2005 Fiscal Year Final Research Report Summary
Investigation for bone mass and trabecular bone turnover through transient regulation of marrow osteogenic and osteoclastogenic potentials follow by climbming exercise
| Project/Area Number |
15591610
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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 |
OKIMOTO Nobukazu UNIVERSITY OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH, SCHOOL OF MEDICINE, ASSISTANT PROFESSOR, 医学部, 助手 (70330991)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Toshitaka UNIVERSITY OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH, SCHOOL OF MEDICINE, PROFESSOR, 医学部, 教授 (50082235)
SAKAI Akinori UNIVERSITY OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH, SCHOOL OF MEDICINE, ASSOCIATE PROFESSOR, 医学部, 助教授 (90248576)
ONISHI HIDEO UNIVERSITY OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH, SCHOOL OF MEDICINE, ASSOCIATE PROFESSOR, 医学部, 講師 (20279342)
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| Project Period (FY) |
2003 – 2005
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| Keywords | osteoclast / bone formation rate / cortical bone / mineralized nodule / alkaline phosphatase / voluntary exercise / osteoblast / climbming |
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| Research Abstract |
Introduction : The relationship between bone mass gain and local bone formation and resorption in mechanically loaded bone are not well understood.
Material and method : 65 C57BL/6J mice, 8 weeks of age, were assigned to 5 groups : a baseline control and two groups each of ground control and climbing exercise mice for 2 and 4 weeks. Mice were housed in a 100-cm tower and had to climb to drink water toward a bottle placed at the top.
Results : Compared to the ground control, bone mineral density (BMD) of the left femur increased in the climbing mice at 4 weeks. At 2 and 4 weeks, bone formation rate (BFR/BS) of periosteal surface, the cross-sectional area, and moment of inertia were increased in the climbing mice, while BFR/BS and eroded surface (ES/BS) of endosteal surface did not differ. The trabecular bone volume (BV/TV) of the proximal tibia increased in climbing mice and their osteoclasts surface (Oc.S/BS) and osteoclast number decreased at 2 weeks. At 4 weeks, there were increases in BV/TV and parameters of bone formation including mineralized surface, mineral apposition rate and bone formation rate. In marrow cell cultures from the tibia, the number of alkaline phosphatase-positive colony forming units-fibroblastic and the area of mineralized nodule formation in climbing mice were increased, and the number of osteoclast like tartrate-resistant acid phosphatase-positive multinucleated cells was lower at 2 weeks. At 4 weeks, these parameters of marrow cell cultures recovered to the levels of the ground controls.
Conclusion : Our results indicated that climbing increased trabecular bone volume and reduced bone resorption, with a subsequent increase in bone formation. Intermittent climbing downregulate marrow osteoclastogenic cells and upregulate osteogenic cells initially, but further exercise appeared to desensitize them. Cortical envelopes were enlarged earlier, but the response seems to differ from trabecular bone.
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