Complex morphology of gastrin-releasing G-cells in the antral region of the mouse stomach

Abstract

Gastrin-releasing enteroendocrine cells (G-cells) are usually described as flask-shaped cells with a large base and a small apical pole, integrated in the epithelium lining the basal region of the antral invaginations in the stomach. By means of a transgenic mouse line in which the enhanced version of GFP is endogenously expressed under the control of a gastrin promoter, we have analyzed the spatial distribution and morphological features of G-cells. We found that G-cells were not only located at the basal region of the invagination but to a lesser extent also at the upper region. Visualization of the entire cellular morphology revealed that G-cells show complex morphologies. Basally located G-cells are roundish-shaped cells which project a prominent apical process towards the lumen and extend basal protrusions containing the hormone gastrin that were frequently found in close proximity to blood vessels and occasionally in the vicinity of nerve fibers. Inspection of G-cells in the upper region of antral invaginations disclosed a novel population of G-cells. These cells have a spindle-like contour and long apical and basal processes which extend vertically along the antral invagination, parallel to the lumen. This G-cell population seems to be in contact with a network of nerve fibers. While the functional role of these untypical G-cells is still elusive, the results of this study provide some useful indications to possible roles of these G-cells.

Topographic distribution pattern of morphologically different G cells in the murine antral mucosa

“…As initially observed in our previous study, 6 G cells differed in their morphology and their localization within the antral invaginations ( Figure 3A ). While basally located G cells were pyramidal- or roundish-shaped ( Figure 3B ), G cells in the upper region of the invaginations had a spindle-like contour and long processes ( Figure 3C ).…”

“… 14-16 Recently we have uncovered that individual G cells showed pivotal differences in their morphology which correlated with their localization in the antral invaginations; while basally located G cells were pyramidal- or roundish-shaped, G cells in the upper region of the invaginations had a spindle-like contour and long processes. 6 Based on preliminary experiments in which we determined the life span of antral G cells using BrdU labeling, we are confident that morphologically different G cells constitute distinct G cell subtypes rather than different developmental stages. By quantifying the number of BrdU-positive cells at distinctive time points post injection, we observed that G cells in the upper region exhibit a life span up to 3 days, whereas G cells in the basal region became 63 days and older.…”

“…In the course of this we uncovered that individual G cells show pivotal differences in their morphology and their localization in the epithelium lining the tubular invaginations. 6 The functional implications of these different G cell types are still elusive. Towards a further characterization of these cells, in this study attempts have been made to elucidate the distribution of the two G cell types, not only along an individual antral tubular gland, but rather throughout the different regions of the antrum.…”

Mechanosensitive ion channel Piezo1 is expressed in antral G cells of murine stomach

“…To overcome this obstacle, we used a transgenic mGas-EGFP mouse line (Takaishi et al 2011 ) in which EGFP is expressed under the promoter of the gastrin gene. The marker EGFP is distributed throughout the cells and thus allows the visualization of the complete morphology of the G cells in the antrum of the mouse stomach (Frick et al 2016 ). On longitudinal sections through the antrum mucosa of the transgenic mouse line, several green fluorescent cells were visible at the base of the invaginations because of the expressed EGFP (Fig.…”

The Gastric and Intestinal Microbiome: Role of Proton Pump Inhibitors

“…It is secreted by G cells of the stomach that are localized to the antrum. [10] Gastrin can stimulate gastric acid production by two distinctive mechanisms. Its major action (indirect mechanism) is via binding to cholecystokinin-2 (CCK-2) receptors found on ECL cells.…”