FIG 3.

Free choline needs to be processed by choline-utilizing bacteria to promote gluconeogenesis. (a) Eight-week-old male T. musculis-free WT mice were treated with vehicle or 1 g/liter free choline in drinking water for 1 week. Pyruvate tolerance testing (PTT) was performed. n = 5 to 10 mice/group. (b) Relative abundance of the choline-utilizing bacteria Desulfovibrio in the cecal contents of WT and HVEM KO mice. (c) Relative abundances of bacteria expressing the choline trimethylamine (TMA)-lyase (cutC) gene in the cecal contents of the indicated mice. (d) Serum levels of TMA in the WT and HVEM KO mice. (e to h) D. vulgaris collected from in vitro culture were administered via oral gavage into the T. musculis-free WT mice. The mice were then treated with vehicle or 1 g/liter free choline in drinking water for 1 week. The relative abundances of Desulfovibrio (e) and cutC-positive bacteria (f) in the cecal contents of the indicated groups of mice were determined, serum TMA and TMAO levels were monitored (g), and PTT was performed (h and i). n = 5 to 10 mice/group. The red and blue asterisks in panel h represent statistical significance of the D. vulgaris group (red) or the D. vulgaris-plus-choline group (blue) when compared to the control group, respectively. (j and k) Eight-week-old male T. musculis-free WT mice that were originally fed on a normal chow diet were orally administered D. vulgaris and then placed on a choline-deficient (CD) diet for 1 week, the serum TMA and TMAO levels were determined (j), and PTT was performed (k). n = 5 mice per group. The experiments were repeated at least twice. The data represent means ± the SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001.