A rat model of radiation‐induced gi mucositis

Abstract

The GI syndrome of acute radiation injury is manifest by nausea, vomiting and diarrhea, followed by self-resolving dehydration, a period of well-being, more diarrhea, and death. No one has survived radiation accidents in which GI damage contributed to the outcome. This study was intended to quantify some of the signs and symptoms in a rat model. Male, SD rats (20/group) were exposed to bilateral 60Co TBI (9–14 Gy; 0.6 Gy/min) at 0.5-Gy intervals. Survival, the onset and duration of diarrhea, and body weights were recorded daily. The presence of hemoglobin (Hb) and leukocytes in the stools of irradiated animals was reported. The classical LD50/6 for the GI syndrome was 11.9 Gy; the LD50/10, 9.9 Gy. A severity scale for diarrhea was used. Diarrhea was positively scored when a) stains were seen in the perianal area, b) woodchips or feces were attached there, or c) stools were soft or malformed. Diarrhea incidence was radiation-dose dependent and 100% diarrhea followed doses of ≥ 11 Gy. However, diarrhea self-resolved in many cases, especially to doses < 11 Gy. The latency to diarrhea was inversely proportional to the irradiation dose. Body-weight decreases were radiation dose-dependent, but severity of weight-loss did not always predict mortality. Preliminary data show that the feces of irradiated rats test positive for leukocytes when compared with control animals but that a simple Hb marker cannot be used in this model.