OBJECTIVETo evaluate the protective effect of N-acetylcysteine (NAC) on the intestinal barrier dysfunction in rats after extensive abdominal radiation with X ray.

METHODSTwenty-four Spraque-Dawley male rats were divided into normal control group (n=8), radiation group (n=8), and radiation+NAC group (300 mg/kg) (n=8). Radiation injury was induced by X ray with a single dose of 10 Gy. NAC was administered from 4 days before irradiation to 3 days after radiation. Three days after radiation, all the rats were euthanized. The terminal ileum was collected for crypt survival assay and ileal villi count. The tissue samples from mesenteric lymph nodes (MLN), spleen, and liver were harvested under sterile conditions for microbiological analysis and ileum samples were harvested for biochemical analysis. The blood levels of D-lactate, endotoxin and diamine oxidase (DAO) and the ileum samples levels of nitric oxide(NO) were also measured.

RESULTSRats in radiation+NAC group had a higher survival rate of intestinal crypt [(76.84+/-4.82)% vs (49.64+/-5.48)%, P<0.01], higher intestinal villus count [(8.56+/-0.68)/mm vs (4.02+/-0.54)/mm, P<0.01], lower NO concentration [(0.48+/-0.12) mumol/g vs (0.88+/-0.16) mumol/g, P<0.01], lower levels of D-lactate, endotoxin and DAO (P<0.05 or P<0.01), and significantly decreased enteric bacteria cultured from mesenteric lymph nodes and other tissues as compared with the radiation group (P<0.05 or P<0.01).

CONCLUSIONNAC protects the small intestine from radiation-induced injury maybe through the inhibition of NO in rats.