Figure 1.

Effects of melatonin on osteoblast proliferation. Melatonin inhibited osteoblast proliferation in a concentration- and time-dependent manner, as determined by MTT assay. Cells were treated with melatonin at various concentrations (1, 2, 3, or 4 mM) or vehicle for 0, 4, 24 or 48 h. Results are displayed as the percent absorbance at 490 nm relative to untreated cells at 0 h. Experiments were performed in triplicate, and data are shown as the mean ± S.E.M. *P < 0.05 or **P < 0.01 compared with control cells.