Effect of retinoids on fetal lung development in the rat

We investigated the effect of retinoids on fetal lung development in the rat. The concentration of retinyl palmitate increased rapidly to a peak on day 17 of gestation and decreased to a minimum on day 21 of gestation; there was a slight increase after birth. Retinoid acid receptor (RAR)-alpha and -beta mRNA were detected in all samples obtained from perinatal and adult rat lung, and only a trace of RAR-gamma mRNA was detected in the fetuses on days 15, 17 and 19 of gestation and in the adults by reverse transcriptase-polymerase chain reaction. After a maternal retinol deficiency of 28 days' duration, fetal body and lung weights were significantly lower than those of controls; the concentrations of retinyl palmitate and phosphatidylcholine (PC) in the lung after a maternal retinol deficiency of 14, 21, or 28 days were significantly lower than those of controls. Expression of RAR-beta mRNA in the group with 28-day retinol deficiency was lower than in controls, that of RAR-alpha mRNA was increased and that of RAR-gamma mRNA was not influenced by retinol deficiency. The rate of choline incorporation into PC in fetal lung explants was significantly higher in the group treated with retinoic acid (RA) than in controls. RA enhanced the effect of epidermal growth factor on choline incorporation and prevented that of dexamethasone.(ABSTRACT TRUNCATED AT 250 WORDS)