Immunoreactive corticotropin-releasing hormone in human plasma during pregnancy, labor, and delivery

We previously reported that immunoreactive corticotropin-releasing hormone (CRH) is present in human placenta and third trimester maternal plasma, and that such material is very similar to rat CRH and the predicted structure of human CRH. We suggested that maternal plasma immunoreactive CRH may be of placental origin. To further investigate this possibility, we measured plasma immunoreactive CRH in women during pregnancy, labor, and delivery and 1 and 2 h postpartum, and in nonpregnant women. Umbilical cord plasma and placental CRH concentrations were also measured. In the first trimester of pregnancy, the mean maternal plasma level was 5.9 +/- 1.0 pg (+/- SEM)/ml (n = 24), not significantly different from that in 10 nonpregnant women (5.8 +/- 0.8 pg/ml). Plasma CRH concentrations progressively increased during pregnancy (second trimester, 35.4 +/- 5.9 pg/ml (n = 39); early third trimester (28-34 weeks), 263 +/- 41 pg/ml (n = 14); late third trimester (35-40 weeks), 800 +/- 163 pg/ml (n = 20)]. There was a significant correlation between maternal plasma CRH levels and weeks of pregnancy. Plasma CRH concentrations were further elevated (2215 +/- 329 pg/ml; n = 9). During early labor, peaked at delivery (4409 +/- 591 pg/ml; n = 28), and declined rapidly after delivery [1 h postpartum, 1042 +/- (353 pg/ml (n = 13); 2 h postpartum, 346 +/- 91 pg/ml (n = 13)]. There was a significant correlation (r = 0.562; P less than 0.01) between matched maternal plasma and placental CRH concentrations. The mean umbilical cord plasma CRH level (50.6 +/- 6.1 pg/ml; n = 28) was much lower than that in the mother at the time of delivery. Umbilical venous plasma CRH levels were significantly greater than those in simultaneously obtained umbilical arterial plasma (70.8 +/- 11.3 and 41.8 +/- 4.9 pg/ml, respectively; n = 11). There was a significant correlation (r = 0.384; P less than 0.05) between maternal and fetal CRH concentrations. Gel filtration of plasma obtained from women during the third trimester, at delivery, and early postpartum and placental extracts revealed two major peaks of immunoreactive CRH: a high mol wt peak and one at the elution position of rat CRH. In contrast, only rat CRH-sized material was detected in plasma from nonpregnant women and umbilical cord plasma. Maternal plasma immunoreactive CRH-sized material stimulated ACTH release from anterior pituitary tissue in a dose-dependent manner and was equipotent with rat CRH.(ABSTRACT TRUNCATED AT 400 WORDS)     

Plasma corticotropin-releasing hormone concentrations during pregnancy and parturition

Plasma CRH was measured in maternal plasma throughout the third trimester of pregnancy, during labor, and postpartum. CRH levels were also measured in arterial and venous umbilical cord plasma samples. In normal pregnant women, plasma CRH increased from 50 +/- 15 (+/- SEM) pg/mL at 28 weeks gestation (n = 41) to 1462 +/- 182 pg/mL at 40 weeks (n = 55) and 1680 +/- 101 pg/mL (n = 65) in labor. Women with pregnancy-induced hypertension (n = 49) had plasma CRH levels significantly elevated above this normal range. Similarly, women who subsequently went into premature labor had raised levels several weeks before the onset of labor. After delivery, plasma CRH returned to normal within 15 h. Total plasma cortisol levels varied little throughout the third trimester, but increased during labor and remained elevated 2-3 days postpartum. There was, therefore, no correlation between plasma cortisol and CRH, implying that this placental CRH is not primarily involved in the control of the maternal hypothalamo-pituitary adrenal axis during pregnancy. The concentrations of CRH in umbilical cord plasma samples were considerably lower than those in the maternal circulation and were close to those in normal nonpregnant adults.     

