Glucocorticoids and fetal lung development

Abstract

Acceleration of fetal lung development by administration of glucocorticoid hormones has been demonstrated in a number of mammalian species. Dexamethasone 10 −5 M significantly depressed protein content per explant in the presence and absence of insulin. Insulin did not alter the protein content but significantly increased radioactive choline incorporation. However, dexamethasone provided no added stimulation above that observed with insulin alone. The incorporation of radioactive choline and specific activities in isolated phosphatidylcholine were almost identical in control and dexamethasone (10 −7 M) treated explants. The data presented demonstrate a modest but significant increase in choline incorporation using a concentration of dexamethasone of 10 −9 M. At higher concentrations of dexamethasone, the incorporation was significantly depressed using an 8 day exposure time. Although choline incorporation increases as a function of gestational age with a burst in rate on the last day of fetal life, dexamethasone suppresses this activity at all developmental ages past 19.5 days. The only conclusion that appears valid at this time is the rat fetal lung system reported here differs in an unknown way when compared to the rabbit monolayer system, the human organ culture, and the in vivo situation.