Effect of clofibric acid on the molecular species composition of diacyl glycerophosphocholine of rat liver microsomes.

The effect of administering p-chlorophenoxyisobutyric (clofibric) acid to rats on the molecular species composition of diacyl-glycerophosphocholine (GPC) of rat liver microsomes was studied. Microsomal choline glycerophospholipids were converted to 1,2-diradyl-3-acetylglycerol and were separated into molecular species by reverse-phase high performance liquid chromatography. Diacyl-GPC consisted of 17 different molecular species. The predominant species were arachidonoyl derivatives, such as 18:0-20:4 (22.2% of the total) and 16:0-20:4 (22.0%). Administration of clofibric acid to rats caused a marked increase in 16:0-18:1 species of diacyl-GPC from 8% to 30%, making these the predominant species of diacyl-GPC in clofibric acid-fed rats. Also, a significant decrease (50% of controls) in 18:0-18:2 and 18:0-20:4 species was observed, whereas the decrease in molecular species containing 16:0 at the 1-position such as 16:0-18:2 and 16:0-20:4 was small (approximately 85% of control). The results show that clofibric acid caused marked changes in the molecular species composition of diacyl-GPC. The participation of 1-acyl-GPC acyltransferase and stearoyl-CoA desaturase in the regulation of the molecular species composition of diacyl-GPC is discussed.