title: Minodronic acid induces morphological changes in osteoclasts at bone resorption sites and reaches a level required for antagonism of purinergic P2X2/3 receptors.
abstract: Minodronic acid is an aminobisphosphonate that is an antagonist of purinergic P2X2/3 receptors involved in pain. The aim of this study was to investigate the action and distribution of minodronic acid and the potential for P2X2/3 receptor antagonism based on the estimated concentration of minodronic acid. Microlocalization of radiolabeled minodronic acid was examined in the femur of neonatal rats. The bone-binding characteristics of minodronic acid and morphological changes in osteoclasts were analyzed in vitro. The minodronic acid concentration around bone resorption lacunae was predicted based on bone binding and the shape of lacunae. In microautoradiography, radioactive silver grains were abundant in bone-attached osteoclasts and were detected in calcified and ossification zones and in the cytoplasm of osteoclasts but not in the hypertrophic cartilage zone. In an osteoclast culture with 1 µM minodronic acid, 65% of minodronic acid was bound to bone, and C-terminal cross-linking telopeptide release was inhibited by 96%. Cultured osteoclasts without minodronic acid treatment formed ruffled borders and bone resorption lacunae and had rich cytoplasm, whereas those treated with 1 µM minodronic acid were not multinucleated, stained densely with toluidine blue, and were detached from the bone surface. In the 1 µM culture, the estimated minodronic acid concentration in resorption lacunae was 880 µM, which is higher than the IC50for minodronic acid antagonism of P2X2/3 receptors. Thus, inhibition of P2X2/3 receptors around osteoclasts may contribute to the analgesic effect of minodronic acid.
authors.affiliation: Research Promotion, Ono Pharmaceutical Co., Ltd., 3-1-1 Sakurai, Shimamoto, Osaka, 618-8585, Japan. mak.tanaka@ono.co.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Oral Histology, Matsumoto Dental University, Nagano, 399-0781, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hosoya
authors.affiliation: Discovery Research Laboratories, Ono Pharmaceutical Co., Ltd., Shimamoto, Osaka, 618-8585, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mori
authors.affiliation: Discovery Research Laboratories, Ono Pharmaceutical Co., Ltd., Shimamoto, Osaka, 618-8585, Japan.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Kayasuga
authors.affiliation: Department of Oral Histology, Matsumoto Dental University, Nagano, 399-0781, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Department of Oral Histology, Matsumoto Dental University, Nagano, 399-0781, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Ozawa
mesh_terms: D000818:Animals; D001345:Autoradiography; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D001862:Bone Resorption / Q000188:drug therapy* / Q000473:pathology*; D002478:Cells, Cultured; D000071538:Cortical Bone / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D004164:Diphosphonates / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D005269:Femur / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology / Q000627:therapeutic use*; D008954:Models, Biological; D010010:Osteoclasts / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D011817:Rabbits; D051381:Rats; D058476:Receptors, Purinergic P2X2 / Q000378:metabolism*; D058477:Receptors, Purinergic P2X3 / Q000378:metabolism*
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D058920:Purinergic P2X Receptor Antagonists; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; C087958:YM 529
keywords: Bisphosphonate; Distribution; Minodronic acid; Osteoclast; P2X2/3 receptor