Anti-osteoclastogenic action of active vitamin D.

Active vitamin D and its analogs, which have been recognized to potentiate both bone resorption and formation, increase bone volume by inhibiting accelerated bone resorption at pharmacological doses. This mechanism is, at least in part, independent of intestinal and renal calcium regulating activities. The study described here found that active vitamin D directly acts upon osteoclast precursor cells and suppresses their differentiation in vitro. Screening vitamin D analogs for this activity led to a new candidate of bone effective drug, suggesting the importance of this activity even in vivo. These findings provide new insight into understanding the effect of vitamin D on bone and the possibility of using active vitamin D as a therapeutic agent.