MODULATION OF PROLIFERATION, 2ND MESSENGER LEVELS, AND MORPHOTYPE EXPRESSION OF THE RAT INTESTINAL EPITHELIAL-CELL LINE IEC-6 BY FERMENTED MILK

Trophic effects of milk fermented with Lactobacillus helveticus, Lacto bacillus paracasei ssp. paracasei, Bifidobacterium sp., or the combina tion of Lactobacillus bulgaricus and Streptococcus thermophilus (yogur t) were studied on the IEC-6 intestinal epithelial cell line. Incorpor ation of [methyl-H-3] thymidine, mitochondrial dehydrogenase activitie s, cyclic AMP production, and differentiation of levels of the IEC-6 s train were evaluated between the 15th and 30th passage in culture. All fermented and unfermented milks enhanced trophic responses of IEC-6 c ells in a dose-dependent manner. Compared with the corresponding milks , supernatant fractions were more effective in stimulating mitochondri al dehydrogenase response. Fermented milk supernatants were also more effective than the corresponding unfermented fractions. Increases in D NA synthesis and cyclic AMP confirmed the activation observed with mit ochondrial dehydrogenase. Yogurt induced the more trophic response wit h an increased number of the more differentiated cell morphotype. Ferm entation with L. casei also demonstrated an important trophic adaptati on of IEC-6 cells. Milk processing by lactic acid bacteria enhanced tr ophic and proliferation responses of intestinal epithelial cell line I EC-6. These results suggested that IEC-B cells could represent an accu rate and easy in vitro model for testing the trophic quality of variou s nutrients and for an optimization of physiological digestive functio ns.