Diet and 14CH3-Methionine Incorporation into Liver Phosphatidylcholine Fractions of Male and Female Rats

Abstract

An experiment was conducted to see whether diet influenced the incorporation of 14CH3-methionine into liver phosphatidylcholines of male and female rats.Rats of both sexes were fed either a stock diet (Purina Chow), a semipurified diet containing 10% flaxseed oil, or a low methionine diet with or without choline. One hour before killing, 14CH3-methionine was injected into the animals. The distribution of the label in subfractions of liver phosphatidylcholines was then determined.Choline phosphatides of female rats fed chow or flaxseed oil diets had higher specific activities than did those of males. In chow-fed female rats the additional radioactivity appeared mainly in the tetraene phosphatidylcholine fraction. In female rats fed flaxseed oil, the extra label appeared in the tetraene as well as in a pentaene fraction.Therefore, changes in the degree of unsaturation of the species of phosphatidylcholine by dietary modification did not alter total incorporation of the label into liver phosphatidylcholines nor did it influence sex differences in the incorporation even though the distribution of the label within particular species of choline phosphatides was changed.No sex differences in incorporation were evident in the low methionine diet whether it contained choline or not. Choline deficiency did not affect total incorporation of the methyl group nor the proportions of phosphatidylcholine subfractions in the phospholipids, although in males it depressed the amount of hepatic phosphatidylcholine.