Abstract
Neurons of the guinea pig IMG are surrounded by nerve fibers containing CGRP-like immunoreactivity (LI). The purpose of this study was to determine whether colonic distension releases CGRP-LI in the IMG and whether opioid peptides and neurotensin(8-13) [NT(8-13)] modulate its release. Colonic distension released CGRP-LI. Methionine-enkephalin acted through mu and/or delta receptors to block release. NT(8-13) had no effect on release of CGRP-LI. Capsaicin pretreatment reduced the content of CGRP-LI in the IMG by 37%. Colonic distension did not release CGRP-LI from capsaicin-insensitive fibers. The data suggest that colonic distension releases CGRP-LI material from capsaicin-sensitive nerves and that enkephalins modulate release of CGRP-LI.
Publication types
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Afferent Pathways / drug effects
-
Afferent Pathways / metabolism
-
Animals
-
Calcitonin Gene-Related Peptide / metabolism*
-
Calcium / pharmacology
-
Capsaicin / pharmacology
-
Colon / innervation
-
Colon / physiology
-
Enkephalin, Leucine / pharmacology
-
Enkephalin, Methionine / pharmacology
-
Ganglia / drug effects
-
Ganglia / metabolism*
-
Guinea Pigs
-
In Vitro Techniques
-
Magnesium / pharmacology
-
Male
-
Mesentery / innervation*
-
Nerve Endings / drug effects
-
Nerve Endings / metabolism
-
Neurotensin / pharmacology
-
Peptide Fragments / pharmacology
-
Potassium / pharmacology
Substances
-
Peptide Fragments
-
Neurotensin
-
Enkephalin, Methionine
-
Enkephalin, Leucine
-
neurotensin (8-13)
-
Magnesium
-
Calcitonin Gene-Related Peptide
-
Potassium
-
Capsaicin
-
Calcium