Effect and mechanism of erythropoietin on light-induced damage in retinal Müller cells

  Objective  To explore the effect and mechanism of erythropoietin(EPO)on light-induced retinal damage in Müller cells.

  Methods  Primary Müller cells of mice cultured were selected and divided into ultraviolet free group (control group) and ultraviolet group, each group was treated with different concentrations of EPO. The 3-(4, 5-demethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to detect cell viability. Western blot was used to detect the rotein kinase B(Akt) levels in EPO-activated Müller cells. Müller cells were divided into dimethyl sulfoxide (DMSO) control group(DMSO group)and inhibitors of Akt MK-2206 group(MK-2206 group). The above cells were treated in three ways: ① no ultraviolet group without treatment; ② ultraviolet group with ultraviolet radiation (30 mJ/cm2) for 30 min; ③ ultraviolet + drug groupthe cells were pretreated with 1 μg/mL EPO for 30 min, and then treated with ultraviolet (30 mJ/cm²) radiation for 30 min. The cell viability was detected by MTT. A total of 24 mice were divided into four groups: no injection group (right eye of mice, n=6), injection group (left eye of mice, n=6), illumination group (no injection eye receiving illumination, n=6) and illumination + injection group (injection eye receiving illumination, n=6). The mice in each group were examined by flash electroretinogram to assess impaired visual function.

  Results  Optical density (OD) values of cells pretreated with different concentrations of EPO in the ultraviolet group showed significant differences compared with those in the no ultraviolet group (P < 0.05). Compared with untreated cells, OD values of pretreated cells by EPO (0.1, 1, 10 μg/mL) were significantly increased by MTT (P < 0.01). The protective effect of Müller cells induced by EPO was also enhanced with the increase of EPO concentration (0.1 and 1 μg/mL, respectively, P < 0.05), while the protective effects of 1 and 10 μg/mL treatments showed no statistically significant differences (P=0.114). After Müller cells were treated with EPO (0, 0.1, 1, 10 μg/mL) for 1 h, western blot analysis showed that the protein expression levels of p-Akt (Ser-473) and Akt1 increased, and there was concentration dependence in the range of 0.1 and 1 μg/mL. There was no significant difference in amplitude between non-injection group and injection group (P=0.17). There were statistically significant differences in amplitude between the no injection group and injection group(P=0.17). There were statistically significant differences in amplitude between the no injection group and the illumination group, the illumination + injection group (P < 0.05). The amplitude of illumination + injection group showed significant difference compared with the illumination group (P < 0.05).

  Conclusion  EPO alleviates retinal light damage in mice by activating Müller cell Akt signaling pathway.