lα, 25-Dihydroxyvitamin D₃ and Analogues of Vitamin D₃ Induce Alkaline Phosphatase Activity in Osteoblastic Cells Derived from Newborn Mouse Calvaria

抄録

In order to study the effects of vitamin D metabolites on bone metabolism, clone MC3T3-E1 cells, which have retained osteoblastic activity, were cultured with various concentrations of the hormone, lα, 25-dihydroxyvitamin D₃ [1α, 25 (OH)₂D₃]. A physiological concentration of 1α, 25 (OH)₂D₃ stimulated alkaline phosphatase (ALP) activity in the cells. Other metabolites-1α, 24-dihydroxyvitamin D₃ [1α, 24 (OH)₂D₃], 1α-hydroxyvitamin D₃ [1α (OH)D₃], and 24R, 25-dihydroxyvitamin D₃ [24R, 25 (OH)₂D₃] -also induced increases in ALP activity in a dose-dependent fashion. However, their effective concentrations were 100 or 1, 000 times greater than that of 1α, 25 (OH)₂D₃. Hormone-induced and native ALP activities in the cells were of the same type as that found in newborn mouse calvaria; that is, they were heat-labile, L-homoarginine- and levamisole-sensitive, and L-phenylalanine-insensitive (liver-bone-kidney type). These results show that vitamin D metabolites stimulate bone formation in vitro and that they may be involved in bone formation in vivo as well.