THE RELATIONSHIP BETWEEN PROGESTERONE CONCENTRATIONS, IMMUNOREACTIVE 3-BETA-HYDROXYSTEROID DEHYDROGENASE AND 15-HYDROXY-PROSTAGLANDIN DEHYDROGENASE IN HUMAN FETAL MEMBRANES

We hypothesized that if the activity of 15-OH prostaglandin dehydrogen ase (PGDH) in human chorion was influenced locally by progesterone, th en activity of chorionic PGDH might correlate with concentrations of p rogesterone or amount of immunoreactive 3 beta-hydroxysteroid dehydrog enase (ir-3 beta HSD). Membranes were obtained from 15 patients at ter m Cesarean section from an area close to the placenta, in the lower ut erine segment, and from a region in between. PGDH activity, progestero ne concentration and amounts of ir-3 beta HSD and ir-PGDH were determi ned. In regions of chorion proximal to the placenta, or from the middl e region, there were significant, positive correlations between PGDH a ctivity and progesterone concentration, and between ir-PGDH and ir-3 b eta HSD in chorion trophoblast cells. These relationships were not sig nificant in tissues from the lower segment. Our results are consistent with progesterone of local (chorionic) origin Stimulating PGDH in som e areas of the uterus, but suggest that regulation of PGDH in the lowe r segment may be influenced by additional factor(s).