title: Low-intensity pulsed ultrasound induces apoptosis in osteoclasts: Fish scales are a suitable model for the analysis of bone metabolism by ultrasound.
abstract: Using fish scales in which osteoclasts and osteoblasts coexist on the calcified bone matrix, we examined the effects of low-intensity pulsed ultrasound (LIPUS) on both osteoclasts and osteoblasts. At 3h of incubation after LIPUS treatment, osteoclastic markers such as tartrate-resistant acid phosphatase (TRAP) and cathepsin K mRNA expressions decreased significantly while mRNA expressions of osteoblastic markers, osteocalcin, distal-less homeobox 5, runt-related transcription factor 2a, and runt-related transcription factor 2b, increased significantly. At 6 and 18h of incubation, however, both osteoclastic and osteoblastic marker mRNA expression did not change at least present conditions. Using GeneChip analysis of zebrafish scales treated with LIPUS, we found that cell death-related genes were upregulated with LIPUS treatment. Real-time PCR analysis indicated that the expression of apoptosis-related genes also increased significantly. To confirm the involvement of apoptosis in osteoclasts with LIPUS, osteoclasts were induced by autotransplanting scales in goldfish. Thereafter, the DNA fragmentation associated with apoptosis was detected in osteoclasts using the TUNEL (TdT-mediated dUTP nick end labeling) method. The multi-nuclei of TRAP-stained osteoclasts in the scales were labeled with TUNEL. TUNEL staining showed that the number of apoptotic osteoclasts in goldfish scales was significantly elevated by treatment with LIPUS at 3h of incubation. Thus, we are the first to demonstrate that LIPUS directly functions to osteoclasts and to conclude that LIPUS directly causes apoptosis in osteoclasts shortly after exposure.
authors: Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto, Ishikawa 927-0553, Japan. Electronic address: nobuos@staff.kanazawa-u.ac.jp.
authors: Nobuo
authors: N
authors: Suzuki
authors: Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto, Ishikawa 927-0553, Japan.
authors: Taizo
authors: T
authors: Hanmoto
authors: Japan Aerospace Exploration Agency, Tsukuba, Ibaraki 305-8505, Japan.
authors: Sachiko
authors: S
authors: Yano
authors: Liberal Arts and Sciences, Faculty of Engineering, Toyama Prefectural University, Kurokawa, Toyama 939-0398, Japan.
authors: Yukihiro
authors: Y
authors: Furusawa
authors: Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Okayama 700-8525, Japan.
authors: Mika
authors: M
authors: Ikegame
authors: Division of Molecular Genetics Research, Life Science Research Center, University of Toyama, Sugitani, Toyama 930-0194, Japan.
authors: Yoshiaki
authors: Y
authors: Tabuchi
authors: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama 930-0194, Japan.
authors: Takashi
authors: T
authors: Kondo
authors: Department of Clinical Laboratory Science, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Kodatsuno, Ishikawa 920-0942, Japan.
authors: Kei-ichiro
authors: K
authors: Kitamura
authors: Department of Marine Biosciences, Division of Marine Science, Tokyo University of Marine Science and Technology, Konan, Minato, Tokyo 108-8477, Japan.
authors: Masato
authors: M
authors: Endo
authors: Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Okayama 700-8525, Japan.
authors: Toshio
authors: T
authors: Yamamoto
authors: Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto, Ishikawa 927-0553, Japan.
authors: Toshio
authors: T
authors: Sekiguchi
authors: Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto, Ishikawa 927-0553, Japan; Institute of Noto SATOUMI Education Research, Noto, Ishikawa 927-0553, Japan.
authors: Makoto
authors: M
authors: Urata
authors: Kanagawa Dental University Graduate School of Dentistry, Inaoka, Kanagawa 238-8580, Japan.
authors: Yuko
authors: Y
authors: Mikuni-Takagaki
authors: Department of Biology, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827, Japan.
authors: Atsuhiko
authors: A
authors: Hattori
mesh_terms: D000818:Animals; D017209:Apoptosis; D006054:Goldfish / Q000378:metabolism*; D023421:Models, Animal; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D014465:Ultrasonics
keywords: Apoptosis; Fish scales; GeneChip analysis; LIPUS; Osteoblasts; Osteoclasts