Effects of RANKL, osteoprotegerin, calcium and phosphorus on survival and activation of Muscovy duck osteoclasts in vitro

The aim of this study was to determine whether receptor activator of nuclear factor NF-κB ligand (RANKL), osteoprotegerin (OPG) and a calcium:phosphorus (Ca:P) ratio of 2:1 could affect survival and activation of Muscovy duck osteoclasts (OCs). Bone marrow cells were obtained from 5-day-old Muscovy ducks and cultured with (Group A) No added factors, (B) 30 ng/mL soluble RANKL (sRANKL), (C) 30 ng/mL sRANKL and 10 ng/mL OPG, (D) 10 ng/mL OPG, (E) 50 ng/mL OPG, (F) 100 ng/mL OPG and (G) 30 ng/mL sRANKL, 6 mmol/L Ca and 3 mmol/L P.sRANKL promoted the survival of OCs on day 2, whereas the number of OCs decreased with addition of OPG in a dose-dependent manner. OPG and Ca:P (2:1) both inhibited OC survival induced by RANKL. RANKL stimulated bone resorption by OCs, whereas OPG, but not Ca:P (2:1), inhibited the activity of OCs induced by RANKL. RANKL promotes the survival and activation of OCs from Muscovy ducks, whereas OPG and, to a lesser extent, Ca:P (2:1) reduce the life span and inhibited the activation of OCs induced by RANKL.