METHODS: The retinal tissues of SD rats from 1-3d as the materials were taken, from which the RGCs were isolated and purified for primary culture. Toluidine blue and immunofluorescence staining methods were adopted to identify the cultured cells. After 48-72h of continuous culture, RGCs were randomly divided into 6 groups and cultured in different glucose concentrations of 5.5mmol/L(normal control group), 20mmol/L, 25mmol/L, 30mmol/L, 35mmol/L and 40mmol/L for 24, 48 and 72h, respectively. Finally, the CCK8 method and TUNEL method were adopted to determine the cell survival rate and apoptosis rate.

RESULTS: The primary RGCs purified and cultured in vitro represented typical cell morphology and grew well, the cells were confluent and aggregated in small lamellar manner, while the axons crisscrossed into a network, in addition, cell halo could be seen around the cell body. Nissl bodies with clear structure were found in the cytoplasm of toluidine blue stained cells, the percentage of neurons was more than 95%. RGCs specific antibodies Thy-1 and Brn-3a were employed to identify the purified cells in vitro, and the positive rate reached more than 90%. The CCK8 results showed that the survival rate of cells decreased(OD value decreased)with the increase of culture time and glucose concentration. When the cells were treated with different glucose concentrations for 24h, the OD values of each group were lower than those of the normal control group, but there was no significant difference between the OD values of each group and the normal control group(all P>0.05). With the extension of culture time, the OD values of 35mmol/L and 40mmol/L glucose concentration intervention RGCs 48h, 30mmol/L, 35mmol/L, 40mmol/L intervention RGCs 72h were significantly lower than those of the normal control group, the difference was statistically significant compared with the normal control group(all P<0.05). TUNEL results revealed that the apoptosis rate of RGCs increased with the increase of glucose concentration and time, among them, the apoptosis rate of RGCs cultured in glucose concentration of 30mmol/L, 35mmol/L and 40mmol/L for 48h and 72h was significantly statistical different from that of normal control group(all P<0.05).

CONCLUSION: The RGCs primary culture method established in this study is capable of separating typical RGCs with high purity. With the increase of glucose concentration in the medium, the survival rate of RGCs have been decreased while the apoptosis rate increased. Notably, the 35mmol/L glucose intervention for 48h can be employed as the optimal intervention concentration and time to effectively induce RGCs to establish the high glucose model.