HYPOCHOLESTEROLEMIC ACTION OF DIETARY PHOSPHATIDYLETHANOLAMINE IN RATS SENSITIVE TO EXOGENOUS CHOLESTEROL

Supplementation of phosphatidylethanolamine (PE) to the cholesterol-free diet decreases the serum cholesterol level in rats. The base portion of PE is responsible for this action, but its mechanism is not clarified yet. As an initial step to understand this mechanism, some of the metabolites of the ethanolamine portion of dietary PE in the liver and blood plasma were determined in the present study by using hypercholesterolemic rats sensitive to exogenous cholesterol. The rats were fed the purified diet containing 1% cholesterol, and either PE or phosphatidylcholine (PC) as a control at 2% level each for 2 weeks. The magnitude of an elevation of the serum cholesterylester level was lower in rats fed PE than in those fed PC. The hepatic levels of triglyceride and cholesterylester tended to be higher in rats fed PE. Fecal steroid excretion was not influenced by the type of the dietary phospholipids. The level of serum ethanolamine and liver phosphoethanolamine was 1.5- and 5.8-fold higher, respectively, in rats fed PE than in those fed PC. The concentration of serum PC was lower and that of the PE was higher in rats fed PE. The level of liver phosphoethanolamine was correlated inversely to that of serum cholesterylester in rats given PE. From these results, it is suggested that inadequate utilization of PC for a component of secretory lipoproteins in the liver and for a substrate donor for cholesterylester formation in the blood serum may be relevant to the cholesterol-lowering action of the dietary PE.