Corticosteroid receptors in the kidney of chick embryo. II. Ontogeny of corticosterone receptor and cellular development.
In this study the ontogeny of cytosol receptors for corticosterone in the chick embryo kidney was examined and then this ontogenic profile was compared with that of an index of cellular development, i.e., the enzyme ornithine decarboxylase (ODC). The corticosterone receptor concentration (nmax) increased by sevenfold from Day 12 to Day 15 of embryogenesis and then declined to its lowest level by the time of hatching (Day 21). Similar results were obtained when dexamethasone was used as ligand, except that the baseline values at Day 9 and 21 were higher than those found with corticosterone. An identical ontogenic profile was obtained when the results were corrected for the endogenous glucocorticoids present in the cytosol. This increase of the corticosterone receptor occurred simultaneously with the enhanced adrenal corticoid synthesis. The ODC also showed a marked increase and a rapid fall during chick embryogenesis, but the enzyme activity was at its maximum when the corticosterone receptor number was still low (Days 12 and 13) and quickly decreased by the time the receptors had reached their highest levels (Days 14 and 15). The lowest level of ODC was observed immediately before hatching. These results indicate that during chick embryogenesis adrenal corticoids may induce the development of the corticosteroid receptor and that such development may cause a suppression of ODC activity. This suppressive effect of glucocorticoids could represent a mechanism of hormonal action on the kidney.
D000367:Age Factors; D000818:Animals; D002642:Chick Embryo; D003907:Dexamethasone / Q000378:metabolism; D007668:Kidney / Q000196:embryology* / Q000201:enzymology / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*
D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; C024357:corticosterone receptor; D003907:Dexamethasone; D009955:Ornithine Decarboxylase