title: Decreased 1,25-dihydroxycholecalciferol and increased 25-hydroxy- and 24,25-dihydroxycholecalciferol in tissues of rats treated with thyroxine.
abstract: The effect of thyroxine on the metabolism of vitamin D was investigated in rats. Vitamin D depleted rats were repleted by injections of radiolabelled cholecalciferol or 25-hydroxycholecalciferol (25OHD3). After 3 weeks, a state of hyperthyroidism was induced by daily injections of L-thyroxine for 21 days. The lipid extracts of the Plasma and tissues were analyzed by successive Sephadex LH-20 and high pressure liquid chromatography. The concentrations of 25OHD3 and of 24,25-dihydroxycholecalciferol (24,25 (OH)2D3) were significantly higher and those of cholecalciferol and of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) were significantly lower in the plasma and tissues of animals treated with thyroxine than in controls. The present study suggests that alterations in the metabolism of vitamin D may be involved in the disturbances of calcium metabolism observed in hyperthyroidism.
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D002112:Calcifediol; D002117:Calcitriol / Q000378:metabolism*; D002762:Cholecalciferol / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D006980:Hyperthyroidism / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000494:pharmacology*
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D002762:Cholecalciferol; D015650:24,25-Dihydroxyvitamin D 3; D002117:Calcitriol; D002112:Calcifediol; D013974:Thyroxine