Fig 2: Effects of TMAO on BV2 cells.A Effects of TMAO on proliferation of BV2 cells, measured using the MTT assay. B Expression of MAOA, MAOB, COMT, AChE, AMP, CHRNA1, and CHRNB1 in TMAO- damaged BV2 cells. C Expression of circNF1-419 and circ_0001239 in TMAO- damaged BV2 cells. D Expression of circNF1-419 and circ_0001239 in Kombucha tea-treated mice. E Ratio of abundance of Bifidobacterium species and Lactobacillus species was imbalanced in mice fed a HSHF diet and in AD-like mice. Data are the mean ± SD of more than five independent experiments (and three independent experiments when using western blotting). *p < 0.05 and **p < 0.01 vs. the model group by one-way ANOVA, followed by the Holm–Sidak test.

Fig 3: Gut microbiota plays an important role in the bioconversion of choline into TMAO and Ach. (A) The body weight changes after administration of choline; (B) Levels of acetylcholine and NADPH/NADP+ in the brain samples after administration of choline; (C) TMAO levels in serum and brain tissues after administration of choline mice; (D) Expression of the proteins MAOA, MAOB and COMT in liver; (E) Expression of the proteins MAOA, MAOB and COMT in brain tissues, and expression of the proteins AChE, AMP, CHRNA1 and CHRNB1 in the brain tissues. Data are presented as the means ± SD of more than 8 independent experiments, and more than 3 independent experiments in Western bolting. **p <0.05 and *p <0.01 vs. the control group by one-way ANOVA test.

Fig 4: C.albicans and Klebsiella pneumoniae influence the cholinergic system in mice.A Expression of AChE, AMP, CHRNA1, CHRNB1, and GAD65 were changed in the intestine (A, p < 0.05) and brain (B). Data are the mean ± SD of three independent experiments. *p < 0.05 and **p < 0.01 vs. the model group by one-way ANOVA, followed by the Holm–Sidak test.