Eicosapentaenoic Acid Reduces Hepatic Synthesis and Secretion of Triacylglycerol by Decreasing the Activity of Acyl Coenzyme A:1,2-Diacylglycerol Acyltransferase, J. Lipid Res. 29, 1417-1426 (original) (raw)

The Journal of Lipid Research

The mechanism for the reduced hepatic production of triacylglycerol in the presence of eicosapentaenoic acid was explored in short-term experiments using cultured parenchymal cells and microsomes from rat liver. Oleic, palmitic, stearic, and linoleic acids were the most potent stimulators of tria~yl[~H]glycerol synthesis and secretion by hepatocytes, whereas erucic, a-linolenic, y-linolenic, arachidonic, docosahexaenoic, and eicosapentaenoic acids (in decreasing order) were less stimulatory. There was a linear correlation (r= 0.85, PcO.01) between synthesis and secretion of tria~yl[~H]glycerol for the fatty acids examined. The extreme and opposite effects of eicosapentaenoic and oleic acids on triacylglycerol metabolism were studied in more detail. With increasing number of free fatty acid molecules bound per molecule of albumin, the rate of synthesis and secretion of tria~yl[~H]glycerol increased, most markedly for oleic acid. Cellular uptake of the two fatty acids was similar, but more free eicosapentaenoic acid accumulated intracellularly. Eicosapentaenoic acid caused higher incorporation of ['Hlwater into phospholipid and lower incorporation into triacylglycerol and cholesteryl ester as compared to oleic acid. No difference was observed between the fatty acids on incorporation into cellular free fatty acids, monoacylglycerol and diacylglycerol. The amount of some 16-and 18-carbon fatty acids in triacylglycerol was significantly higher in the presence of oleic acid compared with eicosapentaenoic acid. Rat liver microsomes in the presence of added 1,2-dioleoylglycerol incorporated eicosapentaenoic acid and eicosapentaenoyl-CoA into triacylglycerol to a lesser extent than oleic acid and its CoA derivative. Decreased formatiop of triacylglycerol was also observed when eicosapentaenoyl-CoA was given together with oleoyl-CoA, whereas palmitoyl-CoA, stearoyl-CoA, linoleoyl-CoA, linolenoyl-CoA, and arachidonoyl-CoA had no inhibitory effect.