1998 Fiscal Year Final Research Report Summary
Trabecular bone turnover and bone marrow cell development after immobilization
| Project/Area Number |
08671706
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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 |
Orthopaedic surgery
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| Research Institution | University of Occupational and Environmental Health |
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Principal Investigator |
SAKAI Akinori University of Occupational and Environmental Health, School of Medicine, Assistant Professor, 医学部, 教授 (90248576)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Toshitaka University of Occupational and Environmental Health, School of Medicine, Profess, 医学部, 教授 (50082235)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Immobilization / Bone marrow / Osteoporosis / Parathyroid hormone / Osteblast / Osteoclast / mRNA / Mouse |
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| Research Abstract |
During the three years from 1996 to 1998, we clarified trabecular bone turnover and bone marrow cell development after immobilization and the effects of parathyroid hormone (PTH) on immobilization-related bone loss.
Methods : 1)6 week-old ddY male mice were subjected to eitherright sciatic neurectomy (Nx) or sham operation for left limbs (Sham). Histomorphometrical study was perfonned on the proximal metaphysis of tibia. 2) Bone marrow cell development was evaluated 3) FACSanalysis was done. Using RT-PCR procedure, mRNA expression of PTH/PTHrP was studied. 4) Either of 4 or4O mug/kgBW of PTH was administered subcutaneously 5 times a week.
Results : 1) Trabecular bone volume significantly decreased 14days after immobilization. The number of osteoclasts transiently increased and bone formation increased after immobilization. 2) Adherent cellnumber transiently decreased andreturned to the same values of the Sham group 12 days after immobilization. The number of osteoclast-like cell formed from the bone marrow cells obtained from the Nx limbs increased under PTH addition. 3) There was no differences in the number of Mac-1positive cells between the Nx and Sham limbs. PTH/PTHrP mRNA was elevated in the bone marrow cells obtained from the Nx limbs on day 7.4)
4)PTH administration prevented immobilization-related bone loss.
These results demonstrated that immbilization caused transient decrease in bone formation and increase in the number of osteoclasts, leading to significant bone loss. The number of adherentmarrow cells increased and the terminal differentiation process of osteoclasts was promoted by PTH.PTH administration prevented immobilization-related bone loss. PTH/PTHrP signaling pathway was promoted in the bone marrow cells of the immobilized limbs.
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