NEW INSIGHTS INTO PROSTAGLANDINS AND MUCOSAL DEFENSE

A role for prostaglandins in maintaining mucosal integrity in the gast rointestinal tract is well documented. While traditionally the effects of prostaglandins on mucosal blood flow and epithelial function have been regarded as critical in the mechanism of action of these fatty ac ids, recent evidence that mucosal ulceration is almost invariably asso ciated with mucosal inflammation has caused a reevaluation of the role of prostaglandins in mucosal defence. This review focuses on the abil ity of prostaglandins to exert anti-inflammatory, and therefore anti-u lcerogenic, effects in the gastrointestinal tract. These effects of pr ostaglandins are attributable to their ability to suppress the release of inflammatory mediators and reactive oxygen metabolites from a numb er of immunocytes, stromal cells and inflammatory cells. There is emer ging evidence for cooperative interactions between prostaglandins and nitric oxide in maintaining mucosal integrity. Recent work on the indu cible isoform of prostaglandin synthase as it pertains to mucosal defe nce is also reviewed.