Alternative Title口腔への味溶液刺激がもたらす随意性嚥下への効果
Effect of oral taste stimulation on voluntary swallowing in healthy humans
Note (General)味覚刺激が嚥下運動にどのような変化を与えるかについて調べることを目的として，異なる濃度の塩味またはうま味溶液を口腔内に微量注入した時の随意性嚥下運動を記録した．健常成人29 名を対象として，出来るだけ早く繰り返し嚥下するよう指示し，その際に咽頭または口腔への溶液刺激（0.2 mL/min）を与えた．咽頭への溶液刺激は蒸留水または0.3 M NaCl 溶液とし，口腔への溶液刺激は蒸留水または3 種類のNa イオン濃度（6 mM，40 mM，240 mM）のうま味溶液（モル濃度比2 対1 のグルタミン酸ナトリウムとイノシン酸ナトリウム混合溶液），うま味溶液と同濃度のNa イオンを含むNaCl 溶液とした．測定開始後4 から9 回目までの各嚥下間の平均時間を嚥下間隔時間として各条件間で比較した．NaCl 溶液，蒸留水いずれの咽頭刺激においても嚥下間隔時間の顕著な個人差が認められた． NaCl 溶液刺激時の嚥下間隔時間は蒸留水よりも有意に長く，咽頭の水受容器による嚥下反射誘発促進効果， NaCl 溶液による水受容器応答の抑制が確認された．さらにNaCl 溶液刺激時の嚥下間隔時間が長い被験者ほど蒸留水刺激による随意性嚥下の促進効果が高かった．一方，口腔への溶液刺激では，うま味溶液刺激時のみ蒸留水に対して有意な短縮を認めた．随意性嚥下能力の高い順から上位群，中位群，下位群ごとに嚥下間隔時間の変化を調べたところ，上位群，下位群では各溶液の濃度の違いによる有意な差は認められなかったのに対して，中位群のみ溶液濃度が高くなるに従って嚥下間隔時間の短縮を認めた．以上の結果は，中位群におけるうま味成分がもつ随意性嚥下への促進効果を示唆するものである．随意性嚥下誘発能力の個人差をもとに，末梢入力に対する嚥下運動誘発の時間間隔を比較したところ，咽頭刺激時とは異なっていたことから，口腔への味覚刺激がもつ嚥下中枢への効果は単なる加重効果として捉えられず，その効果の作用機序の理解に向けてはさらなる議論が必要である．
In the present study, we investigated how taste stimuli applied to the anterior tongue surface and hypopharyngeal area affected swallowing behaviors in humans. Twentynine healthy volunteers were instructed to repeat swallowing as quickly as possible, and swallowing intervals between the fourth and ninth swallow were recorded. During the swallowing test, a taste stimulant was applied to either the oral or hypopharyngeal cavity. For pharyngeal stimulation, distilled water (DW) or 0.3 M NaCl solution was applied at 0.2 mL/min; 0.3 M NaCl solution was used because it is known to completely inhibit water-sensitive responses in the pharyngeal region. For oral stimulation, DW, NaCl solution, or umami solution was applied at the same infusion rate. For NaCl and umami solution, the concentrations of sodium ion used were 6 mM, 40 mM, or 240 mM. The concentration of sodium ion was varied to observe effects on swallowing behaviors. During pharyngeal 0.3 M NaCl or DW stimulation, a wide variation in swallowing intervals was seen among the subjects. The mean swallowing interval was significantly shorter during DW stimulation compared with 0.3 M NaCl stimulation. The longer the swallowing interval with infusion of 0.3 M NaCl solution, the stronger the facilitation of swallowing by DW stimulation. During oral taste stimulation, swallowing interval for umami solution was significantly shorter in a concentration-dependent manner, but this was not the case for NaCl solution. Subjects were then divided into three groups depending on the swallowing interval during 0.3 M NaCl pharyngeal stimulation, high (< 7s), middle (7-11s), or low (> 11s) performance groups. Only middle group exhibited concentration-dependent facilitation by umami stimulation. In addition, the facilitatory effect was different between oral and pharyngeal stimulation, in that there was no significant relationship between the swallowing interval and facilitatory effect with umami solution applied to the oral region. The current results demonstrated facilitatory effects of umami solution applied to the oral region on swallowing behaviors but the effect was not just summative on the swallowing center and the nature of taste inputs on the swallowing network should be discussed.
学位の種類: 博士（歯学）. 報告番号: 甲第3884号. 学位記番号: 新大院博（歯）甲第303号. 学位授与年月日: 平成26年3月24日
新大院博（歯）甲第303号
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Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2015-02-03T05:25:05+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション