EFFECTS OF ENDOTOXIN AND DEXAMETHASONE ON GROUP-I AND GROUP-II PHOSPHOLIPASE A(2) IN RAT ILEUM AND STOMACH

Phospholipase A(2) (EC 3.1.1.4) is a key enzyme in inflammation and is thought to play an important part in inflammatory diseases of the gastrointestinal tract. To investigate the nature and regulation of phospholipase A(2) activity in the gastrointestinal mucosa, the distribution of messenger ribonucleic acid (mRNA) for group II phospholipase A(2) in various parts of the rat gastrointestinal tract was studied, as well as the influence of endotoxin or dexamethasone, or both, on the group I and II phospholipase A(2) mRNA expression and activity in the rat glandular stomach and distal ileum. The results show that (a) group II phospholipase A(2) is present along the whole gastrointestinal tract, but in particularly large amounts in the distal ileum, (b) endotoxin increases group II, but not group I, phospholipase A(2) mRNA expression in the glandular stomach and distal ileum, and (c) dexamethasone reduces the endotoxin induced increases in group II phospholipase mRNA expression and activity in the gastrointestinal mucosa. These findings suggest that phospholipase A(2) of type II is a mediator of endotoxin effects in the gastrointestinal mucosa and that its expression at the mRNA level can be inhibited by corticosteroids.