Activation of RANKL-producing cells under simulated microgravity with a three-dimensional clinostat in regenerating goldfish scales

Exposure to microgravity during space flight has caused astronauts experience decreased bone density, resulting from resorption by osteoclastic activation. Activation of the nuclear factor-?B ligand (RANKL) RANKL-producing cells, a known osteoclastogenesis-promoting factor, seems be induced under microgravity. However, role cells not yet been demonstrated due lack suitable in vitro organ culture osteoblasts, osteoclasts, and osteocytes with intact matrix Previous reports that were detected specific antiserum for goldfish RANKL regenerating scales. In this study, response simulated three-dimensional clinostat was examined using system addition, mRNA expression analysis osteoblastic markers via quantitative real-time PCR conducted together histological cells. After 4 days exposure microgravity, number immune-positive increased compared control The Rankl scales after treatments significantly higher than (1G) osteoprotegerin (Opg), an osteoclastogenesis inhibitory conditions. ratio Rankl/Opg microgravity-treated 1G control. change implied activation is promoted treatments. Actually, exposed markers, such as receptor activator NF?B, cathepsin K, integrin beta-3, cellular-Src, increased. On other hand, (collagen type I alpha 1 osteocalcin) decreased. changes consistent our previously reported experiment on International Space Station. To best knowledge, we are first demonstrate conditions We strongly emphasize fish serve excellent model gravitational responses while maintaining similar vivo.