Effects of Vitamin B-6 Deficiency and 4′-Deoxypyridoxine on Pyridoxal Phosphate Concentrations, Pyridoxine Kinase and Other Aspects of Metabolism in the Rat

Abstract

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.

Oral exposure to the anti-pyridoxine compound 1-amino d-proline further perturbs homocysteine metabolism through the transsulfuration pathway in moderately vitamin B6 deficient rats

“…Given that the inclusion of 1ADP in the CD diet had no impact on performance of the rats is strong evidence that the toxicological effects of 1ADP were due to its impact on B 6 status. Furthermore, prior studies have demonstrated that reductions in weight gain and FER elicited by anti-pyridoxine compounds were not solely the effect of reduced intake but rather due to the metabolic insults on amino acid, carbohydrate and lipid metabolism [37,39]. Clearly, those rats consuming adequate vitamin B 6 are generally protected from the oral exposure to 1ADP, at least as it pertains to growth and feed intake.…”

Effect of tryptophan metabolites on the activities of rat liver pyridoxal kinase and pyridoxamine 5-phosphate oxidase in vitro

“…Van den Berg et al (1982) also reported that the contents of pyridoxal 5-phosphate in rat liver and plasma were dependent on the amount of pyridoxine in the diet. In vitamin B-6deficient rat liver, the activity of pyridoxal kinase as well as the content of pyridoxal 5-phosphate were decreased (Meisler & Thanassi, 1980;Coburn et al, 1981). Pyridoxamine 5-phosphate oxidase activity in rat fed on a pyridoxine-deficient diet was not different from controls (Rasmussen et al, 1979;Meisler & Thanassi, 1980).…”

Effect of Casein and Soy Protein Isolate on Vitamin B(6) Nutritional Status in Rats

“…It can be phosphorylated by pyridoxal kinase to form deoxypyridoxal phosphate, which inhibits pyridoxal-phosphate-requiring enzymes. Cobum et al [3] reported that addition of deoxypyridoxine to a vitamin-B6-dcficicnt diet produced no further decrease in pyridoxal phosphate concentration and pyri doxal kinase activity in tissues compared with the control. It has also been reported that the effects of deoxypyridoxine on taurine metabolism [9], glycine metabolism [10] and liver aminotransferase activity [2] differ from those of dietary vitamin Bö deficiency.…”