Estrogen stimulates the elaboration of cell/matrix surface-associated inhibitory factor of osteoclastic bone resorption from osteoblastic cells.
Osteoblast-like UMR106 cells secreted bone resorption-stimulating activity (BRSA) under stimulation by human parathyroid hormone 1-34. Most of BRSA was associated with cell/matrix surface and could be extracted by 2 M NaCl. Pretreatment with 17 beta-estradiol (E2) reduced BRSA by enhancing the elaboration of an inhibitory factor of BRSA in a dose-dependent manner, and 10(-9) M 17 beta-E2 showed a significant effect. Neither 17 alpha-E2 nor dihydrotestosterone showed a similar effect. The inhibitory factor of BRSA was also bound to cell/matrix surface, showed affinity for heparin, and was trypsin- and heat-sensitive. Furthermore, this factor could also inhibit resorption pit formation stimulated by 1,25-dihydroxyvitamin D3, interleukin (IL)-1 alpha and IL-6. Elaboration of such an inhibitory factor of bone resorption from osteoblasts may play an important role in the protective effect of estrogen against bone resorption.
Ishii
T
T
Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan.
Saito
T
T
Morimoto
K
K
Takeuchi
Y
Y
Asano
S
S
Kumegawa
M
M
Ogata
E
E
Matsumoto
T
T
D000818:Animals; D001685:Biological Factors / Q000378:metabolism*; D001862:Bone Resorption; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004967:Estrogens / Q000494:pharmacology*; D006801:Humans; D010006:Osteoblasts / Q000378:metabolism*; D010010:Osteoclasts / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011817:Rabbits; D019379:Teriparatide
D001685:Biological Factors; D004967:Estrogens; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide