Abstract
BackgroundWestern pattern diets induce neuroinflammation and impair cognitive behavior in humans and animals. Neuroinflammation and cognitive impairment have been associated with microbiota dysbiosis, through the gut-brain axis. Furthermore, microbiota-accessible carbohydrates (MACs) found in dietary fiber are important in shaping the microbial ecosystem and have the potential to improve the gut-brain-axis. However, the effects of MACs on neuroinflammation and cognition in an obese condition have not yet been investigated. The present study aimed to evaluate the effect of MACs on the microbiota-gut-brain axis and cognitive function in obese mice induced by a high-fat and fiber deficient (HF-FD) diet.MethodsC57Bl/6 J male mice were fed with either a control HF-FD or a HF-MAC diet for 15 weeks. Moreover, an additional group was fed with the HF-MAC diet in combination with an antibiotic cocktail (HF-MAC + AB). Following the 15-week treatment, cognitive behavior was investigated; blood, cecum content, colon, and brain samples were collected to determine metabolic parameters, endotoxin, gut microbiota, colon, and brain pathology.ResultsWe report MACs supplementation prevented HF-FD-induced cognitive impairment in nesting building and temporal order memory tests. MACs prevented gut microbiota dysbiosis, including increasing richness, α-diversity and composition shift, especially in Bacteroidetes and its lower taxa. Furthermore, MACs increased colonic mucus thickness, tight junction protein expression, reduced endotoxemia, and decreased colonic and systemic inflammation. In the hippocampus, MACs suppressed HF-FD-induced neuroglia activation and inflammation, improved insulin IRS-pAKT-pGSK3β-pTau synapse signaling, in addition to the synaptic ultrastructure and associated proteins. Furthermore, MACs’ effects on improving colon–cognitive parameters were eliminated by wide spectrum antibiotic microbiota ablation.ConclusionsThese results suggest that MACs improve cognitive impairments via the gut microbiota-brain axis induced by the consumption of an HF-FD. Supplemental MACs to combat obesity-related gut and brain dysfunction offer a promising approach to prevent neurodegenerative diseases associated with Westernized dietary patterns and obesity.
Highlights
Neuroinflammation is a hallmark of neurodegenerative diseases associated with Westernized dietary patterns, including high fat consumption and fiber deficiency [1,2,3]
These results suggest that microbiota-accessible carbohydrates (MACs) improve cognitive impairments via the gut microbiota-brain axis induced by the consumption of an high-fat and fiber deficient (HF-FD)
Diet rich in microbiota-accessible carbohydrate prevented gut microbiota dysbiosis in diet-induced obese mice To investigate the effects of high fat and fiber deficiency on intestinal microbiota and whether microbiotaaccessible carbohydrate could prevent microbiota dysbiosis, qRT-PCR was used to evaluate total fecal bacterial loads
Summary
Neuroinflammation is a hallmark of neurodegenerative diseases associated with Westernized dietary patterns, including high fat consumption and fiber deficiency [1,2,3]. Neurodegenerative diseases such as dementia and Alzheimer’s disease (AD) are not curable; the Lancet commission reported that more than one third of global dementia cases may be preventable through addressing lifestyle factors, including diet [4]. Neuroinflammation and cognitive impairment have been associated with microbiota dysbiosis, through the gut-brain axis. The present study aimed to evaluate the effect of MACs on the microbiota-gut-brain axis and cognitive function in obese mice induced by a high-fat and fiber deficient (HF-FD) diet
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