Experimental radiotherapy-induced enteritis: a probiotic interventional study

Acute radiation of the small intestine causes an immediate and potentially reversible effect on the sensitive regenerative epithelium of the intestinal mucosa while markedly altering the overall intestinal ecosystem. The aim of the present study was test a novel probiotic mixture formulation (Microflorana-F) in an experimental model of acute radiation enteritis with particular interest in endotoxinemia and bacterial translocation.

Male Wistar rats allocated to three groups were fed for 7 days with: (A) a standard balanced diet; (B) a standard diet with the addition of 1 mL t.i.d. of Microflorana-F and (C) the same probiotic but after heat inactivation. Under ketamine anesthesia, abdominal irradiation was performed at a single dose rate of 20 Gy. Sham-radiated healthy rats served as a control (D). Standard food and active/inactive probiotic supplementation schedule was maintained throughout the study period. When they were killed 14 days later a midline laparotomy and a medium sternotomy was carried out. The mesenteric lymph nodes, whole spleen and liver samples as well as blood, the portal vein and bile samples were cultured. Endotoxinemia was also measured.

Early deaths (1 week) occurred mostly in rats fed standard food or inactivated probiotic. The endotoxin level significantly increased in irradiated rats fed standard food and inactivated probiotic while supplementation with the active form of the probiotic mixture significantly improved such parameters (P < 0.05). After radiation injury, mesenteric lymph nodes and portal blood were the samples most frequently yielding bacterial growth. Treatment with only the active form of probiotic significantly reduced the incidence of bacterial contamination in all samples.

These data suggest that the manipulation of gut ecosystem by biologically effective probiotic preparations might be a worthwhile therapeutic and preventive tool in radiation-induced enteritis.