[Changes in steroid enzyme activities with age in human ovary].

It is well documented that sex hormone secretion decreases as age advances. In this study, 17 alpha-hydroxylase (17hy), 20 alpha(beta)-hydroxy steroid dehydrogenase (20-HSD), C17-20 lyase, 17 beta-hydroxy steroid dehydrogenase (17 beta-HSD) and aromatase activities in ovarian tissues were examined in order to study the changes in steroid metabolism in human ovary with age. Tissues were obtained from women aged 30-81 years who had undergone gynecological laparotomy. Enzyme activities were measured by the conversion of 14C-labeled progesterone, 17 alpha-hydroxy progesterone and androstenedione to amounts of corresponding labeled products. Remarkable reduction of C17-20 lyase and 17hy activities were noticed in the ovaries obtained from the women in the premenopausal stage when the activities were compared with those from reproduct women. However, the activities of aromatase, 17 beta-HSD and 20-HSD were not changed. Further, a decrease of 17hy activities was observed in the ovaries obtained from menopausal women. Aromatase activity was also reduced at this stage while the 17 beta-HSD and 20-HSD remained unchanged. In addition, the formation of 17 alpha, 20 beta-OH-P4 from 17P4 was first demonstrated indicating that activity of 20 beta-HSD in postmenopausal ovary and found to be localized in the microsomal fraction. These result indicated that the changes of ovarian steroid enzyme activities with age were characterized by a striking reduction in C17-20 lyase and 17hy activities while 17 beta-HSD and 20-HSD activities were not impaired. Aromatase activity was found to be decreased in ovaries at menopause.

Purification and properties of steroid sulfatase from human placenta.

Steroid sulfatase was purified approximately 170-fold from normal human placental microsomes and properties of the enzyme were investigated. The major steps in the purification procedure included solubilization with Triton X-100, column chromatofocusing, and hydrophobic interaction chromatography on phenylsepharose CL-4B. The purified sulfatase showed a molecular weight of 500-600 kDa on HPLC gel filtration, whereas the enzyme migrated as a molecular mass of 73 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric point of steroid sulfatase was estimated to be 6.7 by isoelectric focusing in polyacrylamide gel in the presence of 2% Triton X-100. The addition of phosphatidylcholine did not enhance the enzyme activity in the placental microsomes obtained from two patients with placental sulfatase deficiency (PSD) after solubilization and chromatofocusing. This result indicates that PSD is the result of a defect in the enzyme rather than a defect in the membrane-enzyme structure. Amino acid analysis revealed that the purified human placental sulfatase did not contain cysteine residue. The Km and Vmax values of the steroid sulfatase for dehydroepiandrosterone sulfate (DHA-S) were 7.8 microM and 0.56 nmol/min, while those for estrone sulfate (E1-S) were 50.6 microM and 0.33 nmol/min, respectively. The results of the kinetic study suggest the substrate specificity of the purified enzyme, but further studies should be done with different substrates and inhibitors.

Steroid sulfatase activities in human leukocytes: biochemical and clinical aspects.

Steroid sulfatase is a membrane-bound microsomal enzyme, present in various tissues. In this report, data on sulfatase activity in peripheral blood leukocytes isolated from normal women and the characterization of its enzyme are studied. In addition, sulfatase activities in placental sulfatase deficiency (PSD) and ichthyosis patients including ichthyosis vulgaris (IV) and recessive X-linked ichthyosis (RXLI) were analysed and were compared with normal subjects. Steroid sulfatase activity was measured by using tritium labeled steroid sulfate as the reaction substrate. It is demonstrated that human leukocytes contain a sulfatase activity for pregnenolone sulfate (P5-S), dehydroepiandrosterone sulfate (DHA-S) and estrone sulfate (E1-S) respectively. This enzyme has a greatest affinity for P5-S, but the activity for E1-S was the highest among the three substrates. The steroid sulfatase activity in female leukocytes is significantly stronger than that in normal males (p less than 0.001) as determined by the cleavage of DHA-S. Sulfatase in leukocytes obtained from the PSD babies and RXLI patients had lower sensitivity. In the case of the mother affected with PSD, the activity was less than half of that in normal men (p less than 0.001) and the levels did not overlap with that in normal women. In patients with IV, the activities were in the normal ranges for both males and females. The measurement of leukocyte sulfatase activity would be a clinically useful tool for the diagnosis of PSD carriers and pedigree analysis.

