An animal model of longitudinal ulcers in the small intestine induced by intracolonically administered indomethacin in rats.

The ulcerogenic effect of intracolonically administered indomethacin was evaluated in rats. Conventionally fed rats aged from 5 to 10 weeks were treated by 8, 16, 24, or 32 mg/kg of intracolonic indomethacin for two days, and any damage to the stomach, small intestine and the colon was investigated. Longitudinal ulcers and scattered small ulcers were found in the small intestine at all doses of indomethacin, and the length of the longitudinal ulcers increase dose-dependently, but this was unrelated to the body weight of the rats. The cecum was frequently affected by irregularly shaped ulcers, and the incidence increased as the dose of indomethacin increased. The colon, other than the cecum, was not involved macroscopically. In contrast, the stomach was affected by only large doses of indomethacin (24 or 32 mg/kg), and the size of gastric ulcers increased according to the body weight of the rats. These findings suggest that intracolonic indomethacin in relatively young rats causes ulcers predominantly in the small intestine and the cecum, which are the frequent site of involvement of human Crohn's disease, and that this animal model may be suitable for investigation of the pathophysiology of inflammatory bowel disease.