糖尿病大鼠视网膜氧化应激损伤及葛根素的干预作用

目的研究糖尿病大鼠视网膜氧化应激指标的变化及葛根素对其的干预作用。方法 40只清结级雄性SD大鼠,其中构建糖尿病大鼠模型30只,随机分为糖尿病模型组、葛根素低剂量组和葛根素高剂量组,每组10只;另设一正常对照组(10只鼠)。造模成功后,葛根素低剂量组与葛根素高剂量组分别给予葛根素250mg·kg-1·d-1和500mg·kg-1·d-1,正常对照组与糖尿病模型组每日给予3mL灭菌生理盐水。均经食道灌胃给药,每日1次,连续4周。4周后测定各组鼠血清及视网膜中超氧化物歧化酶(superoxide dismutase,SOD)、丙二醛(maleic dialdehyde,MDA)、总抗氧化能力(total antioxidant capability,T-AOC)的变化,免疫组织化学法检测视网膜组织8-羟-2’-脱氧鸟苷(8-hydroxy-2’-deoxyguanosine,8-OHdG)和聚腺苷二磷酸核糖聚合酶[poly(ADP-ribose)polymerase,PARP]活性,Western blot法检测p38MAPK蛋白表达。结果造模后4周,与正常对照组相比,糖尿病模型组大鼠血清与视网膜组织中SOD活性明显下降,分别为(83.20±5.51)U·mL-1、(122.96±10.98)U·mg-1;MDA含量显著增高,分别为(29.58±0.41)μmol·L-1、(8.87±0.49)μmol·g-1;视网膜中T-AOC含量明显下降,为(1.72±0.31)U·mg-1(均为P<0.05)。gn糖尿病模型组相比,葛根素低剂量组血清SOD活性升高,为(97.80±1.75)U·mL-1(P<0.05),但其他指标变化不大(均为P>0.05)。与糖尿病模型组相比,葛根素高剂量组血清与视网膜组织中SOD活性升高,分别为(114.17±4.02)U·mL-1、(146.48±8.04)U·mg-1;视网膜TAOC含量升高,为(2.12±0.37)U·mg-1;血清和视网膜MDA含量降低,分别为(20.73±1.51)μmol·L-1、(5.73±0.76)μmol·g-1(均为P<0.05)。正常对照组大鼠视网膜中8-OHdG、PARP阳性细胞极少,糖尿病模型组表达较正常对照组明显增加,葛根素干预后表达明显减弱,葛根素高剂量组作用更显著。Western blot结果显示:各组大鼠视网膜中总p38MAPK表达无明显差异(P>0.05),但糖尿病模型组视网膜p38MAPK的磷酸化程度较正常对照组显著增强,高剂量葛根素干预后p38MAPK的磷酸化程度明显下降(P<0.05)。结论糖尿病大鼠存在视网膜的氧化应激损伤,葛根素可减轻该损伤作用,其机制可能与p38MAPK信号途径有关。

Retinal oxidative damage in diabetic rats and protective effect of puerarin on its

Objective To determine the indexes changes of retinal oxidative damage in diabetic rats and the protective effect of Puerarin(Pue) on its.Methods Forty SPF male SD rats were chosen.Diabetic rat models were induced by streptozotocin(STZ) in 30 rats,then randomly divided into 3 groups:diabetic model group(DM group),diabetic model with Pue 250 mg·kg-1·d-1 group(Pue1 group),diabetic model with Pue 500 mg·kg-1·d-1 group(Pue2 group).The other rat was set as normal control group.After administration for 4 weeks,the superoxide dismutase(SOD),maleicdialdehyde(MDA) and total anti-oxidation capability(T-AOC) were investigated to evaluate the injury of oxidative stress.Retinal 8-Hydroxydeoxyguanosine(8-OHdG) and poly(ADP-ribose)polymerase(PARP) activities were assessed using immunohistochemical labeling.The expression of p38MAPK and p-p38MAPK were measured by Western blot.Results Compared with normal control group,the SOD activities were decreased significantly in serum and retina,which were(83.20±5.51) U·mL-1,(122.96±10.98) U·mg-1,respectively in DM group at 4 weeks after modeling,the content of MDA in serum and retina were increased[(29.58±0.41)nmol·mL-1,(8.87±0.49)nmol·mg-1,respectively],whereas T-AOC in retina(1.72±0.31)U·mg-1 was decreased(all P<0.05).Compared with DM group,the SOD activity in Peu1 group(97.80±1.75) U·mL-1 was increased(P<0.05),but other indexes had little change(all P>0.05).Compared with DM group,the SOD activities in serum and retina in Peu2 group were increased significantly,T-AOC in retina increased and content of MDA in serum and retina decreased(all P<0.05).Seldom 8-OHdG and PARP positive cells were presented within retinas in control group.There were significantly higher positive cells within DM model group,and it was significantly decreased in retina in Pue2 group.The expression of p38MAPK has no difference between each group(P>0.05),but the protein levels of p-p38MAPK in DM group was significantly higher than those in normal retina(P<0.05).High dose Pue could down-regulate the expression of p-p38MAPK in retina of DM group(P<0.05).Conclusion Pue can ameliorate the retina oxidative stress in DM rats induced by streptozotocin,and the p38MAPK singal transduction pathway may participate in protection of DR by Pue.