Department of Ophthalmology, The First Hospital Affiliated to PLA General Hospital, Fucheng Road 51, Haidian District, Beijing, 100048, People's Republic of China.
Neurochem Res. 2013 Mar;38(3):669-76. doi: 10.1007/s11064-012-0966-z. Epub 2013 Jan 9.
One of the main pathological symptoms of early diabetic retinal neuropathy is retina neuronal apoptosis. In the present work we investigated the effects of indoleamine hormone melatonin, a powerful free radical scavenger, on streptozotocin-induced retina neuronal cell apoptosis in high blood glucose rat. After melatonin treatment (10 mg/kg/day), tunel detection was used to monitor the apoptosis rate of neurons in the retinal ganglion cell layer; reversed quantitative PCR was used to measure the mRNA expression of retinal caspase-3, Mn superoxidase dismutase (SOD) and Cu-Zn SOD; and the activities of total SOD (T-SOD) and sub-type SOD was detected using xanthine oxidase enzymatic detection. Our data showed that melatonin treatment leads to a decrease of retinal cell apoptosis and the apoptotic index was (1.67 ± 0.54) % and (7.73 ± 0.95) % at 8 and 12 weeks after treatment. The relative quantitative (RQ) value for caspase-3 mRNA expression was (6.996 ± 1.192) and (7.267 ± 1.178) in melatonin group, which are much lower than the values of diabetic group (12.566 ± 2.272 and (14.297 ± 2.110) at 8 and 12 weeks, respectively) under the same condition. mRNA expression of Mn SOD and Cu-Zn SOD as well as their activities all decreased in the diabetic group compared with the control group. While melatonin treatment induced the expression of Mn SOD mRNA and a continual increase of Mn SOD activity as well as the activity and mRNA expression of Cu-Zn SOD at 12 weeks. Therefore, our results demonstrate that melatonin treatment prevented the decrease in mRNA expression of SOD and the increase in caspase-3 mRNA expression induced by diabetes thus exerts a beneficial effect on retina neuronal apoptosis.
糖尿病性视网膜神经病变的主要病理症状之一是视网膜神经元凋亡。本工作研究了吲哚胺激素褪黑素（一种强大的自由基清除剂）对高血糖大鼠链脲佐菌素诱导的视网膜神经元细胞凋亡的作用。褪黑素治疗（10mg/kg/天）后，采用 TUNEL 检测法监测视网膜神经节细胞层神经元的凋亡率；采用反转录定量 PCR 法检测视网膜半胱天冬酶-3、Mn 超氧化物歧化酶（SOD）和 Cu-Zn SOD 的 mRNA 表达；采用黄嘌呤氧化酶酶促检测法检测总 SOD（T-SOD）和亚型 SOD 的活性。我们的数据表明，褪黑素治疗可降低视网膜细胞凋亡，凋亡指数分别为治疗后 8 周和 12 周时的（1.67±0.54）%和（7.73±0.95）%。半胱天冬酶-3 mRNA 表达的相对定量（RQ）值在褪黑素组中分别为（6.996±1.192）和（7.267±1.178），远低于相同条件下糖尿病组的（12.566±2.272 和 14.297±2.110）。Mn SOD 和 Cu-Zn SOD 的 mRNA 表达及其活性在糖尿病组均低于对照组。而褪黑素治疗可诱导 Mn SOD mRNA 的表达，并在 12 周时持续增加 Mn SOD 活性以及 Cu-Zn SOD 的活性和 mRNA 表达。因此，我们的结果表明，褪黑素治疗可防止糖尿病诱导的 SOD mRNA 表达下降和半胱天冬酶-3 mRNA 表达增加，从而对视网膜神经元凋亡产生有益作用。
