Development of a quantitative method for evaluating small intestinal motility using ultrasonography in mice

Upper gastrointestinal (GI) motility is affected by various drugs and diseases. However, changes in upper GI motility during these conditions are not well understood, as there are few quantitative in vivo methods that assess small intestinal motility in mice. Ultrasonography is a noninvasive method for imaging and evaluating the condition of the abdominal organs. The aim of the present study was to establish a novel method for evaluating small intestinal motility by using ultrasonography in mice. We measured GI motility with and without loperamide, an antidiarrheal medication, by intestinal transit using an orally administered dye, a (13)C-octanoic acid breath test, and ultrasonography. Locomotion activity of the duodenal wall was used for quantifying the GI motility observed via ultrasonography. Our results showed that upper GI transit was significantly delayed by loperamide. The (13)C-octanoic acid breath test revealed decreased gastric emptying in loperamide-treated mice. Through ultrasonography, large peristaltic movements were observed in the duodenum of the control mice. In contrast, after treatment with loperamide, these peristaltic movements were suppressed, and the duodenal lumen was enlarged, suggesting decreased duodenal motility. In accordance with these results, quantifiable locomotion activity was also significantly decreased. In conclusion, ultrasonography is an effective in vivo method to quantify small intestinal motility in mice.