The Effects of Choline Deficiency and Choline Re-Feeding Upon the Metabolism of Plasma and Liver Lipids

Abstract

bibs tractThe disturbance in lipid metabolism caused by deficiency of dietary choline ira rats was investigated with H"-pa%mitic acid as a tracer. The incorporation of radioactivity into blood triglycerides, as compared to that in chcsline-supplemented contrs8s, showed a striking decline in rats taken a t intervals during the development of &olirne deficiency. This was partially corrected by choline refeeding for 2 days and was normal after 4 days of choline re-feeding. Both the total amounts and the radioactivities of phosphatidyl choliile in the liver and total phospholipids in the plasma were reduced in ehsline 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 choiine 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 phosghstidyl choline which is required for lipoprotein formation.-A marked reduction in the transformation of I4C-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 t o be from synthesis by the direct (CBP-cholinej pathway.

Effect of Vitamin B12deficiency on phosphatidylethanolamine methylation in rat liver

“…Changes in the same direction have been observed in livers from rats reared on a diet deficient in choline, methionine or both (Blumenstein, 1964;Haines, 1966;Thompson, MacDonald & Mookerjea, 1969).…”

“…I). In rats fed on a diet deficient in methionine and choline the proportion of phosphatidylethanolamine in the liver increases at the expense of phosphatidylcholine (Blumenstein, 1964;Haines, 1966). In the same condition an increased activity of phosphatidylethanolamine methyltransferase (EC 2 .…”

Choline fails to prevent liver fibrosis in ethanol-fed baboons but causes toxicity

“…Furthermore, orotic acid, which reduces the choline deficiency fatty liver, has no such effect on the ethanol variety (30). Finally, whereas choline deficiency is associated with a reduction in circulating lipoproteins, including high-density lipoproteins (31), the opposite is true of alcohol (32); the increased incorporation of palmitic a~i d -~H into lipoproteins after alcohol contrasts with the decrease observed in choline deficiency (33). Thus, hepatic injury induced by choline deficiency appears to be primarily an experimental disease of rats with little relevance to human alcoholic liver injury.…”

Biochemical and Evolutionary Significance of Phospholipid Methylation

“…The fatty liver observed in rats fed a CD diet could be, at least partially, ascribed to a defect in secretion of triacylglycerol-rich very low density lipoproteins (VLDL) from the liver, resulting in hepatic triacylglycerol accumulation (22,23). Plasma VLDL from Pempt ϩ/Ϫ mice contained less triacylglycerol than did VLDL from wild type mice (Fig.…”