A scanning electron microscopic study of the morphological changes in rat small intestinal mucosa treated by intracolonic indomethacin

Abstract

Rectal administration of indomethacin induces longitudinal ulcers in the rat small intestine. The current study investigated a sequence of progressive villus injury in this enteropathy, especially by the use of scanning electron microscopy. The initial change was the distortion of several villi on the mesenteric side in the mid-small intestine identified at 0.5 h, even though there was no obvious change under light microscope or dissecting microscope at this time. During the subsequent 2h, distortion of the villi was accompanied by several epithelial defects, and epithelial detachment occurred on the villi tips. Extension of epithelial defects and exposure of the villus core progressed during subsequent periods. The injured villi were confluent with each other on the mesenteric side throughout the 12h after dosing. These findings suggest that the initial mucosal injury induced by the rectal route of administration was not extensive; rather, several villi were focally damaged on the mesenteric side in the mid-small intestine, eventually resulting in a longitudinal ulcer. Although the overall progression after indomethacin administration by the rectal route was similar to that occurrmg after subcutaneous administration, villus change seems to occur much earlier after rectal dosage.