17β-雌二醇抗氧化保护SD大鼠视网膜神经细胞光损伤
王少兰，王宝英，冯燕，莫名树，杜芳英，李红波，俞小瑞
（西安交通大学医学院遗传与分子生物学系）
摘要：本研究通过构建光诱导的大鼠视网膜神经细胞的氧化应激损伤模型，观察玻璃体腔预注射17β-雌二醇（βE2）后对视网膜光损伤大鼠的神经保护作用，初步探讨βE2 抗氧化保护视网膜光损伤的分子机制。采用雌性去势和雄性SD 大鼠8000lx 白光照射12 小时构建大鼠视网膜光损伤模型。视网膜电图（ERG）和HE 染色结果显示光照后雌性和雄性大鼠视网膜功能和组织形态学均受到损害，而玻璃体腔预注射βE2（10μM）可以有效改善光诱导的视网膜功能和形态学损伤。通过检测脂质过氧化产物丙二醛（MDA）发现光损伤后，视网膜匀浆中MDA 含量显著升高，给予βE2 可以显著地降低MDA 的生成，提示βE2 抗光诱导的视网膜氧化应激。Real-time PCR 结果显示，雌性大鼠在光损伤过程中视网膜组织中抗氧化酶类SOD 和Gpx 均显著降低，而雄性大鼠没有降低反而出现上调趋势，这些结果表明性别差异可能导致光损伤过程中抗氧化酶类的表调控有所不同。随后，通过玻璃体腔给予βE2 后发现，雌雄大鼠视网膜组织中抗氧化酶SOD,CAT 和Gpx 的表达均显著升高相比于光损伤组，提示SOD,CAT 和Gpx 参与了βE2 的抗氧化作用。通过检测机体非酶类的抗氧化蛋白表明硫氧还蛋白Trx 和转录因子Nrf2 也参与了βE2 的抗氧化作用，而血红素加氧酶HO-1 参与了机体内源性的抗氧化机制而非βE2 介导的抗氧化作用。本研究发现17β-雌二醇通过其抗氧化机制保护视网膜神经细胞免受光损伤，从而为雌激素在视网膜退行性疾病的临床治疗提供新的靶标和理论依据。
关键词：神经保护作用; 17β雌醇；视网膜光损伤;氧化应激;玻璃体腔注射;抗氧化作用
中图分类号：Q7

17β-Estradiol Protects the Sprague-Dawley Rats Retinal from Light-Induced Damage via Anti-oxidation
Wang Shaolan, Wang Baoying, Feng Yan, Mo Mingshu, Du Fangying, Li Hongbo,Yu Xiaorui
(Department of Genetics and Molecular Biology, School of Medicine, Xi’an Jiaotong University, Xi’an 710061, China.)
Foundations: National Natural Science Foundation of China (No: 30672286 and No: 81271013) ，National
Research Foundation for the Doctoral Program of Higher Education of China (No: 20120201110051)
Brief author introduction:Wangshaolan(19860305),Ph.D student
Correspondance author: Xiaorui Yu, MD, Ph.D.

Abstract: Oxidative stress is thought to be a major cause of light induced retinal neurodegeneration. The protective role of 17β-estradiol (βE2) in neurodegenerative disorders is well known, however, the underlying mechanism remains unclear. Here, we applied light induced retinal damage model to explore the mechanism by which βE2 exerts its neuroprotection. Adult male and femaleovariectomized (OVX) rats were exposed to 8000 lx white light for 12h to induce retinal light damage.Electroretinogram (ERG) assay and hematoxylin and eosin (H&E) staining show that exposure to light or 12h resulted in functional damage to the rat retina, histological changes and retinal neurons loss, while intravitreal injection (IVI) with βE2 significantly rescued impaired retina function in both female and male rats. By detecting malonylodialdehyde (MDA) production (a biomarker for oxidative stress)indicated an increasing retinal oxidative stress following exposure to light, and βE2 reduced the light induced oxidative stress. qRT-PCR indicated that antioxidant enzymes SOD and Gpx mRNA level were diminished in female-OVX rats but up-regulated in male rats after exposing to light, suggesting a gender differences in regulating the genes of these antioxidant enzymes in response to light. However,administration of βE2 recovered or enhanced the SOD and Gpx expression upon light stimulation. In spite of the CAT expression was not sensitive to light, βE2 also increased the gene expressions both in
female-OVX and male rats. Further study indicated the antioxidant proteins Trx and Nrf2 were also involved in βE2 mediated anti-oxidation, while cytoprotective HO-1 exerts a key role in endogenous defense mechanisms against light but not via βE2. Taken together, we provide evidence that βE2 protected the retinal from light damage via anti-oxidative effect, the underline mechanism involved in regulation of the genes of antioxidant enzymes (SOD, CAT, Gpx) and proteins (Trx and Nrf2). Our
study will provide the theory evidence for estrogen replacement therapy in postmenopausal women for reducing the risk of Age-related macular degeneration.

Key words: Neuroprotection; 17β-Estradiol; Retinal light damage; Oxidative stress; Intravitrleal injection; Anti-oxidation