[Prolactin, ovarian and adrenal steroid hormone in relation to the vaginal opening in immature female rats].

The serum prolactin levels in human girls are thought to be increased gradually throughout puberty, but some authors have reported that prolactin decreases transitorily before menarche. Prolactin has not been shown to play a significant role on the initiation of human pubertal development. However, in immature female rats, it is thought that prolactin is one of the most important hormones during sexual maturation. In experiment I, the serum concentrations of prolactin, estradiol (E2) and dehydroepiandrosterone-sulfate (DHA-S) in immature female rats were measured. Prolactin increases gradually before vaginal opening and tends to decrease after vaginal opening, while E2 increases throughout sexual maturation. No significant changes were noticed in DHA-S levels. In experiment II, sulpiride, which raises serum prolactin level, was injected daily in to 4 groups of immature female rats starting from 14, 21, 28, and 35 days of age till the day before vaginal opening. Physiological saline solution was injected daily in to age-matched controls. On the day of vaginal opening, serum levels of prolactin, E2 and DHA-S were studied, weights of bodies and internal genital organs were measured, and corpora lutea of the ovaries were inspected. Vaginal opening was accelerated in the group of rats injected with sulpiride 5mg every morning from 14 days of age (p less than 0.05). The weights of their bodies and internal organs were less than those of the control rats (p less than 0.05). Percent of ovaries which contained corpora lutea were lower than the controls. Although their serum levels of prolactin tended to be suppressed, three hormone levels were not different from those of control rats on the day of vaginal opening. However, when mean prolactin levels were depicted on the day of vaginal opening in both groups, a peak was noticed at 37 days of life, indicating that the secretion pattern of this hormone has been programmed according to the day of life. There was a close relation between prolactin and DHA-S levels (p less than 0.05). No significant relation between prolactin and E2 levels was noticed. The possible role of prolactin and DHA-S on the regulation of sexual development is suggested. To our knowledge, this is the first demonstration of a significant relation between prolactin and DHA-S in immature female rats.

Serum steroid hormone levels in neonates born from the mother with placental sulfatase deficiency.

Placental sulfatase deficiency (PSD) is a rare disorder with low estrogen production due to placental enzymatic deficiency. Although many papers have been published on this enzymatic deficiency, little information is available on steroidal environment in newborn babies from PSD mothers. Seven cases of PSD were confirmed and serum concentrations of nine steroids which included cortisol, free and conjugated pregnenolone, 16 alpha-hydroxypregnenolone, DHA and 16 alpha-hydroxy-DHA in cord blood at delivery and peripheral veins during the neonatal period were measured by radioimmunoassay. In all seven instances, healthy male infants were delivered, but six of the babies developed ichthyosis. Conjugated delta 5-steroid concentrations in cord blood were found to be high, while 16 alpha-hydroxypregnenolone was low when the PSD cases were compared with the controls. In the PSD cases, free 16 alpha-hydroxy-DHA and 16 alpha-hydroxy-pregnenolone were both lower than in controls during the first seven days after birth. These results indicate that the production of delta 5-C21 steroid in PSD infants is limited. In the present study of newborn infants with PSD, the pattern of circulating steroids was first demonstrated and the relationship between the sulfatase activity in the neonates and ichthyosis was discussed.

[Study on prognosis of threatened abortion assessed by multivariate analysis].

