Effects of vitamin B-6 deficiency and 4'- deoxypyridoxine on pyridoxal phosphate concentrations, pyridoxine kinase and other aspects of metabolism in the rat.

Male rats about 100 days old were fed a B-6 deficient diet supplemented with 4'-deoxypyridoxine (1 g/kg diet) and/or pyridoxine hydrochloride (22 mg/kg diet) for 30 to 35 days. Addition of 4'-deoxypyridoxine to the B-6-deficient diet produced greater losses in body weight (P less than 0.05) and thymus weight (P less than 0.01) than in B-6-deficient pair-fed controls. 4'-Deoxypyridoxine combined with a B-6-deficient diet produced no decreases in the concentration of pyridoxal phosphate or pyridoxine kinase in the tissues examined when compared with B-6-deficient controls. Addition of deoxypyridoxine to a diet containing adequate B-6 tended to reduce that absolute weight of the adrenal glands and increased (P less than 0.05) plasma cholesterol compared with animals receiving only vitamin B-6. Compared with the B-6-deficient groups, pyridoxal phosphate concentrations in animals receiving normal B-6 were significantly (P less than 0.01) increased in the liver, muscle and adrenal glands but not in the thymus. In all groups the pyridoxine kinase activity was highest in the adrenal glands (3.6-6.3 pmole pyridoxine phosphate/minute/mg tissue) followed by the liver (1.3-3.7) and thymus (0.7-1.3). These high kinase values and the weight changes suggest an important role for vitamin B-6 in these organs. Recent evidence that pyridoxal phosphate may interact with glucocorticoid receptors raises the possibility that the role of vitamin B-6 in these and other organs may involve metabolic regulation by a mechanism independent of the well-established coenzyme function of this vitamin.