Immunocytochemical and autoradiographic studies of the endocrine cells interacting with GABA in the rat stomach

Abstract

There are now increasing evidences suggesting that GABA is able of direct interaction with certain endocrine cells. In the present study, highly specific anti-GABA-glutaraldehyde antibodies and 3H-GABA uptake were used at the light and electron microscope levels to investigate the occurrence of cells containing endogenous GABA or taking up exogenous GABA in the mucosal antrum and corpus of the rat stomach. Only certain endocrine cell types of both regions were immunostained or grain-labelled. However, the morphology of their secretory granules did not allow to identify the nature of their hormone with certainty but suggested that somatostatin-like cells could interact with GABA. The combination of gastrin and somatostatin immunodetection with 3H-GABA uptake autoradiography at the light microscope level, revealed that a subpopulation of somatostatin-like cells and other still unidentified endocrine cells are able to take up GABA, while the gastrin-like cells are not. These results rei... Summary. There are now increasing evidences suggesting that GABA is able of direct interaction with certain endocrine cells. In the present study, highly specific anti-GABAglutaraldehyde antibodies and aH-GABA uptake were used at the light and electron microscope levels to investigate the occurrence of cells containing endogenous GABA or taking up exogenous GABA in the mucosal antrum and corpus of the rat stomach. Only certain endocrine cell types of both regions were immunostained or grain-labelled. However, the morphology of their secretory granules did not allow to identify the nature of their hormone with certainty but suggested that somatostatin-like cells could interact with GABA. The combination of gastrin and somatostatin immunodetection with aH-GABA uptake autoradiography at the light microscope level, revealed that a subpopulation of somatostatin-like cells and other still unidentified endocrine cells are able to take up GABA, while the gastrin-like cells are not. These results reinforce the hypothesis that certain endocrine cell types of the diffuse endocrine system of the digestive tract are able to directly interact with GABA.

Immunocytochemical Evidence Suggesting that Diamine Oxidase Catalyzes Biosynthesis of γ-Aminobutyric Acid in Antropyloric Gastrin Cells

“…Consequently, GABA in gastrin cells is most probably produced via DAO-catalyzed oxidation of putrescine, whereas GABA in somatostatin cells may have another origin. This hypothesis is well in line with the observations that somatostatin cells, but not gastrin cells, are capable of taking up exogenous GABA (Gilon et al 1990). The physiological function of GABA in the antropyloric mucosa is unresolved, but several reports indicate that it may play an active regulatory role.…”

Regulation of Gastrin, Somatostatin and Bombesin Release from the Isolated Rat Stomach by Exogenous and Endogenous Gamma-Aminobutyric Acid

“…In the rat gastric mucosa GABA-and GAD-immunopositive epithelial cells seem to be identical with endocrine cells [11][12][13][14]. It is speculated that GABA is colocalized, at least in part, with other regulatory transmitters in the endocrine cells.…”

“…It is speculated that GABA is colocalized, at least in part, with other regulatory transmitters in the endocrine cells. In contrast to G cells, several D cells of the gastric mucosa contain GABA as shown by immunohistochemical staining [12]. Furthermore, specific GABA A receptors have been demonstrated in the gastric mucosa [17].…”

“…Recently GABA was localized to nerve fibers within the gastric mucosal and submucosal layers and to epithelial cells of the gastric mucosa, in particular of the antral mucosa [1,[10][11][12][13]. The GABA-immunopositive epithelial cells cannot be seen in the surface epithelium but are confined to the middle and lower parts of the gastric glands and show secretory granules like endocrine cells [11][12][13]. Furthermore, GABA seems to be synthesized in mucosal and submucosal nerves and epithelial cells of the gastric glands as reflected by the presence of glutamic acid decarboxylase (GAD), the enzyme of GABA synthesis [14,15].…”

Gamma-Aminobutyric Acid Immunoreactivity in the Enterochromaffin Cells of the Rat Stomach

“…1987Gilon et al, 1988;Rcetz et al, 1991 ] and endocrine cells of the stomach and gut [Gilon et al, 1987[Gilon et al, . 1988[Gilon et al, , 1990[Gilon et al, , 1991Jessen et al, 1988: Davanger et al. 1989.…”