The serum concentrations of various hormones which included hPL, progesterone(P), estradiol(E2) and 17 alpha-hydroxyprogesterone (17P) in serum, and hCG in urine were measured simultaneously in patients with threatened abortion to evaluate the prognosis. Ultrasound scanning was also undertaken. One hundred and thirty-six patients at 5 to 8 weeks of gestation were divided into two groups retrospectively. Group A consisted of 99 patients with a good prognosis and group B consisted of 37 patients who aborted spontaneously. The mean concentrations of hormones, and ultrasound findings (GS, CRL and FHM) were not significantly different in both groups at 5 weeks. An attempt was made to apply the data to the computation in multivariate analysis. By discriminant analysis, 100% reliability was achieved in separating the two groups according to hormone levels only at this stage of pregnancy. At 6 weeks, the hCG, P and E2 values were statistically higher in group A than B. Because of the overlapping of the data, principal component analysis was attempted. Two groups were roughly separated. The values for factor loading indicated that GS, CRL and 17P effective in making the separation possible. At 7 and 8 weeks of gestation, the mean concentrations of hCG, hPL, P and E2 were significantly higher in A than B. The factor loading values indicated that ultrasound findings were essential in separating into two groups. These results suggested that hormonal analysis may be useful in assessing the prognosis in threatened abortion in the early stage of gestation (5 and 6 weeks), while ultrasound findings make an accurate prediction for the prognosis possible after 7 weeks of gestation.

Effects of DHA-S on placental 3 beta-hydroxysteroid dehydrogenase activity, progesterone and 20 alpha-dihydroprogesterone concentrations in placenta and serum.

To study the effects of dehydroepiandrosterone sulfate (DHA-S) on placental steroid metabolism and maternal steroidal profiles at term, the following in vivo and in vitro experiments were performed. Two hundred mg of DHA-S was given to five pregnant women 30 minutes prior to delivery. After delivery, the placenta was collected and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and sulfatase activity was determined by measuring the rate of conversion of pregnenolone to progesterone and DHA-S to DHA. The amount of C21-delta 4-steroid in the placental tissue was measured by gas chromatography mass spectrometry (GC-MS) and compared with the control groups. The maternal serum concentration of several steroids was also measured by GC-MS before and after the administration of DHA-S. 3 beta-HSD activity in the placentae from the mothers who received DHA-S before delivery was significantly lower than in the controls. On the other hand, no significant change was observed in the activity of sulfatase. The serum concentration of progesterone (P) and 20 alpha-dihydro-P (20-P) before DHA-S loading decreased following the administration whereas estradiol (E), DHA, and androstenedione (A) levels increased. To study the direct effect of DHA-S and its related steroids on placental 3 beta-HSD activity, placental tissue samples were incubated with pregnenolone in vitro. Several other steroids were added simultaneously into the medium. It was observed that placental 3 beta-HSD activity was directly inhibited by DHA-S. These results indicate that DHA-S inhibits 3 beta-HSD activity in the placenta and subsequently causes a reduction in P and 20-P.

[Changes in serum steroid concentrations at delivery and during neonatal period after DHA-S injection into mother before delivery].

DHA-S loading has been widely used for the assessment of placental function and ripening of the cervix before delivery. However, changes in the steroidal milieu in both mother and fetus has not been clarified after DHA-S administration. Free (f) and conjugated (c) DHA, delta 5 androstenediol (Adiol), estradiol (E2), estriol (E3), f-testosterone (T) and delta 4 androstenedione (Adione) levels in maternal vein, cord blood and peripheral vein of new born infants after maternal DHA-S administration were measured by radioimmunoassay, and the levels were compared to those in the controls. DHA-S administration resulted in a marked and significant rise in all steroid levels except for E3 in maternal vein. Significant augmentation of T, Adione, c-Adiol, f-DHA, f.c-E2 in umbilical artery, and T, Adione, f.c-Adiol, f-DHA, f-E2 in umbilical vein was observed. Steroid levels during the neonatal period were also measured on the 1st, 3rd and 5th days in both male and female infants, and the levels were compared to those of the controls. Although three androgens in both male and female infants at delivery were significantly higher than the controls, no significant difference was observed on the 5th day of life. Adiol and Adione levels on the 1st day in females, and Adiol levels on the 3rd day in males were higher than those of the controls. E2 levels remained high till the 5th day of life. These results indicated that DHA-S administered to the mother was converted to androgen and estrogen promptly in the placenta and transferred to the fetus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in 13,14-dihydro-15-keto-prostaglandin F2 alpha and dehydroepiandrosterone-sulfate (DHA-S) levels in amniotic fluid and maternal peripheral venous blood in late pregnancy and during labor].

