Effects of probiotic bacteria (VSL#3) on the polyamine biosynthesis and cell proliferation of normal colonic mucosa of rats.

BACKGROUND Probiotics seem to possess tumour inhibitory properties, but few studies have investigated their actions on the cell proliferation of normal colonic mucosa. The effects of a probiotic mixture (VSL#3) on polyamine biosynthesis, Ki-67 levels and apoptosis in the normal colon of rats were studied. MATERIALS AND METHODS For a 4-week period, 20 rats were fed a VSL#3 solution and 20 rats a saline solution. Samples from the colonic mucosa were collected at the end of treatment. Polyamines were detected by HPLC, ornithine decarboxylase activity by a radiometric technique, and apoptosis and Ki-67 by histochemical and immunohistochemical methods. RESULTS VSL#3 caused a significant decrease in colonic polyamine levels, ornithine decarboxylase activity and Ki-67 compared to controls. A significant increase in the apoptotic index was also observed. CONCLUSION Probiotics could also reduce proliferation rates in a condition not affected by hyperproliferative or neoplastic growth, when the normal control mechanisms are still completely effective.