[Biological function of bone cells on the PTH-driven anabolic effect]

Abstract

Parathyroid hormone (PTH) -driven anabolism in bone appears to involve the osteoblastic activation and the increased population of preosteoblastic lineages. Given that the activities of osteoclasts and osteoblasts are intertwined during normal bone remodeling, it is plausible that the anabolic action of PTH is either directly or indirectly related to the osteoclast. We have recently reported that the absence of osteoclasts in c-fos( - / - ) mice might hinder PTH-driven bone anabolism, and that osteoclastic presence may be necessary for full osteoblastic differentiation and enhanced bone formation seen after intermittent PTH administration. Alternatively, it was suggested that PTH administration inhibits sclerostin synthesis by osteocytes, thereby allowing for active bone formation. Taken together, PTH affects bone cells in a dual pathway - mediating osteoblastic (preosteoblastic) activities or osteocytic synthesis of sclerostin -.