Vesicular monoamine transporters in the rat stomach

Cellular distribution of vesicular monoamine transporters (VMATs), known to regulate vesicular storage and release of biogenic amines (i.e., catechola mines, serotonin, histamine, etc.), have been studied in the rat stomach us ing in situ hybridization histochemistry (ISHH) and immunohistochemical (IH C) techniques, S-35-UTP labeled riboprobes showed that mRNAs of both VMATs are expressed in the gastric mucosa. A combination of ISHH and MC verified that most of the parietal cells (among other epithelial cells) express mRNA of the peripheral type transporter (VMAT1) while enterochromaffin-like cel ls (ECL) of the fundic mucosa express mRNA of the central type (VMAT2). In addition, with double fluorescent IHC we detected VMAT1 protein in serotoni nergic enterochromaffin cells (EC) of the stomach and in gastrin producing G cells of the antral mucosa. Similarly to the fundus, VMAT2 protein was pr esent in ECL cells and in the enteric plexus. Surprisingly, serotonin- and/ or histamine-containing cells in the connective tissue compartments of the stomach (i.e,, lamina propria and submucosa), immunoreactive for a mast cel l specific antigen, displayed neither VMAT1 nor VMAT2 immunoreactivity. Dis tribution of VMATs in the rat stomach support our previous observations on aminergic properties of two important gastrointestinal (CT) epithelial cell populations primarily known for other specific secretory products, i.e. do paminergic properties of acid producing parietal cells and histaminergic pr operties of gastrin producing G cells. These data emphasize the existence o f a non-neuronal, intrinsic aminergic system in the GT tract. (C) 2000 Else vier Science Ltd. Published by Editions scientifiques et medicales Elsevier SAS.