Department of Ophthalmology and Vision Sciences and Key Laboratory of Myopia of State Health Ministry, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China.
Exp Eye Res. 2011 Nov;93(5):753-60. doi: 10.1016/j.exer.2011.09.022. Epub 2011 Oct 12.
Some previous studies have showed that transcorneal electrical stimulation (TES) could protect retinal neurons in certain rodent models. However, it is not yet clear whether TES could also definitely protect retinal neurons against ischemic insults. In the present study, we hypothesized that TES had such a neuroprotective effect and further investigated its underlying mechanism. Adult female Sprague-Dawley (SD) rats received TES treatment every other day after ocular ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 60 min. Retinal ganglion cells (RGCs) were labeled retrogradely 7 days before ischemia and were counted 7 and 14 days later. At the same time points, retinal function was assessed by scotopic electroretinography (ERG), combined with retinal histological analysis. The glutamine synthetase (GS) immunoreactivity was compared between ischemic retinas with TES and those with sham stimulation under identical confocal laser microscope conditions. The immunohistochemical indications were confirmed by Western blot analysis. Higher mean density of RGCs was quantified in TES treated retinas compared to retinas with sham stimulation on days 7 and 14 after ischemia. Similarly, histological analysis showed that TES better preserved the mean thickness of separate retinal layers. ERG studies indicated that by undergoing TES treatment, the b-wave amplitude was also significantly preserved on day 7 after ischemia and recovered robustly on day 14. Immunohistochemical and Western blot analysis both revealed that GS levels remarkably increased after TES and lasted for at least 7 days. Our results indicate that TES can protect retinal neurons against ischemic insults, probably related to increasing levels of GS localized in Müller cells. These findings suggest a new approach for potential clinical application to ocular ischemic diseases.
一些先前的研究表明，经角膜电刺激（TES）可保护某些啮齿动物模型中的视网膜神经元。然而，目前尚不清楚 TES 是否也能肯定地保护视网膜神经元免受缺血性损伤。在本研究中，我们假设 TES 具有这种神经保护作用，并进一步探讨了其潜在机制。成年雌性 Sprague-Dawley（SD）大鼠在眼内压升高至 120mmHg 持续 60 分钟引起眼缺血后，每隔一天接受 TES 治疗。在缺血前 7 天逆行标记视网膜神经节细胞（RGCs），并在缺血后 7 和 14 天进行计数。同时，通过暗视电视网膜电图（ERG）评估视网膜功能，并结合视网膜组织学分析。在相同的共聚焦激光显微镜条件下，比较 TES 治疗的缺血视网膜和假刺激的缺血视网膜之间的谷氨酰胺合成酶（GS）免疫反应性。通过 Western blot 分析证实了免疫组织化学指标。与假刺激的视网膜相比，TES 处理的视网膜在缺血后 7 和 14 天的 RGC 平均密度更高。同样，组织学分析表明，TES 更好地保留了单独视网膜层的平均厚度。ERG 研究表明，在 TES 治疗后，b 波振幅在缺血后第 7 天也显著保留，并在第 14 天恢复稳健。免疫组织化学和 Western blot 分析均表明，TES 后 GS 水平显著增加，至少持续 7 天。我们的结果表明，TES 可以保护视网膜神经元免受缺血性损伤，这可能与局部在 Müller 细胞中的 GS 水平升高有关。这些发现为潜在的临床应用提供了一种新的方法，用于治疗眼部缺血性疾病。
