Differential effects of Vitamin D analogs on bone formation and resorption.

Deficiency in Vitamin D and its metabolites leads to a failure in bone formation primarily caused by dysfunctional mineralization, suggesting that Vitamin D analogs might stimulate osteoblastic bone formation and mineralization. In this study, we compare the effect of selected Vitamin D analogs and active metabolite, 1alpha,25-dihydroxyvitamin D(3), 19-nor-1alpha, 25-dihydroxyvitamin D(2), and 1alpha-hydroxyvitamin D(2) or 1alpha,25-dihydroxyvitamin D(2) on bone formation and resorption. In a mouse calvariae bone primary organ culture system, all Vitamin D analogs and metabolite tested-stimulated collagen synthesis in a dose-dependent manner and 19-nor-1alpha, 25-dihydroxyvitamin D(2) was the most efficacious among three.