Influence of Vitamin B 12 and Liver Extract on Nitrogen Balance of Normal and Hyperthyroid Rats. ∗

Abstract

Summary

Vit B₁₂ or liver extract administered to force-fed rats on constant food intake induced neither weight gain nor N retention. When vit B₁₂ was administered to force-fed rats on constant food intake, made hyperthyroid by injection of thyroxine, the weight loss was identical with that of hyperthyroid animals not receiving vit B₁₂. The N loss resulting from the catabolic action of thyroxine, however, was significantly smaller in thyroxine-treated rats receiving B₁₂ than in the thyroxine-treated controls. Liver extract had a, similar action, but the values obtained were statistically not significant. These results suggest that in hyperthyroid rats vit B₁₂ spares protein at the expense of other body constituents.