Radiation-induced proctitis is a common complication associated with radiation directed to the abdomen and/or pelvis in the treatment of rectal, prostate, or cervical malignancies. The direct effect of ionizing radiation during radiation therapy damages the DNA, lipids, and proteins of cells (both cancerous and non-cancerous) in the GI tract. In the acute radiation-induced proctitis model in rodents, disease is induced with a single bolus of radiation directed to the distal colon. Animals are monitored daily and evaluated for overall health and survival in addition to diarrhea and bloody stool incidence. A major readout in the model is proctitis severity determined via longitudinal video endoscopic assessments over the course of the study. Peak proctitis severity typically occurs around Day 7 or Day 8, with disease persisting through the final evaluation which often includes histopathology.

• Advantages: short model duration, consistent disease incidence, good for screening potential drug candidates.
• Disadvantages: less clinically relevant radiation treatment schedule compared to the fractionated model.

• Sprague Dawley Rat, Lewis Rat
• C57Bl/6 Mice

• Percent weight change
• Survival
• Diarrhea and bloody stool Incidence
• Endoscopy: proctitis scoring
• Terminal colon weight and length measurement
• Terminal histopathology and/or IHC analyses

• Tissue protein analyses
• Peripheral lymphoid organ immunophenotyping
• Intestinal lamina propria immunophenotyping
• Custom assays