To study the role of prostaglandin (PG) and steroids on the mechanism of parturition, levels of 13,14-dihydro-15-keto-prostaglandin F2 alpha (dhk.PGF2 alpha) and dehydroepiandrosterone-sulfate (DHA-S) in amniotic fluid and plasma during late pregnancy, labor, and puerperium, were measured by radioimmunoassay and gas chromatography-mass spectrometry. Seven patients at term were selected for this study and labor was induced by amniotomy. Amniotic fluid and maternal peripheral blood were obtained simultaneously from each individual at A) the artificial rupture of the membranes before the onset of labor, B) the onset of labor, C) the second stage of labor, D) the delivery, and E) 2 hours postpartum. No increase in either amniotic fluid or plasma dhk-PGF2 alpha was noticed when compared before and at the onset labor. However, there was a steady increase during labor and the maximum was reached at delivery. The dhk-PGF2 alpha concentration in amniotic fluid correlated well with that in maternal plasma. A similar pattern was observed in the DHA-S levels both in amniotic fluid and plasma. No apparent change was observed before the onset of labor, but there was a tendency to increase during labor. A significant correlation between the levels of dhk.PGF2 alpha and DHA-S in amniotic fluid was noticed. From the results obtained above, it is suggested that PG and DHA-S may be involved not in the initiation of labor but in the promotion of parturition. The biological significance of DHA-S on PG levels remains to be clarified.

[Concentrations of steroid hormones in maternal vein, amniotic fluid and chorionic tissue during early stages of pregnancy].

To study the steroid concentration in human amniotic fluid in early stages of pregnancy between 6-10 weeks, progesterone (P4), 17 alpha-OH-progesterone (17P4), estrone (E1), estradiol (E2) and estriol (E3) levels in amniotic fluid (AF), maternal vein (MV) and chorionic tissue (CH) were measured by RIA. The levels of P4, 17P4, E1, E2 and E3 in CH were significantly higher than in AF and MV. The levels of P4 and E1 in AF were significantly higher than in MV, but the levels of 17P4 in MV were higher than in AF between 6-10 weeks of gestation. Although a peak at 7th week of gestation in AF was noticed, the levels of P4 increased gradually between 6-10 weeks of gestation in AF,MV and CH. There was no significant change in 17P4 levels in AF and CH, except for a slight decrease between 6-8 weeks of gestation in MV. The levels of E2 in MV increased after the 9th week of gestation and the levels were significantly higher than in AF. All estrogens (Es) in CH significantly increased at 10th week of gestation. The levels of P4 in AF and that in CH correlated well. A significant correlation was observed between the levels of E1 and E3 in MV and in CH. These results indicate the possible transference of P4 from CH to AF rather than that to MV. The transference of Es from CH to AF seems to be less than that of P4.(ABSTRACT TRUNCATED AT 250 WORDS)

[Phospholipase A2 activity in human cervical tissue at delivery].

