Hepatic phosphatidylethanolamine methyltransferase activity is decreased by ethanol and increased by phosphatidylcholine.

Abstract

UNLABELLED:

Phosphatidylethanolamine N-methyltransferase participates in the synthesis of membrane phosphatidylcholine. Its activity was reported to be decreased in patients with alcoholic cirrhosis, but it is not known whether this is a consequence of the cirrhosis or precedes it. This question was studied in a baboon model of alcohol-induced fibrosis. Phosphatidylethanolamine N-methyltransferase activity was measured in sequential percutaneous needle liver biopsies by the conversion of phosphatidylethanolamine to phosphatidylcholine, using radioactive S-adenosylmethionine as a methyl donor. Chronic alcohol consumption (1-6 years) significantly decreased hepatic phospholipid and phosphatidylcholine levels and reduced phosphatidyl-ethanolamine N-methyltransferase activity even before the development of fibrosis. These effects were prevented or attenuated by supplementing the diet with 2.8 g/1000 kcal of a preparation rich in dilinoleoyl phosphatidylcholine, a highly bioavailable phosphatidylcholine species. There were significant (p < 0.001) correlations between phosphatidylethanolamine N-methyltransferase activity and both hepatic phosphatidylcholine (r = 0.678) and total phospholipid (r = 0.662).

CONCLUSIONS:

1. Alcohol consumption diminishes phosphatidylethanolamine N-methyltransferase activity prior to the development of cirrhosis and decreases the hepatic content of its product, namely phosphatidylcholine, a key component of cell membranes. This may promote hepatic injury and possibly trigger fibrosis. 2. Phosphatidylcholine administration ameliorates the ethanol-induced decrease in phosphatidylethanolamine N-methyltransferase activity and corrects phospholipid and phosphatidylcholine depletions, thereby possibly contributing to the protection against alcoholic liver injury.

• Authors: C S Lieber, S J Robins, M A Leo
• Journal: Alcoholism, clinical and experimental research (Alcohol Clin Exp Res) Vol. 18 Issue 3 Pg. 592-5 (Jun 1994) ISSN: 0145-6008 [Print] England
• PMID: 7943660 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Membrane Lipids
• Phosphatidylcholines
• Phospholipids
• Ethanol
• Methyltransferases
• Phosphatidylethanolamine N-Methyltransferase

Topics

• Animals
• Biopsy
• Ethanol (toxicity)
• Female
• Liver (enzymology, pathology)
• Liver Cirrhosis, Alcoholic (enzymology, pathology)
• Male
• Membrane Lipids (metabolism)
• Methyltransferases (antagonists & inhibitors, metabolism)
• Papio
• Phosphatidylcholines (metabolism, pharmacology)
• Phosphatidylethanolamine N-Methyltransferase
• Phospholipids (metabolism)