Effect of dexamethasone on the synthesis of dipalmitoyl phosphatidylcholine

Glucocorticoids are known to enhance surfactant production by stimulating the formation of phosphatidylcholine. This study was performed to determine the effect of steroids on one of the pathways involved in the incorporation of palmitic acid into phosphatidylcholine--the 'deacylation-reacylation pathway'. Palmitoyl CoA synthetase, lysopalmitoyl cholineacyltransferase and phospholipase A2 were enhanced significantly as a result of direct administration of dexamethasone into 27-day fetal rabbits. Cycloheximide inhibited the steroid induced enhancement of activity. Immunologic studies demonstrated an accelerated rate of synthesis of palmitoyl CoA as a result of the dexamethasone treatment. The data suggest that steroids are capable of inducing enzymes of the 'deacylation-reacylation pathway' involved in palmitate incorporation into phosphatidylcholine thereby contributing to the acceleration of dipalmitoyl phosphatidylcholine biosynthesis.