Chemospecific alterations in duodenal perception and motor response in functional dyspepsia.

OBJECTIVE: Abnormal gastroduodenal motility and visceral hypersensitivity to intraduodenal acid have recently been recognized as pathophysiological factors in functional dyspepsia. The aim of this study was to assess whether these abnormalities in functional dyspepsia depend on the chemical composition of the stimulus.
METHODS: In 17 patients with functional dyspepsia and 10 healthy controls 20-channel antropyloroduodenal manometry was performed. During phase II of the migrating motor complex small volumes (5 ml) of saline, acid, lipids, and dextrose were administered intraduodenally. Motility parameters and sensation scores for nausea, fullness, and epigastric pain were compared before and after each infusion and among the two groups.
RESULTS: Acid induced a duodenal motor response in both groups, but less pressure waves (p < 0.05) and antegrade propagated pressure waves (p < 0.05) were observed in patients than in controls. In both groups lipids induced a similar, prominent increase in duodenal pressure waves. Acid and lipids suppressed antral-propagated pressure waves in both groups. Dextrose induced a modest increase in duodenal-propagated pressure waves in patients (p < 0.05) but not in controls. Although all infusions induced a mild increase in nausea in patients, only acid induced a significant increase in nausea after 1 min (p < 0.01). None of the infusions affected the sensations of epigastric pain or fullness in patients, nor did any infusions induce sensations in controls.
CONCLUSIONS: In functional dyspepsia alterations in sensor and motor responses to intraduodenal acid and nutrients are chemospecific, suggesting an abnormality at the level of visceral afferents or mucosal chemoreceptors in these patients.