Objective To investigate the effect of silment information regulator factor related enzymes 1 (SIRT1) on the apoptosis of retinal ganglion cells (RGCs) in rats with diabetic retinopathy and its downstream molecular mechanisms.Methods Together 60 healthy male Sprague-Dawley rats were collected and randomly divided into normal group,diabetic group,SIRTI activator-resveratrol treatment group (treatment group),and diabetic rat model was induced by intraperitoneal injection of streptozotocin at 60 mg · kg-1 in the latter two group rats,while the normal group was injected with sodium citrate buffer at 60 mg · kg-1.Then,after 72 h,rats with blood glucose ＞ 16.7 mmol · L-1 were designated as diabetic rats by blood glucose test.Then each rat in the treatment group was treated with SIRT1 activator-resveratrol at 20 g · kg-1 once a day at the 2nd day after the success of the model,and the normal group and diabetic group were given methylene chloride.Finally,after immunohistochemical staining for retina,TUNEL assay was used to evaluate the apoptosis of RGCs,while the expression of SIRTI,p38 MAPK and Caspase-3 protein was detected by Western blot.Results The apoptotic index of RGCs in the normal group,diabetic group and treatment group was (0.848+0.131)％,(19.038 + 1.327)％,(10.461 + 1.089)％ respectively at 8 weeks,and the difference among the three groups was statistically significant (F =670.497,P =0.000),while the differences between each two groups were also statistically significant (all P =0.000).Furthermore,when compared with the normal group (0.132 ± 0.043),the expression of SIRT1 protein in the diabetic group (0.060 ± 0.028) and the treatment group (0.073 ± 0.026) was significantly decreased,and the overall difference among the three groups was statistically significant (F =1 310.663,P =0.000),while the differences between each two groups were also statistically significant (all P =0.000).The expression levels of p38 MAPK and Caspase-3 were increased in diabetic group (1.121 ± 0.082,0.266 ± 0.005) and treatment group (0.574 ± 0.012,0.190 ±0.060) respectively,and the overall difference and pairwise comparison in the three groups approached statistically significance (all P =0.000,0.000).Conelusion Up-regulation of SIRT1,can inhibit the apoptosis of RGCs,and protect RGCs against apoptosis in rat model of diabetic retinopathy,which may be correlated with the downregulation of p38 MAPK signal pathway.%目的 探讨沉默信息调节因子相关酶1(silment information regulator factor related enzymes 1,SIRTl)对糖尿病视网膜病变大鼠视网膜神经节细胞(retinal ganglion cells,RGCs)的保护作用及其机制.方法 取健康清洁级雄性Sprague-Dawley大鼠60只,应用随机数字表法分为正常对照组(正常组)、糖尿病组(病变组)、SIRT1激动剂白藜芦醇治疗组(治疗组).病变组和治疗组大鼠按60 mg·kg-1单次腹腔注射链脲佐菌素以诱导糖尿病大鼠模型;正常组按60 mg· kg-1腹腔注射枸橼酸钠缓冲液.72h后取鼠尾静脉血检测血糖,血糖值＞16.7 mmol·L-1定为糖尿病大鼠.自造模成功后第2天起治疗组每天每只鼠给予白藜芦醇20 g·kg-1灌胃,正常组和病变组每天每只鼠给予亚甲砜灌胃.8周后进行视网膜免疫组织化学染色,TUNEL法检测视网膜RGCs凋亡,Western blot检测SIRT1、p38 MAPK、Caspase-3蛋白的表达.结果 正常组、病变组、治疗组8周后RGCs凋亡指数分别为:(0.848±0.131)％、(19.038±1.327)％、(10.461±1.089)％,三组间差异有统计学意义(F=670.497,P=0.000).进一步两两比较:正常组RGCs凋亡指数与病变组、治疗组间差异均有统计学意义(均为P=0.000);治疗组与病变组间差异亦有统计学意义(P =0.000).与正常组(0.132±0.003)相比,病变组(0.060±0.028)和治疗组(0.073±0.026)大鼠视网膜SIRT1蛋白表达降低,总体差异有统计学意义(F=1310.663,P=0.000).进一步两两比较,病变组和治疗组与正常组间,以及病变组与治疗组间差异均有统计学意义(均为P =0.000).病变组(l.121±0.082,0.266±0.005)和治疗组(0.574±0.012,0.190±0.060)大鼠视网膜p38 MAPK、Caspase-3蛋白表达较正常组(0.402±0.012,0.156±0.006)明显增加,总体差异有统计学意义(F =604.500、1056.709,P=0.000、0.000).进一步两两比较:p38 MAPK、Caspase-3蛋白表达在正常组与病变组间、正常组与治疗组间以及病变组与治疗组间差异均有统计学意义(均为P=0.000).结论 在糖尿病视网膜病变模型中,SIRT1表达上调,抑制RGCs的凋亡,对糖尿病视网膜病变RGCs起保护作用.其抗凋亡作用机制可能与其抑制p38 MAPK的表达相关.p38 MAPK信号通路是糖尿病视网膜病变中SIRT1介导的神经保护作用的重要通路之一.
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