Ethanol-induced changes in methionine metabolism in rat liver

The administration of alcohol to rats fed a protein-restricted diet results in significant changes in the hepatic content of four enzymes of methionine metabolism. The levels of s-adenosylmethionine synthetase, cystathionine synthase, and betaine-homocysteine methyltransferase increase while the level of methyltetrahydrofolate-homocysteine methyltransferase decreases. These changes represent a reversal of the normal adaptive response to protein-restriction. The resultant impairment in methionine conservation could explain the alcohol-induced increase in the dietary lipotrope requirement.