Molecular and cellular analysis of retinotopic projection pattern during degeneration of visual pathway

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K23235
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0908:Society medicine, nursing, and related fields
• Research Institution: International University of Health and Welfare
• Principal Investigator: ISHII TAKAYA 国際医療福祉大学, 医学部, 助手 (30882716)
• Project Period (FY): 2020-09-11 – 2023-03-31
• Keywords: 視覚経路 / in situ ハイブリダイゼーション / mRNA定量 / Retinotopy / 中枢神経機能再生 / 視覚回路 / 神経配列

Outline of Final Research Achievements

The purpose of this study is to elucidate how the retinotopic pattern is formed on the optic nerve projections. The distribution of EphA5 and ephrinA2 immunoreactivities in the midbrain were studied using fluorescent immunohistochemistry in the optic nerve dissected rat. The immunoreactivities of EphA5 and ephrinA2 still showed retinotopic gradient pattern from rostral to caudal in the contralateral side. Semi-quantitative analysis suggested that these immunoreactivities in the contralateral side were greater than the ipsilateral side. We strongly speculate that the retinotopic gradient of EphA5 and ephrinA2 is decided not by the number of immunopositive neurons but the intensity on each cell. Further analysis will reveal molecular and cellular mechanisms of retinotopic projection in the developmental stage and optic nerve regrowth.

Free Research Field

社会医学、看護学およびその関連分野

Academic Significance and Societal Importance of the Research Achievements

視神経損傷後に再発現したEphA5とephrinA2が、発達期と同様の現象なのか、投射する視神経再生の誘導に備えての反応なのか、再伸長した視神経のシナプス再結合を阻害する反応なのかという疑問点は、未だに解決されていない。両分子が視神経損傷後に、網膜神経節細胞と上丘の「どの部分で」、「どの程度」分布し、かつ細胞単位での「定量的な発現量」を明らかにする必要がある。哺乳類でRetinotopyを備えた視神経回路の再構築が起こらない理由、および末梢神経移植によってもRetinotopyが再構築されない理由が明らかになれば、脊髄運動系の機能再建等を含めた将来の中枢神経機能再生へと応用できる可能性がある。