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目的检测半胱天冬酶12(caspase-12)在糖尿病(DM)大鼠视网膜的表达情况,探讨内质网应激在糖尿病视网膜病变(DR)中的作用。方法健康雄性SD大鼠30只随机分成空白组(CON组)15只,糖尿病1月组(DM1组)、糖尿病2月组(DM2组)、糖尿病3月组(DM3组),每组5只。分别于造模后1,2,3个月摘除眼球,行HE染色、免疫组织化学染色,观察视网膜形态,计数视网膜神经节细胞(RCGs),并检测caspase-12在视网膜的表达情况。结果视网膜HE染色显示DM组大鼠视网膜神经节细胞减少,内外核层细胞稀疏,排列紊乱,网状层空泡样变性等改变,且随病程延长逐渐加重。RCGs计数结果 CON组、DM1组、DM2组、DM3组结果分别是281.20±7.98,263.60±13.37,240.60±11.78,194.80±13.16,各组组间差异均有统计学意义(P<0.05)。免疫组织化学染色显示,caspase-12在CON组没有阳性表达,在DM组主要表达于神经节细胞层。随着病程进展,内核层也有表达,且表达强度逐渐增强。DM1组、DM2组、DM3组caspase-12表达的平均光密度值(IOD/area)分别是0.0173±0.0039,0.0348±0.0050,0.0579±0.0074,DM2组和DM3组与DM1组比较差异有统计学意义(P<0.01)。结论随着DM病程进展,DR大鼠RGCs凋亡逐渐增加,caspase-12诱导的内质网凋亡在DR发病中有重要作用,内质网应激促进了DR的发生、发展。
Objective To detect the expression of caspase-12 in the retina of diabetic rats and explore the role of endoplasmic reticulum stress in diabetic retinopathy (DR). Methods Thirty healthy male Sprague-Dawley rats were randomly divided into three groups: CON group (CON group), diabetes mellitus group (DM1 group), diabetes mellitus group (DM2 group) and diabetes mellitus group (DM3 group) . The eyeballs were removed at 1, 2, and 3 months after modeling respectively. HE staining and immunohistochemical staining were performed to observe the retinal morphology. Retinal ganglion cells (RCGs) were counted and the expression of caspase-12 in the retina was detected. Results Retinal HE staining showed that the number of retinal ganglion cells in the DM group was decreased, the cells in the inner and outer nuclear layers were sparse, disordered, vacuolar degeneration in the reticular layer, and gradually increased with the prolongation of the duration of the disease. The results of RCGs in CON group, DM1 group, DM2 group and DM3 group were 281.20 ± 7.98, 263.60 ± 13.37, 240.60 ± 11.78 and 194.80 ± 13.16, respectively. There were significant differences among the groups (P <0.05). Immunohistochemical staining showed that caspase-12 was not expressed in CON group and mainly in ganglion cell layer in DM group. As the disease progresses, the inner nuclear layer is also expressed, and the expression intensity gradually increases. The average optical density (IOD / area) of caspase-12 expression in DM1 group, DM2 group and DM3 group was 0.0173 ± 0.0039, 0.0348 ± 0.0050 and 0.0579 ± 0.0074, respectively. There was significant difference between DM2 group and DM3 group and DM1 group (P <0.01). Conclusion With the progression of DM, the apoptosis of RGCs in DR rats gradually increases. The apoptosis of endoplasmic reticulum (ER) induced by caspase-12 plays an important role in the pathogenesis of DR. Endoplasmic reticulum stress promotes the development and progression of DR.