Radioprotective effect of captopril on the mouse jejunal mucosa

Captopril, an inhibitor of angiotensin I converting enzyme, has been shown to modify radiation damage and prevent radiation injury of normal tissue in rats and pigs. The present study was carried out to determine whether captopril would reduce radiation changes in the proximal small bowel in mice.

Mice were subjected to whole body irradiation with 9 Gy or 15 Gy. Captopril was administered 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 before irradiation to the end of each designed experiment. The jejunal damage was evaluated microscopically by crypt count per circumference and by histologic damage grading.

Crypt number in the sham-irradiated control was 133 +/- 6.8/circumference. In both captopril group I and II, crypt numbers and histologic scores were not significantly different from those in the normal group. The 9 Gy and 15 Gy radiation alone groups showed significantly lower crypt counts and histologic scores compared with the sham-irradiated control group (p < 0.05). The groups exposed to 9 Gy radiation plus captopril I and II showed significantly higher crypt counts and lower histologic damage scores on the third 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 plus 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 group succumbed to intestinal radiation death.

Our results suggest that captopril provides protection from acute radiation damage to the jejunal mucosa in mice.