High interdigestive and postprandial motilin levels in patients with the irritable bowel syndrome

Motilin shows cyclic variation with the different phases of the migrating motor complex (MMC). Altered motilin levels have been found in irritable bowel syndrome (IBS) patients, but in these studies motilin levels were analysed without the knowledge of the phases of MMC. We included 13 healthy controls (HC) and 24 patients with IBS [12 diarrhoea-predominant (IBS-D) and 12 constipation-predominant (IBS-C)]. We performed interdigestive and postprandial antroduodenojejunal manometry and blood samples for analysis of motilin were drawn. Group differences in plasma levels of motilin were analysed during mid-phase II, just before the start of phase III (pre-III), during phase I, immediately before the meal and 30 and 60 min after the 500 kcal mixed meal. Higher motilin levels were observed in IBS vs HC in both the interdigestive and postprandial periods (P < 0.05). No significant differences between IBS-C and IBS-D were observed. The cyclic variation of motilin during MMC and the meal response was similar in IBS and controls. IBS patients, irrespective of the predominant bowel habit, demonstrate higher motilin levels than HCs in all phases of the MMC and also after a meal. These findings may bear some pathophysiological importance in IBS and relate to the gastrointestinal dysmotility often seen in these patients.