Lycium barbarum polysaccharide ameliorates radiation-induced brain injury by regulating gut microbiota

To determine the extent to which Lycium barbarum polysaccharide (LBP) improves 60Co γ-ray radiation-induced brain injury (RIBI) by regulating the gut microbiota. The RIBI model of mice was established with the appropriate dose of 60Co γ-ray to identify the changes in the body weight, behaviors, gut microbiota, and inflammatory reactions of mice. Mice were randomly divided into healthy, RIBI model, and LBP groups. The related inflammatory cytokines were determined using an enzyme linked immunosorbent assay kit. Then, 16S rRNA sequencings of feces were carried out to evaluate the differences in intestinal flora. Compared with the spontaneous activity and exploratory spirit of the healthy group, those traits in the RIBI model mice in the open field significantly decreased, the freezing time in the elevated plus maze (EPM) significantly increased, and the number of times the mice discriminated the novel object was significantly lower. Hematoxylin-eosin slides showed that the main histopathological changes of RIBI occurred in the hippocampus. In addition, the diversity and relative abundances ratio of the gut bacterial phylum, order, family, and genus in the model group varied widely. Changes in Bacteroidetes, Firmicutes, and Proteobacteria were the most obvious after head radiation exposure. In comparison, LBP could accelerate the recovery of weight loss in RIBI mice. The frequency that mice entered the center of the open field, facing the open arm in the EPM, and the number of times they discriminated the novel object were significantly increased with LBP administration. LBP could also reduce the levels of inflammatory factor caused by RIBI. LBP increased the diversity and abundance of gut microbiota in RIBI model mice. In addition, LBP increased the relative abundance of Bacteroidetes but decreased the levels of Firmicutes and Proteobacteria for irradiated mice. LBP can improve depression and tension by regulating the composition of gut microbiota, including lowering the relative abundance of Clostridia and Burkholderiales and raising that of Lactobacillales. Thus, LBP provides a new strategy for improving the protective effects of RIBI.