Variations in the levels of cytoplasmic glucocorticoid receptors in lungs of various species at different developmental stages.

TLDR: Cytoplasmic fractions obtained from lungs of several animal species at different stages of development were examined for dexamethasone receptors and lower but significant levels of the dexamETHasone binding component were found in lungs of mature rabbits but it could not be detected in lungs in adult rats, mice, hamsters or guinea pigs.

Abstract: Cytoplasmic fractions obtained from lungs of several animal species at different stages of development were examined for dexamethasone receptors. Specific dexamethasone binding was measured by a charcoal assay and by sucrose density gradient centrifugation. Dexamethasone receptors were demonstrated in the lungs of rabbit fetuses between the 21st day of gestation and birth, rat fetuses during the last 3 days of pregnancy, guinea pig fetuses at 35–45 days of gestation and human fetuses at the 9th to 17th gestational weeks. The dexamethasone receptors present in all the species examined sediment near 7S on linear 10–30% sucrose gradients. In human fetal lung cytosol the concentration of binding sites increased about 3-fold between the 9th and the 17th week of gestation. Lower but significant levels of the dexamethasone binding component were found in lungs of mature rabbits but it could not be detected in lungs of adult rats, mice, hamsters or guinea pigs. More detailed studies in the rat showed that the rec...