miR-26a/PTEN在糖尿病小鼠视网膜神经变性中的作用及其机制

目的　探讨 microRNA-26a-5p (miR-26a)/PTEN在早期糖尿病小鼠视网膜神经变性（DRN）中的作用及其机制。方法　66只C57BL/6J小鼠随机分为实验组和对照组，实验组小鼠腹腔注射链脲佐菌素建立糖尿病动物模型。实验组小鼠造模成功后随机分为糖尿病组和miR-26a组，miR-26a组小鼠玻璃体内注射miR-26a mimic上调视网膜组织中miR-26a的表达。玻璃体内注射2周后所有小鼠用100 g·L^-1水合氯醛腹腔注射麻醉并处死，立即摘除眼球。HE染色及透射电镜分别观察各组小鼠视网膜形态学及超微结构变化，免疫荧光半定量检测并定位PTEN、胶质细胞原纤维酸性蛋白（GFAP）在小鼠视网膜各层的表达，qRT-PCR测量各组小鼠视网膜中miR-26a、PTEN和GFAP的mRNA表达。结果　糖尿病组小鼠视网膜神经上皮层厚度较对照组变薄，视网膜神经节细胞(RGC)数量减少，差异均有统计学意义（均为 P<0.05）；视网膜组织中miR-26a mRNA表达下降（P<0.05），GFAP及PTEN的mRNA表达较对照组小鼠均明显升高（均为 P<0.05）。与糖尿病组小鼠相比，miR-26a组小鼠视网膜全层厚度明显增厚（均为 P<0.05），RGC丢失减少,视网膜组织中miR-26a mRNA表达升高，而GFAP及PTEN的mRNA表达均降低，差异均有统计学意义（均为 P<0.05）。结论　miR-26a可能通过下调视网膜组织中PTEN的表达减轻糖尿病小鼠的DRN。

Effects of miR-26a/phosphatase and tensin homolog on retinal neurodegeneration in diabetic mice and its underlying mechanism

Objective　To discuss the effect of microRNA-26a-5p (miR-26a)/PTEN on early diabetic retinal neurodegeneration (DRN) and identify the underlying mechanism.Methods　A total of 66 C57BL/6J mice were randomly divided into the experimental group and control group. Mice in the experimental group were intraperitoneally injected with streptozotocin to establish models of diabeties mellitus (DM). The DM mice were then randomly divided into the DM group and miR-26a group. Mice in the miR-26a group were intravitreally injected with miR-26a mimic to up-regulate the expression of miR-26a in the retina. Two weeks later, the mice were sacrificed by anesthesia with 100 g·L^-1 chloral hydrate intraperitoneally, and their eyes were enucleated immediately for examinations. Hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM) were used to observe the changes in the retinal morphology and ultrastructure of mice in each group, respectively. The PTEN and GFAP expression in the retina were examined semi-quantitatively with an immunofluorescence assay. The mRNA expression of miR-26a, PTEN and GFAP in the retina was measured with quantitative real-time PCR (qRT-PCR).Results　Mice in the DM group had significantly reduced neuroretinal thickness and retinal ganglion cells (RGC) (all P<0.05). The mRNA expression of miR-26a in the retina was decreased (P<0.05), while the mRNA expression of GFAP and PTEN was significantly increased compared with the control group (both P<0.05). Compared with the DM group, mice in the miR-26a group had retinal thickness significantly increased and RGC loss decreased; the mRNA expression of miR-26a in the retina was increased, and the mRNA expression of GFAP and PTEN was decreased, with the differences being statistically significant (all P<0.05).Conclusion　MiR-26a may relieve the DRN of DM mice by down-regulating PTEN expression in the retina.