Cannabinoid CB1 Receptors Are Expressed by Parietal Cells of the Human Gastric Mucosa

Experimental data suggest that the endogenous cannabinoid system is involved in gastric function in different animal species. In most of them, CB₁ receptors have been localized on vagal terminals innervating the external wall of the stomach. We aimed at studying the putative presence and distribution of these receptors in the human gastric mucosa. To this end, we first performed Western blotting, RT-PCR, in situ hybridization, and immunohistochemical analysis of CB₁ protein distribution in biopsy samples of healthy individuals. To determine the precise cell populations expressing CB₁ receptors, we performed double immunofluorescence plus confocal microscopy analysis of the same samples. Our results show that CB₁ receptors are present in the gastric epithelium of the mucosa. Specifically, they are expressed by a subpopulation of mucosal cells, the acid-secreting parietal cells, as shown by double immunohistochemical staining and by their differential abundance in subregions of the gastric mucosa. These results reinforce the notion of a prominent role for the endocannabinoid system in the gastric function in humans and postulate the use of cannabinoid CB₁ receptors in parietal cells as new therapeutic targets for the regulation of gastric acid production. (J Histochem Cytochem 56:511–516, 2008)