| Project/Area Number |
05454489
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Morphological basic dentistry
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
MAEDA Norihiko Hiroshima School of University Dentistry Professor, 歯学部, 教授 (60049418)
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| Co-Investigator(Kenkyū-buntansha) |
NIIDA Shumpei Hiroshima School of University Dentistry Instructor, 歯学部, 助手 (10137630)
HOSOI Mitsuteru Hiroshima School of University Dentistry Associate Professor, 歯学部, 助教授 (00034190)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1993: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Masticatory system / Masseter muscle / Postnatal development / Sexual dimorphism / Androgenic hormones / Peridontal ligaments / Trigeminal motor neuron / Trigeminal sensory neuron / Op / op mouse / Masseter muscle / Trigeminal motoneuron / Periodontal ligament / LDH isozyme / Sexual dimorphism / Androgenic hormones |
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| Research Abstract |
Postnatal changes in the masticatory system and regulation factors were investigated, and following results were obtained.
1.Sexual dimorphism of isozyme patterns of lactate dehydrogenase gradually appeared in the masseter muscle of developing mice. Testectomy inhibited the appearance, but not ovariectomy.
2.Androgenic hormones induced the sexual differences in the masseter muscle. Cyproterone acetate which is an androgen antagonist inhibited the induction.
3.Androgen receptors were certainly observed in masseter muscles of male and female mice. The receptors apppeared with maturation of male and female animals. No sexual difference was observed.
4.Short-term denervation of the masseter nerve did not inhibit the appearance of sexual dimorphism in the masseter muscle.
5.Sexual dimorphism in the trigeminal motor neurons innervating the mouse masseter muscle was observed. Estrogenic and androgenic hormones were involved in induction of the dimorphism.
6.Less-developed periodontal ligaments in op/op mice caused the precocious atrophy of the masseter muscle, and induced the reduction in the number of motor and sensory neurons involved in the jaw-opening reflex in the mice.
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