摘要背景 闪烁光可以诱导轴性近视的发生,但是参与近视发生的机制尚不明确.早期生长反应基因(Egr-1)作为即早基因的一种,对视觉刺激反应灵敏,但其对近视发展的作用值得研究. 目的 探讨Egr-1基因在闪烁光诱导(FL)眼小鼠视网膜中的动态表达及意义,并与形觉剥夺(FD)眼对照.方法 采用随机数字表法将150只28日龄健康C57 BL/6J(B6)小鼠随机分为正常对照组、FD组和FL组.FD组小鼠使用半透明塑料眼罩遮盖右眼2周,而FL组小鼠用频率为2 Hz的闪烁光照射2周,以建立近视眼模型,然后2个组小鼠均在正常环境中喂养1周.分别于造模前、造模1h、1d、1周、2周时及造模后1周使用红外偏心验光仪和动物专用A型超声仪测量所有小鼠右眼的屈光度及眼轴长度.分别于造模前后各时间点任意处死各组10只小鼠,分离视网膜组织,分别采用Western blot法和免疫组织化学法检测Egr-1蛋白在小鼠视网膜中的相对表达量和定位,采用荧光免疫化学法检测小鼠视网膜中Egr-1标志物的表达,采用逆转录PCR(RT-PCR)法检测小鼠视网膜中Egr-1 mRNA的表达.结果 造模2周时,FL组小鼠的屈光度为(0.32±0.14)D,屈光度改变小于FD组小鼠的近视(-0.66±0.43)D,差异有统计学意义(t=6.78,P=0.00).RT-PCR检测显示,造模1h时,FD组小鼠和FL组小鼠视网膜中Egr-1 mRNA的表达量分别为0.626±0.044和0.695±0.058,明显低于正常对照组的1.009±0.089,差异有统计学意义(t=14.81,P=0.01;t=9.15,P=0.03),造模2周时均持续低于正常对照组,差异均有统计学意义(均P＜0.05),而造模终止后1周FD组和FL组小鼠视网膜中Egr-1mRNA表达量明显高于正常对照组,差异有统计学意义(t=4.13,P=0.01;t=4.26,P=0.01).Western blot检测显示,FD组和FL组小鼠视网膜中Egr-1蛋白相对表达量随造模后时间的延长逐渐下降,造模2周时最低,FD组比FL组下降更为明显,造模后1周Egr-1蛋白表达量升高,但仍低于正常对照组,差异均有统计学意义(t=6.32,P=0.00;t=5.45,P=0.01).免疫组织化学检测显示,正常对照组Egr-1蛋白主要表达于视网膜神经节细胞层、内核层和感光细胞层,造模2周时FD组和FL组小鼠视网膜中Egr-1蛋白表达明显减弱,造模终止后1周Egr-1蛋白表达增强.免疫荧光检测显示,Egr-1标志物Neuron和蛋白激酶C(PKC)-α在正常小鼠神经节细胞和双极细胞均呈阳性表达.结论 FL诱导后小鼠眼屈光度向近视方向发展,视网膜中Egr-1基因的表达量随屈光度下降的程度而下调,这个动态变化过程与FD模型眼一致.

abstractsBackground Flicker light can induce myopia,but its mechanism remains unclear.As one of immediate early genes,early growth response-1 (Egr-1) gene can generate rapid response to visual stimulation,however,its effect on the formation and development of myopia is below understood.Objective This study was to investigate the dynamic expression of Egr-1 gene in retinas of flicker light-induced eyes (FL) and compare the results with form deprived eyes (FD).Methods One hundred and fifty 28-day-old C57BL/6J mice were randomly assigned to the normal control group,FD group and FL group.The right eyes of mice were occluded with a semitransparent hemispherical thin plastic shell for 2 weeks in the FD group,and the right eyes of mice were stimulated by 2 Hz flicker light for 2 weeks in the FL group,and then the mice were fed in the normal light environment for 1 week.The refractive state and axial length of the model eyes were measured by murine-specific eccentric infrared photorefraction and A-scan ultrasonography before modeling and 1 hour,I day,1 week,2 weeks after modeling as well as 1 week after termination,respectively.The mice were sacrificed in above-mentioned time points to isolate the retinas.The expressions and location of Egr-1 protein and mRNA in the retinas were detected by Western blot,and reverse transcription PCR (RT-PCR) and immunochemistry.The expressions of Egr-1 markers,neuron and protein kinase C (PKC)-α,in the retinas were assayed by using immunofluorescence.The care and use of the animals followed the administration regulations for experimental animals of Jiangsu Province.Results Two weeks after modeling,the refraction of the FL group was (0.32±0.14) D,which was significantly lower than (-0.66±0.43)D in the FD group (t=6.78,P=0.00).One hour after modeling,The expression levels of Egr-1 mRNA in mouse retinas were 0.626±0.044 and 0.695±0.058 in the FD group and FL group,which were significantly declined in comparison with 1.009±0.089 of the normal group (t=14.81,P=0.01;t=9.15,P=0.03).In 2 weeks after modeling,the expression levels of Egr-1 mRNA were still lower in the FD group and F:L group compared with the normal group (all at P＜0.05).However,the expression levels were significantly elevated in the FD group and FL group compared with the normal group (t=4.13,P=0.01;t=4.26,P=0.01) at 1 week after termination.Western blot showed a dynamic decrease in the expressions of Egr-1 protein with lapse of time in the FD group and FL group with the lowest expressing level in the second week after modeling.In I week after termination of modeling,the expressing level was raised in the FD group or the FL group,but it was still lower than that ir the normal group (t =6.32,P=0.00;t =5.45,P=0.01).Egr-1 protein was mainly expressed in the retinal ganglion cell (RGC) layer,inner nuclear layer and photoreceptor layer in the normal mice,and the expression intensity was obviously weaker in the FD mice and FL mice 2 weeks after modeling.Htowever,the expression was enhanced in 1 week after termination of modeling.Neuron and PKC-α were strongly expressed in the RGCs and bipolar cells in the normal mice.Conclusions The eyes show a myopic trend after induce of flicker light in B6 mice.The expression level of Egr-1 gene in the retina down-regulates with the reduce of refraction in FL eyes,and its dynamic expressing change is consistent between the FD eyes and FL eyes.