IBS Model and Acetylcholine Writhing Model
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Irritable Bowel Syndrome (IBS) is a syndrome that is expressed as abdominal cramping, gastrointestinal pain and disturbances in GI transit. These conditions are produced by colonic spasticity and irregular contractility.
The disturbances in GI transit can be modelled by examining expulsion of a colonically-inserted glass bead or the Charcoal Meal model. The cramping and pain component of IBS can be modelled by injecting acetylcholine (ACh) into the peritoneum of mice. Intra-peritoneal administered acetylcholine promotes smooth muscle contractility and can be monitored, in animals, by quantifying the writhing response. Therefore, the Acetylcholine Writhing Model serves both as a gastrointestinal function model (an IBS model) as well as a representative of animal models for pain.
In this study, the acetylcholine (ACh) writhing response was validated as a model of smooth muscle contractility and visceral pain. This model was validated using an opioid as a reference anti-nociceptive compound.
The Acetylcholine Writhing IBS Model of pain is typically run in an acute mode (study completed in one day) by evaluating test articles after a single administration. The variability is relatively low and statistical significance may be achieved with group sizes of about 8 to 10 animals. It can be performed in both mice and rats.