Inflammation, capillary leakage and healing of experimental gastric ulcers in the rat

Little information is available on the role of inflammation and small vessel alteration in the development and healing of peptic ulcers. We studied the spontaneous healing of experimental ulcers in the rat stomach with a novel radio-isotope technique for the monitoring of capillary damage in ulcer-related inflammation. Following ulcer induction, healing was assessed on days 1, 7 and 15 by macroscopical and histological determinations of ulcer size and lesion area, parietal cell counts in the ulcer margin and nuclear imaging of the lesion area using Nanocoll, a 99mTc-labelled colloid. The ulcers were re-epithelized after 15 days. However, Nonocoll activity was still significantly enhanced in the ulcer area, and regression of the microscopically visible lesion area, which, from day 1 on, occupied a zone considerably larger than the ulcer itself, was delayed and still incomplete at the end of the study. Compared to the intact mucosa, parietal cells were reduced in the scar tissue up to 15 days (24-40%). However, despite macroscopical and histological re-epithelization, small vessel leakage and substantial tissue alteration persisted in the ulcer scar.