Effect of oestrogen and 1,25-dihydroxycholecalciferol on 25-hydroxycholecalciferol metabolism in primary chick kidney-cell cultures.
Primary cultures of chick kidney cells convert 25-hydroxycholecalciferol into more-polar metabolites. Cells from vitamin D-deficient chicks have high 25-hydroxycholecalciferol 1 alpha-hydroxylase (1 alpha-hydroxylase) activity, but no 25-hydroxycholecalciferol 24-hydroxylase (24-hydroxylase) activity. Physiological concentrations of 1,25-dihydroxycholeclaciferol suppress 1 alpha-hydroxylase and induce 24-hydroxylase activity. The inhibition of 1 alpha-hydroxylase preceded the induction of 24-hydroxylase. In contrast, oestradiol-17 beta had no effect on the activity of either hydroxylase under a variety of experimental conditions. These results clearly demonstrate that 1,25-dihydroxycholecalciferol, but not oestrogen, acts directly on the kidney cells to regulate the metabolism of 25-hydroxycholecalciferol.
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D006887:Hydroxycholecalciferols / Q000378:metabolism* / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D004958:Estradiol; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase