2019 Fiscal Year Final Research Report

New concept of electroretinography in photoreceptor degenerative diseases

Research Project

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Project/Area Number	17K19721
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Research Field	Surgery related to the biological and sensory functions and related fields
Research Institution	Mie University
Principal Investigator	Kondo Mineo 三重大学, 医学系研究科, 教授 (80303642)
Co-Investigator(Kenkyū-buntansha)	杉本昌彦三重大学, 医学部附属病院, 講師 (00422874) 生杉謙吾三重大学, 医学系研究科, 准教授 (10335135) 松原央三重大学, 医学部附属病院, 講師 (20378409)
Project Period (FY)	2017-06-30 – 2020-03-31
Keywords	網膜電図 / 動物モデル / ウサギ / a波 / ERG / 視細胞変性 / 網膜色素変性
Outline of Final Research Achievements	It is widely believed that the origin of the a-wave of electroretinogram (ERG) is mainly the photoreceptors. However, it was unknown this hypothesis is really true in the retina with severe photoreceptor degeneration. In this study, we studied the origin of the a-wave in the retina with severe photoreceptor degeneration using transgenic (Tg) rabbit model of photoreceptor degeneration. Aged Tg rabbit model of 2-3 years were used. The a-waves were recorded before and after intravitreal injection of tetrodotoxin (TTX)and N-methyl-D-aspartic acid (NMDA) in aged Tg rabbits. We found that the small a-wave, which was seen in in aged Tg rabbits, was nearly completely suppressed after intravitreal injection of TTX and NMDA. These results suggested that the small a-waves which are seen in patients with severe photoreceptor degeneration, like retinitis pigmentosa, can originate from retinal third-order neurons.
Free Research Field	眼科学
Academic Significance and Societal Importance of the Research Achievements	今回の我々の成果によって、網膜変性をERG で評価する際の原理に新しい解釈が加わる可能性がある。「進行した網膜色素変性から記録されるERG のa 波には視細胞の成分はほとんど含まれておらず、その多くは3 次ニューロン由来である」、という今回の結果は、視覚科学の分野で長年信じられてきたERG の常識を大きく変える可能性がある。また、今回の我々の成果は、視細胞が変性していく過程で網膜内に起こっている二次的な回路の変化（視細胞変性後の網膜内ニューロンのリモデリング：Jones, Kondo, et al. Jpn J Ophthalmol. 2012）にも新しい知見を加えると考えている。