Elucidation of new molecular mechanism of calcium regulation in the inner ear

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K18738
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56050:Otorhinolaryngology-related
• Research Institution: Nagoya City University
• Principal Investigator: Minakata Toshiya 名古屋市立大学, 医薬学総合研究院(医学), 助教 (10770612)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: カルシウム感知受容体 / ラセン靭帯 / カルシウム恒常性

Outline of Final Research Achievements

We investigated the expression of calcium sensing receptor (CaSR) in the inner ear. First, we confirmed that molecule that had same molecular weight as that in the kidney by western blotting, so we investigated immunostaining, assuming that CaSR is also expressed in the inner ear. By immunostaining revealed the expression of CaSR in the spiral ligament of the inner ear. We performed calcium imaging whether to confirm the expression in the inner ear was functional and confirmed that the expression of spiral ligament was functional. Next, we administered CaSR agonist and antagonist directory to the inner ear via the round window and confirmed that hearing thresholds was elevated by administration of CaSR agonist and antagonist. These results suggested that CaSR is functionally expressed in the spiral ligament in the inner ear and contribute for hearing.

Free Research Field

中耳内耳

Academic Significance and Societal Importance of the Research Achievements

カルシウム感知受容体（Calcium sensing receptor: CaSR）は生体内のカルシウム濃度調整に必要不可欠な受容体の一つ、腎臓、骨、副甲状腺といった血液内のカルシウム濃度の制御に関わる臓器の他、中枢・末梢神経、血管平滑筋細胞などでも発現が確認されている。本研究では新たにCaSRが内耳のラセン靭帯に発現していることを発見した。らせん靭帯は内耳のイオンの恒常性維持に重要な役割を果たしている。本研究ではカルシウムイメージングにてらせん靭帯での機能的な発及び内耳への阻害薬、作動薬を投与による聴力低下を発見し、CaSRが聴覚に寄与している可能性を示唆した。