氧诱导小鼠视网膜组织VEGF和iNOS的早期表达及意义

目的明确血管内皮生长因子（VEGF）和诱导型一氧化氮合酶（iNOS）在氧诱导小鼠视网膜组织中早期的表达特征,并探讨上述促血管生成因子的表达在缺氧状态下视网膜新生血管生成中的意义。方法新生C57BL/6J小鼠暴露于高氧环境5d后转置于相对低氧环境,以建立视网膜新生血管小鼠模型,分别于暴露低氧环境0、2、6、24h后摘除眼球,应用RT-PCR及免疫组织化学技术检测全视网膜组织中VEGF及iNOS的表达情况。结果在低氧环境下,VEGF的表达水平呈现较明显的时间依赖性特征,与0h时间点相比,缺氧2hVEGFmRNA表达升高,6h尤为明显,24h下降。iNOSmRNA表达亦呈相似的特征,其表达高峰出现在缺氧2h,6h起即呈逐渐下降趋势。VEGF主要定位于视网膜节细胞层（RGCL）及内网层（IPL）的细胞浆,而iNOS蛋白表达于GCL的细胞浆;上述蛋白表达亦呈现与基因转录水平相一致的时间依赖性。结论暴露于缺氧环境下24h内视网膜VEGF和iNOS表达均上调,且随暴露时间呈动态变化,提示视网膜缺氧性病变早期即出现促血管生成因子的表达变化。

Expression of VEGF and iNOS in oxygen-induced early stage of retinopathy in mouse

Objective Hypoxia retinopathy is a potential eye disease leading to blindness.The main pathology of these diseases is retinal new blood vessel formation.The purpose of this study was to investigate the expression patterns and signification of vascular endothelial growth factor(VEGF)and inducible nitric oxide synthase(iNOS)in oxygen-induced retinopathy of mouse.MethodsA total of 24 new born mice were randomly divided into 4 groups.Model of oxygen-induced retinopathy was created by exposing C57BL/6 mice to hyperoxia(75% oxygen)for 5 day and then returned to normoxia(room air).Experimental mice(n= 4 in each group)were respectively sacrificed at 0,2,6 and 24 hours after returned in normoxia immediately,and normal mice were put in normal environments as control group.RT-PCR and immunohistochemistry were used for determination of expression levels of retinal VEGF and iNOSmRNA and their protein respectively.ResultsVEGF expression of animal model followed a time-dependent pattern:There was no distinct VEGF expression in retina of mice at 0 hours group,and the retinal VEGF level of mice was elevated at 2 hours and peaked at 6 hours,and then a progressively decreased tendency was seen at 24 hours.VEGF protein was expressed in the cytoplasm of retinal ganglion cell and inner plexiform layer(IPL).Inducible NOS showed a similar expression pattern mainly in the ganglion cell layer with its expressive peak at 2 hours.ConclusionVEGF and iNOS are expressed at the oxygen-induced retinopathy model,implying these two cytokines participate in the angiogenesis under the hypoxia condition and may be a potential interventional target in treatment of new blood vessel.