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Ethanol Lowers Glutathione in Rat Liver and Brain and Inhibits Methionine Synthase in a Cobalamin-dependent Manner

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Specialty Psychiatry
Date 2010 Dec 3
PMID 21121936
Citations 15
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Abstract

Background: Methionine synthase (MS) is a ubiquitous enzyme that requires vitamin B12 (cobalamin) and 5-methyl-tetrahydrofolate for the methylation of homocysteine to methionine. Previous studies have shown that acute or chronic ethanol (ETOH) administration results in the inhibition of MS and depletion of glutathione (GSH), and it has been proposed that GSH is required for the synthesis of methylcobalamin (MeCbl).

Methods: We measured GSH levels and investigated the ability of different cobalamin cofactors [cyano- (CNCbl), glutathionyl- (GSCbl), hydroxo- (OHCbl), and MeCbl] to support MS activity in liver and brain cortex from control and ETOH-treated rats.

Results: In control animals, MS activity was higher in liver than in cortex for all cobalamins and MeCbl-based activity was higher than for other cofactors. S-adenosylmethionine (SAM) was required for OHCbl, CNCbl, and GSCbl-based activity, but not for MeCbl. Feeding an ETOH-containing diet for four weeks caused a significant decrease in liver MS activity, in a cobalamin-dependent manner (OHCbl ≥ CNCbl > GSCbl > MeCbl). In brain cortex, OHCbl, CNCbl, and GSCbl-based activity was reduced by ETOH treatment, but MeCbl-based activity was unaffected. GSH levels were reduced by ETOH treatment in both liver and cortex homogenates, and addition of GSH restored OHCbl-based MS activity to control levels. Betaine administration had no significant effect on GSH levels or MS activity in either control or ETOH-fed groups.

Conclusions: The ETOH-induced decrease in OHCbl-based MS activity is secondary to decreased GSH levels and a decreased ability to synthesize MeCbl. The ability of MeCbl to completely offset ETOH inhibition in brain cortex, but not liver, suggests tissue-specific differences in the GSH-dependent regulation of MS activity.

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References
1.
Blusztajn J, Zeisel S, Wurtman R . Developmental changes in the activity of phosphatidylethanolamine N-methyltransferases in rat brain. Biochem J. 1985; 232(2):505-11. PMC: 1152909. DOI: 10.1042/bj2320505. View

2.
Finkelstein J . Metabolic regulatory properties of S-adenosylmethionine and S-adenosylhomocysteine. Clin Chem Lab Med. 2007; 45(12):1694-9. DOI: 10.1515/CCLM.2007.341. View

3.
Li Z, Agellon L, Allen T, Umeda M, Jewell L, Mason A . The ratio of phosphatidylcholine to phosphatidylethanolamine influences membrane integrity and steatohepatitis. Cell Metab. 2006; 3(5):321-31. DOI: 10.1016/j.cmet.2006.03.007. View

4.
McKeever M, Weir D, Molloy A, Scott J . Betaine-homocysteine methyltransferase: organ distribution in man, pig and rat and subcellular distribution in the rat. Clin Sci (Lond). 1991; 81(4):551-6. DOI: 10.1042/cs0810551. View

5.
Kharbanda K . Alcoholic liver disease and methionine metabolism. Semin Liver Dis. 2009; 29(2):155-65. DOI: 10.1055/s-0029-1214371. View