X‐ray analysis of gastrointestinal motility in conscious mice. Effects of morphine and comparison with rats

• Published in: Neurogastroenterology and motility Vol. 28; no. 1; pp. 74 - 84
• Main Authors: Girón, R., Pérez‐García, I., Abalo, R.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.01.2016
• Subjects: Animals; barium marker; Barium Sulfate; Contrast Media; gastrointestinal motility; Gastrointestinal Motility - drug effects; Gastrointestinal Tract - diagnostic imaging; Gastrointestinal Tract - drug effects; Male; Mice; Mice, Inbred ICR; morphine; Morphine - pharmacology; Motility; mouse; Narcotics - pharmacology; Radiography; radiology; rat; Rats; Rats, Wistar; Reproducibility of Results; Rodents; gastrointestinal motility; mouse; rat; barium marker; radiology; morphine
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/nmo.12699

Background Non‐invasive methods to study gastrointestinal (GI) motility are of high interest, particularly in chronic studies. Amongst these, radiographic techniques after contrast intragastric administration may offer many advantages. In previous studies, we have successfully and reproducibly applied these techniques together with a semiquantitative analysis method to characterize the effect of different drugs, acutely or repeatedly administered in rat models, but we have never before used these techniques in mice. These are very convenient in basic research. Our aim was to determine if our method is also valid in mice. Additionally, we determined the effect of morphine on GI motor function in both species. Methods Animals received an intraperitoneal administration of morphine (at 10 and 5 mg/kg for rats and mice, respectively). Twenty min later, barium contrast (at 2 g/mL) was gavaged (2.5 and 0.4 mL for rats and mice respectively) and serial X‐rays were obtained 0–8 h after contrast. X‐rays were analyzed as previously described, using a semiquantitative score to build motility curves for each GI region. Key Results Motility was much faster in mice than in rats for all GI regions. Morphine at the doses used significantly depressed motility in both species to a similar extent if the whole gut or the upper GI regions (stomach, small intestine) were considered, although its effect seemed to be more intense in the lower GI regions (caecum, colorectum) in rats than in mice. Conclusions & Inferences We have validated our X‐rays method for its use in mice. Here, we validated our non‐invasive radiographic methods to analyse gastrointestinal (GI) motility in mice. We confirmed that GI motility in mice is much faster than in rats and that morphine depresses GI motility in both species. Furthermore, at doses that seemed equipotent for depressing motility in the stomach and small intestine (10 mg/kg for rats and 5 mg/kg for mice), morphine seemed to depress motility in the caecum and colorectum in rats more intensely than in mice, an intriguing finding that warrants more investigation.