PULMONARY PHOSPHOLIPID SATURATION INCREASES WITH GLUCOCORTICOID RECEPTOR MESSENGER-RNAS IN LATE-GESTATION BUT NOT DUE TO LABOR IN THE FETALRHESUS-MONKEY

We report here changes in abundance of pulmonary cytosolic phospholipa se A(2) (cPLA(2)) and glucocorticoid receptor (GR) mRNAs and phospholi pid (PL) fatty acids (FA) with gestational age, in either spontaneous or androstenedione-induced premature labor for 15 fetal rhesus monkeys and 1 neonate. Pulmonary RNA and lipids were extracted from the lungs of the rhesus monkeys, gestational ages ranging from 140 days to term . Northern hybridization analysis was performed for both cPLA(2) and G R mRNAs. The results demonstrated the transcript of the cPLA(2) consta ntly expressed and that of GR increased gradually in the lungs during the gestational stages studied. Phosphatidylcholine (PC), phosphatidyl glycerol (PG) and phosphatidylinositol (PI) were separated by thin lay er chromatography and the fatty acid composition in these PL was quant ified by gas chromatography (GC). Regression analysis demonstrated tha t the expression of GR, mRNAs increased significantly with gestational age (P < 0.01). Furthermore, the level of GR mRNA is significantly co rrelated with that of cPLA(2), with Pearson correlation coefficient of 0.83 (P < 0.01). The PC palmitate percentage increased significantly with gestational age (P < 0.01), while the PC unsaturation index and t otal polyunsaturated FA decreased during late gestation (P < 0.01). Ch anges in PG FA with gestational age were similar to those in PC, while PI FA did not change with gestational age. There was no effect of eit her spontaneous or induced labor on mRNA levels of cPLA(2) and GR or t he FA composition of pulmonary PL studied. We conclude that the pulmon ary PL FA compositions are under developmental control.