| Project/Area Number |
07838020
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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 | 時限 |
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| Research Field |
咀嚼
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SUEMUNE Setsuko Hiroshima University, School of Dentistry, research assistant, 歯学部, 教務員 (80112209)
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| Co-Investigator(Kenkyū-buntansha) |
MAEDA Norihiko Hiroshima University, School of Dentistry, professor, 歯学部, 教授 (60049418)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | impaired dentition / input from periodontal ligaments / masticatory muscle / trigeminal motor nucleus |
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| Research Abstract |
In osteopetrotic (B6C3Fe-a/a-op-op) mouse in which no eruption of teeth ever occurs, the periodontal tissue of the impacted tooth in the lowerjaw, the primary afferent neurons and central therminals of the inferior alveolar nerve were studied by the horseradish peroxidase (HRP) trasing methods in the first year. The number of labeled neurons in the trigeminal mesencephalic nucleus (Me5) and the trigeminal ganglion (TG) were significantly reduced, and the primary afferent terminals to the supratrigeminal nucleus (Su5) and the trigeminal sensory nucleus oralis (Sp5O) were also reduced. As this results imply the undeveloped periodontal tissue and the reduction of the afferent input to the premotor neurons of the trigeminal motor nucleus (Mo5), the effect on the jaw opening and closing motoneurons which compose the trigeminal motor nucleus and the effect on the jaw opening and closing muscles which are the masticatory motor apparatus are researched in this year. Each five animals of the op/op mouse fed with the granulated diet and the normal op/+ mouse fed with the solid or granulated diet were used three months after birth. The masseter nerve and the mylohyoidal nerve which are innervating the jaw closing and opening muscle respectively are performed by the HRP method. The results were the significant reduction of labeled cells in Mo5 and TG in the op/op. The number of muscle spindle was not changed but the fibers of the masseter muscle were severely atorophied and the muscle diameter was significantly reduced.
The present results lead us to conclude that the sensory input from the sensory endings in the periodontal ligaments may play an important role on the maintenance of homeostatic conditions with respect to sensory and motor neurons that are involved in the masticatory reflex.
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