| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1990: ¥900,000 (Direct Cost: ¥900,000)
|
|---|
| Research Abstract |
The effect of sex hormones i.e. estrogen and androgen, for bone formation and resorption was morphologically examined using medullary bone, which was formed in laying hens under the existence of both estrogen and androgen, of Japanese quails. Laying quails, male quails and castrated male quails were employed as experimental animals. Estrogen and androgen induced medullary bone formation accompanying cell proliferation and differentiation of endosteal lining cells and/or osteoblasts into active osteoblasts. A single dosage of estrogen or androgen did not induced bone formation. Both estrogen and androgen were essential for the formation. The interruption of the hormone after medullary bone formation caused the appearance of active osteoclasts and resulted bone resorption of the bone. For the bone resorption by the hormone deficiency, estrogen deficiency was greater than that of androgen. Administration of anti-estrogen, namely tamoxifen (TAX) or anti-androgen, namely cyproterone (CPA) in laying quails caused inhibition of osteoclastic activity respectively, and the result was indicative that the anti-sex hormone agents (TAX and CPA) impaired the bone metabolism, such as bone formation and resorption during laying cycle, by inhibiting osteoclasts. Immunohistochemical study revealed estrogen receptors in osteoblasts indicating estrogen acts directly to medullary bone osteoblasts. But negative osteoblasts also existed. The functional significance of two types of osteoblasts on the reactivity was unclear.
|
