Glucocorticoid receptors in murine visceral yolk sac and liver during development

Abstract

Specific binding of triamcinolone acetonide was analyzed in cytosols from developing mouse visceral yolk sac and fetal, neonatal and adult liver. In the visceral yolk sac, binding capacity increased from 1 × 10 3 sites/cell on day 10 to maximal levels (9 × 10 3 sites/cell) on day 14 of gestation. In fetal liver, binding sites were low (2 × 10 3 sites/cell) from day 14 to 18, increased rapidly after birth to approx. 1.7 × 10 4 sites/cell by day 9 postpartum and were present at approx. 3 × 10 4 sites/cell in adult liver. Scatchard analysis of the data indicated the presence of a single class of cytosolic binding sites of limited capacity and high affinity ( K d = 2–4 nM). The level of specific nuclear binding 2 h after injection of [ 3H]triamcinolone acetonide was proportional to the number of cytosolic binding sites/cell for each tissue tested. The physicochemical characteristics of cytosolic glucocorticoid-receptor complexes were examined by DEAE-Sephadex A-50 column chromatography. “Unactivated” complexes from visceral yolk sac, fetal and adult liver eluted at approx. 0.4 M KCl. Heat “activated” complexes from fetal and adult liver eluted at approx. 0.25 M KCl, whereas those from visceral yolk sac eluted in the prewash fractions (0.02 M potassium phosphate buffer). These results provide evidence that quantitative but not qualitative changes in glucocorticoid receptors occur during liver development and also establish the presence of glucocorticoid receptors in the midgestation mouse visceral yolk sac.