RADIOPROTECTIVE EFFECT OF CAPTOPRIL ON THE MOUSE JEJUNAL MUCOSA

Purpose: Captopril, an inhibitor of angiotensin I converting enzyme, h as been shown to modify radiation damage and prevent radiation injury of normal tissue in rats and pigs. The present study was carried out t o determine whether captopril would reduce radiation changes in the pr oximal small bowel in mice. Methods and Materials: Mice were subjected to whole body irradiation with 9 Gy or 15 Gy. Captopril was administe red in drinking water at a regimen of 62.5 mg/kg/day (captopril group I) and 125 mg/kg/day (captopril group II), continuously from 7 days be fore irradiation to the end of each designed experiment. The jejunal d amage was evaluated microscopically by crypt count per circumference a nd by histologic damage grading. Results: Crypt number in the sham-irr adiated control was 133+/-6.8/circumference. In both captopril group I and II, crypt numbers and histologic scores were not significantly di fferent from those in the normal group. The 9 Gy and 15 Gy radiation a lone groups showed significantly lower crypt counts and histologic sco res compared with the sham-irradiated control group (p < 0.05). The gr oups exposed to 9 Gy radiation plus captopril I and II showed signific antly higher crypt counts and lower histologic damage scores on the th ird day, and lower histologic damage scores on the fifth day compared with the 9 Gy radiation alone group (p < 0.05). The 15 Gy radiation pl us captopril I and II groups had significantly higher crypt counts and lower histologic damage scores on the third day than those of the 15 Gy radiation alone group (p < 0.05). All mice of the 15 Gy radiation g roup succumbed to intestinal radiation death. Conclusion: Our results suggest that captopril provides protection from acute radiation damage to the jejunal mucosa in mice.