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Modulation by opioid peptides of mechanosensory pathways supplying the guinea‐pig inferior mesenteric ganglion.
Author(s) -
Ma R C,
Szurszewski J H
Publication year - 1996
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1996.sp021227
Subject(s) - distension , vasoactive intestinal peptide , endocrinology , enkephalin , medicine , chemistry , agonist , (+) naloxone , receptor , substance p , ganglion , receptor antagonist , antagonist , neuropeptide , opioid , biology , anatomy
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.