Influence of estrogen on renal vitamin D hydroxylases and serum 1alpha,25-(OH)2D3 in chicks.
The influence of estrogen on the metabolism of 25-hydroxyvitamin D3 was studied in 2- to 5-wk-old chicks. Single injections of at least 500 microgram diethylstibestrol (DES) increased the conversion of 25-hydroxyvitamin D3 to 1alpha,25-dihydroxyvitamin D3 (1alpha,25-(OH)2D3) and suppressed the production of 24,25-dihydroxyvitamin D3 in chick kidney homogenates. Acute (one 5-mg) injections of testosterone or progesterone did not enhance the 25-hydroxyvitamin D3-1alpha-hydroxylase, indicating specificity. However, chronic pretreatment with DES appeared to allow the potentiation of previously unstimulatory steroids such as progesterone and testosterone. In addition, the hormonal metabolite of vitamin D3, 1alpha,25-(OH)2D3, was measured in 4- to 6-wk chick plasma after steroid treatment. Greater than 1 mg DES per day for 5 days was necessary to enhance the circulating level of 1alpha,25-(OH)2D3; testosterone alone had no effect. This elevation was rapid, occurring within 12--24 h after injection. These data suggest that estrogen (as evidenced by DES treatment) is a modulator of vitamin D metabolism along with other known regulators such as parathyroid hormone, phosphate, and 1alpha,25-(OH)2D3. The mechanism of the regulation is as yet unknown.
D000818:Animals; D002136:Calcium, Dietary / Q000008:administration & dosage; D002645:Chickens; D002762:Cholecalciferol; D004054:Diethylstilbestrol / Q000494:pharmacology; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D008297:Male; D011374:Progesterone / Q000494:pharmacology; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism*
D002136:Calcium, Dietary; D004100:Dihydroxycholecalciferols; D004967:Estrogens; D006887:Hydroxycholecalciferols; D014807:Vitamin D; D002762:Cholecalciferol; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D004054:Diethylstilbestrol; D013250:Steroid Hydroxylases