Effect of Pyridoxine Deficiency on Tyrosine Transaminase Activity and Growth of Four Morris Hepatomas2

Abstract

The effect of pyridoxine deficiency on the growth of 4 Morris hepatoma lines (#7777, 5123A, 7316B, and 7800) and the activity of tyrosine transaminase were investigated. Buffalo strain female weanling rats were fed for 21 days a commercially prepared diet either lacking or supplemented with pyridoxine. They were then inoculated with tumor cells in the hind legs and divided into 4 groups: Group A was continued on the deficient diet; group B was changed to the control diet and pair-fed to group A; group C was changed to the control diet and fed ad libitum; and group D was fed the control diet ad libitum from the start of the test. Host livers and hepatomas were removed and weighed at death, and tyrosine transaminase specific activity levels were determined. The results showed that hepatomas grown in animals fed the vitamin-deficient diet weighed the least. The difference between average tumor weights of hepatomas from animals receiving the pyridoxine-supplemented diet either on a restricted (pair-fed) or ad-libitum basis and from animals fed the vitamin-deficient diet was highly significant (P<0.001). In all cases, pyridoxine reduced host liver enzyme levels. Animals bearing hepatomas #7777 and 7316B showed a similar specific enzyme activity pattern; however, the pattern was reversed in animals bearing #5123A and 7800 hepatomas; i.e., lower host liver enzyme levels were found than in respective tumors in the deficient state, whereas the opposite was true for the nondeficient (normal) state.