Efeito da L-Arginina e Glicina na parede do cólon irradiado Estudo experimental em ratos

Abstract

Radiotherapy is widely used for the treatment of pelvic tumors, including malignancies of the bladder, intestine, and rectum. Radiotherapy has harmful effects, especially on tissues with intense cellular turnover, with the intestinal mucosa being highly susceptible. Within this context, dietary amino acid supplementation has proved to be a promising therapy for the minimization of this damage. The objective of the present study was to determine the effect of dietary supplementation with the amino acids L-arginine and glycine on the structure of the colon wall of rats submitted to abdominal irradiation. Forty male Wistar rats were randomly assigned to four groups of ten animals each: I non-irradiated control with no amino acid supplementation, II irradiated control with no amino acid supplementation, III irradiated group supplemented with L-arginine, and IV irradiated group supplemented with glycine. The animals received dietary supplementation for 14 days, with irradiation being applied on the 8th day of the experiment. Stereologic analysis showed that irradiation induced a reduction of the total volume of the colon wall of group II and III animals compared to healthy controls, but not of group IV. The mucosal layer of the irradiated animals of all groups was reduced compared to healthy non-irradiated animals. The irradiated animals that did not receive amino acid supplementation presented reduction of the muscle layer of the mucosa compared to groups I and IV, and the group of rats supplemented with glycine presented a significant increase of the submucosal layer compared to groups I and II. Group III animals showed a reduction of the muscularis propria layer compared to groups I and IV. Supplementation with L-arginine was effective in maintaining the partial volume of the epithelium of the mucosal layer. The present results suggest that glycine supplementation had a superior effect on the structure of the colon wall of rats submitted to abdominal irradiation compared to L-arginine supplementation since it was able to maintain the thickness of the wall and the epithelial surface of the mucosa, whereas L-arginine maintained the partial volume of the epithelium and the epithelial surface, but not the total volume of the intestinal wall.