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Identification of cells expressing somatostatin receptor 2 in the gastrointestinal tract of Sstr2 knockout/lacZ knockin mice

journal contribution
posted on 2023-05-17, 06:15 authored by Allen, JP, Alison CantyAlison Canty, Schultz, S, Humphrey, PP, Emson, PC, Young, HM
Somatostatin is found in neurons and endocrine cells in the gastrointestinal tract. The actions of somatostatin are mediated by a family of G-protein-coupled receptors that compose five subtypes (SSTR1-5), each of which is encoded by a separate gene. lacZ "knockin" mice, in which the reporter gene lacZ was engineered into the genomic locus of Sstr2 by gene targeting, were used to examine the expression pattern of Sstr2 and identify potential targets for neurally released and hormonal somatostatin in the gastrointestinal tract. In the body of the stomach, a large proportion of epithelial cells and subpopulations of myenteric neurons expressed Sstr2. Double- or triple-labeling with antisera to H(+)K(+)ATPase (to identify parietal cells) and/or histidine decarboxylase (to identify enterochromaffin-like [ECL] cells) combined with beta-galactosidase staining revealed that both parietal cells and ECL cells expressed Sstr2, and these two cell types accounted for almost all of the Sstr2-expressing epithelial cells. Somatostatin inhibits gastric acid secretion. The presence of SSTR2 on both parietal and ECL cells suggests that somatostatin acting on SSTR2 may reduce acid secretion by both acting directly on parietal cells and by reducing histamine release from ECL cells. In the small and large intestine, subpopulations of neurons in the myenteric and submucosal plexuses expressed Sstr2, and many of the Sstr2-expressing myenteric neurons also showed SSTR2(a) immunostaining. Most of Sstr2-expressing neurons in the myenteric plexus showed nitric oxide synthase (NOS) immunoreactivity. Previous studies have shown that NOS neurons are descending interneurons and anally projecting, inhibitory motor neurons. Thus, somatostatin acting at SSTR2 receptors on NOS neurons might modulate descending relaxation.

History

Publication title

The Journal of Comparative Neurology

Volume

454

Pagination

329-340

ISSN

0021-9967

Department/School

Tasmanian School of Medicine

Publisher

Wiley-Liss

Place of publication

Div John Wiley & Sons Inc, 605 Third Ave, New York, USA, Ny, 10158-0012

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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