Effects of endogenous adenosine on hippocampal CA1 synaptic plasticity induced by synaptic inputs of hippocampal EEG patterns

• Project/Area Number: 17K01971
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Basic / Social brain science
• Research Institution: Yamagata University
• Principal Investigator: Satoshi Fujii 山形大学, 医学部, 教授 (80173384)
• Co-Investigator(Kenkyū-buntansha): 後藤 純一 山形大学, 医学部, 助教 (70435650)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: hippocampus / EEG / synaptic plasticity / LTP / LTD / adenosine / IP3 receptors / inhibitory inter neurons / 長期増強（LTP） / 海馬CA1シナプス / アデノシン受容体 / IP3受容体 / 抑制性応答 / 高周波数バースト入力 / 低周波入力 / 長期抑圧（LTD) / 低周波基本律動入力 / 長期増強 / 海馬脳波 / 海馬θ波 / 長期抑圧 / バースト波 / 脳とリズム

Outline of Final Research Achievements

Neurons in the hippocampus fire synchronously at low frequencies in groups and burst at high frequencies individually. Therefore, synaptic plasticity is considered to be induced in hippocampal neurons by synaptic inputs in which bursts are superimposed on low-frequency rhythms.
In this study, we clarified "how burst input and low-frequency input to synapses induce synaptic plasticity" in the induction of excitatory synaptic plasticity in the hippocampal CA1 region. In particular, we focused on the fact that endogenous adenosine, which is released as a co-transmitter during synaptic input, attenuates synaptic transmissions in the inhibitory circuits and modulates the depolarization and excitatory neurons, and elucidated the involvement of adenosine in the induction of synaptic plasticity in hippocampal CA1 neurons.

Academic Significance and Societal Importance of the Research Achievements

本研究は「シナプスは入力周波数・入力時間を弁別して可塑性の方向を決定する」メカニズムの解明を目的とする。脳のニューロンは全として低周波数で同期して興奮しつつ、個々が高周波数でバースト発火している。ニューロンネットワーク内のシナプスには、高周波バーストと持続的な低周波入力が重畳して入力されて可塑性が誘導され「記憶情報」として蓄積される。
「記憶と学習の基礎過程としての海馬シナプス可塑性がその時点のシナプスの属するネットワークの活動性に影響される性質」に依存するならば、「シナプスが入力パターンに応じて可塑性が誘導されるメカニズム」を解明することは、記憶や学習のメカニズムを解明するうえで重要である。

Research Products

• [Journal Article] Synaptic plasticity in hippocampal CA1 neurons of mice lacking inositol-1,4,5-trisphosphate receptor-binding protein released with IP3 (IRBIT) (2022)
  • Author(s): Goto Jun-Ichi、Fujii Satoshi、Fujiwara Hiroki、Mikoshiba Katsuhiko、Yamazaki Yoshihiko
  • Journal Title: Learning & Memory Volume: 29 Issue: 4 Pages: 110-119
  • DOI: 10.1101/lm.053542.121
  • Peer Reviewed / Open Access
• [Journal Article] Depotentiation depends on IP3 receptor activation sustained by synaptic inputs after LTP induction (2020)
  • Author(s): Satoshi Fujii, Yoshihiko Yamazaki, Junichi-Goto, Hiroki Fujiwara, Katsuhiko Mikoshiba
  • Journal Title: Learning & Memory Volume: 16 Issue: 2 Pages: 52-64
  • DOI: 10.1101/lm.050344.119
  • Peer Reviewed
• [Journal Article] Modulatory effects of perineuronal origodendrocytes on neural activity in the rat hippocampus (2018)
  • Author(s): Y.Yamazaki, H.Hozumi, K.Kaneko, S.Fujii
  • Journal Title: Neurochem Res Volume: 43 Pages: 27-40
  • Peer Reviewed
• [Presentation] Facilitative effects of nicotinic acetylcholine receptors on synaptic plasticity in the hippocampus (2022)
  • Author(s): Yamazaki Y, Fujiwara H, Goto JI, Fujii S.
  • Organizer: 第99回日本生理学会大会
• [Presentation] Depotentiation at the hippocampal CA1 synapse depends on the basal synaptic transmission (2019)
  • Author(s): 1)Goto JI, Fujii S, Kaneko K, Fujiwara H, Yamazaki Y, Mikoshiba K
  • Organizer: 9th Federation of the Asian and Oceanian Physiological Societies, Kobe
  • Int'l Joint Research
• [Presentation] 海馬CA1シナプス脱長期増強誘導のシナプス活動依存性 (2018)
  • Author(s): 藤井聡
  • Organizer: 日本生理学会東北地方会