Growth and function of the placenta--with special reference to various enzymes involved in the biosynthesis of steroids in the human placenta.

To study the function of the placenta from the viewpoint of placental aging, we measured the activity of various enzymes, sulfatase, 3 beta-hydroxysteroid dehydrogenase + isomerase (3 beta-HSD) and aromatizing enzyme, which are involved in the synthesis of estrogen in the placenta, as well as placental RNA and DNA levels during gestation. Our results are as follow; Enzymes involved in estrogen synthesis in human placental villi. Sulfatase activity (n mole/flask/10 min) in each trimester was not significantly different (4.10 +/- 0.10 in the first, 3.40 +/- 0.49 in the second and 4.33 +/- 0.67 in the third). 3 beta-HSD activity (n mole/flask/10 min) in each trimester was not significantly different (2.57 +/- 0.55 in the first, 2.70 +/- 0.30 in the second and 2.90 +/- 0.53 in the third). Aromatizing enzyme activity (n mole/flask/30 min) in cytosome fraction in each trimester was not significantly different (1.80 +/- 0.28 in the first, 1.60 +/- 0.28 in the second and 2.40 +/- 0.28 in the third). However, in the total homogenate, it was significantly higher in the third trimester (6.27 +/- 0.25) than in the first (3.83 +/- 0.85) or second (3.40 +/- 0.14). RNA and DNA concentrations in human placental villi. The RNA concentration (mg/g tissue) in each trimester was insignificantly different (2.48 +/- 0.20 in the first, 2.57 +/- 0.58 in the second and 2.63 +/- 0.42 in the third). However, the DNA concentration was significantly higher in the second (2.49 +/- 0.34) and third (2.42 +/- 0.45) trimesters than in the first (1.62 +/- 0.32).(ABSTRACT TRUNCATED AT 250 WORDS)