Prostaglandins (PGs) play an important role in cervical ripening. It is known that the hydrolytic release of arachidonic acid from phospholipids regulates the rate of PG formation. To study the PG biosynthesis in cervical tissue, phosphatidylcholine containing 14C-arachidonic acid in Sn-2 position was incubated with the 800 X g supernatant of cervical tissue obtained from pregnant women at delivery. The only recognizable radiolabeled metabolite, 14C-arachidonic acid, was found on an autoradiogram of TLC, which corresponded to authentic arachidonic acid. Therefore, phospholipase A2 activity was calculated as the rate of the release of arachidonic acid from phosphatidylcholine under the conditions used. The optimal pH of phospholipase A2 activity in 800 X g supernatant was found to be 7.0. It was found that the addition of Ca2+ increased the enzyme activity. It was demonstrated that the concentrations of DHA-sulfate (DHA-S) and conjugated estrogens were higher in ripened cervical tissue than in non-ripened tissue and that PGI2 and PGE2 production increased following the addition of DHA-S. The effects of steroids mainly derived from feto-placental unit, cortisol, pregnenolone, 20 alpha-dihydroprogesterone, pregnenolone-sulfate, DHA, DHA-S, estrone, estradiol and estriol on arachidonic acid release were also studied in vitro. After the onset of labor. DHA-S was administered to the patients in vivo and their cervical tissues were collected at delivery. It was found that steroids including DHA-S did not affect phospholipase A2 activity under the conditions used. These results indicate that cervical tissue possesses the ability to release arachidonic acid from phospholipid, although this step in PG formation might not be affected by steroids including DHA-S.

[Changes in steroid enzyme activity in the human endometrium during the menstrual cycle].

Sulfokinase, sulfatase, 17 beta-HSD, 20 alpha-HSD, 3 beta-HSD and 5 alpha-reductase activity and steroid concentrations including estradiol, estrone, estrone-sulfate, progesterone, 20 alpha-dihydroprogesterone, DHA and DHA-sulfate in endometrial tissue were examined in order to study the changes in steroid metabolism in relation to the menstrual cycle in the human endometrium. Thirty-one (14) proliferative and 17 secretory) endometrial tissue samples were obtained from women who underwent hysterectomy. Low enzymatic activity of sulfokinase, sulfatase and 17 beta-HSD activity were observed in the proliferative phase (0.25, 8.5, 3.1 nmole/mg protein/h). A pronounced increase in enzymatic activity was observed in the early secretory phase and activity gradually decreased toward the mid and late secretory phase. On the other hand, 20 alpha-HSD and 3 beta-HSD activity did not change during the cycle. 5 alpha-reductase activity was not detectable under the conditions used. The concentration of progesterone in the secretory phase was significantly higher than that in the proliferative phase. The concentration of estradiol in the proliferative phase was significantly higher than that in the secretory phase. There was no significant change in the concentration of estrone, estronesulfate, 20 alpha-dihydroprogesterone, DHA or DHA-sulfate during the cycle. The relationship between the steroid concentration and the enzymatic activity was discussed. The results suggested an active role of the endometrium in controlling the biological effect of steroids.

[Biosynthesis of prostaglandin in human cervical tissue].

It is known that prostaglandin (PG)E2 and PGI2 can contribute to the ripening of the uterine cervix. To study the PG biosynthesis in cervical tissue, 14C-arachidonic acid was used to incubate the preparation of human cervical tissue obtained from pregnant women at delivery and non pregnant women at hysterectomy. Labeled PGE2 and 6-keto-PGF1 alpha (6PG), a stable metabolite of PGI2 were isolated on TLC, and the enzymatic activity was calculated from the formation of PGE2 and 6PG from arachidonic acid. The capacity to metabolize arachidonic acid to PGE2 and 6PG in cervical tissue obtained from pregnant women was 6 times higher than that from non pregnant women. Low enzymatic activity in the formation of PGE2 and 6PG were observed in cervical tissues from the patients with placental sulfatase deficiency and preterm delivery which were known to have a low estrogen environment. On the other hand, DHA-S administration to patients increased the formation of both PGE2 and 6PG. These results demonstrate that human cervical tissue possesses the ability to synthesize PGE2 and PGI2, and enzymatic activity increased during pregnancy, and was further enhanced by the administration of DHA-S. The results suggest that the steroids in the fetoplacental unit may be involved in the mechanism controlling the formation of PGs in the cervical tissue which lead the cervix to ripen at term.

