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目的:建立N-甲基-N-亚硝脲(N-methyl-N nitrosourea,MNU)损伤视网膜的模型,研究视网膜神经元凋亡对Müller细胞生物学特性的影响及神经营养因子的表达变化。方法:腹腔注射MNU建立视网膜损伤模型,免疫荧光染色方法研究感光细胞缺失对Müller细胞的生物学特性的影响,并检测主要神经营养因子表达的变化。结果:TUNEL法显示,腹腔注射MNU后2 d,视网膜外核层细胞凋亡现象明显。核增殖抗原(PCNA)及细胞周期素CyclinD_1的表达明显增高。与此同时,Müller细胞也开始表达神经干细胞抗原巢蛋白(nestin);RT-PCR显示胰岛素样生长因子(IGF),碱性成纤维细胞生长因子(bFGF)和肝细胞生长因子(HGF)mRNA的表达均升高。结论:在视网膜受到损伤时,Müller细胞增殖、去分化呈现出干细胞的特性。而视网膜中IGF、bFGF和HGF等细胞因子的表达明显增高,提示视网膜损伤后可能通过大量分泌细胞生长因子,促进Müller细胞的增殖。
OBJECTIVE: To establish a model of retinal injury induced by N-methyl-N nitrosourea (MNU) in retina to study the effects of retinal neuronal apoptosis on the biological characteristics of Müller cells and the changes of neurotrophic factor. Methods: The model of retinal injury was established by intraperitoneal injection of MNU. The effect of photoreceptor cell loss on the biological characteristics of Müller cells was studied by immunofluorescence staining and the changes of the expression of major neurotrophic factors were detected. Results: The results of TUNEL showed that after 2 days of intraperitoneal injection of MNU, apoptosis in the outer nuclear layer of retina was obvious. The expression of nuclear proliferative antigen (PCNA) and cyclinD_1 was significantly increased. In the meantime, Müller cells also began to express neural stem cell antigen nestin. RT-PCR showed that insulin-like growth factor (IGF), basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF) mRNA The expression increased. Conclusion: Müller cells proliferate and dedifferentiate to show the characteristics of stem cells when the retina is damaged. The retinal IGF, bFGF and HGF and other cytokines expression was significantly increased, suggesting that after retinal damage may be a large number of secreted cell growth factor, promote Müller cell proliferation.