Neuropeptides in the human appendix - Distribution and motor effects

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Abstract

At present our knowledge of enteric peptide-containing neurons in man is limited. In this study we have used human appendices removed at surgery to examine the peptidergic innervation by immunocytochemistry, immunochemistry, and pharmacological in vitro experiments. Immunocytochemistry revealed a variety of peptide-containing nerve fiber populations in the human appendix. VIP/PHI-, VIP/PHI/NPY-, SP/NKA-, galanin-, and enkephalin-containing nerve fibers were numerous; CGRP- and GRP- containing nerve fibers were moderate in number, while only scattered NPY-, enkephalin/BAM-, and somatostatin-containing nerve fibers could be found. No CCK-, dynorphin A-, or dynorphin B- immunoreactive nerve fibers could be detected. The coexistence of VIP/PHI, SP/NKA, and enkaphalin/BAM can be anticipated from the known sequence of their respective precursors. However, the coexistence of VIP/PHI and NPY was unexpected but corroborates previous observations in other species. Interestingly, SP and CGRP did not seem to coexist in nerve fibers of the human appendix. Immunochemistry (RIA and HPLC) confirmed the presence of VIP, NPY, SP, galanin, CGRP, GRP, enkephalin, and somatostatin. Motor activity studies suggest that acetylcholine plays a major role in the electrically evoked contractions, since atropine suppressed these contractions. Galanin (10-8-10-6 M) and GRP (10-9-10-7 M) caused concentration-dependent contractions that were unaffected by tetrodotoxin and thus probably reflect a direct action on smooth muscle receptors. GRP (10-9 M) enhanced the electrically induced cholinergic contraction (to 193±24%), while met-enkephalin (10-6 M) reduced it (to 54±6%). Both peptides failed to affect the contractile response to exogenous acetylcholine and probably act to modulate the release of acetylcholine. NPY, VIP, CGRP, SP, and somatostatin failed to induce contraction or to affect the electrically evoked contractions.

Detaljer

Författare
Enheter & grupper
Externa organisationer
  • Lund University
Forskningsområden

Nyckelord

Originalspråkengelska
Sidor (från-till)1217-1230
Antal sidor14
TidskriftDigestive Diseases and Sciences
Volym34
Utgivningsnummer8
StatusPublished - 1989 aug 1
PublikationskategoriForskning
Peer review utfördJa