Introduction: Intestinal mucositis is the most prevalent side effect of antineoplastic drug 5-flurouoracil (5-FU). Probiotics are live microorganisms that improve intestinal immune regulation. So, probiotics might have a beneficial effect to reduce the chemotherapy-induced enterotoxicity.
Aim: This study was designed to assess mucositis induced by 5-FU and the possible protective effect of probiotics
Methods: 50 healthy albino adult male rats were divided into five equivalent groups. Control group, Probiotic group was given 100 µL of suspension containing 1x107 ( CFU) of probiotic cocktail daily.5-FU group was received 50 mg/kg B.W. of 5-FU by intraperitoneal (IP) injection once daily for 5 consecutive days. Probiotic plus 5-FU group was given 50 mg/kg B.W. of 5-FU by IP injection for 5 consecutive days with probiotic cocktail once daily for 9 consecutive days. Recovery group was received 50 mg/kg body weight 5-FU by IP injection once daily for 5 consecutive days then left without medication till rats had been sacrificed on 9th day .The intestinal tissues have been processed for a light microscopic study.

Results: Rats of 5-FU group showed broadening, fusion and sloughing of villi into lumen, ulcerations, marked depletion of goblet cells, strong iNOS, marked caspase 3 and weak Ki-67 immunoreactions . Rats treated with 5-FU plus probiotic showed preservation of normal intestinal architecture with improvement of histological and immunohistological features of mucositis . Rats of recovery group showed decrease histological and immunohistochemical features of mucositis.

Conclusion: oral intake of the probiotic can protect against chemotherapy-causing intestinal mucositis in a rat model.