INHIBITION OF PGE1 INDUCED INTESTINAL SECRETION BY THE SYNTHETIC ENKEPHALIN ANALOG FK-33-824

1. The effects of the enkephalin analogue, FK 33-824 were compared with those of morphine and naloxone on the prostaglandin E1-induced increase in intestinal fluid volume in unanaesthetized and pithed rats. 2. FK 33-824 inhibits, the prostaglandin E1-induced increase in intestinal fluid volume both in unanaesthetized and pithed rats. 3. Naloxone abolished the inhibitory effect of FK 33-824 in both experimental models. 4. It can be concluded from the experiments in pithed rats that the inhibitory effect of FK 33-824, like that of morphine, on prostaglandin E1-induced secretion is caused by a peripheral action. 5. It is assumed that endogenous enkephalins protect against prostaglandin-mediated loss of fluid into the gut lumen. This protective effect can be mimicked by an enkephalin analogue and blocked by naloxone. © 1979 Springer-Verlag.