Effects of betaine supplementation on hepatic metabolism of sulfur-containing amino acids in mice.
OBJECTIVE
We previously reported that acute betaine treatment induced significant changes in the hepatic glutathione and cysteine levels in mice and rats. The present study was aimed to determine the effects of dietary betaine on the metabolism of sulfur-containing amino acids.


RESULTS
Male mice were supplemented with betaine (1%) in drinking water for up to 3 weeks. Changes in hepatic levels of major sulfur amino acid metabolites and products were stabilized after 2 weeks of betaine supplementation. Betaine intake increased methionine, S-adenosylmethionine, and S-adenosylhomocysteine levels significantly, but homocysteine and cystathionine were reduced. Methionine adenosyltransferase activity was elevated to three-fold of control. Cysteine catabolism to taurine was inhibited as evidenced by a decrease in cysteine dioxygenase activity and taurine levels in liver and plasma. Despite the significant changes in the transsulfuration reactions, neither hepatic cysteine nor glutathione was altered. Betaine supplementation decreased the hepatotoxicity induced by chloroform (0.5 ml/kg, ip) significantly.


CONCLUSIONS
Betaine supplementation enhances recycling of homocysteine for the generation of methionine and S-adenosylmethionine while reducing its utilization for the synthesis of cystathionine and cysteine. However, the hepatic levels of cysteine or glutathione are not affected, most probably due to the depression of taurine generation from cysteine.
Kim
Sang K
SK
College of Pharmacy, Chungnam National University, Daijeon, 222 Gung-Dong, Yuseong-Ku, Daijeon, South Korea.
Kim
Young C
YC
D000603:Amino Acids, Sulfur / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001622:Betaine / Q000494:pharmacology*; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism; D002725:Chloroform / Q000633:toxicity; D003545:Cysteine / Q000097:blood / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008082:Lipotropic Agents / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000097:blood / Q000378:metabolism; D008716:Methionine Adenosyltransferase / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D012436:S-Adenosylmethionine / Q000378:metabolism; D012997:Solvents / Q000633:toxicity; D013654:Taurine / Q000097:blood / Q000378:metabolism
D000603:Amino Acids, Sulfur; D008082:Lipotropic Agents; D012997:Solvents; D013654:Taurine; D001622:Betaine; D012436:S-Adenosylmethionine; D002725:Chloroform; D008715:Methionine; D008716:Methionine Adenosyltransferase; D005978:Glutathione; D003545:Cysteine