| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Experiments on humans : We investigated how dieting, menstrual cycle and body fat rate would influence a change in the bone mass in 401 female college students with an informed consent. There were significant positive relationships between the diet-experience and the bone mass (p<0.01), and the body fat rate and the bone mass (p<0.01), contrary to our assumption. These results suggest that individuals dieting to obtain a slim body did not necessarily lose their body weight and higher pressure to the bone due to their greater weight positively influenced the bone mass. The menstrual cycle had no relationship to the bone mass. In addition, we investigated the estrogen receptor (ER) polymorphisms among 166 students who agreed to this experiment. We carried out RFLP (Restriction Fragment Length Polymorphism) analysis of ER alpha-intron I using Pvu II and Xba I, after obtaining their DNA. Students having menstrual cycle problems (48.3%) fell to the ppxx (n=60) group, and this group's bone s
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tiffness (77.0) showed the second lowest value, next to that of the PPXX group (89.0, n=4). Physical activity showed a positive influence on the bone mass (p<0.05) in the Ppxx, PpXx and ppxx groups, suggesting that the effects of physical activity differ among the genetic traits. These results suggest that, especially among the Ppxx, PpXx and ppxx type individuals, a modest effort to keep a proper body weight and daily practice of light physical activity may be effective in preventing the loss of bone mass and, consequently, in preventing an increase in the number of the bedridden among the aged population.
Experiments on osteoblasts : We investigated the effects of estrogen (1 nM) or testosterone (100 nM) on the expression of vitamin D3 receptor mRNA in osteoblastic ROS17/2.8 cells. Treatment of the cells with either one of the hormones for 24 hours increased the receptor expression. However, the testosterone effect was suppressed by a non-steroidal reversible aromatase inhibitor, letrozole. These results strongly suggest that aromatase present in osteoblasts contributes to the synthesis of estrogen in these cells. Less
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