title: Estrogen directly down-regulates the bone-resorbing activity of mature osteoclasts through nuclear estrogen receptor alpha.
abstract: The decrease in estrogen level that follows the onset ofmenopause causes rapid bone loss, resulting in osteoporosis.However, the mechanism remains unclear, especially concerningthe regulation of bone-resorbing osteoclasts. Here we analyzedthe function of estrogen and its receptor in matureosteoclasts. We found that estrogen directly inhibitedbone-resorption by purified rabbit mature-osteoclasts.Moreover, using a RT-PCR technique, we report that nuclearestrogen receptor (ER) alpha but not ERbeta is expressed in mature osteoclasts. The antisense oligodeoxynucleotide for ERalpha inhibited the reductionin osteoclastic bone-resorbing activity caused by estrogen. We conclude that in part estrogen directly inhibits the bone-resorbing activity of mature osteoclasts through the ERalpha.
authors.affiliation: Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo, 156-8502, Japan, h-mano@nodai.ac.jp.
authors.forename: H
authors.initials: H
authors.lastname: Mano
authors.forename: Y
authors.initials: Y
authors.lastname: Hakeda
authors.forename: M
authors.initials: M
authors.lastname: Kumegawa