Models of acute radiation enteritis: a comparison and evaluation of two modeling methods

Abstract

Objective To investigate the reliable methods for establishing models of acute radiation enteritis (ARE) and the criteria used to judge whether the model is successfully established. Methods A total of 98 rats were randomly divided into normal control group (group A), fractionated dose group B (4 Gy/fraction for 3 fractions), fractionated dose group C (4 Gy/fraction for 4 fractions), fractionated dose group D (4 Gy/fraction for 5 fractions), single fraction group E (12 Gy in a single fraction), single fraction group F (16 Gy in a single fraction), and single fraction group G (20 Gy in a single fraction). Abdominal irradiation was performed for all rats, and the changes in body weight and defecation were observed. Magnetic resonance imaging (MRI) was performed on days 3-5 after irradiation, and on the 4th day, anatomy was performed to measure the length of small intestine with edema, blood samples were collected to measure endotoxins, and the specimens of small intestine were collected to observe pathological changes. The independent-samples t-test was used for comparison between groups. Results After irradiation, groups D, E, F, and G experienced varying degrees of diarrhea and had positive results from endotoxins test. Group D had a longer length of small intestine with edema than group C (P=0.00) and had a similar length as group E (P=0.46). Groups E, F, and G showed dilation and dropsy in the intestinal canal on MRI, and groups F and G showed patchy signals of dropsy in the abdominal cavity. Groups F and G showed varying degrees of necrosis in the small intestine and died within 14 days after irradiation. Conclusions When the radiation dose is 33-46 Gy (biologically equivalent dose), both single dose and fractionated dose can successfully establish the model of ARE, while fractionated dose can be better controlled. Key words: Animal model; Acute radiation enteritis; Radiation-induced intestinal injury