The effect of streptomycin and erythromycin on vitamin B12 nutrition in rats in which coprophagy was prevented.

Abstract

1. Vitamin B12nutrition was studied in normal, coprophagy-prevented and antibiotic-treated rats on Vitamin B12-deficient diets with and without a vitamin B12supplement; the indices used were excretion of total urinary ether-soluble acid (TUESA) and methylmalonic acid, and vitamin B12assays on the liver and intestinal tract.2. A significant positive correlation (r= 0.61) was found between TUESA excretion and weight of rats, and a significant negative correlation (r= −0.89) between TUESA excretion and liver vitamin B12contents.3. Although prevention of coprophagy reduced the contents of vitamin B12in the stomach and small intestine, no effect on vitamin B12nutrition, as assessed by TUESA excretion and liver vitamin B12contents, was found. Rats in which coprophagy was permitted became vitamin B12-deficient, when given a diet in which vitamin B12was low.4. The amounts of TUESA and methylmalonic acid excreted indicated that streptomycin and erythromycin administered orally prevented vitamin B12deficiency in rats on a diet deficient in vitamin B12. Liver vitamin B12contents were, however, very low in these rats. this anomaly was thought to be due to the non-specificity of theEuglena gracilisassay for vitamin B12.5. It was concluded that, under the conditions of these experiments, coprophagy was not necessary to the vitamin B12-sparing action of antibiotics.