[The site (central or peripheral) of the anti-ulcer action of dalargin, a synthetic analog of endogenous opioids in an experimental model of cysteamine-induced duodenal ulcer in rats].

Dalargin injected subcutaneously at a dose of 10 micrograms/kg decreased 4-5 fold ulcer manifestations in rats with cysteamine-induced duodenal ulcers. Intracerebroventricular dose of 2 micrograms diminished the manifestations to a lesser extent Dalargin only at a dose exceeding 500 micrograms intraperitoneally decreased significantly the in vivo binding of 3H-D-Ala2, D-Leu5-enkephalin with brain opiate receptors. We believe that Dalargin injected peripherally in small doses does not penetrate the blood-brain barrier and that its antiulcer activity is due to the interaction with peripheral opioid receptors. It seems possible that the disturbances in the central/peripheral ratio of the opioid activity plays an important role in the pathogenesis of duodenal peptic ulcer.