Faculty Collaboration Database

Identification of cells that express 5-hydroxytryptamine1A receptors in the nervous systems of the bowel and pancreas. J Comp Neurol 1996 Jan 15;364(3):439-455

Date

01/15/1996

Pubmed ID

8820876

DOI

10.1002/(SICI)1096-9861(19960115)364:3<439::AID-CNE5>3.0.CO;2-5

Scopus ID

2-s2.0-0030068336 (requires institutional sign-in at Scopus site)   72 Citations

Abstract

Although serotonin (5-HT)1A receptors are known to be present on neural elements in both the bowel and the pancreas, the precise location of these receptors has not previously been determined. Earlier investigations have suggested that 5-HT1A receptors are synthesized in enteric, but not pancreatic ganglia, and that they mediate pre-and postjunctional inhibition. Wholemount in situ hybridization was used to identify cells that contain mRNA encoding 5-HT1A receptors, and immunocytochemistry was employed to locate receptor protein. mRNA encoding 5-HT1A receptors was found in the majority of neurons in both submucosal and myenteric plexuses. 5-HT1A immunoreactivity, however, was abundant only on the surfaces of a limited subset of nerve cell bodies and processes. 5-HT-immunoreactive axons were found in close proximity to sites of 5-HT1A immunoreactivity. Myenteric, but not submucosal calbindin-immunoreactive neurons (with Dogiel type II morphology) were surrounded by rings of 5-HT1A immunoreactivity. The cytoplasm of the cell bodies and dendrites of a small subset of Dogiel type I neurons was also intensely 5-HT1A immunoreactive. Most of the Dogiel type I 5-HT1A-immunoreactive myenteric neurons, and some of the type II neurons that were ringed by 5-HT1A immunoreactivity became doubly labeled following injections of the retrograde tracer, FluoroGold (FG), into the submucosal plexus. 5-HT1A-immunoreactive neurons in distant submucosal ganglia also became labeled by retrograde transport of FG. None of the 5-HT1A-immunoreactive cells were labeled by the intraluminal administration of the beta-subunit of cholera toxin, a marker for vasoactive intestinal peptide-containing secretomotor neurons. These observations suggest that some of the myenteric 5-HT1A-immunoreactive neurons project to submucosal ganglia and that the submucosal 5-HT1A-immunoreactive cells are interneurons. In addition to neurons, a subset of 5-HT-containing enterochromaffin cells expressed 5-HT1A immunoreactivity, which was co-localized with 5-HT in secretory granules. In the pancreas, 5-HT1A immunoreactivity was observed in ganglia, acinar nerves, and glucagonimmunoreactive islet cells. Serotonergic enteropancreatic axons have been found to terminate in close proximity to each of these structures, which may thus be the targets of this innervation. The abundance of 5-HT1A receptor immunoreactivity on nerves of the gut and pancreas suggests that drugs designed to interact with these receptors may have unanticipated visceral actions.

Author List

Kirchgessner AL, Liu MT, Raymond JR, Gershon MD

Author

John R. Raymond MD President, CEO, Professor in the President department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Calbindins
Enteric Nervous System
Female
Fluorescent Dyes
Guinea Pigs
Immunohistochemistry
In Situ Hybridization
Intestinal Mucosa
Intestines
Male
Motor Neurons
Myenteric Plexus
Nerve Tissue Proteins
Pancreas
RNA, Messenger
Rats
Receptors, Serotonin
S100 Calcium Binding Protein G
Stilbamidines