Early skeletal mineralization and the role of Vitamin D: An electron probe microanalysis

Summary

The effect of vitamin D on the calcium (Ca) and phosphorus (P) contents of metaphyseal trabecula bone (MT) and calcified cartilage (CC) were analyzed by electron probe microanalysis during the periweaning period in rats that had been divided into three groups: group N was fed a normal experimental diet, group R was fed a vitamin D deficient, low P diet, group D was fed the same diet as group R and also injected with 1α-hydroxyvitamin D₃(1α(OH)D₃) (0.2 μg/kg each day). In group R, the Ca and P contents of the CC gradually decreased from weaning until 14 days after weaning when the Ca and P had become minimal. However, in the MT, the Ca and P had decreased significantly at 7 days after weaning. In group D the serum concentrations of Ca and P were lower than in group N until 7 days after weaning, but the Ca and P contents in the CC were restored at 3 days after weaning. However, in the MT, the Ca and P contents in group D were not significantly different from those in group N. These results indicate that (1) vitamin D becomes progressively more important after weaning in mineralization of cartilage and bone and (2) the sensitivity of the CC to vitamin D deficiency is higher than that of MT.