Effect of DL-Homocysteine on some Hepatic Folate Enzymes and Folate Concentration in Cobalamin-Deficient Rats

Abstract

Male weanling wistar rats were fed either a vitamin B(12)-deficient diet or a vitamin B(12)-deficient diet supplemented with DL-homocysteine for 12 weeks. The control group was given a vitamin B(12)-supplemented diet for 12 weeks. Hepatic folate, hepatic 5,10-methylene THF reductase (EC 1.1.1.68) and hepatic 5-methyl THF; homocysteine- methyl transferase (EC 2.1.1.13) activities were assayed in all the rats after killing. The hepatic folate activity was very low among the homocysteine-supplemented rats. 5,10-methylene THF reductase and 5-methyl THF; homocysteine methyl transferase activities were increased in the homocysteine-fed rats. These results show that dietary DL-homocysteine has some regulatory effect on the two enzymes involved in the production of ‘free’ THF.