叔丁基对苯二酚激活Nrf2信号通路增强对2型糖尿病大鼠视网膜的保护作用

目的 研究叔丁基对苯二酚(tertiary butyl hydroquinone,tBHQ)对2型糖尿病大鼠视网膜的保护作用及相关机制.方法 取雄性Sprague Dawley大鼠60只,分为正常对照组(NC组)、糖尿病组(DM组)和tBHQ组.剔除饲养过程死亡大鼠,最终NC组、DM组、tBHQ组分别为12只、20只、20只大鼠纳入研究.造模采用高脂高糖饲料喂养4周后腹腔内注射链脲佐菌素诱导2型糖尿病模型,tBHQ组于造模后1周在高脂高糖饲料中添加质量分数1％ tBHQ进行干预,于造模后4周和12周心脏采血,检测血清空腹血糖(fasting plasma glucose,FPG)、血清空腹胰岛素(fasting serum insulin,FINs)含量.采用免疫组织化学法及qRT-PCR法定量检测各组大鼠视网膜中Nrf2、HO-1、Bcl-2、VEGF蛋白及mRNA的分布和表达.结果 3组大鼠在4周和12周的FPG水平总体比较差异有统计学意义(F分组=78.531,P=0.000);DM组及tBHQ组高于NC组,DM组12周高于4周,tBHQ组12周明显低于4周,差异均有统计学意义(均为P＜0.05).3组大鼠在4周和12周的FINs水平总体比较差异有统计学意义(F分组=22.480,P=0.000);其中DM组及tBHQ组高于NC组,tBHQ组12周高于4周,差异均有统计学意义(均为P＜0.05).光学显微镜显示12周时NC组无明显改变;DM组大鼠视网膜组织结构排列疏松,内、外核层排列紊乱,细胞水肿明显;tBHQ组大鼠视网膜组织结构较清晰,部分细胞水肿.4周和12周时各组中均可见Nrf2、HO-1、Bcl-2、VEGF的阳性表达.Nrf2主要分布于视网膜节细胞层、内核层,HO-1、Bcl-2主要分布于视网膜节细胞层、内核层、外核层;VEGF主要分布于神经纤维层、节细胞层和内核层.免疫组织化学及qRT-PCR检测显示,各组大鼠在造模后不同时间点视网膜中Nrf2、HO-1、Bcl-2、VEGF蛋白及mRNA的相对表达量的总体比较差异均有统计学意义(均为P＜0.05).4周时,DM组Nrf2、HO-1、VEGF的表达较NC组增加,差异均有统计学意义(均为P＜0.05);tBHQ组Nrf2、HO-1、Bcl-2的表达较DM组增加,VEGF的表达较DM组降低,差异均有统计学意义(均为P＜0.05).12周时,DM组Nrf2、HO-1、Bcl-2、VEGF的表达较NC组增加,差异均有统计学意义(均为P＜0.05);tBHQ组Nrf2、HO-1、Bcl-2的表达较DM组增加,VEGF的表达较DM组降低,差异均有统计学意义(均为P＜0.05).12周与4周比较,DM组VEGF的表达较4周增加,HO-1较4周降低,差异均有统计学意义(均为P＜0.05);tBHQ组Nrf2、HO-1、Bcl-2的表达较4周增加,差异均有统计学意义(均为P＜0.05).结论 tBHQ对DM大鼠胰岛功能具有一定的保护作用;可促进DM大鼠视网膜组织中Nrf2、HO-1、Bcl-2的表达,降低VEGF的表达,对视网膜组织有抗氧化应激损伤、减少细胞凋亡、抑制视网膜血管增殖等作用.tBHQ可能通过Nrf2/HO-1/VEGF及Nrf2/Bcl-2途径对DM大鼠视网膜起保护作用.

tBHQ activates Nrf2 signaling pathways to enhance retinal protection in type 2 diabetic rats

Objective To study the protective effects of tBHQ on type 2 diabetic rats retina and its related mechanism.Methods Sixty SD rats were divided into normal control group (NC group),model group (diabetes mellitus,DM group) and tBHQ group.After feeding with high fat and high sugar diets for 4 weeks,the rats in model group were induced by intraperitoneal injection of STZ for the model of type 2 diabetes mellitus.1％ tBHQ were added into the high fat and high sugar feed 1 week later after successfully modeled in the tBHQ group.Fasting plasma glucose (FPG) and fasting serum insulin (FINs) were detected at 4 and 12 weeks after modeled.Immunohistochemical method and real-time fluorescent quantitative PCR (qRT-PCR) were respectively used to detect the distributions and relative expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2),heme oxygenase 1 (HO-1),B-cell lymPhoma 2 (Bcl-2) and vascular endothelial growth factor (VEGF) in retinas of the rats.Results FPG levels totally comparative differences were statistically significant between each group (F =78.531,P =0.000).The level of FPG in DM and tBHQ group were obviously higher than that in NC group,the 12 weeks was higher than 4 weeks in DM group,and the 12 weeks was lower than 4 weeks in tBHQ group (all P ＜ 0.05).Totally comparative differences in the level of FINs were statistically significant (F=22.480,P =0.000),NC group was lower than DM and tBHQ group,12 weeks was higher than 4 weeks (all P ＜ 0.05).Immunohistochemical detection showed that each factor in each group were expressed in the retina of rat,and the relative expressions of Nrf2,HO-1,Bcl-2 and VEGF protein in retina have totally statistically differences in different time points after modeled (all P ＜0.05).The expressions of each factor in DM group were more than those in the NC group.The Nrf2,HO-1 and Bcl-2 in tBHQ group were more than those in the DM group,but the VEGF was lower.At 12 weeks,the expressions of VEGF and Nrf2 in DM group were more than those at 4 weeks,but the HO-1 was lower;the Nrf2,HO-1 and Bcl-2 in tBHQ group were more than those at 4 weeks (all P ＜ 0.05).PCR tests revealed that the relative expressions of Nrf2,HO-1,Bcl-2 and VEGF mRNA in retina have totally statistically differences in different time points after modeled(all P ＜ 0.05).The expressions of each factor in DM group were more than those in the NC group.The Nrf2,HO-1 and Bcl-2 mRNA in tBHQ group were more than those in the DM group,but the VEGF mRNA was lower.At 12 weeks,VEGF mRNA in DM group and Nrf2,HO-1,Bcl-2 in tBHQ group were more than those at 4 weeks (all P ＜ 0.05).Conclusion tBHQ maybe have protection for islet function on diabetic rat,and can induce the expressions of Nrf2,HO-1,Bcl-2 in retina of diabetic rats and reduce the expression of VEGF,inhibit the oxidative stress of retinal tissue damage,reduce cell apoptosis and inhibit the proliferation of retinal blood vessels.tBHQ may protect the retina of diabetic rats through the Nrf2/HO-1/VEGF and Nrf2/Bcl-2 way.