Static and dynamic hypergravity responses of osteoblasts and osteoclasts in medaka scales

Sachiko Yano, Kei Ichiro Kitamura, Yusuke Satoh, Masaki Nakano, Atsuhiko Hattori, Toshio Sekiguchi, Mika Ikegame, Hiroshi Nakashima, Katsunori Omori, Kazuichi Hayakawa, Atsuhiko Chiba, Yuichi Sasayama, Sadakazu Ejiri, Yuko Mikuni-Takagaki, Hiroyuki Mishima, Hisayuki Funahashi, Tatsuya Sakamoto, Nobuo Suzuki

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Fish scales are a form of calcified tissue similar to that found in human bone. In medaka scales, we detected both osteoblasts and osteoclasts and subsequently developed a new scale assay system. Using this system, we analyzed the osteoblastic and osteoclastic responses under 2-, 3-, and 4-gravity (G) loading by both centrifugation and vibration. After loading for 10 min, the scales from centrifugal and vibration loading were incubated for 6 and 24 hrs, respectively, after which the osteoblastic and osteoclastic activities were measured. Osteoblastic activity significantly increased under 2- to 4-G loading by both centrifugation and vibration. In contrast, we found that osteoclastic activity significantly decreased under 2- and 3-G loading in response to both centrifugation and vibration. Under 4-G loading, osteoclastic activity also decreased on centrifugation, but significantly increased under 4-G loading by vibration, concomitant with markedly increased osteoblastic activity. Expression of the receptor activator of the NF-αB ligand (RANKL), an activation factor of osteoclasts expressed in osteoblasts, increased significantly under 4-G loading by vibration but was unchanged by centrifugal loading. A protein sequence similar to osteoprotegerin (OPG), which is known as an osteoclastogenesis inhibitory factor, was found in medaka using our sequence analysis. The ratio of RANKL/OPG-like mRNAs in the vibration-loaded scales was significantly higher than that in the control scales, although there was no difference between centrifugal loaded scales and the control scales. Accordingly, medaka scales provide a useful model by which to analyze bone metabolism in response to physical strain.

Original languageEnglish
Pages (from-to)217-223
Number of pages7
JournalZoological science
Issue number3
Publication statusPublished - Mar 2013


  • OPG
  • gravity response
  • medaka
  • osteoblast
  • osteoclast
  • scale

ASJC Scopus subject areas

  • Animal Science and Zoology


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