Developing a novel model of simulated microgravity environment through investigation of vestibular system(Fostering Joint International Research)

• Project/Area Number: 16KK0179
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Rehabilitation science/Welfare engineering
• Research Institution: Kyoto University
• Principal Investigator: Tajino Junichi 京都大学, 医学研究科, 研究員 (00755697)
• Project Period (FY): 2017 – 2019
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥12,480,000 (Direct Cost: ¥9,600,000、Indirect Cost: ¥2,880,000)
• Keywords: 微小重力 / ラット / 歩行 / 三半規管・耳石器官 / 前庭器官 / 宇宙インフラ / リハビリテーション

Outline of Final Research Achievements

The purpose of this study was to figure out quantitative evaluation of functional motion and behavior deficits evoked through sedentarism. We utilized simulated microgravity environment for rats by using tail suspension model and artificial hyper gravity intervention with animal-sized centrifuge to counteract the deficits caused by the microgravity environment.
Rats that were exposed to microgravity significantly extended their knee and ankle joints during their walking, which is called "toe gait". On the other hand, hyper-gravity intervention (1.5 times of normal gravity for 80 minutes per day) significantly prevented these motion alterations. Also, their spatial learning ability also declined through microgravity environment, which was prevented with hyper-gravity intervention.
In addition to this, we found that the vestibular system, which detects gravity and accelerations might be able to be re-trained through adaptation. This approach could be useful as Vestibular Rehabilitation.

Academic Significance and Societal Importance of the Research Achievements

本研究の目的はリハビリテーションの重要な課題のひとつである不動・不使用に対する対応策を疑似微小重力環境・遠心人工重力を用いて検証し、他分野への応用の足掛かりとすることでした。
ラットを疑似的な微小重力環境に置くと、伸びあがり歩行という歩行動作の変化が生じますが、遠心人工重力発生装置を用いた高重力介入によって、これを抑制することができました。探索行動・学習能力の評価においても、同様の効果を得ました。
また本研究を進める過程で、従来は困難と考えられていた三半規管・耳石器官の適応が一定の条件では可能かもしれないという知見を得ました。この成果は将来の平衡機能リハビリテーションへの応用が期待されます。

Research Products

• [Int'l Joint Research] アイオワ大学(米国) (2018)
  • Year and Date: 2018-01-06
• [Int'l Joint Research] オハイオ州立大学(米国) (2018)
• [Journal Article] Taking the Next Steps in Regenerative Rehabilitation: Establishment of a New Interdisciplinary Field (2020)
  • Author(s): Willett NJ, Aoyama T, Ito A, Kuroki H, Tajino J, Ambrosio F, et al.
  • Journal Title: Physical Medicine and Rehabilitation Volume: 101 Pages: 917-923
  • DOI: 10.1016/j.apmr.2020.01.007
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] 3D Kinematic Analysis for the Functional Evaluation in the Rat Model of Sciatic Nerve Crush Injury (2020)
  • Author(s): Wang Tianshu、Ito Akira、Tajino Junichi、Kuroki Hiroshi、Aoyama Tomoki
  • Journal Title: JOVE-Journal of Visualized Experiments Volume: －
  • DOI: 10.3791/60267
  • Peer Reviewed / Open Access
• [Journal Article] Lower-body positive pressure diminishes surface blood flow reactivity during treadmill walking (2019)
  • Author(s): Tajino J, Ito A, Torii Y, Tsuchimoto K, Iijima H, Zhang X, Tanima M, Yamaguchi S, Ieki H, Kakinoki R, Kuroki H
  • Journal Title: BMC Research Notes Volume: 12 Pages: 733-733
  • DOI: 10.1186/s13104-019-4766-2
  • Peer Reviewed / Open Access
• [Presentation] Artificial gravity with centrifuge and optimal dose of the intervention to counteract gait alteration in rats exposed to simulated microgravity (2019)
  • Author(s): Junichi Tajino
  • Organizer: 70th International Astronautical Congress (IAC2019)
  • Int'l Joint Research