[Steroid profiles in patients with amenorrhea during induction of ovulation with HMG].

Serum concentrations of various hormones in seven normal women were measured daily for 5 days before and after ovulation. Steroid levels were also measured in severe amenorrheic patients during the induction of ovulation with HMG-HCG. Blood samples from the patients of II grade amenorrhea were collected on the day when the cervical mucus increased more than 200 mm3 in HMG therapy. HCG was given after the blood samples were obtained. Ovulation was successfully induced in six patients and they were classified as group I. In 8 patients induction of ovulation did not succeed and these patients were classified as group II. Hormone levels including LH, FSH, estradiol (E2), progesterone (P4), 17 alpha OH-P4 (17P4), delta 4 androstenedione (delta 4 A), testosterone (Tes.), pregnenolone (P5), 17 alpha OH-P5 (17P5), DHA, delta 5 androstenediol (delta 5 AD), and 20 alpha OH-P4 (20P4) were measured by specific RIA. The following results were obtained. Steroid levels during normal ovulatory cycle: Levels of E2 (380 +/- 16 pg/ml), P5 (6.9 +/- 4.1 ng/ml), and Tes. (3.3 +/- 1.2 ng/ml) showed a peak on the day before LH surge. A significant increase in P4, 17P5 and 20P4 levels was observed after ovulation. Hormone levels in group I: FSH in group I was significantly higher while LH was lower than that in normal women measured during -1 to -3 days from LH surge. On the other hand, among the steroids measured, significantly low Tes. and high 17P5, and E2 levels were noticed in group I. Comparison of hormone levels between group I and II: FSH and LH levels showed no significant difference between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aromatization by skeletal muscle.

Because peripheral aromatization is the major source of circulating estrogens in men and postmenopausal women, we studied the aromatase activity in muscle tissue from both men and postmenopausal women. To do so, the in vitro conversion of tritiated androstenedione to estrogen in homogenates of skeletal muscles obtained at autopsy was studied. Samples from lower limb muscles of both men and postmenopausal women produced estrogen, ranging from 8.5-39.8 pg/g wet wt. The conversion was almost the same as that reported for human adipose tissue, suggesting that the contributions of muscle and fat to the extraglandular production of estrogens in these subjects might be similar. This is the first direct confirmation of muscle aromatase activity and indicates the possible importance of muscle as an extragonadal source of estrogen in both men and postmenopausal women.

Microsomal 20 alpha-hydroxysteroid dehydrogenase activity for progesterone in human placenta.

Placental 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) activity was studied in order to evaluate the mechanism of continuation of pregnancy and initiation of labor. The placentas obtained at various gestational weeks were homogenized and fractionated into "nuclear", "mitochondrial", "microsomal" and "supernatant" fractions. Each fraction was incubated with 14C-progesterone and a hydrogen donor. Enzymatic activity was measured by the conversion of progesterone to 20 alpha-dihydroprogesterone. The highest activity of 20 alpha-HSD for progesterone was found to be localized in "microsomal" fraction. The Km constant of 20 alpha-HSD was 4.5 X 10(-6)M for progesterone in "microsomal" fraction. It was found that placental microsomal 20 alpha-HSD required NADPH as well as NADH. 20 alpha-HSD activity for progesterone increased as gestational weeks advanced. The addition of DHA-sulfate and DHA inhibited 20 alpha-HSD activity for progesterone significantly, suggesting that the steroid produced by the feto-placental unit may be involved in the metabolism of progesterone in human placenta.

[Changes in placental enzymatic activities in relation to estrogen production during pregnancy].

