Behavioral analysis of pain control by optogenetic insular cortex stimulation with PV-ChR2 rat

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K21024
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0907:Oral science and related fields
• Research Institution: Nihon University
• Principal Investigator: KAJIWARA Mie 日本大学, 歯学部, 専修医 (70906354)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 光遺伝学的手法 / 島皮質 / 光刺激 / PV細胞 / channelrhodopsin-2(ChR2) / 疼痛 / 行動生理学

Outline of Final Research Achievements

The peripheral neuropathy due to dental procedures such as extraction of wisdom tooth cause neuropathic pain. However, there are few effective treatments for the neuropathic pain. Previously, it was showed that the peripheral neuropathy causes hyperexcitability of the insular cortex (IC). In this study, I performed the experiment activating inhibitory neurons to suppress excitatory neurons in IC using an optogenetic technology. To modulate inhibitory neurons, AAV5-EF1α-Flex-hChR2(H134R)-mCherry were injected and the optical fiber was also inserted in IC of parvalbumin-Cre transgenic rats. The nociceptive laser irradiation was applied to the cheek of rats, and the laser intensity was examined to find that inducing escape behaviors. When the blue light irradiation to IC and the nociceptive laser irradiation to the cheek were applied simultaneously, escape behaviors tended to decrease compared to the condition in which only nociceptive laser irradiation was applied.

Free Research Field

歯科麻酔学

Academic Significance and Societal Importance of the Research Achievements

智歯抜歯やインプラント手術，根管治療などの歯科治療はしばしば末梢神経障害を引き起こす。これらの歯科・口腔外科治療における末梢神経損傷は，神経障害性疼痛を惹起し難治性の経過を辿ることが多く未だ有効な治療法は少ない。本研究は光遺伝学的手法を用いて顔面領域の疼痛抑制効果を行動学的に検証した。結果，抑制性ニューロンを活性化させる光照射によって疼痛からの逃避行動量が減少する傾向にあった。これは今後の神経障害性疼痛の制御実験につながると考えられる。