Tanaka Makoto, Hosoya Akihiro, Mori Hiroshi, Kayasuga Ryoji, Nakamura Hiroaki, Ozawa Hidehiro
Research Promotion, Ono Pharmaceutical Co., Ltd., 3-1-1 Sakurai, Shimamoto, Osaka, 618-8585, Japan.
Department of Oral Histology, Matsumoto Dental University, Nagano, 399-0781, Japan.
J Bone Miner Metab. 2018 Jan;36(1):54-63. doi: 10.1007/s00774-017-0814-y. Epub 2017 Feb 27.
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 IC for minodronic acid antagonism of P2X2/3 receptors. Thus, inhibition of P2X2/3 receptors around osteoclasts may contribute to the analgesic effect of minodronic acid.
米诺膦酸是一种氨基双膦酸盐，是参与疼痛的嘌呤能P2X2/3受体的拮抗剂。本研究的目的是基于米诺膦酸的估计浓度，研究其作用、分布以及P2X2/3受体拮抗的潜力。在新生大鼠的股骨中检查放射性标记米诺膦酸的微定位。体外分析米诺膦酸的骨结合特性和破骨细胞的形态变化。根据骨结合和吸收陷窝的形状预测骨吸收陷窝周围的米诺膦酸浓度。在显微放射自显影中，放射性银颗粒在附着于骨的破骨细胞中丰富，在钙化和骨化区域以及破骨细胞的细胞质中检测到，但在肥大软骨区域未检测到。在含有1μM米诺膦酸的破骨细胞培养物中，65%的米诺膦酸与骨结合，C端交联端肽释放受到96%的抑制。未经米诺膦酸处理的培养破骨细胞形成皱褶缘和骨吸收陷窝，细胞质丰富，而用1μM米诺膦酸处理的破骨细胞不是多核的，用甲苯胺蓝染色浓密，并从骨表面脱离。在1μM培养物中，吸收陷窝中米诺膦酸的估计浓度为880μM，高于米诺膦酸对P2X2/3受体拮抗的IC。因此，破骨细胞周围P2X2/3受体的抑制可能有助于米诺膦酸的镇痛作用。
