[Central inhibition of external pancreatic secretion by D-ala-2-metenkephalinamide in rats]

Intracerebroventricular injections of D-Ala-2-Metenkephalinamide (D Alamide), a slowly metabolized Metenkephalin analogue, were made to conscious rats equipped with a chronic pancreatic fistula allowing the collection of pure pancreatic juice in its entirety. D Alamide induced a dose-related decrease in the volume of basal pancreatic secretion, as well as of bicarbonate and protein outputs. The effective doses of D Alamide were of the same order of magnitude as those necessary to induce analgesia or to decrease intestinal transit time in rats, as reported by others. The effect of D Alamide was totally blocked by naloxone, an opiate antagonist known to easily traverse the blood-brain barrier, while no blockade was found with naloxone methyl-bromide, an opiate antagonist which traverses the blood-brain barrier poorly and thus acts only peripherally. These results strongly suggest that the inhibition of pancreatic secretion induced by D Alamide is a central effect.