title: 1,25-Dihydroxyvitamin D3 receptor replenishment in the chicken intestine.
abstract: 1,25-Dihydroxyvitamin D3 intestinal receptor replenishment was examined in rachitic chickens after hormone administration. A single injection of 1,25-dihydroxyvitamin D3 caused an increase in the level of occupied receptors with a concomitant decrease in the amount of unoccupied receptors. Maximum occupancy occurred 1 h after hormone injection. The metabolic inhibitor of protein synthesis, cycloheximide, was employed to obtain additional information concerning the fate of 1,25-dihydroxyvitamin D3 receptor complexes. Cycloheximide, at a dose that effectively blocked protein synthesis, had no effect on the time-course or the magnitude of replenishment of nuclear receptors. Additionally, repletion with vitamin D3 or administration of several injections of 1,25-dihydroxyvitamin D3 did not lead to a lag in replenishment time or a significant decrease in total receptor levels. These findings demonstrate that recycling of receptors plays an important functional role for the replenishment of unoccupied 1,25-dihydroxyvitamin D3 intestinal receptors.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D003513:Cycloheximide / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007700:Kinetics; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000378:metabolism
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D003513:Cycloheximide; D002117:Calcitriol