血管内皮生长因子mRNA在高氧诱导新生鼠视网膜异常新生血管化模型中的表达

Expression of mRNA of vascular endothelial growth factor in a rat model of hyperoxia-induced retinopathy

目的分析血管内皮生长因子(VEGF)在高氧诱导视网膜异常新生血管化大鼠模型中的表达变化,探讨VEGF在高氧诱导视网膜新生血管化进程中所起的作用。方法150只SD新生大鼠随机分为氧诱导模型组和正常对照组,各75只。氧诱导模型组大鼠吸入浓度(80±2)%7d,随后在正常空气环境。视网膜铺片ADP酶染色了解视网膜血管形态改变;常规苏木精-伊红染色定量反映视网膜血管增生情况,判断建模成功。半定量逆转录-聚合酶链反应(RT-PCR)定量反映视网膜VEGFmRNA转录水平的变化。结果氧诱导模型组7日龄时视网膜血管明显收缩、阻塞,出现大片无灌注区;14日龄见新生血管形成;苏木精-伊红染色见模型组14日龄大鼠视网膜出现较多新生血管内皮细胞核;RT-PCR结果显示,氧诱导模型组7d时VEGFmRNA转录水平明显低于对照组,停氧后逐渐增强。VEGFmRNA的表达在新生血管发生前升高,随新生血管退行逐渐下降。结论未成熟视网膜VEGFmRNA的转录水平与组织氧状态呈密切负性相关关系;停氧后视网膜的相对缺氧导致VEGFmRNA转录上调,促使视网膜血管病理性增生。VEGF的异常表达在ROP的新生血管化进程中起重要作用。

Objective To examine the expression of mRNA of vascular endothelial growth factor （VEGF） in a rat model of hyperoxia-induced retinopathy and to investigate the role of VEGF in the process of neovascularization in retinopathy. Methods One hundred fifty one-day-old neonatal Sprague-Dawley rats were randomly divided into hyperoxia- induced retinopathy and normal control groups. The rats in the retinopathy group were exposed to （ 80 ±2） % oxygen for 7 days and then replaced by room air. The rats in the control group were exposed to room air all the time of the experiment. The morphologic changes of retinal vessels were estimated by observing the vascular pattern in adenosine diphosphate ase （ADPase） stained retina flat mounts. The newborn vessels were quantified by haematoxylin and eosin staining. Reversal transcription-polymerase chain reaction （ RT-PCR ） was used to detect the VEGF mRNA expression. Results In the retinopathy group at 7 days of age, most of central radial vessels became constricted and blocked, and central perfusion decreased obviously. After switching to room air exposure for 7 days （14 days of age）, noticeable retinal neovascularization appeared. The expression of VEGF mRNA in the retinopathy group at 7 days of hyperoxia exposure was noticeably lower than in the control group, and increased gradually after switching to room air exposure. At 9 and 14 days of age, the expression of VEGF mRNA in the retinopathy group was noticeably higher than in the control group. The expression of retinal VEGF mRNA in the retinopathy group increased before neovascularization occurred, and decreased with regression of new vessels. Condusions Hyperoxia exposure may decrease the transcription of VEGF mRNA and the growth of retinal blood vessels. The relative hypoxia after hyperxia withdrawal can up-regulate the transcription of VEGF mRNA, resulting in a significant retinal neovascularization. The abnormal expression of VEGF in the retina may play an important role in the development of neovascularization in retinopathy.