Simulation with pharmacological agents of radiation damage to small intestinal villi.

Irradiation induces damage to intestinal villi, resulting in a progressive decline in villous height and changes in topography. Gamma and neutron radiation are reported to cause changes in the structure of smooth muscle and nerve twigs of the intestinal wall. It is possible, therefore, that villous collapse may be due partly to changes in the underlying stromal elements as a result of damage to nerve or muscle. To test this hypothesis, mice were treated with the drug reserpine which is known to affect the neural control of intestinal smooth muscle function and the small intestine was examined for topographical and histological changes. Two dose levels of reserpine were used and a group of mice were exposed to a single dose of whole body 15 Gy X-irradiation. Comparable villous collapse was observed in each group. Resin embedded semi-thin sections revealed changes in the smooth muscle cells of the muscularis externa after each treatment, suggesting a correlation between villous collapse and smooth muscle damage in response to both irradiation and drug treatment.