Figure 6.

Osteoclastogenesis negatively regulated by melatonin was BMMSC dependent and was mediated by the MT2/NF‐κB pathway. (a) Osteoclastogenesis of primary bone marrow monocytes treated with different concentrations of melatonin was visualized by TRAP staining, and the number of osteoclasts and their area were determined. (b–c) In direct‐contact and indirect‐contact co‐culture systems, osteoclastogenesis of primary BMMs was visualized by TRAP staining, the number of osteoclasts and their area were determined (b), and the expression of cathepsin K and c‐Fos (osteoclastogenic markers) was measured by western blot (c). (d) In the indirect‐contact co‐culture system, bone marrow mesenchymal stem cells (BONE MARROW MONOCYTESCs)were pretreated with lentiviral shRNA transfer or JSH‐23, and the osteoclastogenesis of Bone marrow monocytes was determined by TRAP staining (d, e) and western blot (f). In b–f, the concentration of melatonin was 10 nM. Data are expressed as the mean ± SD, and n = 5 in each group; *P < .05, significant differences between each indicated group. NS, not significant. NC, negative control