Localization of the Histamine H 2-Receptor and Gene Transcripts in Rat Stomach: Back to Parietal Cells

Abstract

In contrast with many physiological studies suggesting that histamine H 2 receptors are present on acid-secreting parietal cells of the gastric epithelium, it was recently shown that immune cells in the lamina propria are the only cells expressing H 2-receptor mRNAs (Mezey and Palkovits, Science,1992, 258, 1662-1665). We have reinvestigated the cellular localization of H 2 receptors in the rat stomach by visualizing both the H 2 receptor mRNA and the H 2-receptor protein itself. In situ hybridization histochemistry performed with an antisense riboprobe for the rat H 2 receptor, and autoradiographic distribution of 125I-aminopotentidine binding sites, a highly selective H 2-receptor ligand, did not show any labeling of the lamina propria. Signals were clearly and solely detected in the gastric epithelium, the strongest being observed in the upper part of the glands where the H 2 receptor gene transcripts were only detected within parietal cells. In situ hybridization performed with an antisense riboprobe for L-histidine decarboxylase mRNA confirmed the basal localization of the histamine-synthetizing cells in the rat gastric gland, at some distance from parietal histamine-sensitive cells.