Enzyme Activities in Vitamin B 6 -Deficient,Normal,and Tumor-Bearing Animals: Effect of Hydrocortisone

Abstract

Summary

The effect of vitamin B₆, deficiency on the activity of two vitamin B₆-requiring enzymes and the induction of these enzymes by hydrocortisone was studied in normal and hepatoma #7794A-bearing Buffalo rats. Enzyme activities were generally lower in vitamin B₆-deficient animals. Serine dehydratase was absent in this hepatoma. Administration of hydrocortisone resulted in increased transaminase activity of normal, host liver, and hepatoma. The increase in activity was greater in animals fed the pyridoxine-supplemented basal diet. Cycloheximide blocked the hormonally induced rise in enzyme activity. Hormonal induction of serine dehydratase was not seen in the host liver or tumor of animals fed the basal diet. However, a small increase in activity did occur in the host liver of animals fed the pyridoxine-supplemented basal diet. Administration of hydrocortisone with or without cycloheximide resulted in lower activity values of this enzyme in the host liver of vitamin B₆-deficient animals.