A study of somatosensory receptors at the periphery of the taste system

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K09810
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 57060:Surgical dentistry-related
• Research Institution: Osaka University
• Principal Investigator: YOKOTA Yusuke 大阪大学, 歯学部附属病院, 助教 (10448128)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 鼓索神経 / 体性感覚レセプター / 味覚 / TRPチャネル / 舌動脈

Outline of Final Research Achievements

Chorda tympani nerve (CT) fibers have cell bodies in the geniculate ganglion and respond to taste stimuli of anterior tongue. However, CT has also been known to be involved in somatosensory perception such as temperature and touch sensation. In addition, expressions of TRPV1, TRPA1, and TRPM8 channels have been reported in rat geniculate ganglion neurons, which would suggest that CT has also other functions like mechano-sensor. In present study, we applied each channel blockers to the lingual artery of rat in vivo.
Cold and tactile stimuli were applied to the anterior tongue, and action potentials were recorded from CT. TRP channel blockers were selectively injected to the lingual artery with intra-arterial administration, then the thermal and mechanical stimuli were applied again. Our findings suggest that TRPA1 and TRPM8 channels on rat tongue dorsum play a role in CT thermal responses, and TRPV1 and TRPA1 channels play a role in CT tactile responses, respectively.

Free Research Field

外科系歯学

Academic Significance and Societal Importance of the Research Achievements

広義の味覚は、各種レセプターの解明が進んでいる5基本味 (甘・塩・酸・苦・うま味) を中心にその他の味 (辛・渋味等)、嗅覚、そして一般体性感覚が複雑に絡み合った複合感覚として理解されているものの、その詳細は未だ不明な点が多い。舌前方における一般体性感覚の主たる支配神経は三叉神経 (舌神経) であるが、同部の味覚を司る鼓索神経にも温度および機械的刺激に応答する単一ニューロンが存在している。これらのニューロンは長年あまり重要視されてこなかったが、味覚に影響を与える重要な因子である可能性があり、その解明は今後の有用な知見になり得ると考える。