ROLE OF PROSTAGLANDINS IN GASTROPROTECTION

Numerous agents increase gastric mucosal resistance against intralumin al ulcerogens. Although the precise mechanisms of gastroprotection are uncertain, various endogenous mediators involved in gastroprotective effects have been characterized. As prostaglandins exert potent protec tive effects and inhibition of prostaglandin formation abolishes ''ada ptive gastroprotection,'' they have been proposed as key mediators in mucosal defense. This paper reviews the role of endogenous prostagland ins showing striking differences between different forms of gastroprot ection. Thus, whereas the protective effect of the antiulcer drug reba mipide involves prostaglandins as essential mediators, the protection conferred by the antacid hydrotalcit is prostaglandin-independent. Fur thermore, gastroprotection can occur even when mucosal prostaglandin g eneration is suppressed. This phenomenon has been observed with some n onsteroidal antiinflammatory drugs, agents that modulate sulfhydryls a nd certain metals. Recent data suggest that both cyclooxygenase-1- and cyclooxygenase-2-derived prostaglandins can increase mucosal resistan ce. The precise role of constitutive and inducible forms of cyclooxyge nase in gastroprotection, however, remains to be established.