Figure 3.

Mice maintained on vitamin B12-deficient diet have reduced plasma cobalamin concentrations and increased plasma MMA and plasma Hcy concentrations. (A) The plasma cobalamin concentration is greatly reduced in all mice fed with the vitamin B12-deficient diet (red bars) for 12 weeks (P-value < 0.001). Plasma cobalamin concentrations were normalized to control mice fed with the vitamin B12-supplemented diet (control-yellow bar) and plotted to show mean and SD. Mice fed with the vitamin B12-supplemented diet (yellow bars) had equivalent levels of plasma cobalamin as control mice fed with the standard mouse chow (white bar). Cd320 KO mice fed with standard mouse chow appear to have lower plasma cobalamin concentration (P-value < 0.01), although only a small number of mice were tested (n = 2). (One-way ANOVA with Tukey’s multiple comparison test.) Comparing between the two mouse genotypes fed with the vitamin B12-deficient diet (red bars), plasma cobalamin concentrations are significantly increased in Cd320 KO mice compared to controls (P-value < 0.0001 Mann–Whitney test). (B) After 24 weeks, all mice maintained on the vitamin B12-deficient diet (red symbols) had highly elevated plasma MMA concentrations compared to mice fed with the vitamin B12-supplemented diet (yellow symbols). However, no significant difference in plasma MMA was found between genotypes fed with the same diet for 24 weeks (one-way ANOVA with Tukey’s multiple comparisons test, mean with SD). (C) All mice maintained on the vitamin B12-deficient diet (red symbols) for 24 weeks had elevated concentrations of plasma Hcy compared to mice fed with the vitamin B12-supplemented diet (yellow symbols) (one-way ANOVA with Tukey’s multiple comparison test, mean with SD).