Combined effect of sesamin and soybean phospholipid on hepatic fatty acid metabolism in rats

Abstract

We studied the combined effect of sesamin (1:1 mixture of sesamin and episesamine) and soybean phospholipid on lipid metabolism in rats. Male rats were fed diets supplemented with 0 or 2 g/kg sesamin, and containing 0 or 50 g/kg soybean phospholipid, for 19 days. Sesamin and soybean phospholipid decreased serum triacylglycerol concentrations and the combination of these compounds further decreased the parameter in an additive fashion. Soybean phospholipid but not sesamin reduced the hepatic concentration of triacylglycerol. The combination failed to cause a strong decrease in hepatic triacylglycerol concentration, presumably due to the up-regulation of Cd36 by sesamin. Combination of sesamin and soybean phospholipid decreased the activity and mRNA levels of hepatic lipogenic enzymes in an additive fashion. Sesamin strongly increased the parameters of hepatic fatty acid oxidation enzymes. Soybean phospholipid increased hepatic activity of 3-hydroxyacyl-CoA dehydrogenase although it failed to affect the activity of other enzymes involved in fatty acid oxidation. Sesamin strongly increased hepatic concentration of carnitine. Sesamin and soybean phospholipid combination further increased this parameter, accompanying a parallel increase in mRNA expression of carnitine transporter. These changes can account for the strong decrease in serum triacylglycerol in rats fed a diet containing both sesamin and soybean phospholipid.

Keywords: carnitine; hepatic fatty acid oxidation; hepatic lipogenesis; sesamin; soybean phospholipid.

Fig. 1

Effect of sesamin and soybean phospholipid on the activities of lipogenic enzymes in rat liver. Values are the means ± SEM, n = 7. The data were analyzed by two-way ANOVA. When the interaction of two factors (sesamin and soybean phospholipid) was significant, the data were reanalyzed by one-way ANOVA and Tukey’s post-hoc test. Means without a common letter differ (p<0.05). PL, phospholipid; ns, not significant.

Fig. 2

Effect of sesamin and soybean phospholipid on mRNA levels of lipogenic enzymes, adiponutrin, fatty acid desaturases and SREBP-1c in rat liver. Values are the means ± SEM, n = 7. The data were analyzed by two-way ANOVA. When the interaction of two factors (sesamin and soybean phospholipid) was significant, the data were reanalyzed by one-way ANOVA and Tukey’s post-hoc test. Means without a common letter differ (p<0.05). PL, phospholipid; ns, not significant.

Fig. 3

Effect of sesamin and soybean phospholipid on carnitine concentration, and mRNA levels of carnitine transporter and enzymes involved in carnitine biosynthesis in rat liver. Values are the means ± SEM, n = 7. The data were analyzed by two-way ANOVA. When the interaction of two factors (sesamin and soybean phospholipid) was significant, the data were reanalyzed by one-way ANOVA and Tukey’s post-hoc test. Means without a common letter differ (p<0.05). PL, phospholipid; ns, not significant.