Modulation by opioid peptides of mechanosensory pathways supplying the guinea-pig inferior mesenteric ganglion.
1. Radioimmunological techniques were used in isolated guinea-pig inferior mesenteric ganglion (IMG)-colon preparations to determine whether opioid peptides and neurotensin8-13 (NT8-13), the C-terminal region of NT1-13 recognized by neurotensin receptors, modulate distension-induced release of substance P (SP)- and vasoactive intestinal polypeptide (VIP)-like immunoreactive (LI) material. 2. Colonic distension significantly increased the amount of SP- and VIP-LI material released in the ganglionic superfusate. A low-Ca2+ (0.1 mM), high-Mg2+ (15 mM) solution blocked their release. 3. In vivo capsaicin pretreatment abolished release of SP-LI material during colonic distension but had no significant effect on distension-induced release of VIP-LI material. 4. The addition of [Leu5]enkephalin, [Met5]enkephalin, PL017 (a mu-receptor agonist) and DPDPE (a delta-receptor agonist) to the ganglion side of a two-compartment chamber blocked distension-induced release of SP-LI material. The addition of naloxone and ICI-174,864 (a delta-receptor antagonist) to the ganglion compartment reversed the inhibitory effect of the mu- and delta-receptor agonists. 5. Addition of [Leu5]enkephalin and [Met5]enkephalin to the ganglion compartment had no significant effect on release of VIP-LI material during colonic distension. 6. Addition of NT8-13 to the ganglion compartment significantly increased in the amount of SP-LI material released during colonic distension but had no affect on distension-induced release of VIP-LI material. 7. The results suggest the hypothesis that under in vivo conditions, enkephalinergic nerves decrease and neurotensinergic nerves increase the release of SP from peripheral branches of primary afferent sensory nerves.
Ma
R C
RC
Department of Physiology and Biophysics, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
Szurszewski
J H
JH
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D005724:Ganglia / Q000187:drug effects*; D006168:Guinea Pigs; D008297:Male; D009434:Neural Pathways / Q000187:drug effects; D018847:Opioid Peptides / Q000494:pharmacology*; D011863:Radioimmunoassay; D013373:Substance P / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
D018847:Opioid Peptides; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D013779:Tetrodotoxin; D001920:Bradykinin