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


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
We have validated our X-rays method for its use in mice.
Área de Farmacología y Nutrición y Unidad Asociada al Instituto de Química Médica (IQM) y al Instituto de Investigación en Ciencias de la Alimentación (CIAL) del Consejo Superior de Investigaciones Científicas (CSIC), Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain.
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R
Girón
Área de Farmacología y Nutrición y Unidad Asociada al Instituto de Química Médica (IQM) y al Instituto de Investigación en Ciencias de la Alimentación (CIAL) del Consejo Superior de Investigaciones Científicas (CSIC), Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain.
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I
Pérez-García
Área de Farmacología y Nutrición y Unidad Asociada al Instituto de Química Médica (IQM) y al Instituto de Investigación en Ciencias de la Alimentación (CIAL) del Consejo Superior de Investigaciones Científicas (CSIC), Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain.
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R
Abalo
D000818:Animals; D001466:Barium Sulfate; D003287:Contrast Media; D005769:Gastrointestinal Motility / Q000187:drug effects*; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging* / Q000187:drug effects; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*; D011859:Radiography; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results
D003287:Contrast Media; D009294:Narcotics; D001466:Barium Sulfate; D009020:Morphine
barium marker; gastrointestinal motility; morphine; mouse; radiology; rat