Phosphatidylcholine and phosphatidylethanolamine metabolites may regulate brain phospholipid catabolism via inhibition of lysophospholipase activity

Brain levels of glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE), abundant metabolites of phosphatidylcholine and phosphatidylethanola mine, are increased in several disorders of the human brain. To determine w hether accumulation of these compounds may alter phospholipid metabolism, w e assessed the ability of GPE and GPC to modulate the activities of phospho lipase A,, lysophospholipase, and other enzymes involved in phospholipid me tabolism, in preparations of human brain parietal cortex. GPC and GPE acted as competitive inhibitors of lysophospholipase activity, but failed to alt er the activity of the other enzymes tested. Our results suggest that GPC a nd GPE may normally act to inhibit lysophospholipid hydrolysis, thereby red ucing the rate of membrane phospholipid degradation. (C) 1999 Elsevier Scie nce B.V. All rights reserved.