Initiation of human parturition: XIII. Phospholipase C, phospholipase A2, and diacylglycerol lipase activities in fetal membranes and decidua vera tissues from early and late gestation.

Abstract

Phospholipase C, phospholipase A2, and diacylglycerol lipase activities in human amnion, chorion laeve, and uterine decidua vera tissues obtained in early and late gestation were examined. The specific activities of phospholipase C in amnion tissues obtained at 13–17 and 38–41 weeks gestation were 1.1 and 6.3 μmol • h−1 • mg−1 protein, respectively. A similar fold-increase in the specific activity of phospholipase A2 in amnion tissue obtained from early and late gestational periods was also observed (3.5 to 12.6 nmol • h−1 • mg−1 protein). In late gestation, the specific activities of phospholipase A2 and phospholipase C were greater in amnion tissue than in either chorion laeve or decidua vera tissues. Diacylglycerol lipase activity also was demonstrated in these three tissues. No change in the specific activity of diacylglycerol lipase was observed in any of the three tissues as gestation advanced. The specific activity of diacylglycerol lipase was greatest in decidua vera tissue. The increase in amnion tissue of the specific activities of phospholipase C and A2 during gestation suggests that this tissue may occupy a central role in the regulation of prostaglandin formation that accompanies human parturition and may provide an explanation for the preferential loss of arachidonic acid from phosphatidylinositol and phosphatidylethanolamine in amnion that occurs during early labor in the human.