[Effects of parathyroid hormone on osteoprotegerin expression and osteoprotegerin ligand and their related cytokines in human osteoblasts].

OBJECTIVE: To investigate the pathway and mechanism of parathyroid hormone (PTH) in regulating bone resorption. METHODS: We observed the regulative effects of PTH on the expression of osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) and their related cytokines (M-CSF and TRAIL) in human osteoblasts (HOBs). The expressions of OPG, OPGL, M-CSF, and TRAIL mRNA were determined by RT-PCR. The expressions of OPG and OPGL proteins were measured by Western blotting. RESULTS: PTH down-regulated the expression of OPG but up-regulated the expressions of OPGL, M-CSF and TRAIL in HOBs. CONCLUSION: PTH can promote the bone resorption by decreasing the expression of OPG, increasing the expressions of some bone-resorbing cytokines such as OPGL, M-CSF, and TRAIL in osteoblasts, and then stimulating the osteoclast differentiation and activity.