Chen Ying-Jen, Huang Yuahn-Sieh, Chen Jiann-Torng, Chen Yi-Hao, Tai Ming-Cheng, Chen Ching-Long, Liang Chang-Min
Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Invest Ophthalmol Vis Sci. 2015 Feb 5;56(3):1506-16. doi: 10.1167/iovs.14-15726.
To investigate the protective effects of glucosamine (GlcN) using oxidative stress and rat models of ischemia-reperfusion (I/R) injury and to determine the antiapoptotic and anti-inflammatory mechanisms of GlcN treatment.
We determined the effects of GlcN and the levels of O-linked N-acetylglucosamine (O-GlcNAc) in in vitro retinal ganglion cells (RGCs) treated with or without H₂O₂. The survival and apoptosis rates of RGCs were compared after the addition of GlcN, glucose, or O-(2-acetamido-2-deoxy-Dglucopyranosylidene) amino-N-phenylcarbamate (PUGNAc). Retinal I/R injury was induced in Sprague-Dawley rats by elevating the IOP to 110 mm Hg for 60 minutes. An intraperitoneal injection of GlcN (1000 mg/kg) or normal saline was administered in the different groups, including a control group, a GlcN group, an I/R group, a GlcN+I/R group (1000 mg/kg GlcN 24 hours before I/R injury), and an I/R+GlcN group (7-day period of 1000 mg/kg GlcN 24 hours after I/R injury). The rats were killed 7 days after the I/R injury, and the retinas were collected from each rat for thickness measurements. Quantitative analysis of RGC survival was further determined using labeling with FluoroGold.
The GlcN increased levels of O-GlcNAc in a dose-dependent manner in the RGCs treated with or without H₂O₂. The GlcN resulted in increased cell survival and reduced apoptosis in the RGCs under oxidative stress conditions. In the rat model of I/R injury, GlcN significantly protected against I/R-induced retinal thinning and suppressed the I/R-induced reductions in a- and b-wave amplitudes of the ERG. In terms of RGC survival, significant incremental density of RGCs was found in the I/R+GlcN group compared with the I/R group. Notably, the use of GlcN in the rat retina decreased apoptosis and the formation of reactive oxygen species (ROS) after I/R injury. We also found that mitogen-activated protein kinase signal pathways played a critical role in the GlcN-mediated attenuation of ROS-induced damage in vitro and I/R injury in vivo.
Glucosamine treatment provides multiple levels of retinal protection, including antiapoptotic, anti-inflammatory, and antioxidative benefits. More research on the role of GlcN as a potential agent for the prevention and treatment of glaucoma is warranted.
利用氧化应激和缺血再灌注（I/R）损伤大鼠模型研究氨基葡萄糖（GlcN）的保护作用，并确定GlcN治疗的抗凋亡和抗炎机制。
我们测定了GlcN对体外培养的视网膜神经节细胞（RGCs）的影响以及在有或无过氧化氢（H₂O₂）处理情况下O-连接的N-乙酰葡糖胺（O-GlcNAc）的水平。在添加GlcN、葡萄糖或O-（2-乙酰氨基-2-脱氧-D-吡喃葡萄糖亚基）氨基-N-苯基氨基甲酸酯（PUGNAc）后，比较RGCs的存活率和凋亡率。通过将眼压升高至110 mmHg持续60分钟，在Sprague-Dawley大鼠中诱导视网膜I/R损伤。不同组分别腹腔注射GlcN（1000 mg/kg）或生理盐水，包括对照组、GlcN组、I/R组、GlcN+I/R组（I/R损伤前24小时给予1000 mg/kg GlcN）和I/R+GlcN组（I/R损伤后24小时给予1000 mg/kg GlcN，为期7天）。I/R损伤7天后处死大鼠，从每只大鼠收集视网膜进行厚度测量。使用FluoroGold标记进一步确定RGC存活情况的定量分析结果。
在有或无H₂O₂处理的RGCs中GlcN均以剂量依赖性方式提高了O-GlcNAc水平。在氧化应激条件下，GlcN使RGCs的细胞存活率增加且凋亡减少。在I/R损伤大鼠模型中，GlcN显著保护视网膜免受I/R诱导的变薄，并抑制I/R诱导的视网膜电图a波和b波振幅降低。就RGC存活而言，与I/R组相比，I/R+GlcN组发现RGCs密度显著增加。值得注意的是，在大鼠视网膜中使用GlcN可减少I/R损伤后的凋亡和活性氧（ROS）形成。我们还发现丝裂原活化蛋白激酶信号通路在GlcN介导的体外ROS诱导损伤减轻和体内I/R损伤减轻中起关键作用。
氨基葡萄糖治疗提供多层次的视网膜保护，包括抗凋亡、抗炎和抗氧化作用。有必要对GlcN作为预防和治疗青光眼的潜在药物的作用进行更多研究。
