Breeding Severely Vitamin B₁₂-Deficient Mice as Model Animals

Newborn mice weaned from mice fed on a B₁₂-deficient diet during pregnancy and lactation were fed on a B₁₂-deficient diet for 90 days after weaning, and the state of B₁₂ deficiency was evaluated. The effect of B₁₂ deficiency on the testicular tissue was also examined. The body weight of the mice fed on a B₁₂-deficient diet for 90 days was slightly lower than that of the control mice administrated CN-B₁₂, and the urinary excretion of methylmalonic acid (MMA) was increased. The B₁₂ concentrations in the liver and testes were markedly depressed by B₁₂ deficiency, being about 13 and 10 pmol/g, respectively, on 90 days. The testes weight was clearly reduced by B ₁₂ deficiency. The testes weight/100 body weight was also lowered. Clear morphological changes were observed in the testicular tissue of the B ₁₂-deficient mice. These results showed that mice in a severely B₁₂-deficient state could be produced by dietary B₁₂ deprivation. These B₁₂-deficient mice could be useful as model animals not only for elucidating the functions of B₁₂ in vivo, but also for biochemical studies.