Effects of xylo-oligosaccharide on gut microbiota, brain protein expression, and lipid profile induced by high-fat diet.

Midlife overweight and obesity are risk factors of cognitive decline and Alzheimer' s disease (AD) in late life. In addition to increasing risk of obesity and cognitive dysfunction, diets rich in fats also contributes to an imbalance of gut microbiota. Xylo-oligosaccharides (XOS) are a kind of prebiotic with several biological advantages, and can selectively promote the growth of beneficial microorganisms in the gut. To explore whether XOS can alleviate cognitive decline induced by high-fat diet (HFD) through improving gut microbiota composition, mice were fed with normal control or 60% HFD for 9 weeks to induce obesity. After that, mice were supplemented with XOS (30 g or 60 g/kg-diet) or without, respectively, for 12 weeks. The results showed that XOS inhibited weight gain, decreased epidydimal fat weight, and improved fasting blood sugar and blood lipids in mice. Additionally, XOS elevated spatial learning and memory function, decreased amyloid plaques accumulation, increased brain-derived neurotrophic factor levels, and improved neuroinflammation status in hippocampus. Changes in glycerolipids metabolism-associated lipid compounds caused by HFD in hippocampus were reversed after XOS intervention. On the other hand, after XOS intervention, increase in immune-mediated bacteria, Faecalibacterium was observed. In conclusion, XOS improved gut dysbiosis and ameliorated spatial learning and memory dysfunction caused by HFD by decreasing cognitive decline-associated biomarkers and changing lipid composition in hippocampus.

Fish oil ameliorates neuropsychiatric behaviors and gut dysbiosis by elevating selected microbiota-derived metabolites and tissue tight junctions in rats under chronic sleep deprivation.

Neuropsychiatric behaviors caused by sleep deprivation (SD) are severe public health problems in modern society worldwide. This study investigated the effect of fish oil on neuropsychiatric behaviors, barrier injury, microbiota dysbiosis, and microbiota-derived metabolites in SD rats. The rats subjected to SD had significantly elevated blood levels of corticosteroid and lipopolysaccharides and exhibited anxiety-like behavior in the open field test, depression-like behavior in the forced swim test, and cognitive impairment in the Morris water maize test. We observed that the upregulation of proinflammatory cytokines in the SD rats resulted in colonic epithelial barrier injury including a decreased number of goblet cells and increased expression of selected tight junction proteins in the gut and brain. The gut microbiome status revealed a significant decrease in the microbial diversity in the SD rats, especially in probiotics. By contrast, a fish oil-based diet reversed SD-induced behavioral changes and improved the epithelial barrier injury and dysbiosis of the microbiota in the colon. These findings could be attributable to the increase in probiotics and short-chain fatty acid (SCFAs) production, improvement in selected intestinal barrier proteins, increase in SCFA receptor expression, and decrease in blood circulation proinflammatory status due to fish oil supplementation.