Abstract
ABSTRACT: The liver microsomal C-25 hydroxylation of [3H]-vitamin D3 was evaluated in 19- and 22-day-old rat fetuses, and in 1-, 2-, 3-, 14-, 30-, and 60-day-old pups. The hepatic production of [3H]-25-hydroxyvitamin D3 by the 19- and 22-day-old fetuses was evaluated at 2.3 ± 0.6 and 5.9 ± 0.6 fmol·min-1·15 mg-1 microsomal protein, respectively. Values stayed unchanged during the 1st day after birth but increased on days 2 and 3 of chronologic age. Thereafter, the activity remained at a plateau of 11.2 ± 0.6 fmol·min-1·15 mg-1 microsomal protein with no further statistically significant increase in the activity of the vitamin D3-25 hydroxylase through 60 days of chronologic age. The microsomal cytochrome P-450 specific content increased during the perinatal period with values ranging from 0.15 nmol·mg protein-1 in 22-day-old fetuses to 0.44 in 60-day-old rats; the developmental pattern of the cytochrome P-450 was similar to that observed for the vitamin D3-25 hydroxylase activity. When the amount of [3H]-25-hydroxyvitamin D3 formed was expressed in relation to the amount of enzyme present in the reaction medium, a constant C-25 hydroxylation capacity in all age groups was observed suggesting that the cytochrome P- 450 isoenzyme responsible for the C-25 hydroxylation of vitamin D3 may be constitutionally determined and that its appearance originates during fetal life.
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Plourde, V., Haddad, P. & Gascon-Barré, M. Microsomal C-25 Hydroxylation of [3H]-Vitamin D3 by the Fetal and Neonatal Rat Liver. Pediatr Res 19, 1206–1209 (1985). https://doi.org/10.1203/00006450-198511000-00019
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DOI: https://doi.org/10.1203/00006450-198511000-00019
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