DIACYLGLYCEROL METABOLISM AND ARACHIDONIC-ACID RELEASE IN HUMAN-FETAL MEMBRANES AND DECIDUA VERA

Diacylglycerol lipase activity was demonstrated in human fetal membranes and decidual vera tissues. The specific activity of the enzyme is highest in the microsomal fraction of decidual vera tissue. The acylester bond at sn-1 position of 1,2-diacyl-sn-glycerol is hydrolyzed followed by release of the fatty acid at the sn-2 position. The diacylglycerol lipase activity present in the microsomal fraction of decidual vera tissue hydrolyzes preferentially a diacylglycerol containing an arachidonoyl group in the sn-2 position. Monoacylglycerol lipase activity was also demonstrated in these tissues. The specific activity of monoacylglycerol lipase was significantly greater than that of diacylglycerol lipase and catalyzed preferentially the hydrolysis of monoacylglycerols containing an arachidonoyl group in the sn-2 position. Based on the subcellular distribution and the differential effects of various inhibitors, the monoacylglycerol lipase and diacylglycerol lipase in decidua vera tissue are apparently 2 distinct enzymes. Diacylglycerol kinase specific activity was also examined. It was 4-5 times greater in amnion than in chorion laeve or decidua vera. The importance of diacylglycerol metabolism in the mechanism of arachidonic acid release and prostaglandin biosynthesis is discussed.