The effects of glucocorticoids on the distribution and mobilisation of arachidonic acid in fat cell ghosts

Abstract

1 The prostaglandin synthesizing enzymes were found to be present in fat cell ghosts isolated from rabbit adipose tissue. 2 Prostaglandin E2 (PGE2) and PGF2, were synthesized by ghosts after stimulation with adrenocorticotrophic hormone (ACTH). 3 Indomethacin was found to inhibit this synthesis but not the synthesis of lipoxygenase products. 4 When fat cell ghosts were stimulated by ACTH, fatty acid release was observed from both neutral lipids and phospholipids. 5 The arachidonic acid (AA) pool within the ghosts and identified: approximately 90% was present in the phospholipid fraction, 8.5% in the neutral lipids and 1.5% unbound. 6 The glucocorticoids were found to stimulate incorporation of [14C]-AA into neutral lipids and inhibit its incorporation into phospholipids. 7 When fatty acid release was stimulated with ACTH, the glucocorticoids were found to inhibit the mobilisation of [14C]-AA from the phospholipids and enhance its release from the neutral lipids. 8 The glucocorticoids inhibit prostaglandin formation in fat cell ghosts.