Huang Jia, Qu Xiao-Mei, Chu Ren-Yuan
Department of Ophthalmology, Eye and ENT Hospital Affiliated to Fudan University, Shanghai, 200031, China.
Int J Ophthalmol. 2011;4(2):131-6. doi: 10.3980/j.issn.2222-3959.2011.02.04. Epub 2011 Apr 18.
All-trans retinoic acid (RA) is the only extrinsic biochemical candidate known to date that could act as a growth controller, the aim of this study was to investigate the expression cellular retinoic acid binding proteins I (CRABP-I) and retinoic acid receptor-β (RAR-β) in retina of the guinea pig eyes with experimental myopia.
Ninety guinea pigs aged 14 days were equally and randomly divided into three groups: form deprivation (FD), -5D lens, and control. The diffusers for FD were white translucent hemispheres, and -5D lenses were used to introduce hyperopic defocus. Refraction was measured with streak retinoscopy after cycloplegia, and axial length was calculated with Cinescan A/B ultrasonography. Retina harvested at different time points were used to measure RA level with HPLC and expressions of cellular retinoic acid binding proteins I (CRABP-I) and RA receptor-β (RAR-β) were assayed with Western blot and Real-time PCR. SPSS13.0 software was used for statistical analysis.
Up-regulations of CRABP-I and RAR-β in ocular tissues correlated with changes in the refractive status and growth rate of the guinea pig eye (P<0.05). 14 days of monocular form-deprivation led to -5.14D myopia and a 0.281mm axial elongation; 14 days of monocular defocus produced -3.64D myopia and a 0.163 mm axial elongation. The level of retinal RA started to elevate in 7 days (P<0.05) after visual manipulation in both FD and -5D lens groups and became more prominent by 14 days (P<0.01) . The expressions of CRABP-I and RAR-β increased by 14 days after visual manipulation (P<0.05), the mRNA level of RAR-β, however, increased by 7 days after visual manipulation (P<0.05), which suggested that changes of expressions of CRABP-I and RAR-β might lag behind the change of RA.
The levels of CRABP-I and RAR-β were elevated in retina of the guinea pig eye with experimental myopia. During the progression of experimental myopia, the retinal RA level increased rapidly, and there might be a positive feedback between the increase of RA and up-regulation of RAR-β.
全反式维甲酸（RA）是目前已知的唯一可作为生长调控因子的外源性生化物质，本研究旨在调查实验性近视豚鼠眼视网膜中细胞维甲酸结合蛋白I（CRABP-I）和维甲酸受体-β（RAR-β）的表达情况。
将90只14日龄的豚鼠平均随机分为三组：形觉剥夺（FD）组、-5D透镜组和对照组。FD组使用白色半透明半球形扩散器，-5D透镜组用于引入远视性离焦。使用带状检影法在睫状肌麻痹后测量屈光度数，并用Cinescan A/B超声测量眼轴长度。在不同时间点采集视网膜，用高效液相色谱法测量RA水平，并用蛋白质免疫印迹法和实时荧光定量PCR法检测细胞维甲酸结合蛋白I（CRABP-I）和维甲酸受体-β（RAR-β）的表达。采用SPSS13.0软件进行统计分析。
豚鼠眼组织中CRABP-I和RAR-β的上调与屈光状态及眼生长速率的变化相关（P<0.05）。单眼形觉剥夺14天导致-5.14D近视及眼轴伸长0.281mm；单眼离焦14天导致-3.64D近视及眼轴伸长0.163mm。在FD组和-5D透镜组中，视觉干预后7天视网膜RA水平开始升高（P<0.05），至14天时更为显著（P<0.01）。视觉干预14天后CRABP-I和RAR-β的表达增加（P<0.05），然而，RAR-β的mRNA水平在视觉干预7天后增加（P<0.05），这表明CRABP-I和RAR-β表达的变化可能滞后于RA的变化。
实验性近视豚鼠眼视网膜中CRABP-I和RAR-β水平升高。在实验性近视进展过程中，视网膜RA水平迅速增加，且RA增加与RAR-β上调之间可能存在正反馈。
