Background The pathogenesis of myopia is currently unclear. Studies showed that retinoic acid regulates the development of myopia. Whether IRBP, a retinoid transport proteins, participates in the development of myopia or not is unknown. Objective The aim of this study was to investigate the expression of interphotoreceptor retinoid-binding protein (IRBP) in the retina of guinea pig with lens-induced myopia and study the relationship between IRBP expression and experimental myopia. Methods Fifty guinea pigs were randomized into the normal controls(n=10) ,defocus Ⅰ group (n=20) and defocus Ⅱ group (n=20). Guinea pigs in the defocus Ⅰ groups wore -10. 00 D lenses on the right eyes for 14 days and the defocus Ⅱ group for 28 days. The left eyes of both defocus groups did not wear any lens served as self-control. The refraction diopter and axial length were measured before and after wearing lenses. The protein expression of IRBP in the retina was detected by immunohistochemisty and Western blot. RT-PCR was used to observe the level of IRBP mRNA in the retina. Result Compared with the control eyes,the right eyes in the defocus Ⅰ and Ⅱ groups developed to ( -5. 53±1.93) D and (-8.69±2.46) D, and the ocular axial length elongated to (0. 31±0. 15 ) mm and (0.41 ±0. 13 ) mm, showing statistically significant differences between them ( group Ⅰ: t= 12. 57,29.63 ,P＜0.05 ;group Ⅱ :t= 15.82,44.35 ,P＜0.05 ) ,and the degree of myopia was lower and axial length was shorter in group Ⅰ than the eyes of group Ⅱ ( P＜0.05 ). There was no statistically significant differences found between the left eyes of defocus group Ⅰ and defocus group Ⅱ or eyes of the control group in diopter and axial length (P＞0.05). Immunochemistry revealed that the mean gray value of IRBP protein expression was 165.62t4. 93 and 171.00±4. 25 in defocus Ⅰ group and defocus Ⅱ group and was significantly higher than that of the self-control eyes and the normal control group ( 156. 31±4.00,155.26 ±3.49 and 158.61 ±4. 58 ) ( P＜0.05 ). Western blot demonstrated that the expressios of IRBP protein were down-regulated and RT-PCR showed the IRBP mRNA level of IRBP was significantly lower in defocusIgroup and defocusⅡgroup,compared with the self-control eyes and the normal control group (P＜0. 05). Conclusion Expression of IRBP in guinea pig may play a role in lens-induced myopia.%背景 目前近视的发病机制尚不明确.视黄酸作为一种近视相关性因子调控实验性近视的发生发展,但转运维生素A类物质的蛋白是否参与实验性近视的形成和近视中视黄酸的转运系统目前研究较少.目的 研究豚鼠离焦型近视眼视网膜中光感受器间维生素A类结合蛋白(IRBP)的表达变化,探讨IRBP表达对实验性近视的作用机制.方法 将3～4周龄的花色豚鼠50只按随机数字表法分成3组,空白对照组10只,离焦Ⅰ组和离焦Ⅱ组各20只.离焦Ⅰ组和离焦Ⅱ组豚鼠左眼作为自身对照眼,右眼戴-10.00D凹透镜,分别戴镜14 d、28 d后摘去镜片,测量双眼实验前后屈光度及眼轴长度.应用免疫组织化学法及Western blot法检测各组豚鼠视网膜中IRBP蛋白的表达变化,应用逆转录聚合酶链反应(RT-PCR)技术检测视网膜中IRBP mRNA的表达变化.结果 右眼戴镜14 d、28 d后与左眼相比,离焦Ⅰ组和Ⅱ组豚鼠分别形成了(-5.53±1.93)D和(-8.69±2.46)D的相对近视,眼轴分别延长(0.31±0.15)mm和(0.41±0.13)mm,Ⅰ组和Ⅱ组豚鼠离焦眼屈光度、眼轴长度的前后变化差异均有统计学意义(屈光度:F组别=1.90,P=0.04;F眼别=2.08,P＜0.05;F造模前后=2.43,P＜0.05.眼轴长度:F组别=2.04,P＜0.05;F眼别=4.15,P＜0.05;F造模前后=6.40,P＜0.05),离焦Ⅱ组屈光度的绝对值增加较离焦Ⅰ组明显(P＜0.05).戴镜后离焦Ⅰ组、Ⅱ组左眼及空白对照组的屈光度和眼轴长度比较差异均无统计学意义(P＞0.05).免疫组织化学染色表明,离焦Ⅰ组和Ⅱ组右眼测得的IRBP蛋白表达的平均灰度值为165.62±4.93和171.00±4.25,明显高于各组的左眼值和空白对照眼的156.31±4.00、155.26±3.49、158.61±4.58,且离焦Ⅱ组右眼IRBP表达量低于离焦Ⅰ组右眼,差异均有统计学意义(P＜0.05);Western blot检测发现,与自身对照眼及空白对照组相比,离焦Ⅰ组和Ⅱ组右眼视网膜IRBP蛋白表达下调;RT-PCR检测表明,离焦Ⅰ组和Ⅱ组右眼视网膜IRBP mRNA表达减少,与自身对照眼和空白对照组相比差异均有统计学意义(P＜0.05).结论 视网膜IRBP的表达变化可能在豚鼠离焦型近视眼的发生发展中发挥一定的作用.
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