[Effect of a dinorphin fragment and naloxone on the development of experimental duodenal ulcer in rats].

The influence of dinorphine 1-6 and naloxone on the appearance of experimental duodenal ulcers, induced by cysteamine, was studied in rats. It was revealed that the 15 micrograms/kg dose of dinorphine 1-6 distinctly blocks the formation of ulcers. Naloxone prevents dose-dependently the effect of dinorphine 1-6 on ulcer-formation, indicating that dinorphine acts through specific opiate receptors. Naloxone itself also shows moderate anti-ulcer activity, that disappears with the increase of the preparation dose. Mechanisms of the paradoxical naloxone action in the given experimental model from the point of view of existence of its own pharmacological activity are being discussed.