Abstract

Epidemiological and experimental studies provide evidences that diet and intestinal microflora play an important role in colon carcinogenesis. In recent years, it has been suggested that lactic acid bacteria (LAB) used to ferment dairy products have an inhibitory effect on the colon cancer. This study was designed to determine the effect of Bifidobacterium longum HY8001 (Bif) and Lactobacillus acidophilus HY2104 (Lac) of Korean origin on azoxymethane (AOM)-induced colonic preneoplastic lesions such as aberrant crypt foci (ACF) formation and cecal pH. At five weeks of age, Spraque-Dawley rats were divided at random into four (AOM alone, Bif, Lac, and Bif+Lac) groups. Animals were weighed weekly and oral administration of LAB cultures were performed daily until the termination of the study. Two weeks later, all animals were given a subcutaneous injection of AOM dissolved in normal saline at a dose of 15 mg/kg of body weight once per week for 2 weeks. All rats were necropsied 7 weeks after the last AOM injection, and the ACF were visualized under light microscopy in the formalin-fixed, unsectioned methylene blue-stained colons. The total number of aberrant crypt in Bif, Lac, and Bif+Lac groups were significantly lower than that of the AOM alone group and the percentage of inhibitions weas 35.0, 45.4 and 45.0%, respectively. Significant inhibition (p<0.001) in the total number of ACF was also observed in LAB treated groups (Bif, Lac, and Bif+Lac group by 30.3, 38.6, and 41.2%, respec-tively). Furthermore, cecal pH appeared to significantly decrease by LAB administration. The results of present study provide some evidences for potential colon tumor-inhibitory properties of lactic cultures and fermented dairy products.

• Keywords: Bifidobacterium longum HY8001; Lactobacillus acidophilus HY2104; azoxymethane; colon cancer; aberran