Activation of mucosal phospholipase D in a rat model of colitis

Background and Aims: Phospholipase D (PLD) hydrolyzes phosphatidylcholine a nd produces lipid second messengers. Although cellular PLD has recently bee n recognized as an important signal-transmitting enzyme, the role of PLD in pathophysiologic conditions is largely unknown. In particular, the regulat ion of PLD in intestinal inflammation has not been previously investigated. The aim of the present study was to elucidate the role of PLD in experimen tal colitis. Methods: Rats were intracolonically administered acetic acid and assessed f or mucosal damage, mucosal PLD activity, mucosal myeloperoxidase activity, mucosal chemiluminescence and luminal concentration of leukotriene B-4. Ace tic acid treatment induced acute mucosal injury that was maximal at 24 h af ter treatment. Results: Mucosal PLD activity was significantly elevated and correlated wit h mucosal damage. Chemiluminescence in colitic mucosa was inhibited by the addition of ethanol which suppresses the formation of phosphatidic acid cat alyzed by PLD. Conclusion:These results suggest that PLD is activated in experimental coli tis in rats and that PLD may play a role in mucosal damage induced by react ive oxygen metabolites. (C) 2000 Blackwell Science Asia Pty Ltd.