使用多电极阵列系统（Med-64）于视网膜退化模型中检测...
使用多电极阵列系统（Med-64）于视网膜退化模型中检测局部视网膜失效的研究
光刺激通过光感受器中的光转导信号来抑制视网膜暗电流。视网膜电图（Electroretinography (ERG)）虽可检测暗电流的堵塞 （视网膜电图a-波）。然而，标准视网膜电图代表了视网膜神经的综合平均活动信号，不能得到个别或局部功能区域的信息。在这项研究中，我们使用了多电极阵列系统（Med-64），并直接记录了视网膜光感受器活动。视网膜从黑暗适应的啮齿动物分离出来，玻璃体面覆盖在电极阵列上。经光刺激后，负波被每个电极记录下来。 结果 ： 加入氨基丁酸 （乃一种表达于ON-双极细胞mGluR6的选择性激动剂）后并没有阻止负电流的反应产生。反应力度大小随着视网膜发展而增加。当视网膜局部受伤，光引起的反应只是在受伤的视网膜区域减少。本实验也测试了从大鼠分离出来并经MNU（N-methyl-N-nitrosourea）处理的视网膜。在经MNU处理的大鼠视网膜的中央位置，反应随着MNU注射逐渐减弱。与此相反，在视网膜周边位置，反应的力度却保留，跟从免疫组化实验对视网膜厚度的观测一致。结论是，视网膜之光诱发反应可用Med-64记录。Med-64系统有利于检测不起眼但重要的局部光感受器活动。这些二维信息于临床领域及视网膜功能恢复研究十分重要 （例如基因转移或细胞移植等方面）。
Detection of localized retinal malfunction in retinal degeneration model using a multielectrode array system.
Homma K, Osakada F, Hirami Y, Jin ZB, Mandai M, Takahashi M.
Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Chou-ku, Kobe, Japan.
Light stimulation inhibits the retinal dark current through phototransduction signals in the photoreceptors. Electroretinography (ERG) detects the blockage of the dark current as the a-wave of the ERG. However, standard ERGs represent the summed neural activity of the retina, and information on localized functions cannot be obtained. In this study, we used a multielectrode array (MEA) system and directly recorded the focal activities of the photoreceptors of the retina. Retinas were isolated from dark-adapted rodents and were draped over the electrode array with vitreal surface of the retina on the electrode array. After light stimulation, negative waves were recorded from each electrode. Adding aminobutyric acid, a selective agonist of mGluR6 expressed on ON-bipolar cells, to the media did not block the generation of the responses. The amplitude of the response increased with increasing retinal development. When the retina was locally injured, light-elicited responses were diminished only in the injured areas of the retina. Retinas isolated from rats given N-methyl-N-nitrosourea (MNU) were also tested. In central retinas of MNU-treated rats, the responses were progressively decreased following injection of MNU. In contrast, in the peripheral retinas, amplitude of the responses was relatively retained, consistent with the retinal thickness observed by immunohistochemistry. In conclusion, light-evoked responses were recorded with the MEA system. The MEA system was useful for detecting subtle and focal activation of photoreceptors. This spatial information should be valuable in investigating local functional recovery in therapeutically treated areas, such as in gene transfer or cell transplantation. (c) 2009 Wiley-Liss, Inc.
