l-Glutamine supplementation optimizes the repair of the colonic mucosa in rats subjected to abdominal irradiation

Radiotherapy plays an important role in cancer treatment but may be associated with several gastrointestinal complications. The present study investigated the role of l-glutamine supplementation in the repair of the colonic mucosa of rats subjected to abdominal irradiation (AI). Sixty adult male Wistar rats were divided into 6 study groups: healthy—animals not subjected to abdominal radiation; control—irradiated rats without amino acid supplementation; Gly-Gly—irradiated rats with glycine supplementation throughout the study; Gln-Gln—irradiated rats with l-glutamine supplementation throughout the study; Gly-Gln—irradiated rats with glycine supplementation 7 days before irradiation and with l-glutamine supplementation 7 days after irradiation; and Gln-Gly—irradiated rats with l-glutamine supplementation 7 days before irradiation and with glycine supplementation 7 days after irradiation. Animals belonging to the control, Gly-Gly, Gln-Gln, Gly-Gln, and Gln-Gly groups were subjected to AI on the eighth day of experimentation. All animals underwent laparotomy on the 15th day for resection of a circumferential colonic segment for stereological analysis. Partial volume of the epithelium and epithelial surface of groups Gln-Gln and Gly-Gln were similar to those of healthy animals but significantly increased compared with control animals (P < .05 for both groups regarding partial epithelium volume; P < .001 and P < .05, respectively, regarding epithelial surface). The present findings suggest that dietary supplementation with l-glutamine before and after AI or only after irradiation is beneficial for the repair of the colonic mucosa of rats, optimizing its recovery.