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.