Synergistic effect of PTH on the mechanical responses of human alveolar osteocytes

The aim of this study is to characterize the response of alveolar osteocyte s to stretching and parathyroid hormone, (1-34) PTH, Osteocytes from primar y human alveolar bone were used in the study. Compared to osteoblasts, oste ocytes were observed to express lower levels of alkaline phosphatase mRNA a nd higher levels of osteocalcin mRNA, We found that the effect of PTH and s tretching on osteocalcin expression is synergistic, The upregulated steady- state level of osteocalcin mRNA is further upregulated in the presence of P TH (at 1 h after the initiation of stretching), On the other hand, the down regulated level of the message is further downregulated in the presence of PTH (at 3 h after the 3-h stretching). The synergy can be either way, posit ive or negative, in the course of the response. From this, we presume that related mechanisms are at work between the PTH signaling pathways and the m echanotransduction pathways activated by stretching. (C) 1999 Academic Pres s.