THE EFFECTS OF CHOLINE DEFICIENCY AND CHOLINE RE-FEEDING UPON THE METABOLISM OF PLASMA AND LIVER LIPIDS

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Abstract
The disturbance in lipid metabolism caused by deficiency of dietary choline in rats was investigated with H3-palmitic acid as a tracer. The incorporation of radioactivity into blood triglycerides, as compared to that in choline-supplemented controls, showed a striking decline in rats taken at intervals during the development of choline deficiency. This was partially corrected by choline re-feeding for 2 days and was normal after 4 days of choline re-feeding. Both the total amounts and the radioactivities of phosphatidyl choline in the liver and total phospholipids in the plasma were reduced in choline deficiency and were restored by choline re-feeding, whereas phosphatidyl ethanolamine in the liver was not affected. The findings confirm that the fatty liver of choline deficiency is the result of an impairment in the transport of triglyceride from the liver, and support the hypothesis that it occurs because of a restriction in the synthesis of phosphatidyl choline which is required for lipoprotein formation.A marked reduction in the transformation of14C-ethanolamine into phosphatidyl choline was evident in choline deficiency, but most of the increase in liver phosphatidyl choline which occurred subsequent to choline re-feeding appeared to be from synthesis by the direct (CDP-choline) pathway.