Role of intestinal chemoreception in the induction of gastrointestinal sensations

Both distension of the stomach and activation of small intestinal chemorece ptors by nutrients have been implicated in the induction of postprandial se nsations. Studies were performed in healthy human subjects to investigate t he roles of gastric distension and activation or inhibition of small intest inal chemoreceptors in the generation of pleasant (fullness) and unpleasant (nausea, pain) gastrointestinal sensations. The proximal stomach was diste nded by inflating a balloon attached to a gastric tube with air, while the duodenum was perfused with nutrient solutions, either lipid or carbohydrate s. In additional experiments, the upper small intestinal mucosa was anaesth etised by topical anaesthesia or an antagonist to cholecystokinin(CCK)-A re ceptors given intravenously during duodenal lipid infusion. Gastric distens ion induced sensations of epigastric pressure and pain, while during duoden al infusion of both carbohydrate and lipid, fullness was described as a mor e meal-like sensation. In addition, lipid but not carbohydrate infusion res ulted in significant nausea. The sensory experience evoked by lipid was dim inished by both topical mucosal anaesthesia and CCK-A receptor blockade. Th e data provide evidence for the involvement of small intestinal chemorecept ors in the modulation of sensations induced by gastric distension.