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Objective@#To study the damage effects of blue-light exposure on retinal morphology and function in mouse.@*Methods@#Twenty 8-week-old clean C57BL/6J mice were randomly divided into blue-light exposure group and normal control group by coin tossing method.The mice in the blue-light exposure group was exposed to 10 000 lx blue light for 5 days after dark adaptation for 24 hours, and the mice in the normal control group was kept under the normal light intensity for 5 days at 12-hour light/12-hour darkness cycles.The retinal thickness was detected by optical coherence tomography (OCT), and retinal function was evaluated by electroretinogram (ERG). The mice was sacrificed and the frozen section and flat mount of eyeball wall was created at 24 hours after irradiation.The expressions of rhodopsin (Rho), zonula occludens-1 (ZO-1) and β-catenin in the retinas were detected by immunofluorescent staining.The use and care of the experimental animals adhered to ARVO Statement by American Society of Visual and Ophthalmological Sciences (No.IACUC-1803029).@*Results@#The thickness of the retinal outer nuclear layer at 200, 400, 600, 800 and 1 000 μm from the superior and inferior to optic nerves were thinned in the mice of the blue-light exposure group compared with those of the normal control group, showing significant differences between the two groups (all at P<0.05). The b-wave amplitude of the scotopic and photopic ERG was (305.50±41.52)μV and (119.50±6.67)μV in the blue-light exposure group, respectively, which was significantly reduced in comparison with (415.50±28.77)μV and (139.75±8.26)μV of the normal control group (both at P<0.05). Immunofluorescent staining showed that the retinal pigment epithelial (RPE) cells of the mice exhibited hexagonal shape with regular arrangement, retinal morphology was regular, and the expressions of Rho, ZO-1 and β-catenin proteins showed stronger fluorescence in the retinas of normal control group.However, structural disorder, diminishing fluorescence intensity of Rho, ZO-1 and β-catenin were found in the blue-light exposure group.The morphology of the retina was disordered while the cell structure was destroyed.@*Conclusions@#Blue-light irradiation results in morphological and functional damages of retina.
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Objective To study the damage effects of blue-light exposure on retinal morphology and function in mouse.Methods Twenty 8-week-old clean C57BL/6J mice were randomly divided into blue-light exposure group and normal control group by coin tossing method.The mice in the blue-light exposure group was exposed to 10 000 lx blue light for 5 days after dark adaptation for 24 hours,and the mice in the normal control group was kept under the normal light intensity for 5 days at 12-hour light/12-hour darkness cycles.The retinal thickness was detected by optical coherence tomography (OCT),and retinal function was evaluated by electroretinogram (ERG).The mice was sacrificed and the frozen section and flat mount of eyeball wall was created at 24 hours after irradiation.The expressions of rhodopsin (Rho),zonula occludens-1 (ZO-1) and β-catenin in the retinas were detected by immunofluorescent staining.The use and care of the experimental animals adhered to ARVO Statement by American Society of Visual and Ophthalmological Sciences (No.IACUC-1803029).Results The thickness of the retinal outer nuclear layer at 200,400,600,800 and 1 000 μm from the superior and inferior to optic nerves were thinned in the mice of the blue-light exposure group compared with those of the normal control group,showing significant differences between the two groups (all at P＜0.05).The b-wave amplitude of the scotopic and photopic ERG was (305.50±41.52) μV and (119.50±6.67)μV in the blue-light exposure group,respectively,which was significantly reduced in comparison with (415.50±28.77) μV and (139.75±8.26) μV of the normal control group (both at P＜ 0.05).Immunofluorescent staining showed that the retinal pigment epithelial (RPE) cells of the mice exhibited hexagonal shape with regular arrangement,retinal morphology was regular,and the expressions of Rho,ZO-1 and β-catenin proteins showed stronger fluorescence in the retinas of normal control group.However,structural disorder,diminishing fluorescence intensity of Rho,ZO-1 and β-catenin were found in the blue-light exposure group.The morphology of the retina was disordered while the cell structure was destroyed.Conclusions Blue-light irradiation results in morphological and functional damages of retina.
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Background The light damage model of retinal pigment epithelium (RPE) cells is a research direction of retinal degeneration diseases,and RPE cell apoptosis induced by light damage and inflammation is an important pathologic basis of light-induced RPE cell damage.However,whether endoplasmic reticulum stress (ERS) paticipates in light-induced RPE cell damage is rarely reported.Objective This study was to explore the effects of ERS on light-induced RPE cell damage.Methods Human RPE cell line (ARPE-19) was cuhured,and light damage models were created by irradiating the cells for 3-,6-,12-and 24-hours with white fluorescent lamp with the intensity of (2 000±500)lx for the selection of optimal irradiating time,and the cells in the normal control group were cultured in the dark environment.The cells were divided into normal control group,light exposure group and 4-phenylb utyric acid (4-PBA) pretreated +light exposure group.The cells from 4-PBA pretreated +light exposure group were cultued firstly with 4-PBA for 30 minutes and followed by light exposure for 12 hours.The apoptisis rate of the cells and intracellular reactive oxygen species (ROS) content were detected by flow cytometry;the concentrations of interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the cell supernatant were assyed by ELISA.The relative expressing levels of activating transcription factor 6 (ATF-6),C/enhancer binding protein homologous protein (CHOP) and caspase-12 mRNA and protein in the cells were detected by real-time quantitative PCR and Western blot,respectively.Results The cultured cells showed a long spindle shape,the border was not clear,the cytoplasm was degranulation,and the cell fragments increased.Flow cytometry showed that compared with the normal control group,the ROS content in the cells and the apoptosis rate were evidently increased with the lapse of light exposure time (F=763.00,119.30,both at P＜0.01).ELISA results showed that the concentrations of IL-1β and TNF-α in the cell supernatant were significantly higher in the light exposure 6-hour group than those in the normal control group with the peak value in the light exposure 12-hour group.Compared with the normal control group,the relative expression levels of ATF-6,CHOP and caspase-12 mRNA and protein in the cells were elevated in the light exposure group and peaked in the light exposure 12-hour group.In addition,the relative expression levels of ATF-6 mRNA,CHOP mRNA and caspase-12 mRNA in the cells were significantly reduced in 4-PBA pretreated+light exposure group compared with the light exposure group (F=281.69,473.88,308.45,all at P＜0.01),and their proteins were also significantly reduced (F =47.86,57.93,106.59,all at P ＜ 0.01).The apoptosis rate,concentrations of IL-1β and TNF-α in the cell supernatant were significantly reduced in 4-PBA pretreated+light exposure group compared with the light exposure group (F =88.64,245.47,101.01,all at P＜0.01).Conclusions The light exposure at (2 000 ± 500)lx induces intracellular ROS accumulation and activates the ERS response,which results in apoptosis and inflammatory process of human RPE cells.4-PBA,a inhibitor of ERS,can suppress light-induced ERS response and therefore reduces the apoptosis rate and inhibits inflammatory process.