EFFECTS OF DIETARY SPHINGOLIPIDS ON LEVELS OF SERUM AND LIVER LIPIDS IN RATS

Sphingosine addition to cultured cells has been shown to provoke divergent physiological reactions. The present study was carried out to determine if dietary sphingolipids, which presumably liberate sphingosine during passage through the intestine, influence serum and liver lipids in rats. Rats were given purified diets containing cholesterol (1%) and sphingolipids (0.5 and 2%, composed mainly of ceramide and sphingomyelin) for 2 weeks. Food intake, body weight gain and liver weight were not affected by the supplementation of sphingolipids. The concentration of triglycerides in the serum, but not in the liver, decreased significantly in sphingolipid fed rats, and the accumulation of esterified cholesterol in the liver, but not in the serum, was partly suppressed. The concentration of sphingomyelin in the serum increased, depending on the level of dietary sphingolipids. However, no significant changes were observed in the concentration and proportion of the liver phospholipids at 0.5% supplementation, but significant elevation of liver phospholipids when supplemented at 2% level. Thus, it is suggested that sphingosine derived from the dietary sphingolipids can modify serum and liver lipid metabolism.