葡萄籽原花青素对大鼠视网膜缺血-再灌注损伤的保护作用

目的　探讨葡萄籽原花青素（grape seed proanthocyanidin extract，GSPE）对大鼠视网膜缺血-再灌注损伤（retinal ischemia-reperfusion injury，RIRI）的保护作用及其机制。方法　将120只大鼠分为假手术组（Sham组，灌胃生理盐水）、模型组（RIRI组，眼内灌注加压法制备，灌胃生理盐水）及GSPE低、中、高剂量组（GSPE-L组、GSPE-M组、GSPE-H组，灌胃0.13 g·kg^-1 GSPE、0.25 g·kg^-1 GSPE、0.50 g·kg^-1 GSPE）、阳性对照组（α-LA组,灌胃100 mg·kg^-1 α-硫酸锌）。采用苏木精-伊红（HE）染色观察各组大鼠视网膜组织形态学变化情况；ELISA法检测血清肿瘤坏死因子-α（TNF-α）、iNOS、白细胞介素-6（IL-6）水平，氮蓝四唑显色法检测血清超氧化物歧化酶（SOD）活性；双抗体夹心法检测血清丙二醛（MDA）水平，铁离子还原法检测活性氧（ROS）水平；TUNEL法检测各组大鼠视网膜组织神经细胞凋亡；免疫组织化学法检测各组大鼠视网膜组织中核因子E2-相关因子2（Nrf2）、血红素加氧酶-1（HO-1）、Caspase-3表达情况；Western blot法检测各组大鼠视网膜组织中细胞外信号调节激酶1/2（ERK1/2）、p-ERK1/2表达情况。结果　GSPE-L组、GSPE-M组、GSPE-H组、α-LA组、RIRI组和Sham组视网膜厚度分别为（139.31±11.43）μm、（127.05±12.73）μm、（113.16±13.25）μm、（110.58±13.47）μm、（161.48±10.26）μm、（92.35±16.54）μm,Nrf2蛋白阳性表达率分别为（29.93±4.21）%、（34.06±5.17）%、（43.12±7.23）%、（45.35±7.46）%、（11.86±3.19）%、（52.27±8.36）%，ERK1/2蛋白磷酸化水平分别为0.41±0.05、0.62±0.07、0.89±0.09、0.92±0.05、0.23±0.04、1.16±0.25，RIRI组与Sham组比较，差异均有统计学意义（均为P<0.05）， GSPE-L组、GSPE-M组、GSPE-H组、α-LA组与RIRI组比较，差异均有统计学意义（均为P<0.05），且GSPE表现出剂量依赖性。与Sham组相比，RIRI组神经细胞凋亡率、Caspase-3阳性表达率、TNF-α、IL-6、iNOS、MDA、ROS水平显著升高，HO-1阳性表达率、SOD水平显著降低（均为P<0.05）；与RIRI组相比，GSPE-L组、GSPE-M组、GSPE-H组、α-LA组神经细胞凋亡率、Caspase-3阳性表达率、TNF-α、IL-6、iNOS、MDA、ROS水平显著降低，HO-1阳性表达率、SOD水平显著升高，且GSPE表现出剂量依赖性剂量依赖性（均为P<0.05）。结论　GSPE能够抑制视网膜组织神经细胞凋亡，保护视网膜组织，其作用机制可能与ERK/Nrf2/HO-1通路活化有关。

Protective effect of grape seed proanthocyanidin extract on retinal ischemia-reperfusion injury in rats

Objective To investigate the protective effect of grape seed proanthocyanidin extract(GSPE)on retinal ischemia-reperfusion injury(RIRI)in rats and its mechanisms.Methods Totally 120 rats were divided into sham operation group(Sham group;intragastric administration of normal saline),model group(RIRI group;prepared by intraocular perfusion under pressure process,and intragastric administration of normal saline),low,medium and high dosage groups(GSPE-L group,GSPE-M group and GSPE-H group;0.13 g·kg-1,0.25 g·kg-1,0.50 g·kg-1 GSPE for intragastric administration)and positive control group(α-LA group;100 mg·kg-1 ofα-LA for intragastric administration).Histopathological changes of retina in rats were observed by hematoxylin-eosin(HE)staining,the levels of serum TNF-α,iNOS and IL-6 were measured by Elisa method,the activity of superoxide dismutase(SOD)in serum was detected by nitroblue tetrazolium colorimetry,the level of serum malondialdehyde(MDA)was measured by double antibody sandwich method,the level of reactive oxygen species(ROS)was measured by iron ion reduction method,the apoptosis of retinal cells was detected by TUNEL method,the expressions of nuclear factor-E2-related factor 2(Nrf2),heme oxygenase-1(HO-1)and Caspase-3 were detected by immunohistochemistry,and the expression of extracellular signal-regulated kinase 1/2(ERK1/2)and p-ERK1/2 were detected by Western blotting.Results For rats in GSPE-L,GSPE-M,GSPE-H,α-LA,RIRI and sham groups,the retinal thickness of were(139.31±11.43)μm,(127.05±12.73)μm,(113.16±13.25)μm,(110.58±13.47)μm,(161.48±10.26)μm and(92.35±16.54)μm;the positive expression rates of Nrf2 protein were(29.93±4.21)%,(34.06±5.17)%,(43.12±7.23)%,(45.35±7.46)%,(11.86±3.19)%and(52.27±8.36)%;the phosphorylation levels of ERK1/2 protein were 0.41±0.05,0.62±0.07,0.89±0.09,0.92±0.05,0.23±0.04 and 1.16±0.25.The differences was statistically significant between RIRI group and Sham group(all P<0.05).There were significant differences for GSPE-L,GSPE-M,GSPE-H,α-LA groups comparing with RIRI group(all P<0.05),showing dose-dependent manner.Compared with Sham group,the neuron apoptosis rate,Caspase-3 positive expression rate,TNF-α,IL-6,iNOS,MDA and ROS levels in RIRI group were significantly higher,HO-1 positive expression rate and SOD level decreased significantly in RIRI group(all P<0.05).Compared with RIRI group,the apoptosis rate of nerve cells,Caspase-3 positive expression rate,TNF-α,IL-6,iNOS,MDA and ROS levels decreased significantly,HO-1 positive expression rate and SOD level increased significantly in GSPE-L,GSPE-M,GSPE-H,α-LA groups(all P<0.05).Conclusion GSPE can inhibit the apoptosis of retinal neurons and protect retinal tissues,and the mechanism may be related to the activation of ERK/Nrf2/HO-1 pathway.