The Hypotriglyceridemic Effect of Sciadonic Acid is Mediated by the Inhibition of D9-Desaturase Expression and Activity
2018
Pédrono, Frédérique,
Sciadonic acid (Scia; 20:3 5,11,14) is a distinctive fatty acid (FA) with a polymethylene-interrupted double bond at C5. It is specifically found in seeds from gymnosperms such as pine nuts. Published papers describe a decrease in liver and plasma triacylglycerols in rats fed with this nutriment. The present study sought to identify the action mechanism of Scia on triacylglycerol synthesis and secretion. In this way, its nutritional effect on FA metabolism involving the hepatic 9-desaturase named Stearoyl-CoA Desaturase 1 (SCD1) was investigated.Scia was discerned in trace amount in various tissues of rats, as well as in human serum. Despite its unusual non-malonic structure absent in mammals, it was produced by 5-desaturation of 20:2n-6 in rat primary hepatocytes and also in human transfected SH-SY5Y cell lines. When Scia was incubated with cultured hepatocytes as a nutrient, the cellular FA profile was modified. In particular, the proportion of linoleic acid (18:2n-6) was increased, whereas the proportion of the monoenes (18:1n-9, 18:1n-7, 16:1n-7) were all decreased, correlating to the reduction of triacylglycerol amounts. This effect was mediated by the inhibition of the gene and protein expression of SCD1. Furthermore, Scia, as well as 20:3n-6 and 20:3n-9 but not 20:3n-3, strongly inhibited the SCD1 activity measured on liver microsomes.Overall this study showed that Scia, in spite of its unusual structure, contributes to the FA metabolism and reduced triacylglycerol release by inhibiting SCD1 activity in hepatocytes.
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