Comparison of the effects of vitamin D metabolites on collagen synthesis and resportion of fetal rat bone in organ culture.
We compared the effects of four vitamin D metabolites, 1 alpha,25 dihydroxy vitamin D3 (1 alpha,25(OH)2D3), 1 alpha hydroxy vitamin D3 (1 alpha OH D3), 25 hydroxy vitamin D3 (25 OH D3), and 24R,25 dihydroxy vitamin D (24R,25(OH)sD3) on resorption and collagen synthesis in fetal rat bone maintained in organ culture. Resorption was quantitated by measuring the release of previously incorporated 45Ca from long bone shafts of 19-day fetal rats, and collagen synthesis was assessed by measuring the incorporation of 3H-proline into collagenase digestible protein (CDP) in calvaria from 21-day fetal rats. All four compounds stimulated bone resorption and inhibited collagen synthesis, but 1 alpha,25(OH)2D3 was approximately 1000 times more potent in both organ culture systems. Although the differences were small among the other three compounds, the order of potency was 1 alpha OH d3 > 25 OH D3 greater than or equal to 24R,25(OH)2D3. These results suggest that the receptor for 1 alpha 25(OH)2D3 in both bone resorbing and bone forming cells has similar affinities for several vitamin D metabolites.
D000818:Animals; D001862:Bone Resorption / Q000187:drug effects*; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D003094:Collagen / Q000096:biosynthesis*; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005333:Fetus; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D009924:Organ Culture Techniques; D011247:Pregnancy; D051381:Rats; D013329:Structure-Activity Relationship
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D003094:Collagen