Motilin kinetics and effects on proximal stomach in patients with functional dyspepsia (FD) and healthy volunteers

Motilin is involved in the regulation of upper gastrointestinal (GI) motility and it has been suggested that motilin may play a role in the pathogenesis of poorly understood clinical entities such as FD. The present study was performed in order to further investigate the effects of exogenous motilin on the proximal stomach of healthy volunteers and patients with FD. Eight healthy volunteers and 12 FD patients (Rome II, early satiety) were infused with synthetic motilin (4 pmol kg−1 min−1) or placebo over 90 min in a double-blind, randomized, cross-over study. Proximal gastric volume was measured with a barostat device at a predefined pressure and during isobaric distensions. Abdominal symptoms such as fullness, nausea and abdominal pain were scored by Visual Analogue Scales (VAS). Gallbladder volume was measured by ultrasonography and plasma motilin concentrations were measured with an radioimmuno-assay. Treatment effect within a patient group was estimated with paired Student's t-test, and differences between the two groups were investigated using unpaired Student's t-test. Data are given as mean (± s.d.) and differences are expressed with the corresponding 95% confidence intervals (95% CI). The plasma concentration–time curves for motilin were similar between healthy volunteers and patients. Baseline gastric volumes were similar for both groups; 269 ± 147 ml (healthy volunteers) and 265 ± 98 ml (FD patients). Compared with placebo, motilin reduced proximal gastric volume by 112 ml (95% CI: 29, 195 ml) in FD patients and by 96 ml (95% CI: −7.3, 200) in healthy volunteers (Figure 1). Figure 1 Mean (s.d.) proximal gastric volume (ml) during the constant pressure procedure (MDP + 3 mmHg), corrected for baseline volume in dyspeptic patients (n = 12) during motilin (▪) and placebo (□) and in healthy volunteers (n = 8) during motilin ... In the FD-patients, motilin decreased maximal compliance by 76.1 ml mm Hg−1 (95% CI: 8.8, 143.4) compared with placebo, and was similar to that observed in healthy volunteers. Patients were significantly more nauseous (p = 0.04) during motilin compared with placebo, whereas healthy volunteers did not experience nausea. Motilin reduced gall bladder volume by 33% (95% CI: 20, 45) in the FD patients and by 6% (95% CI: −13, 25) in the healthy volunteers. The difference in gall bladder volume was significant between the groups. Motilin significantly reduced proximal gastric volume and compliance in dyspeptic patients and healthy volunteers by a similar magnitude. In dyspeptic patients, motilin induced nausea, and evoked a greater gall bladder volume reduction.