title: Modulation of PTH-stimulated osteoclastic resorption by bisphosphonates in fetal mouse bone explants.
abstract: We examined the effects of the bisphosphonates Cl2MDP, APD, and Me2APD on osteoclastic resorption in the absence and presence of PTH using fetal mouse osteoclast-free bone explants cocultured with fetal liver as a source of osteoclast precursors. Results revealed qualitative and quantitative differences among the bisphosphonates tested. With Cl2MDP and APD fractional inhibition of resorption (measured as 45Ca release) in the presence of PTH was proportional to that obtained in its absence. In contrast, Me2APD, which is the most potent inhibitor of the three, was found at low concentrations (less than or equal to 5 x 10(-7) M) to enhance the PTH-stimulated osteoclastic resorption. APD as well, at concentrations that could not inhibit resorption, had a similar effect, but Cl2MDP did not. These studies describe a new phenomenon, that low doses of nitrogen-containing bisphosphonates can act synergistically with PTH and enhance osteoclastic resorption. These findings may have clinical implications in the management of patients with increased osteoclastic resorption due to parathyroid overactivity.
authors.affiliation: Department of Endocrinology, University Hospital, Leiden, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: van der Pluijm
authors.forename: C W
authors.initials: CW
authors.lastname: Löwik
authors.forename: H
authors.initials: H
authors.lastname: de Groot
authors.forename: M J
authors.initials: MJ
authors.lastname: Alblas
authors.forename: L J
authors.initials: LJ
authors.lastname: van der Wee-Pals
authors.forename: O L
authors.initials: OL
authors.lastname: Bijvoet
authors.forename: S E
authors.initials: SE
authors.lastname: Papapoulos
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000188:drug therapy*; D002118:Calcium / Q000032:analysis; D004002:Clodronic Acid / Q000494:pharmacology*; D046508:Culture Techniques; D004164:Diphosphonates / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D000077268:Pamidronate; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011247:Pregnancy
chemical_list: D004164:Diphosphonates; D010281:Parathyroid Hormone; D004002:Clodronic Acid; C055774:olpadronic acid; D000077268:Pamidronate; D002118:Calcium