[Improvement effect of Daikenchuto on morphine-induced constipation through gastrointestinal peptides]

Development of a novel mouse constipation model

AIM: To establish a novel mouse constipation model.

METHODS: Animals were randomly divided into three groups, and intragastrically administered 0-4 °C saline (ice-cold group) or 15-20 °C saline (saline control group) daily for 14 d, or were left untreated (blank control group). Stools were collected 3-24 h after treatment to record the wet and dry weights and the stool form. Intestinal propulsion experiments were carried out and defecation time was measured for six days continuously after suspending treatments. The expressions of PGP9.5 were detected by immunohistochemistry.

RESULTS: Based on the percentage of stool weight changes compared with baseline (before irritation) in 9-14 d, stool weight changes were classified into three levels. Each level shows a different body state, which is state I (no change: plus or minus 5%), state II (slightly decreased: 5%-15%) and state III (decreased: 15%-25%). In state III, between day 9-14, the stool weights decreased by 15%-25% compared with the baseline, and changed at a rate > 10% compared with blank control values, and the stools became small and dry. Additionally, intestinal functions degenerated in these animals, and PGP9.5-positive expression markedly decreased in jejunum, ileum and proximal colon myenteric plexus.

CONCLUSION: Irritation with ice-cold saline is a stable, repeatable method in building constipation model in mice for exploring the pathogenesis and treatment options of constipation, and the change of stool weight and size may serve as a useful tool to judge a constipation model success or not.