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Glucagon-like peptide-1 (GLP-1) relaxes the stomach during fasting but decreases hunger and food consumption and retards gastric emptying. The interrelationships between volume, emptying, and postprandial symptoms in response to GLP-1 are unclear. We performed, in healthy human volunteers, a placebo-controlled study of the effects of intravenous GLP-1 on gastric volume using (99m)Tc-single photon emission computed tomography imaging, gastric emptying of a nutrient liquid meal (Ensure) using scintigraphy, maximum tolerated volume (MTV) of Ensure, and postprandial symptoms 30 min after MTV. The role of vagal cholinergic function in the effects of GLP-1 was assessed by human pancreatic polypeptide (HPP) response to the Ensure meal. GLP-1 increased fasting and postprandial gastric volumes and retarded gastric emptying; MTV and postprandial symptoms were not different compared with controls. Effects on postprandial gastric function were associated with reduced postprandial HPP levels. GLP-1 does not induce postprandial symptoms despite significant inhibition of gastric emptying and vagal function; this may be partly explained by the increase in postprandial gastric volume.

Background :Measuring colonic transit time (CTT) by the radio-opaque marker method is simple, widely available and important for the diagnosis of slow transit constipation. Moreover, the effects of gender and menstrual cycle on CTT remain controversial. Thus, in this study, we examined the effects of gender and menstrual cycle on CTT in healthy subjects.Methods :We measured CTT in 42 healthy subjects (21M, 21F) by using a radio-opaque marker, Kolomark™. Two simple abdominal radiographs were taken on the 4th and 7th days. Average daily intake of dietary fiber and menstrual history were surveyed.Results :The mean CTT of the 42 healthy subjects was 26.5±19.4 hours. The mean CTT was not significantly different between the male and female subjects (22.3±16.1 h vs. 30.1±21.4 h, p>0.05). However, the mean CTT of 11 female subjects in the luteal phase was significantly longer than that of 10 female subjects in the follicular phase (40.9±19.0 h vs. 20.6±19.2 h, p<0.05). Serum progesterone level, age, BMI, and the average daily intake of dietary fiber did not correlate with CTT.Conclusion :The effects of the menstrual cycle should be considered in interpreting CTT in young women.

SPECT imaging noninvasively measures fasting and postprandial gastric volumes in humans. Half the patients with idiopathic nonulcer dyspepsia had impaired gastric accommodation or emptying. Reduced gastric "accommodation" was observed in 41% of a group with idiopathic nonulcer dyspepsia. Abnormal gastric emptying is less frequent (22%).

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