Gut Bacteria Are Required for the Benefits of Black Raspberries in ApcMin/+ Mice

BACKGROUND: The gut microbiota plays a pivotal role in the development of inflammatory bowel disease and colorectal cancer. OBJECTIVE: To determine whether the gut microbiota is required for the chemoprotective effects of black raspberries (BRBs) in Apc(Min/+) mice. METHODS: Apc(Min/+) mice were given (a) a control diet for 8 weeks, or (b) the control diet for 4 weeks and then a 5% BRB diet for additional 4 weeks, or (c) the control diet and antibiotics for 4 weeks followed by the 5% BRB diet and antibiotics for the next 4 weeks. At the end of the study, all the mice were euthanized, and colonic and intestinal polyps were counted. mRNA expression levels of TLR4, NF-kappa B1, and COX2 were determined in colon and small intestine of these Apc(Min/+) mice by quantitative real-time PCR. RESULTS: 5% BRBs significantly suppressed intestinal and colonic polyp development in the Apc(Min/+) mice, whereas antibiotics significantly abolished BRBs' chemoprotective effects. BRBs decreased mRNA levels of TLR4, NF-kappa B1, and COX2 in colon, whereas significantly enhanced mRNA levels of TLR4 and NF-kappa B1 were observed in small intestine of BRB-treated Apc(Min/+) mice fed antibiotics. CONCLUSIONS: The gut microbiota is required for BRBs' chemoprotection against polyp development in Apc(Min/+) mice.