Table 3.

Indices of methyl donor status and global DNA methylation in blood and tissues from rats fed a folate-supplemented (F+) or folate-deficient (F) diet for 24 wk

Methylation status
F+F
Plasma total homocysteine (μmol/L)5.01 ± 0.27 (12)6.91 ± 0.32* (12)
Plasma B12 (pg/mL)503.1 ± 40.5 (10)579.3 ± 53.5 (10)
Lymphocyte B12 (pg/105 cells)13.94 ± 0.40 (10)12.39 ± 0.70 (10)
Liver B12 (pg/mg protein)366.8 ± 27.1 (10)437.8 ± 44.7 (10)
Distal colon B12 (pg/mg protein)622.7 ± 50.5 (10)618.2 ± 78.6 (10)
Liver SAM81.60 ± 4.93 (10)79.22 ± 4.99 (10)
Liver SAH14.53 ± 0.9 (10)15.78 ± 1.06 (10)
Liver SAM:SAH ratio5.63 ± 0.12 (10)5.04 ± 0.13 (10)
Colon SAM32.47 ± 4.36 (10)28.36 ± 2.91 (10)
Colon SAH3.57 ± 0.47 (10)4.48 ± 0.52 (10)
Colon SAM:SAH ratio9.75 ± 1.34 (10)7.09 ± 1.03 (10)
Liver DNA methyltransferase (absorbance/h/mg nuclear protein)4.38 ± 0.90 (12)6.70 ± 2.33 (12)
Liver 5-methyldeoxycytidine (ng/μg DNA; LC MS/MS)2.62 ± 0.32 (12)2.12 ± 0.23 (12)
Liver genomic DNA methylation (%; LC MS/MS)4.63 ± 0.10 (12)4.54 ± 0.04 (12)
Colon 5-methyldeoxycytidine (ng/μg DNA; LC MS/MS)4.56 ± 0.22 (12)3.47 ± 0.51 (12)
Colon genomic DNA methylation (%; LC MS/MS)4.87 ± 0.09 (12)4.61 ± 0.15 (12)

NOTE: Values are the mean ± SE, with number of rats sampled per group in parentheses. Significance refers to differences between F+ versus F animals at the end of the experiment.