| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2000: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Bone tissues are sensitive to microgravity, leading to the decrease of bone mineral density. Many people are going to stay and live in the space in near future. Therefore, it is important to know the mechanism of bone destruction and to know the drugs to overcome the situation.
In this reseach, the effects of quasi-microgravity on the osteoblasts were studied to infer the effect of microgravity in the space.
Quasi-microgravity generated by the clinostat culture brought the temporal decrease of alkaline phosphatase activity of osteoblasts, and brought the continued increase of osteocalcine synthesis. Osteocalcine is regarded as the stimulator of bone resorption. Therefore, the decrease of bone mineral density in the space seems to be depend on the temporal decrease of bone formation and the continued increase of bone resorption. The temporal decrease of alkaline phosphatase activity was recovered by the treatment of active vitamin D3, 1 α,25-(OH)2D3, suggesting that 1 α ,25-(OH)2D3 is active for bone deseases even if in the space. The increase of osteocalcine synthesis induced by the exposure of quasi-microgravity was largely inhibited by the treatment of cytochalasin B, a destructive agent of actin filament, indicating that cytoskeleton, especially actin filament, is important for the induction of osteocalcine. However, the decrease of alkaline phosphatase activity was not changed by the treatment of cytochalasin B. Quasi-microgravity caused the increase of intracellular cAMP contents. This increase of cAMP was also not changed by the treatment of cytochalasin B. These results showed that actin fiaments do not participate the increase of intracellular cAMP contents and the decrease of alkaline phosphatase activity induced bu the exposure of quasi-microgravity.
Now, I am going to analyze the network system between cAMP, cytoskeleton, and cell function of osteoblasts including osteocalcine synthesis and alkaline phaophatase activity.
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