摘要:
目的 观察研究内质网应激(ERS)在糖尿病膀胱(DCP)逼尿肌病变发生进展过程中的效应及其机制.方法 以链脲佐菌素(STZ)构建并鉴定糖尿病大鼠模型,在4、8、12和16周观察电镜下逼尿肌细胞(DSMCs)超微结构,用苦味酸酸性复红法(VG染色法)测逼尿肌胶原纤维所占面积比例,链霉亲和素-生物素复合物法(SABC法)测DSMCs细胞增殖核抗原(PCNA)表达,末端脱氧核苷酸转移酶介导的dUTP缺口末端标记测定法(TUNEL法)测DSMCs凋亡水平;实时荧光定量聚合酶链式反应(RT-qPCR)及Western blot法测ERS相关性凋亡标志因子葡萄糖调节蛋白78(GRP78)、CCAAT/增强子结合蛋白同源蛋白(CHOP)及半胱氨酰天冬氨酸特异性蛋白酶(Caspase)-12在mRNA及蛋白水平的表达.结果 DSMCs超微结构随病程进展渐出现核旁内质网区域脱颗粒及空泡化,伴正常结构破坏.除DM4W组[(8.02±0.43)%]外,DM8W组[(13.38±2.65)%]、DM12W组[(18.14±1.93)%、DM16W组[(19.71±3.05)%]逼尿肌胶原纤维面积比例与对照组[(7.86±0.72)%]比较均显著升高(P<0.05);各实验组PCNA平均阳性表达率随病程进展均显著升高[(20.34±4.55)%、(46.88±7.12)%、(39.78±1.93)%、(22.15±5.64)%比(16.26±2.43)%,P<0.05],在8周达峰;各实验组大鼠平均凋亡指数(AI)均逐渐升高[(17.12±2.78)%、(28.12±4.09)%、(28.12±4.09)%、(43.39±6.82)%比(6.32±1.23)%,P<0.05].GRP78、Caspase-12及CHOP的mRNA及蛋白表达水平均显著高于对照组(P<0.05),其中Caspase-12及CHOP表达随病程进展均逐渐升高,而GRP78的mRNA表达于12周达峰,其蛋白表达于8周达峰.结论 糖尿病膀胱逼尿肌组织形态、超微结构及细胞数量变化呈现时间依赖性,其病情进展与ERS相关性凋亡密切相关.%Objective To observe the effect of Endoplasmic Reticulum Stress (ERS) on detrusor muscle apoptosis in Streptozotocin (STZ)-induced diabetic rats.Methods At 4,8,12,and 16 weeks after induction of diabetic rat models,the sections of detrusor muscle tissue were made and were stained with Van Gieson solution,the collagen fibers of each group were observed and their proportions were calculated;the sub-cellular ultrastructure was observed by Transmission Electron Microscopy (TEM).Proliferating Cell Nuclear Antigen (PCNA) assay kit and Strept Avidin-Biotin Complex (SABC) staining were used for the evaluation of Detrusor Smooth Muscle (DSM) cell proliferation.Moreover,the expression of three hallmarks of ERS-associated apoptosis,including Glucose-regulated protein 78 (GRP78),CCAAT/enhancer-binding protein homologous protein (CHOP),and cysteinyl aspartate-specific protease (Caspase)-12,was detected by Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting.Results The proportion of collagen fibers showed a significant climbing trend [(13.38±2.65)%,(18.14±1.93)%,(19.71 ±3.05)% vs.(7.86±0.72)%,P<0.05] since DM8w group,except DM4w group [(8.02 ± 0.43) %].With the time prolonged,the swelled and fused cisternaes started to show;the mild particle fusion and degranulation also could be seen in the zone of ER;the distorted or pyknotic nucleus contained clusters of unidentified dark-stained granules that could be observed.Compared with the control group,the increased PCNA-positive percentages [(20.34 ± 4.55) %,(46.88±7.12)%,(39.78±1.93)%,(22.15±5.64)% vs.(16.26±2.43)%,P<0.05] and apoptosisindexes [(17.12±2.78)%,(28.12±4.09)%,(28.12±4.09)%,(43.39 ±6.82)% vs.(6.32 ± 1.23)%,P <0.05] can be seen in model groups.Elevated expression of GRP78,CHOP,and Caspase-12 at both protein and mRNA levels in a time-dependent fashion were detected (P < 0.05).Conclusion Morphological and ultrastructural damages to the DSM as well as the cell proliferation and apoptosis indicate the time-dependent alterations.The occurrence of ERS may be involved in the development of diabetic cystopathy (DCP) and may contribute to the diabetic detrusor muscle apoptosis.