[Establishment of rat slow transit constipation model by selective chemical ablation of the enteric plexus]

To establish an innovative rat model of slow transit constipation by selective chemical ablation of the colon enteric plexus.

Sprague Dawley rats, 5-6 weeks old, were randomly divided into normal control group, sham operation group, treatment group I, II, III, IIII. The normal control group did not receive treatment. Rats in the sham operation group and the treatment groups received abdominal operation under anesthesia, and the gauze containing 0.9% normal saline, 0.05%, 0.1%, 0.25%, 0.5% benzalkonium chloride (BAC) was applied into colon for 30 minutes. Two weeks after operation, the number of feces, fecal dry weight in 24 h and gastrointestinal transit time were recorded, then hematoxylin-eosin (HE) staining, immunohistochemistry, ELISA were used for the evaluation of colonic pathology, enteric plexus, Interstitial cells of Cajal and neurotransmitters 5-hydroxytryptamine(5-HT).

Compared to the normal control group and the sham operation group, the gastrointestinal transit time was significantly prolonged and fecal dry weight was lower in the treatment group II, III (all P<0.05). HE and immunohistochemical staining showed varying degrees of pathological changes in the treatment groups and in line with the pathological changes of slow transit constipation. 5-HT concentration reduced significantly in treatment group III compared to other groups (P<0.01).

The animal model of STC is successfully established by applying 0.25% BAC selective chemical ablation of the colon enteric plexus. This model is simple, stable, and is more in line with pathological changes of slow transit constipation.