Background Modification of the gut microbiota has been reported to reduce the incidence of type 1 diabetes mellitus (T1D). We hypothesized that the gut microbiota shifts might also have an effect on cognitive functions in T1D. Herein we used a non-absorbable antibiotic vancomycin to modify the gut microbiota in streptozotocin (STZ)-induced T1D mice and studied the impact of microbial changes on cognitive performances in T1D mice and its potential gut-brain neural mechanism. Results We found that vancomycin exposure disrupted the gut microbiome, altered host metabolic phenotypes, and facilitated cognitive impairment in T1D mice. Long-term acetate deficiency due to depletion of acetate-producing bacteria resulted in the reduction of synaptophysin (SYP) in the hippocampus as well as learning and memory impairments. Exogenous acetate supplement or fecal microbiota transplant recovered hippocampal SYP level in vancomycin-treated T1D mice, and this effect was attenuated by vagal inhibition or vagotomy. Conclusions Our results demonstrate the protective role of microbiota metabolite acetate in cognitive functions and suggest long-term acetate deficiency as a risk factor of cognitive decline.

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Scope: Obesity is becoming a major public health problem due to excess dietary fat intake. Dendrobium officinale (D. officinale) is a medicine food homology plant and exerts multiple health-promoting effects. However, its antiobesity effects and the potential mechanisms remain unclear. Methods and results: High-fat diet (HFD)-fed mice are administered D. officinale dietary fiber (DODF) daily by gavage for 11 weeks. The results show that treatment with DODF alleviates obesity, liver steatosis, inflammation, and oxidant stress in HFD-induced obese mice. Improved glucose homeostasis in obese mice after DODF treatment is achieved by enhancing insulin pathway and hepatic glycogen synthesis. DODF restructures the gut microbiota in obese mice by decreasing the relative abundance of Bilophila and increasing the relative abundances of Akkermansia, Bifidobacterium, and Muribaculum. Also, DODF reshapes the metabolic phenotype of obese mice as indicated by up-regulating energy metabolism, increasing acetate and taurine, and reducing serum low density/very low density lipoproteins (LDL/VLDL). These beneficial effects are partly transferred by FMT, implying the gut microbiota as a target for the protective effect of DODF on obesity-related symptoms. Conclusion: The results suggest that DODF can be used as a novel prebiotics to maintain the gut microbial homeostasis and improve metabolic health, preventing obesity and related metabolic syndrome.

Following the publication of the original article [1], the author realized that they made a translation mistake between Chinese character and English name for one of the authors' name. Xiaokui Li should be revised to Xiaokun Li.The original article has been updated.