| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2001: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
Aromatase is a sole enzyme which converts androgen into estrogen. In this study, we have found that aromatase-knockout (ArKO) mice showed bone loss by increased bone resorption not only in female but also in male mice, suggesting the essential roles of estrogen in bone metabolism in both sexes. To clarify the relationship between estrogen and androgen in bone metabolism in males, 7-weeks-old ArKO mice were orchidectomized (ORX) to induce the double deficiency of estrogen and androgen. In wild type mice, ORX reduced trabecular bone mass in the femur 4 weeks after operation. Due to estrogen deficiency, sham-operated ArKO mice showed the reduced trabecular bone mass compared with sham-operated wild-type mice. In ArKO mice, ORX induced the further loss of trabecular bone in the femur compared with sham-operated mice due to the further increase in bone resorption, and the ArKO/ORX mice showed a severe osteopenia. Therefore, androgen and estrogen individually regulate bone turnover in adult male mice. When 3-weeks-old wild-type mice were ORX, periosteal bone formation in the femur was markedly reduced 4 weeks after operation. In contrast, cortical bone formation in the same age of ArKO mice was normal. Therefore, periosteal bone formation is regulated by androgen at puberty. Estrogen and androgen may share the work to maintain bone mass in male mice before and after sexual maturity
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