To study the mechanism of production of estrogen during pregnancy, the following in vitro and in vivo studies were undertaken; 1) Weight of human placenta and total estradiol (E2) levels in the maternal peripheral vein were measured at different weeks of gestation. 2) Changes in E2 levels after DHA-S 100mg loading were calculated at the 1st, 2nd and 3rd trimesters. 3) Steroid enzyme activities including sulfatase, 3 beta-HSD and aromatase in placenta obtained in the 1st, 2nd and 3rd trimesters were measured. Results were as follows; 1) The weight of the human placenta increased gradually as gestation progressed. Twofold placental weight was noticed from the 2nd to the 3rd trimester. 2) Total E2 in the maternal peripheral vein increased steadily, being 4.07 +/- 1.74 ng/ml at the 1st trimester, 27.72 +/- 11.67 ng/ml and 104.12 +/- 57.89 ng/ml at the 2nd and 3rd trimesters respectively. The increase in E2 from the 2nd to the 3rd trimester was greater than that of the placental weight. 3) Increases in E2 following DHA-S loading were 1.01 ng/ml at the 1st, 29.2 ng/ml at the 2nd and 98.2 ng/ml at the 3rd trimester. 4) No significant differences were observed between placental 3 beta-HSD and sulfatase activities in the placenta obtained at the three different stages of pregnancy, while aromatase activity was found to be significantly higher in the placenta of the 3rd trimester than that of 2nd trimester. These results indicate that the remarkable increase in estrogen production in the 3rd trimester may be explained partially by increased aromatizing enzyme activity in the placenta.

Enhancement of human amniotic phospholipase A2 activity by steroid-sulphate derived from the foeto-placental unit.

To study the control of production of prostaglandins (PG) during pregnancy and parturition, amniotic membranes obtained from normal vaginal delivery were incubated with the substrate of phosphatidylcholine containing [14C]arachidonic acid in the Sn-2 position. Phospholipase A2 activity was calculated as the rate of release of [14C]arachidonic acid from the substrate. Various steroids were added to the incubation medium to elucidate the effect of steroids on the enzymatic activity. The addition of dehydroepiandrosterone-sulphate (DHA-sulphate) to the medium increased by 7-fold the rate of [14C]arachidonic acid release from phosphatidylcholine at a concentration of 1.67 mM. The enhanced rate of arachidonic acid release suggests that DHA-sulphate stimulates phospholipase A2 activity. The same amounts of pregnenolone-sulphate and oestrone-sulphate also enhanced the enzymatic activity, while cholesterol-sulphate, free steroids such as DHA, progesterone, cortisol and oestrogens revealed no effect. These results suggest that steroid sulphates may be involved in the regulatory mechanism for PG synthesis in amniotic membrane.

[Changes in steroids in amniotic fluid in relation to the initiation of labor].

To study the changes in steroid concentrations in amniotic fluid (AF) in relation to the initiation of parturition, eleven steroids in AF which included cortisol(F), progesterone (P4), 20 alpha-dihydroprogesterone, free(f-) and conjugated(c-) pregnenolone, DHA, estradiol(E2) and estriol(E3) were measured by RIA. Experiment 1: Samples were obtained at I) elective cesarean section (not in labor, n = 9), II) vaginal delivery after the spontaneous onset of labor (in labor, n = 13). Experiment 2: AF were collected serially from each individual at A) the artificial rupture of the membrane before the onset of labor, B) the initiation of labor and C) second stage of delivery. Samples of B and C were obtained with a catheter which was placed in the uterine cavity at the rupture of the membrane. The mean concentrations of F,c-E2,f- and c-E3,DHA in I were significantly higher than those in II. In experiment 2, except for P4, all steroid concentrations tended to increase during the course of labor. The levels of F increased significantly from A to C but not from A to B. Free DHA increased from B to C. The percentage increase in steroid levels was also caliculated and it was found that the steroid increase from A to B was f-E2 while P4 decreased. E2/P4 ratio increased significantly from A to B. These results suggested that the increase in F and DHA may be due to the fetal response to the stress of labor. A possible role of increased E2 and decreased P4, and subsequently increased E2/P4 ratio, in AF on the onset of labor is suggested.