Adrenergic stimulation of osteoclastogenesis mediated by expression of osteoclast differentiation factor in MC3T3-E1 osteoblast-like cells

It is well known that adrenergic agonists efficiently activate beta -adreno ceptors on osteoblastic cells and can stimulate bone resorption in intact m ouse calvaria. Recently, an osteoclastogenic factor of osteoblastic origin was found to be a novel tumor necrosis factor ligand family member and was termed osteoclast differentiation factor (ODF). Using a reverse transcripti on-polymerase chain reaction approach, we investigated the effect of epinep hrine on mRNA levels of ODF and its decoy receptor, osteoclastogenesis inhi bitory factor (OCIF), in MC3T3-E1 cells. Treatment with epinephrine (1 muM) rapidly increased ODF and OCIF mRNA levels, which peaked after 0.5 hr of t reatment. Epinephrine (1 muM) also increased interleukin (IL)-6, IL-11, and cyclooxygenase (COX)-II mRNA levels, as well as increased prostaglandin E- 2 (PGE(2)) accumulation in the culture medium. Treatment of the cells with IL-11 (10 ng/mL) or PGE(2) (1 muM) increased ODF and OCIF mRNA levels as ob served with epinephrine. However, increases in ODF and OCIF mRNA levels by epinephrine were more rapid than those by IL-11, and were not influenced by NS-398 (100 muM; an inhibitor of COX-II), suggesting a direct effect of ep inephrine on ODF and OCIF mRNA expressions as well as an indirect effect me diated by IL-11 and PGE(2) production. Epinephrine-induced increases in ODF and OCIF mRNA levels were inhibited by pretreatment with timolol (1 muM; b eta -antagonist) and phentolamine (1 muM; alpha -antagonist), respectively. Furthermore, the formation of tartrate-resistant acid phosphatase-positive multinucleated cells from mouse bone marrow cells was stimulated by isopro terenol (0.1 to 10 muM) or epinephrine (0.1 to 10 muM). The action of isopr oterenol, a beta -agonist, was clearly stronger than that of epinephrine, s uggesting the importance of the physiological balance between ODF and OCIF productions for osteoclastogenesis. These findings suggest that beta -adren ergic stimulation induces not only IL-6, IL-11, and PGE(2) but also ODF exp ression in osteoblastic cells, leading to a stimulation of osteoclastogenes is. (C) 2000 Elsevier Science Inc. All rights reserved.