Influence of dietary cholesterol on the relative synthesis of hepatic glycerides and molecular classes of 1,2-diglycerides and phospholipids in the gerbil in vivo

Abstract

The influence of dietary cholesterol on the relative rates of synthesis of hepatic lipids in the male Mongolian gerbil,Meriones unguiculatus, was studied. The semi-purified starch-based diet used lard as the dietary fat and was fed with or without a 0.5% (by wt.) cholesterol supplement. Each animal received 300 μCi [2-³H]-glycerol i.p. after 3 or 7 days on the dietary regimens. Relative rates of [2-³H]-glycerol incorporation into the major hepatic glycerides in vivo was not affected significantly by dietary cholesterol (0.5% level), suggesting that alteration in the relative biosynthesis of these lipids could not readily account for the higher triglyceride (TG) to phospholipid (PL) mass ratio in liver with cholesterol feeding. However, there was evidence for an increased formation of 1,2-diglyceride (1,2-DG). The complement of molecular species of hepatic 1,2-DG, phosphatidylcholine (PC), and phosphatidylethanolamine (PE) formed de novo, as measured using isotopic glycerol, was not influenced greatly by dietary cholesterol, although lower mean rates of synthesis of tetraenoic relative to dienoic species of phospholipids were indicated in cholesterol-fed gerbils.