STUDIES ON THE ACTION OF DEXAMETHASONE ON PROSTAGLANDIN PRODUCTION BYFRESHLY DISPERSED AMNION CELLS

The human amnion may be an important source of prostaglandins (PGs) du ring pregnancy and possibly labor. Glucocorticoids stimulate PG produc tion in confluent amnion cell cultures, but in freshly dispersed cells they inhibit PG production. The purpose of the present study was to d etermine if this inhibitory effect occurred at the level of arachidoni c acid release from lipids. Cells were labeled with radioactive arachi donate and the release of radioactivity was measured in the presence o r absence of dexamethasone. No significant effect of dexamethasone tre atment was observed. The possibility that glucocorticoid treatment inh ibited the release of arachidonate from a specific species of phosphol ipid was also examined. However, no difference was found in the distri bution of arachidonate between lipids isolated from glucocorticoid-tre ated and untreated cells. Furthermore. dexamethasone treatment did not alter the lipocortin 1 and 2 content of dispersed cells, determined f ollowing sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. These studies indicate that the inhibition of prostag landin production by dispersed amnion cells by glucocorticoids most li kely occurs at a point distal to arachidonic acid release.