Elucidation of co-control mechanism of respiration and swallowing by uncertain raphe nucleus network

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K10136
• 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: Yamanishi Tadashi 大阪大学, 大学院歯学研究科, 招へい教員 (20397780)
• Co-Investigator(Kenkyū-buntansha): 近藤 敬秀 大阪大学, 大学院歯学研究科, 招へい教員 (90870444)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 嚥下活動 / 嚥下中枢 / 呼吸活動 / in situ 標本 / セロトニン受容体

Outline of Final Research Achievements

The aim of this study is to reveal the central mechanism by which neurons in the medullary raphe nucleus, which co-produce substance P (SP) and serotonin (5-HT), control respiratory and swallowing activities. Using juvenile rats aged 3 weeks, we developed in situ preparation, in which a wide range of neural networks within the brainstem were functionally preserved, and successfully induced stimulus-responsive activity by electrical stimulation of the superior laryngeal nerve. This activity showed sequential muscle activities, including the masseter muscle, digastric muscle, pharyngeal constrictor muscle, and upper esophageal muscle in a certain order. This sequence was consistent with swallowing activity. With drug administration experiments, we found that 5-HT receptors in the medulla oblongata raise the threshold of swallowing activity and affect continuous muscle activity.

Free Research Field

顎口腔機能の神経科学

Academic Significance and Societal Importance of the Research Achievements

嚥下活動の障害が原因となる誤嚥性肺炎は、本邦の死因第６位であり、超高齢化を迎えたわれわれの社会において重大な問題である。しかしながら嚥下中枢の神経機構の解明はあまり進んでいない。本研究では、嚥下中枢を選択的に分析するためのin situ実験標本を作成し、嚥下活動を誘発することに成功した。このアプローチを用いて、延髄内のセロトニン受容体が嚥下活動の発現閾値や筋活動に影響を及ぼすことを明らかにした。以上の研究は嚥下活動の中枢神経メカニズムを明らかにする新たな成果となった。