Protective effects of light preconditioning on retinal photoreceptor cells aganist light damage / 眼科新进展

ABSTRACT

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.