Effects of nicotine on cultured cells suggest that it can influence the formation and resorption of bone

The acute effects of nicotine [1-methyl-2-(3-pyridyl)pyrrolidine] on the fo rmation and resorption of bone were examined in cultures of clonal rat calv arial osteogenic cells (ROB-C26) and clonal mouse calvarial preosteoblastic cells (MC3T3-E1), as well as in osteoclast-like cells formed during cocult ure of mouse bone marrow cells and clonal stromal cells from mouse bone mar row, ST2 cells, at concentrations that occur in the saliva of smokeless tob acco users. Nicotine stimulated the rate of deposition of Ca2+ by ROB-C26 c ells, as well as the alkaline phosphatase activity of these cells, in a dos e-dependent manner. However, both activities decreased in MC3T3-E1 cells th at had been exposed to nicotine. These results indicate that nicotine affec ted osteoblastic differentiation in osteoblast-like cells. By contrast, nic otine reduced, in a dose-dependent manner, the formation of tartrate-resist ant acid phosphatase (TRAP)-positive multinucleated cells (MNCs) and the fo rmation of pits on slices of dentine, both of which are typical characteris tics of osteoclasts. Our results suggest that nicotine might have critical effects on bone metabolism. (C) 1999 Elsevier Science B.V. All rights reser ved.