High temporal resolution gastric emptying breath tests in mice

• Published in: Neurogastroenterology and motility Vol. 30; no. 8; pp. e13333 - n/a
• Main Authors: Miller, K. E., Bajzer, Ž., Hein, S. S., Phillips, J. E., Syed, S., Wright, A. M., Cipriani, G., Gibbons, S. J., Szurszewski, J. H., Farrugia, G., Ordog, T., Linden, D. R.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-08-2018
• Subjects: Animal models; Atropine; Diabetes; Diabetes mellitus; Digestive system diseases; Excretion; Gastric emptying; gastrointestinal physiology; ileal brake; intestinal feedback; murine; Nutrients; Octanoic acid; Physiology; Rodents; Small intestine; Spectroscopy; Streptozocin; gastrointestinal physiology; murine; ileal brake; intestinal feedback
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/nmo.13333

Background
Gastric emptying is a complex physiological process regulating the division of a meal into smaller partitions for the small intestine. Disrupted gastric emptying contributes to digestive disease, yet current measures may not reflect different mechanisms by which the process can be altered.
Methods
We have developed high temporal resolution solid and liquid gastric emptying breath tests in mice using [13C]‐octanoic acid and off axis‐ integrated cavity output spectroscopy (OA‐ICOS). Stretched gamma variate and 2‐component stretched gamma variate models fit measured breath excretion data.
Key Results
These assays detect acceleration and delay using pharmacological (7.5 mg/kg atropine) or physiological (nutrients, cold exposure stress, diabetes) manipulations and remain stable over time. High temporal resolution resolved complex excretion curves with 2 components, which was more prevalent in mice with delayed gastric emptying following streptozotocin‐induced diabetes. There were differences in the gastric emptying of Balb/c vs C57Bl6 mice, with slower gastric emptying and a greater occurrence of two‐phase gastric emptying curves in the latter strain. Gastric emptying of C57Bl6 could be accelerated by halving the meal size, but with no effect on the occurrence of two‐phase gastric emptying curves. A greater proportion of two‐phase gastric emptying was induced in Balb/c mice with the administration of PYY (8‐80 nmol) 60 min following meal ingestion.
Conclusions and Inferences
Collectively, these results demonstrate the utility of high temporal resolution gastric emptying assays. Two‐phase gastric emptying is more prevalent than previously reported, likely involves intestinal feedback, but contributes little to the overall rate of gastric emptying.
High temporal resolution gastric emptying breath tests can measure accelerated or delayed gastric emptying of liquids and solids and resolve 1‐phase vs two‐phase gastric emptying. These analyses discovered that two‐phase gastric emptying is more prevalent that previously described, is strain‐dependent and may involve intestinal feedback, yet contribute little to the overall rate of gastric emptying.