氯沙坦抑制内质网特有凋亡途径在糖尿病大鼠肾脏中的保护作用

目的探讨血管紧张素II受体1拮抗剂氯沙坦对糖尿病大鼠肾脏细胞凋亡及内质网应激标志蛋白的影响。方法单侧肾切除大鼠腹腔注射链脲佐菌素诱发糖尿病,每日灌胃给予氯沙坦(40mg·kg-1)共8周。应用免疫组织化学检测细胞增殖核抗原(proliferating cell nuclear antigen,PCNA)、GRP78和Caspase-12的表达与定位,TUNEL染色检测细胞凋亡部位,流式细胞术检测细胞凋亡程度,并对GRP78、Caspase-12表达水平进行半定量分析,同时观察尿蛋白、BUN、尿肌酐等反映肾功能的相关指标。结果建模8周,糖尿病组大鼠较对照组肾小球、肾小管凋亡细胞数明显增多,GRP78、Caspase-12表达增强。氯沙坦治疗组较糖尿病组凋亡细胞数减少,GRP78、Caspase-12表达减弱,但尚未降至正常水平。3组间PCNA阳性细胞数无差异。结论氯沙坦部分通过影响内质网应激特有凋亡途径减少肾脏细胞凋亡,从而发挥肾脏保护作用。

Protective effect of losartan on the kidney of diabetic rats by inhibition of endoplasmic reticulum-specific apoptosis pathway

Aim To investigate the influence of angiotensinⅡ receptor 1 antagonosm losartan on apoptosis and the expression of GRP78 and Caspase-12 in the kidney of diabetic rats.Methods Intraperitoneal injection of STZ(65 mg·kg-1) was used to induce diabetes in uninephrectomized Wistar rats.Losartan(40 mg·kg-1) was administered daily by gavage from the next day of the induction to diabetes for 8 weeks.The expression and distribution of GRP78,Caspase-12,PCNA were examined by immunohistochemistry.Flow cytometry was used to detect the levels of protein of GRP78 and Caspase-12.Apoptosis was evaluated by means of TUNEL and flow cytometry.Scr,BUN and 24hour urine protein excretion were checked.Results Compared with those in normal control group,the num-bers of apoptosis and the expression of GRP78,Caspase-12 in glomerular and tubular cells were much higher in the diabetic kidneys at week 8.After losartan treatment,decrement was found in the expression of GRP78,Caspase-12 and the numbers of apoptotic cells,while there was no significant difference of PCNA protein observed in three groups.Conclusion Inhibition of apoptosis and regulation of endoplasmic reticulum stress might be responsible for the renal protective effects of losartan on uninephrectomized Wistar rats with diabetes.