著者

橋本 和佳 松田 秀人 高田 和夫 吉田 真琴 高橋 健太 滝口 俊男 斉藤 滋

出版者

Japanese Society for Mastication Science and Health Promotion

雑誌

日本咀嚼学会雑誌 (ISSN:09178090)

巻号頁・発行日

vol.14, no.1, pp.23-28, 2004-05-31 (Released:2010-07-21)

参考文献数

17

被引用文献数

3

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C-peptideは膵臓でのインスリン生成時にプロインスリンから分離され, 新たに生成されたインスリンの量を反映する.今回, ブドウ糖摂取時のインスリン分泌の咀嚼の有無による違いを検討するため, ガム咀嚼後にブドウ糖液を摂取させた群と, ガム咀嚼を行わずにブドウ糖液を摂取させた群とでブドウ糖液摂取後の血中C-peptide値の変化を観察した.被験者は女性19名, 年齢平均20歳, Body Mass Index (BMI) は25以下である. これらの被験者に香料や甘味料を含まないガムベースを15分間咀嚼させた後に経口ブドウ糖負荷試験 (oralglucosetolerance test, 以下OGTT) を行うガム咀嚼群と, ガム咀嚼を行わずにOGTTを行うコントロール群とに分け, OGTT後15, 30, 60, 120分に採血を行い, 血糖値, 血中インスリン値, 血中C-peptide値を測定した.その結果, 血中C-peptide値は, ガム咀嚼群でOGTT30分後, コントロール群でOGTT60分後に最高値に達した. また, ガム咀嚼群はOGTT時の血糖値の上昇がコントロール群に比べて緩やかで, 血糖値の急激な上昇が抑えられることが明らかとなった. これらのことから, ブドウ糖摂取前の咀嚼の有無はインスリンの分泌に影響を与え, 過食や肥満との関連を有する可能性が明らかとなった.

著者

成田 紀之

出版者

Japanese Society for Mastication Science and Health Promotion

雑誌

日本咀嚼学会雑誌 (ISSN:09178090)

巻号頁・発行日

vol.18, no.1, pp.12-21, 2008-05-31 (Released:2010-07-21)

参考文献数

49

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The prefrontal cortex (PFC) is involved in movement execution, sensory processing, cognition, memory, and learning. Notably, chewing-related PFC activity is not fully understood in regard to its critical participation in orofacial sensorimotor functions. In the present study, we attempted to clarify the following aspects: 1) involvement of chewing-related activation of the PFC in movement execution and programming, and sensory processing, 2) effects of chewing imagery on PFC activation, 3) functional significance of oral sensory input on PFC activity, 4) efficacy of prosthodontic treatment for activating the prefrontal cortex, and 5) functional characteristics of chewing-related PFC activity in patients with psychiatric disorders and occlusal dysesthesia. Eleven adult subjects (10 healthy, 1 with a psychiatric disorder) participated in this study. Near-infrared spectroscopy (HITACHI Medical Co., ETG-100) was used to determine the hemoglobin concentration ([oxy-Hb]) in the PFC. The task utilized was chewing gum (Lotte Co., Freezone), which was composed of 5 chewing trials, each conducted for 10 seconds. Deafferentation of oral sensory input was performed by applying lidocaine anesthesia into the unilateral inferior alveolar nerve. Our results for the five studied aspects are as follows. 1) Chewing-related PFC activity was indicated in the middle part of the dorsal PFC. 2) Chewing imagery activated the bilateral middle part of the dorsal PFC. 3) The right hemisphere was predominantly decreased in the post-anesthesia condition as compared with pre-anesthesia. 4) PFC activation was clearly initiated by wearing a partial denture prosthesis. 5) Chewing-related PFC activities in the subject with a psychiatric disorder showed a lower level of activation than in the healthy subjects. It is considered that the middle part of the dorsal PFC is involved in movement planning and execution, oral somatosensory processing, and sensorimotor integration in regard to chewing performance. Wearing a partial denture prosthesis activates the PFC, which might help to prevent cognitive and memory impairments in elderly individuals. Furthermore, patients with psychiatric disorders and persistent occlusal dysesthesia indicate that hypofrontality might be related to cognitive disruption of oral somatosensory input .

著者

小野塚 実 渡邊 和子 藤田 雅文 斉藤 滋

出版者

Japanese Society for Mastication Science and Health Promotion

雑誌

日本咀嚼学会雑誌 (ISSN:09178090)

巻号頁・発行日

vol.11, no.2, pp.109-116, 2002-03-30 (Released:2011-07-05)

参考文献数

26

被引用文献数

2

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In recent years, dysfunctional mastication, which is resulted from decreased number of residual teeth, use of unsuitable dentures, or reduced biting force, has been suggested to be related to the development of senile dementia. Recently, in senescence-accelerated mice (SAMP8 mice), we have studied the involvement of masticatory dysfunction, e.g. cut off of the upper molar teeth, extract of the upper molar teeth, or cut of the one side of the masseteric nerve, in the senile process of learning and memory. First, we found that conditions of such dysfunctional mastication progress age-related deficits in spatial memory storage in a water maze test and in hippocampal pyramidal neurons. These pathological phenomena were begun to occur in middle-aged mice, suggesting that masticatory disfunction may lead to hippocampal pathological changes in the elderly.Second, it was found that cutting off the upper molar teeth causes a reduction in the protein product, Fos, of the immediate early gene, c-fos, in the hippocampal CA1 subfield. Interestingly, both the suppression of memory storage ability and the decrease in Fos induction in this subfield induced by cutting off the upper molars were considerably improved by restoring the lost molars with artificial crowns, suggesting that normal mastication may be an important factor in maintaining normal hippocampal activities.Third, in biochemical and immunohistochemical studies examining the effect of masticatory dysfunction on age-related changes in the septohippocampal cholinergic system, we have foundthat, in aged mice, masticatory disfunction induces a decrease in acetylcholine release and choline acetyltransferase activity in the hippocampus and a reduction in the number of choline acetyltransferase-immunopositive neurons in the medial septal nucleus. However, these effects were not seen in young mice, implying that dysfunctional mastication may enhance an age-related decline in the septohippocampal cholinergic system.Finally, stress may be linked to hippocampal pathological changes induced by masticatory dysfunction. As expected, in the aged mice, conditions under masticatory dysfunction brought about a chronic elevation in plasma corticosterone levels. However, pretreatment with metyrapone, which suppresses the stress-induced rise in this hormone levels, prevented dysfunctional mastication-induced increase in plasma corticosterone levels, reduction in hippocampal pyramidal neuron numbers, and impairment of spatial memory. These findings suggest a link between the masticatory dysfunction and the glucocorticoid response, which may be involved in deficits in learning and memory and hippocampal neuronal death.In conclusion, we suggest that normal mastication may be effective in preventing senile dementia by maintaining normal function in the hippocampus, which is the most sensitive region to aging processes.