Homma Kohei, Osakada Fumitaka, Hirami Yasuhiko, Jin Zi-Bing, Mandai Michiko, Takahashi Masayo
Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Chou-ku, Kobe, Japan.
J Neurosci Res. 2009 Jul;87(9):2175-82. doi: 10.1002/jnr.22024.
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.
光刺激通过光感受器中的光转导信号抑制视网膜暗电流。视网膜电图（ERG）检测到暗电流的阻断作为ERG的a波。然而，标准的ERG代表视网膜的总和神经活动，无法获得局部功能的信息。在本研究中，我们使用多电极阵列（MEA）系统直接记录视网膜光感受器的局部活动。从暗适应的啮齿动物中分离出视网膜，并将视网膜的玻璃体表面覆盖在电极阵列上。光刺激后，从每个电极记录到负波。向培养基中添加氨基丁酸（一种在ON双极细胞上表达的mGluR6的选择性激动剂）不会阻断反应的产生。反应幅度随着视网膜发育而增加。当视网膜局部受损时，光诱发反应仅在视网膜的受损区域减弱。还测试了从给予N-甲基-N-亚硝基脲（MNU）的大鼠中分离出的视网膜。在MNU处理大鼠的中央视网膜中，注射MNU后反应逐渐降低。相反，在周边视网膜中，反应幅度相对保留，与免疫组织化学观察到的视网膜厚度一致。总之，用MEA系统记录了光诱发反应。MEA系统对于检测光感受器的细微和局部激活很有用。这种空间信息在研究治疗区域（如基因转移或细胞移植）的局部功能恢复方面应该是有价值的。
