hormone-induced variation of phosphatidate phosphohydrolase activity in various tissues of pregnant rats

variations in phosphatidate phosphohydrolase (pap) activity and triacylglycerol concentration were measured in pregnant and hormone-treated non-pregnant female rats. pap activity in adipose tissue was elevated by 61% during pregnancy. the increase in the enzyme activity was paralleled with a rise in serum triacylglycerol concentration (44%). estradiol injecting into non-pregnant rats increased pap activity of both adipose tissue (19.8%) and the liver (26%). progesterone also elevated the enzyme activities of adipose tissue and liver by 10% and 55%, respectively. both hormones increased serum triacylglycerol concentration (20-29%). the data demonstrated that hypertriglyceridemia observed during pregnancy was mediated through the hormonal effects on pap activity, a key enzyme in glycerolipid metabolism.