An exaggerated sensory component of the gastrocolonic response in patientswith irritable bowel syndrome

Background/aims-Visceral hypersensitivity is a feature of the irritable bow el syndrome (IBS). Postprandial symptoms are common in these patients. The effects of nutrients on colonic perception in IBS are incompletely understo od. Subjects-We studied 13 healthy subjects and 16 patients with IBS-eight had diarrhoea predominant (IBS-D) and eight constipation predominant (IBS-C) IB S. Methods-Colonic perception thresholds to balloon distension and viscerosoma tic referral pattern were assessed before and after duodenal infusion of li pid or saline, respectively. At the end of the infusions, plasma levels of gastrointestinal peptides were determined. Results-Lipids lowered the thresholds for first sensation, gas, discomfort, and pain in the IBS group but only for gas in the control group. The perce nt reduction in thresholds for gas and pain after lipids was greater in the IBS and IBS-D groups but not in the IBS-C group compared with controls. IB S patients had an increased area of referred discomfort and pain after lipi ds compared with before infusion whereas the referral area remained unchang ed in controls. No group differences in colonic tone or compliance were obs erved. In both groups higher levels of cholecystokinin, pancreatic polypept ide, peptide YY, vasoactive intestinal polypeptide, and neuropeptide Y were seen after Lipids. Motilin levels were higher in patients and differences in the subgroups were observed. Levels of corticotrophin releasing factor w ere lower in the constipated group than in the diarrhoea group. Conclusions-Postprandial symptoms in IBS patients may be explained in part by a nutrient dependent exaggerated sensory component of the gastrocolonic response.