Effects of vitamin D2 analogs on calcium metabolism in vitamin D-deficient rats and in MC3T3-E1 osteoblastic cells.
The effects of 1 alpha-hydroxyvitamin D2 on calcium metabolism in vivo and of 1 alpha, 25-dihydroxyvitamin D2, which is an active metabolite of 1 alpha-hydroxyvitamin D2, on bone metabolism in vitro was studied and compared with that of 1 alpha-hydroxyvitamin D3 or 1 alpha,25-dihydroxyvitamin D3. 1 alpha-Hydroxyvitamin D2 and 1 alpha-hydroxyvitamin D3 was equally potent in stimulating intestinal calcium transport by using the everted sac method and of calcium mobilization from bone in vitamin D-deficient rats. On the other hand, the hypercalcemic activity of 1 alpha-hydroxyvitamin D2 was much lower than that of 1 alpha-hydroxyvitamin D3 in normal mice and rats. 1 alpha,25-Dihydroxyvitamin D2 and 1 alpha,25-dihydroxyvitamin D3 stimulated alkaline phosphatase activity in osteoblastic MC3T3-E1 cells and bone resorption in newborn mouse calvaria maintained in organ culture. These results show that 1 alpha-hydroxyvitamin D2 as well as 1 alpha-hydroxyvitamin D3 promote calcium absorption and may accelerate bone remodelling via direct action on osteoblasts. In addition, they suggest that 1 alpha-hydroxyvitamin D2 may be more useful than 1 alpha-hydroxyvitamin D3 for the treatment of senile osteoporosis, because hypercalcemia is one of the major side effects of 1 alpha-hydroxyvitamin D3.
Sato
F
F
Department of Geriatrics, Faculty of Medicine, University of Tokyo, Japan.
Ouchi
Y
Y
Okamoto
Y
Y
Kaneki
M
M
Nakamura
T
T
Ikekawa
N
N
Orimo
H
H
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D016723:Bone Remodeling / Q000187:drug effects; D001862:Bone Resorption / Q000139:chemically induced; D002117:Calcitriol / Q000494:pharmacology* / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004872:Ergocalciferols / Q000494:pharmacology* / Q000627:therapeutic use; D006887:Hydroxycholecalciferols / Q000494:pharmacology* / Q000627:therapeutic use; D006934:Hypercalcemia / Q000139:chemically induced; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D012886:Skull / Q000166:cytology / Q000378:metabolism; D013268:Stimulation, Chemical; D014808:Vitamin D Deficiency / Q000150:complications / Q000188:drug therapy / Q000378:metabolism*
D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; C042533:1 alpha-hydroxyergocalciferol; C003564:1,25-dihydroxyergocalciferol; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002118:Calcium; C008088:alfacalcidol