Figure 1. The effect of NAD⁺ and its Ca²⁺-releasing metabolites NAADP⁺ and cyclic ADPribose on osteoclast formation.

(Top picture) Ficol-purified bone marrow cells were plated at 3×10^4 cells/ well with 60 ng/mL murine RANK-L and 30 ng/mL murine M-CSF. After 5 days, the cells were stained for TRAP and a photograph taken at 4× power on an inverted microscope. The second row shows the effects of increasing concentration of NAD⁺ on RANK-L-induced osteoclast formation; there were no significant effects of NAD⁺ at the concentrations tested. The third row displays the effects of increasing doses of NAADP⁺ on osteoclast formation; there were no significant effects of NAADP⁺ at the concentrations tested. The last row shows the effects of increasing doses of cyclic ADPribose; cyclic ADPribose increased osteoclast formation at 5 μM, with effects peaking at 15 μM and dropping off by 45 μM.