Mechanism of offset analgesia modulation in rats with neuropathic pain: an electrophysiological analysis in the dorsal horn

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K16459
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 55050:Anesthesiology-related
• Research Institution: Osaka City University
• Principal Investigator: Funai Yusuke 大阪市立大学, 大学院医学研究科, 講師 (60722486)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: オフセット鎮痛 / 脊髄後角 / 下行性疼痛抑制系

Outline of Final Research Achievements

Offset analgesia (OA) is a significant change in pain sensation during a slight decrease of a noxious heat stimulus that is more pronounced than would be expected by the temperature change. Although the involvement of the descending pain inhibitory system has been suggested, the mechanism of OA is not fully understood. We performed extracellular recordings in rat spinal dorsal horn with
applying various thermal stimulus sequences using a precise thermal stimulator (UDH-300). We tried various thermal protocol in combination with some parameters as below, the initial temperature was ranged to 43-49 ℃, the rise range was 1-3 ℃, and the duration of stimuli was 5-20 seconds, but the significant OA phenomenon could not be recorded because of the too much electrical noise from the thermal stimulator. Regardless of the detailed verification and repair of the internal circuit and the thermal probe, the electrical noise could not be removed enough to accomplish our initial research purpose.

Free Research Field

麻酔科学

Academic Significance and Societal Importance of the Research Achievements

オフセット鎮痛（Offset analgesia; OA）とは、熱刺激を短時間で増減させた際に痛み感覚が温度変化と不釣り合いに大幅に減少する現象を指すが、脊髄後角レベルでの機序は明らかでなかった。これまで下行性疼痛抑制系の関与や、神経障害性疼痛患者ではオフセット鎮痛が減弱することが示されてきた。OAの機序を解明することで神経障害性疼痛の治療に応用できる可能性があると考え、我々の持つ実験技術を用いて脊髄後角でのOA反応を明らかにする着想に至った。