Glucagon inhibits phosphatidylcholine biosynthesis via the CDP-choline and transmethylation pathways in cultured rat hepatocytes.
The short-term influence of insulin and glucagon on phosphatidylcholine biosynthesis in monolayer cultures of rat hepatocytes was investigated. Under conditions in which insulin (100 nM) stimulated [3H]acetate incorporation into fatty acid almost twofold, synthesis of phosphatidylcholine via CDP-choline and from phosphatidylethanolamine were unaffected. By contrast, glucagon (100 nM), even in the presence of insulin (100 nM), reduced the rate of phosphatidylcholine formation from [Me-3H]phosphocholine by approximately 25% (p less than 0.05) within 1 h. Similarly, [3H]phosphatidylethanolamine incorporation into phosphatidylcholine was inhibited in cells exposed to glucagon. Insulin and glucagon had little or no effect on [Me-3H]choline uptake by the hepatocytes. No changes in the activities of the phosphatidylcholine biosynthetic enzymes in cytosol and microsomes from glucagon-treated cells could be detected.
D000818:Animals; D001622:Betaine / Q000378:metabolism; D002478:Cells, Cultured; D002794:Choline / Q000031:analogs & derivatives*; D003566:Cytidine Diphosphate Choline / Q000378:metabolism*; D003864:Depression, Chemical; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005934:Glucagon / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008745:Methylation; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D005227:Fatty Acids; D007328:Insulin; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D001622:Betaine; D003566:Cytidine Diphosphate Choline; D005934:Glucagon; D002794:Choline