title: Osteoprotegerin is produced when prostaglandin synthesis is inhibited causing osteoclasts to detach from the surface of mouse parietal bone and attach to the endocranial membrane.
abstract: Osteoclast differentiation and activation is controlled, at least in part, by the counterbalancing influences of osteoprotegerin ligand (OPGL) and osteoprotegerin (OPG). Nonsteroidal anti-inflammatory drugs have been shown to inhibit bone loss in vivo and bone resorption in vitro, and this is associated with a loss of osteoclasts from the bone surface. We test the hypothesis that OPG mediates the inhibition of osteoclast activity that occurs with indomethacin in the mouse calvaria. Recombinant human OPG, like indomethacin, was found to cause osteoclasts to detach from the bone surface and attach to the adjacent endocranial membrane (periosteum). Recombinant human OPG also inhibited the stimulatory effect of prostaglandin E2 (PGE2), parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D3 (1,25D3) on osteoclast adhesion to bone after an incubation with indomethacin. A function-blocking antibody to OPG and soluble human OPGL both inhibited the effect of indomethacin, leaving active osteoclasts on the bone. OPG activity was detected in the culture medium from indomethacin-treated bones and PTH, PGE2, 1,25D3, and dexamethasone all inhibited the production of OPG activity. We conclude that, in the absence of specific stimulators of bone resorption, OPG is produced by the mouse calvaria in vitro, which inhibits bone resorption by causing osteoclasts to detach from the bone surface.
authors.affiliation: Charles Salt Centre, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Owestry, Shropshire, UK.
authors.forename: E A
authors.initials: EA
authors.lastname: O'Brien
authors.forename: J H
authors.initials: JH
authors.lastname: Williams
authors.forename: M J
authors.initials: MJ
authors.lastname: Marshall
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D015232:Dinoprostone / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis* / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D039661:Integrin beta3; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009924:Organ Culture Techniques; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D053244:Osteoprotegerin; D010281:Parathyroid Hormone / Q000494:pharmacology; D010294:Parietal Bone / Q000166:cytology*; D010521:Periosteum / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis*; D018124:Receptors, Tumor Necrosis Factor
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D015703:Antigens, CD; D002120:Calcium Channel Agonists; D002352:Carrier Proteins; D006023:Glycoproteins; D039661:Integrin beta3; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D010281:Parathyroid Hormone; D010980:Platelet Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D002117:Calcitriol; D015232:Dinoprostone; D007213:Indomethacin