STIMULATION BY ENKEPHALINS OF D-GLUCOSE ABSORPTION IN RABBIT ILEUM

In intact tissue, DAGO ([D-Ala(2), MePhe(4), Gly-ol(5)]enkephalin; 10( -5) M; mu-ligand; addition on the serosal side) stimulated D-glucose a bsorption and D-glucose-dependent variations in short-circuit current (Delta I-sc,I-glu); naloxone (10(-6) M) antagonized these effects. DAD LE ([D-Ala(2), D-Leu(5)]enkephalin, mainly a delta-ligand; 10(-5) M) a nd (pCl-Phe(4))-DPDPE ([D-pen(2), p-chloro-Phe(4), D-Pen(5)]enkephalin , a more selective delta-ligand; 10(-5) M) did not significantly stimu late Delta I-sc,I-glu (addition on the serosal side). In the absence o f the muscularis and myenteric plexus or using intact tissue treated w ith tetrodotoxin (TTX; 3x10(-7) M), DAGO was unable to increase Delta I-sc,I-glu. Addition of DAGO to the mucosal side did not induce any va riations in Delta I-sc,I-glu. In conclusion, DAGO is able to increase D-glucose absorption by interacting with mu-receptors located in the m yenteric plexus.