Mode of action of choline. V. Sequential changes in hepatic and serum lipids of choline-deficient rats

Abstract

A sequential study of the alterations in phospholipid composition of liver and serum was made in rats in early choline deficiency. After 2 days on a choline-deficient (c.d.) diet, the phosphatidylcholine to phosphatidylethanolamine ratio (PC/PE) was decreased in the rough and smooth microsomal membranes relative to the choiine-supplemented (c.s.) controls. The decrease in PC/PE was also noted in total hepatic phospholipids after 1 day on the c.d. diet and persisted for at least 12 days. The serum total phospholipids and light-density lipoprotein phospholipids were significantly lower after 2 days in the c.d. rats relative to the c.s. controls. The high-density lipoprotein phospholipids showed a significant decrease after 3 days and levelled off. The earliest detectable change occurring 9 h after ingestion of a c.d. diet was an increase in hepatic triglyceride with no significant change in the PC/PE ratio either in total hepatic or microsomal phospholipids. These results indicate that an alteration in the phospholipid composition of the microsomal fraction (105 000 g postmitochondrial sediment) is not primarily responsible for triglyceride accumulation. However, they do not rule out the possibility of an alteration in some other subcellular fraction being responsible for the fatty livers.