光预适应对小鼠视网膜光感受器细胞光损伤的保护作用

摘要

Objective To investigate the protective role of light preconditioning in retinal photoreceptor cells and the underlying mechanisms after light damage.Methods Together 42 BALB/c mice were randomly divided into normal control group,light damage group,light preconditioning + light damage group and light preconditioning group.Mice in the light damage group were exposed to 4000 Lux intensity of cool white fluorescent light for 4 h continually;mice in the light reconditioning + light damage group were maintained in 600 Lux cyclic bright light for preconditioning (12 h ON and 12 h OFF) for 6 days,and then exposed to 4000 Lux bright-light for the induction of the damage;mice in the light reconditioning group were maintained in 600 Lux cyclic bright light for preconditioning (12 h ON and 12 h OFF) for 2 days,4 days,6 days.Then the function and morphology of retinal photoreceptor cells were detected by flash electroretinogram (FERG) and histopathological examination in the normal control group,light damage group and light preconditioning + light damage group,while real-time polymerase chain reaction (PCR) was used to detect the mRNA relative expression of leukemia inhibitory factor (LIF) and Western blot analysis was used to detect the phosphoprotein relative expression of signal transducer and activator of transcription 3(STAT3) in the light preconditioning group.Results FERG results showed the amplitudes of scotopic ERG a wave of the light damage group were decreased when compared with the normal control group,with significant difference (P =0.000).Compared with the light damage group,the amplitudes of scotopic ERG a wave of the light preconditioning + light damage group were increased significantly (P =0.000).Histopathological examination results showed that the number of photoreceptor nuclei in the light damage group was decreased compared with the normal control group,and the difference was statistically significant (P =0.000).Compared with light damage group,the number of photoreceptor nuclei in light preconditioning + light damage group was increased significantly (P =0.000).Real-time PCR results showed light preconditioning enhanced the LIF mRNA relative expression in a time-dependent manner (F=128.776,P =0.000).Western blot results showed light preconditioning up-regulated the phosphoprotein relative expression of STAT3 protein in a time-dependent manner (F =73.493,P =0.000).Conelusion Light preconditioning can protect retinal photoreceptor cells against light damage which may results from the activation of LIF/STAT3 signaling pathway.%目的 探讨光预适应对视网膜光感受器细胞光损伤的保护作用及其机制.方法 42只小鼠随机分为正常对照组、光损伤组、光预适应+光损伤组和光预适应组.光损伤组采用4000 Lux白色冷光源对BALB/c小鼠进行4h持续照射;光预适应+光损伤组先采用600 Lux白色冷光源与黑暗(12 h/12 h)交替环境下饲养6d,然后采用4000 Lux白色冷光源持续照射4h;光预适应组仅采用600 Lux白色冷光源与黑暗(12 h/12 h)交替环境下饲养不同时间(2d、4d和6d).正常对照组、光损伤组和光预适应+光损伤组分别采用闪光视网膜电图(flash electroretinogram,FERG)和组织病理学检查检测视网膜光感受器细胞的功能和形态学变化.光预适应组运用实时荧光定量PCR法检测预适应对小鼠视网膜中白血病抑制因子(leukemia inhibitory factor,LIF)mRNA相对表达水平的影响;运用Western blot法检测光预适应对信号转导子和转录激活因子3(STAT3)蛋白磷酸化水平的影响.结果 FERG检查结果显示,与正常对照组相比,光损伤组暗适应ERGa波振幅下降,差异有统计学意义(P =0.000);与光损伤组相比,光预适应+光损伤组暗适应ERG a波振幅显著增加,差异有统计学意义(P =0.000).组织病理学检查结果显示,与正常对照组相比,光损伤组小鼠视网膜外核层细胞核数量明显减少,差异有统计学意义(P=0.000);与光损伤组相比,光预适应+光损伤组外核层细胞核数量明显增多,差异有统计学意义(P=0.000).实时荧光定量PCR检测结果显示,光预适应显著增加LIF mRNA的相对表达量,且呈时间依赖性(F=128.776,P=0.000).Western blot检测结果显示,光预适应显著增加STAT3蛋白磷酸化的相对表达量,且呈时间依赖性(F =73.493,P=0.000).结论光预适应对视网膜光感受器细胞光损伤具有保护作用,其可能通过激活LIF/STAT3信号通道发挥作用.