Effect of maternal dexamethasone treatment on fetal lung vitamin A stores in the perinatal rat.

Vitamin A (retinol) is essential for normal differentiation of developing respiratory epithelium. Significant vitamin A storage occurs in the fetal lung near term (gestational day 21) in the perinatal rat, and the developing lung may be dependent on these local vitamin A stores during growth and differentiation. The growth and differentiation of fetal lungs can be enhanced by maternal treatment with glucocorticosteroids. We conducted this study in rats to determine the effect of maternal dexamethasone treatment on the lung stores of vitamin A in the offspring. Vitamin A-sufficient pregnant rats were given by intraperitoneal injection a single dose of either dexamethasone (300 micrograms) or 0.9% saline solution on gestational day 16. High performance liquid chromatography was used to measure concentrations of vitamin A and its esters, retinyl palmitate and stearate, in fetal and neonatal lungs and livers at times ranging from gestational day 19 through 21, and from postnatal day 1 through 7. The concentrations of vitamin A esters in the lungs of fetuses and newborn pups of the dexamethasone-treated animals were significantly lower than those of the control group in all determinations, the values ranging between 22 and 50% of controls. In contrast, the concentrations of vitamin A esters in the livers did not differ significantly between study groups. We conclude that a prompt, sustained, and selective decrease in the fetal lung stores of vitamin A appears to occur following maternal antenatal dexamethasone treatment. This decrease in the fetal lung vitamin A stores might be due to increased utilization of vitamin A associated with enhanced differentiation of the fetal lung induced by maternal dexamethasone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)