Effect of high fiber diet on activation and function of microglia in mouse brain / 解放军医学杂志

ABSTRACT

Objective To compare the levels of short-chain fatty acids produced by high-fiber diet and low-fiber diet in the intestinal metabolism of mice for exploring the effects of different fiber diets on the activation and function of microglia in mouse brain. Methods Mice fed with low-fiber and high-fiber diets were detected for the levels of three major short-chain fatty acids (acetic acid, propionic acid, butyrate) in the cecum. The distributions of microglia in the brain of different diet mice were compared by immunofluorescence. Real-time fluorescence quantitative PCR was used to detect expressions of genes associated with microglia activation in mouse brain between the above two groups of mice. Results The acetate level in the cecum of mice in high fiber diet group was higher than that of mice in low fiber diet group. There were no significant differences between the two groups in the levels of propionic acid and butyrate and the number and distribution of microglia. However, the levels of microglial activation-associated inflammatory cytokines such as IL-1β, IL-6, TNF-α, IL-12, CCL2, CCL5 and CCL7 mRNA were higher in high fiber diet group than in low fiber diet group after the intracranial stimulation by LPS. Conclusion The quantity of fiber in the diet after weaning can affect the maturation and activation of microglia in the brain, which may because of different levels of acetic acid after metabolism of different dietary structures by the intestinal flora.