Cellular distribution of prostanoid EP receptors mRNA in the rat gastrointestinal tract

The inhibition of PGE(2) synthesis resulting from sustained NSAIDs therapy has been linked to gastrointestinal irritations and ulceration. The multiple physiological effects of PGE(2) in the gut are mediated through the activation of four receptors termed EP(1-4). The aim of the study was to determine the precise distribution of the four prostaglandin E(2) receptors in the rat stomach, small intestine, and colon. We used non-radioactive in situ hybridization techniques on paraffin-embedded tissue. Mucous cells of the stomach and goblet cells of the small intestine and colon were found to express mRNA for all four EP subtypes. A positive hybridization signal for EP(1), EP(3), and EP(4) was detected in the parietal cells of the stomach whereas the chief cells expressed low levels of EP(1) and EP(3). The EP(1) and EP(3) receptor mRNA could also be detected in the muscularis mucosa, longitudinal muscle and enteric ganglias of the stomach and small intestine. However, close examination of the enteric ganglias indicated that most of the positive labeling was localized to the glial cells, although some neurons did express EP(3). In conclusion, we have detailed the distribution of prostanoid EP receptors in the gut at the cellular level, giving new insights to the role of prostaglandins in gastrointestinal functions.