Glutathione levels and related enzyme activities in vitamin B-6-deficient rats fed a high methionine and low cystine diet.
We examined the change in glutathione metabolism in vitamin B-6-deficient rats. Vitamin B-6-deficient rats were fed a vitamin B-6-deficient diet containing 0.56% methionine and 0.075% cystine for 8 wk. Controls were fed an identical diet supplemented with 10 mg pyridoxine hydrochloride/kg diet. Glutathione concentrations in each organ examined were similar in control and vitamin B-6-deficient rats, and the values were comparably lower after intraperitoneal injection of diethylmaleate. However, buthionine sulfoximine caused a significantly greater decrease in glutathione levels in the liver and lungs of vitamin B-6-deficient rats relative to controls. Glutathione peroxidase activity in the liver of vitamin B-6-deficient rats was higher than in control animals; however, glutathione transferase activity in tissues other than liver of vitamin B-6-deficient rats was higher than in the controls. The activities of gamma-glutamyl-transferase in the liver and spleen of vitamin B-6-deficient rats were significantly lower than control values. The holoenzyme activities of cystathionine beta-synthase and cystathionine gamma-lyase in the liver of vitamin B-6-deficient rats were markedly reduced. These findings indicate that although the activities of enzymes that synthesize cysteine from methionine were decreased by vitamin B-6 deficiency, the level of synthesis and supply of cysteine in vitamin B-6-deficient rats were sufficient to maintain the same glutathione level as in controls, and that glutathione utilization in the liver was accelerated by vitamin B-6 deficiency.
Takeuchi
F
F
Department of Biochemistry, Aichi Medical University, Japan.
Izuta
S
S
Tsubouchi
R
R
Shibata
Y
Y
D000818:Animals; D001835:Body Weight; D003553:Cystine / Q000008:administration & dosage* / Q000378:metabolism; D004032:Diet; D005978:Glutathione / Q000378:metabolism* / Q000493:pharmacokinetics; D005980:Glutathione Reductase / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000008:administration & dosage* / Q000378:metabolism; D011736:Pyridoxine / Q000008:administration & dosage; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D026681:Vitamin B 6 Deficiency / Q000378:metabolism*
D003553:Cystine; D008715:Methionine; D005980:Glutathione Reductase; D005978:Glutathione; D011736:Pyridoxine