Effect of vitamin B12-deficiency on the activity of hepatic cystathionine beta-synthase in rats.
The effect of vitamin B12(B12)-deficiency on the activities of hepatic methionine synthase, homocysteine methyltransferase, and cystathionine beta-synthase was investigated in rats. The rats bred from B12-deficient dams were fed the B12-deficient diets for 150 days after weaning. Growth retardation of the B12-deficient rats was already observed on day 30 and continued through 150 days. But dietary supplementation of 0.5% DL-methionine slightly improved the growth retardation. Urinary excretion of methylmalonic acid increased to about 15 mg/mg creatinine and hepatic B12 concentration declined to about 2 ng/g liver after a 150-day feeding of the B12-deficient diets. Hepatic methionine synthase activity in rats fed the B12-deficient diets supplemented with or without methionine decreased to about 5% of B12-supplemented controls. Hepatic betaine-homocysteine methyltransferase activity showed no significant change caused by B12-deficiency. Hepatic cystathionine beta-synthase activity in rats fed the B12-deficient diets supplemented with or without methionine decreased to about 61% and 27% of their B12-supplemented controls, respectively, but the decrease was partially improved by methionine supplementation. In conclusion, the rats bred from B12-deficient dams showed a severe B12-deficiency after a 150-day feeding of the B12-deficient diets. The decrease of hepatic cystathionine beta-synthase activity was supposed to be due to the adaptation by the defect of methionine resynthesis.
Doi
T
T
Department of Agricultural Chemistry, Tokyo University of Agriculture, Japan.
Kawata
T
T
Tadano
N
N
Iijima
T
T
Maekawa
A
A
D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000378:metabolism; D000818:Animals; D050940:Betaine-Homocysteine S-Methyltransferase; D003541:Cystathionine beta-Synthase / Q000378:metabolism*; D006836:Hydro-Lyases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008764:Methylmalonic Acid / Q000652:urine; D008780:Methyltransferases / Q000378:metabolism; D011506:Proteins / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014806:Vitamin B 12 Deficiency / Q000201:enzymology* / Q000652:urine
D011506:Proteins; D008764:Methylmalonic Acid; D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D050940:Betaine-Homocysteine S-Methyltransferase; C494550:Bhmt protein, rat; D006836:Hydro-Lyases; D003541:Cystathionine beta-Synthase