Lower Levels Of Phosphatidylcholine Research Articles

Time sequence of liver phospholipid alterations during deprivation of dietary choline.

Liver phospholipids of rats fed a choline-deficient diet low in methionine were examined at 0, 1, 2, 4, 8, 16, and 24 days. The level of arachidonic acid in both the total phospholipids and in phosphatidylethanolamine was significantly lower in the choline-deficient group than in the choline-supplemented group by 4 days. In phosphatidylethanolamine the levels of docosapentaenoic and docosahexaenoic acids were elevated in the deprived group within 2 days. No significant alterations in fatty acid concentrations were detected after 1 day, but low levels of phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin were evident at that time. Impaired interconversions of phospholipids may be a major effect of the diet fed.

The replacement of lipid-bound choline by other bases in the phospholipids of the housefly, Musca domestica

Larvae of the housefly, Musca domestica, bred on chemically defined diets under aseptic conditions incorporate β-methylcholine into the phospholipids in place of choline when the dietary source of choline is replaced by either acetyl- β-methylcholine or carnitine. A low level of phosphatidylcholine is found in such larvae. Larvae fed on diets containing a β-methylcholine source pupate normally and the adults obtained retain the abnormal phospholipid when fed on glucose and water. Adult houseflies incorporate only small amounts of β-methylcholine into their phospholipids when fed on acetyl- β-methylcholine solutions. No phosphatidyl- β-methylcholine was found in adult flies fed on carnitine solutions. It appears, therefore, that the adults unlike the larvae are unable to decarboxylate carnitine. Adult houseflies bred from larvae fed on diets containing carnitine in place of choline convert most of their phosphatidyl- β-methylcholine to phosphatidylcholine when choline is available. Acetylcholine levels in the heads of adult flies bred from larvae fed on diets containing acetyl- β-methylcholine or carnitine were reduced to approximately 30 per cent of the level found in adults bred from larvae fed on diets containing choline. This compares with a reduction of the phosphatidylcholine level in the whole insect to about 6 per cent of that found in normal flies. Larvae bred on a medium containing no added choline had an increased amount of phosphatidylethanolamine and a low level of phosphatidylcholine. Larvae bred on a medium containing added monomethylaminoethanol or dimethylaminoethanol incorporate these bases into their phospholipids. Both these bases replace choline and partially replace ethanolamine in the phospholipids.