| Project/Area Number |
09832012
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
咀嚼
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| Research Institution | Kanagawa Dental College |
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Principal Investigator |
NISHIYAMA Katsuhiro Kanagawa Dental College, DENTISTRY ASSISTANT PROFESSOR, 歯学部, 講師 (20084783)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Kazuko GIF UNIVERSITY MEDICINE ASSISTANT PROFESSOR, 医学部, 講師 (40158621)
SAITO Shigeru Kanagawa Dental College, DENTISTRY PROFESSOR, 歯学部, 教授 (80084713)
川瀬 俊夫 神奈川歯科大学, 歯学部, 教授 (30084784)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Hippocampal / mastication / oncogene / MRI / c-Fos / Morris water maze / human / brain derived factor / 記憶 / アセチルコリン / 神経 |
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| Research Abstract |
In the present study, we evaluated the effect of reduced mastication on the neuronal mechanism responsible for age-related memory impairment, by examining the effects of the cutting off of the upper molars (molarless) on hippocampal expression of c-fos protein (c-Fos) and spatial memory in the senescence-accelerated mouse (SAM-P8) and the senescence-resistant mouse (SAM-R1). In the Morris water maze test, the escape latency for intact SAM-P8 to find the hidden platform was longer in the first several days and thereafter almost the same as that for the SAM-R1 control. Immunohistochemical analysis following this behavioral test (on day 10) revealed no significant density of c-Fos-immunopositive cell nuclei in the hippocampal formation between these two groups. However, in molarless SAM-P8, both a marked increase in escape latency in the water maze and a significant decrease in c-Fos-immunoposive nuclei density were seen, the greatest effect being found in the CAl subfield, followed by the CA3 subfield, then the dentate gyrus. These changes became more pronounced with the increasing duration of the molarless condition. In contrast, the molarless SAM-R1 did not show any significant changes in maze leaning and c-Fos expression. Furthermore, the molarless condition had no effect on GFAP-positive cell density in the hippocampal formation in either SAM-R1 or SAM-PS mice. These results suggest that impaired mastication may cause the age-related reduction in hippocampal activity, linked to impairment of memory.
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