Stimulation by enkephalins of D-glucose absorption in rabbit ileum.
In intact tissue, DAGO ([D-Ala2, MePhe4, Gly-ol5]enkephalin; 10(-5) M; mu-ligand; addition on the serosal side) stimulated D-glucose absorption and D-glucose-dependent variations in short-circuit current (delta Isc,glu); naloxone (10(-6) M) antagonized these effects. DADLE ([D-Ala2, D-Leu5]enkephalin, mainly a delta-ligand; 10(-5) M) and (pCl-Phe4)-DPDPE ([D-pen2, p-chloro-Phe4, D-Pen5]enkephalin, a more selective delta-ligand; 10(-5) M) did not significantly stimulate delta Isc,glu (addition on the serosal side). In the absence of the muscularis and myenteric plexus or using intact tissue treated with tetrodotoxin (TTX; 3 x 10(-7) M), DAGO was unable to increase delta Isc,glu. Addition of DAGO to the mucosal side did not induce any variations in delta Isc,glu. In conclusion, DAGO is able to increase D-glucose absorption by interacting with mu-receptors located in the myenteric plexus.
Meyer
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G
Dipartimento di Fisiologia e Biochimica Generali, Università degli Studi di Milano, Italy.
Bottà
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G
Cremaschi
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D
D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism; D009197:Myenteric Plexus / Q000502:physiology; D011817:Rabbits; D017450:Receptors, Opioid, mu / Q000187:drug effects
D004745:Enkephalins; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D005947:Glucose