Stimulation of fetal lung surfactant production by administration of 17beta-estradiol to the maternal rabbit.

We have investigated the effect of 17beta-estradiol on lung surfactant production in the fetal rabbit. Pregnant rabbits were administered intramuscularly 75microgram of 17beta-estradiol per day at 25 and 26 days' gestation. Control rabbits were similarly injected with the solvent only. At 27 days' gestation the fetuses were delivered by cesarean section and the lungs of the newborn rabbits were lavaged in situ with 0.9 per cent NaCl. Analysis of lung lavage and lavaged lung tissue phospholipids yielded the following results: (a) The 17beta-estradiol--treated group had three to four times more total phospholipid and phosphatidylcholine in the lung lavage than the control group. (b) The phosphatidylcholine/sphingomyelin ratio in the lung lavage was significantly higher in the treated than in the control group. (c) The lavaged lung tissue of the treated group had almost twice as much total phospholipid and phosphatidylcholine as the control group. These changes in lung phospholipid content and composition are in the direction of increased lung maturity and suggest that estrogen may have a role in fetal lung maturation and surfactant production.