Neuropeptides in the human appendix - Distribution and motor effects

Research output: Contribution to journalArticle

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.

Details

Authors
Organisations
External organisations
  • Lund University
Research areas and keywords

Keywords

  • appendix, neuropeptides
Original languageEnglish
Pages (from-to)1217-1230
Number of pages14
JournalDigestive Diseases and Sciences
Volume34
Issue number8
Publication statusPublished - 1989 Aug 1
Publication categoryResearch
Peer-reviewedYes