Anti-inflammatory steroids reduce tissue PG synthetase activity and enhance PG breakdown

Anti-inflammatory steroids reduce prostaglandin (PG) synthesis in intact cells and isolated organs by interfering indirectly with the phospholipase(s) which release the poly-unsaturated fatty acid precursors for both cyclooxygenase and lipoxygenase pathways. This action requires nucleic acid transcription and synthesis of new protein, and a soluble factor capable of inhibiting PG generation has been identified. However, it is not known whether these steroids affect either the actions or content of the enzymes of the PG system after administration in vivo, nor is it known if they affect PG-metabolizing enzymes. We show here that treatment of rats with anti-inflammatory steroids causes rapid changes in tissue activities of enzymes which synthesize and inactivate PGs, with apparent levels reduced and increased respectively.