Region-specific distribution of the P2y(4) receptor in enteric glial cells and interstitial cells of Cajal within the guinea-pig gastrointestinal tract

Although there is pharmacological evidence to assume that the P2Y(4) receptor is a regulator of epithelial ion transport, no detailed data about its distribution within the gut are available. Therefore, this study, using whole mounts and cryosections, aimed to reveal the expression pattern of P2Y(4) along the entire guinea-pig gastrointestinal tract. P2Y(4) immunoreactivity was absent from enteric neurons but present in enteric glial cells of the stomach, small and large intestine. In the esophagus, P2Y(4) appeared to be exclusively located within striated muscle cells. P2Y(4) showed also a region dependency regarding its presence in different subpopulations of interstitial cells of Cajal: in myenteric interstitial cells of Cajal in the stomach and ileum; in some intramuscular interstitial cells in the stomach and cecum; in some deep muscular plexus interstitial cells in the ileum; and in some submucosal surface interstitial cells in the colon. These results and the knowledge that P2Y(4) activation causes intracellular Ca2+ recruitment led us to suggest that P2Y(4) in enteric glia plays a modulatory role in intercellular Ca2+ waves, while P2Y(4) in interstitial cells of Cajal modulates intracellular Ca2+ oscillations. (c) 2006 Elsevier B.V. All rights reserved.