位VS 0 .92± 0 .0 5任意光密度单位 ,P <0 .0 1)。另外 ,在糖尿病视网膜血管磷酸化Flt 1和Flk 1表达也明显上调。结论 本文结果提示VEGF VEGFR系统在BDR大鼠视网膜表达上调 ,此可能参与了BDR特征性毛细血管渗漏等病理生理过程。

Objective Vascular endothelial growth factor (VEGF) is a major contributor to diabetes induced retinal neovascularization. To exam whether VEGF and its high affinity tyrosine kinase receptor (Flt 1, Flk 1) are involved in development of early background diabetic retinopathy. Methods The dot blotting and immunohistochemistry techniques were used to analysis the abundance and distribution of VEGFmRNA and protein of retina in the streptozotocin induced diabetic rat model. Immunopreciptation and immunoblotting were also used to detect the expression of phosphorylated Flk 1, Flt 1 of retinal vessels in wistar rats. In addition, diabetic retinopathy was assessed by quantitative morphometry of retinal digest preparations and electronic microscopy. Results The lesion of diabetic retinal vessel confined wihtin the inner limit membrane, and the number of acellular capillary only slightly elevated 2 fold, but deep capillary basement abnormalities significantly increased in diabetic animals with 6 months follow up. Distribution of VEGF protein were not altered in diabetic retina compare with control. But the VEGF protein localized at the blood vessels, inner nuclear, outer plexiform layers were significantly elevated in diabetic rats and VEGF mRNA level also significantly increased in diabetic animals compared with nondiabetic control. In addition, upregulation of expression of phosphorylated Flt 1 and Flk 1 were found in diabetic retina vessles. Conclusion The finding show direct evidence of upregulation of VEGF/ VEGFR system in diabetic rodent model. Which may be implicated in the pathogenesis of capillary leakage characteristic of backgroud diabetic retinopathy.