Thyroid hormone-mediated actin dynamics regulate the reopening of the sensitive period of filial imprinting in chicks

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K06667
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 47030:Pharmaceutical hygiene and biochemistry-related
• Research Institution: Teikyo University
• Principal Investigator: Shinji Yamaguchi 帝京大学, 薬学部, 教授 (60398740)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 刷り込み / 記憶 / 甲状腺ホルモン / アクチン

Outline of Final Research Achievements

Some types of learning can only be learned during the limited critical period after birth. Using newly-hatched chicks, we found that thyroid hormone (T3) opens the critical period of imprinting learning, which is limited to a few days after hatching. On the other hand, it was found that inhibitors of actin polymerization activity open a critical period similar to the effect of T3. From this, it was considered that the actin polymerization state in the spines was changed by the action of T3. Using a two-photon laser scanning microscope, we analyzed the spine structures while keeping the chicks alive. As a result, it was clarified that 1-3 hours after the administration of T3, the actin filaments of nerve cells were depolymerized and the proportion of highly polymerized spines increased.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

ある種の学習は、生後の限られた臨界期又は感受性期と呼ばれる時期にしか習得できない。刷り込み学習はその典型例である。臨界期が閉じたヒナに、T3を注射すると、再び臨界期が開く。本研究では、T3が学習臨界期を開く分子機構の解明を試みた。そして、薬理学的にアクチン重合因子の活性阻害剤が、T3と同様に臨界期を開くことを見出した。このことから、T3が作用すると、神経微細構造でのアクチン重合状態が変化しているのではないかと考えられた。T3がヒナの脳内の神経細胞に作用し、刷り込み記憶を成立させるためには、神経細胞のアクチンダイナミックスを一過的に再編成することが必要であることを示唆している。