Plasma and amniotic fluid immunoreactive neuropeptide-Y level changes during pregnancy, labor, and at parturition

This study was designed to determine the presence of and possible changes in plasma and amniotic fluid immunoreactive neuropeptide-Y (irNPY) levels in pregnant women during gestation and at parturition. We studied 127 healthy pregnant and 12 nonpregnant women. The peptide was extracted from plasma or amniotic fluid with a propanolformic acid mixture and measured by RIA. The mean plasma irNPY concentration in 15 pregnant women during the first trimester of gestation was 129 +/- 12 (+/- SE) pmol/L, compared to 40 +/- 8 pmol/L in nonpregnant women (p less than 0.01). The mean values were 144 +/- 13 and 156 +/- 24 pmol/L, respectively, in 15 pregnant women during the second trimester and 33 women during the third trimester. These values did not differ from that during the first trimester. Amniotic fluid irNPY levels were similar to those in plasma and did not vary among the 3 groups of women studied during the various trimesters of gestation. During labor, plasma irNPY levels progressively increased, reaching the highest levels at the most advanced stages of cervical dilatation (greater than 8 cm, 351 +/- 38 pmol/L) and at the time of vaginal delivery (416 +/- 73 pmol/L). Plasma irNPY levels then decreased significantly 2 h after vaginal delivery. The amniotic fluid irNPY levels in women during the early or late stages of labor were similar. Moreover, plasma and amniotic fluid irNPY levels at the time of elective cesarean section also were similar. These results indicate that pregnant women have high plasma and amniotic fluid irNPY levels and that the stress of labor results in a further increase in plasma levels, suggesting a possible role of NPY in human pregnancy and parturition.     

Significant increase in maternal plasma leptin concentration in induced delivery: a possible contribution of pro-inflammatory cytokines to placental leptin secretion

Maternal plasma leptin concentration is significantly increased during pregnancy. However, its roles in pregnancy, especially in labor, have not been fully clarified. We measured plasma leptin concentrations in pregnant women during the course of induced labor, just after spontaneous vaginal delivery and Cesarean section at term. We also studied the regulation of leptin secretion from term placental tissue and BeWo cells, a trophoblastic cell-line. Plasma leptin concentrations increased significantly during labor (58.9 +/- 9.2 ng/ml) compared to those before labor induction (37.5 +/- 5.8 ng/ml, P<0.05), then decreased 3-6 days postpartum (14 +/- 3 ng/ml, n = 6, P<0.0001) to the levels of normal nonpregnant women. Leptin concentrations within an hour and 24 hours after spontaneous vaginal delivery were significantly higher than those after Cesarean section (P<0.05 for both comparisons). Similarly, leptin mRNA expression in placental tissues obtained after spontaneous vaginal delivery was significantly greater than that in those obtained after Cesarean section without labor (P<0.05). IL-1alpha and TNF-alpha treatment significantly stimulated leptin secretion and leptin mRNA expression in explant culture of human term placental tissue and in BeWo cells as compared with those in vehicle controls (P<0.05, for all comparisons). By contrast, oxytocin and prostaglandin F(2alpha) treatment had no effects on leptin secretion from explant culture of human term placental tissue or from BeWo cells. These data indicate that pro-inflammatory cytokines might stimulate placental leptin secretion, thus finally contributing to the increase in plasma leptin concentration during labor.     

Plasma 20 alpha-dihydroprogesterone, progesterone and 17-hydroxyprogesterone in normal human pregnancy

The peripheral plasma levels of 20alpha-dihydroprogesterone (20alpha-DHP), progesterone (P) and 17-hydroxyprogesterone (17-OHP) were measured by radioimmunoassay techniques in 440 samples during normal human pregnancy between weeks 4 and 41. The levels of 20alpha--DHP in plasma from the 4th to the 6th week were between 6.0 and 6.6 ng/ml. From then until the 21st week the average plasma 20alpha-DHP concentrations remained at the same level between 4.0 and 6.3 ng/ml; they then rose significantly to and beyond term, levels reaching over 40 ng/ml. The range of mean plasma concentration of P during the first trimester of pregnancy fell to a nadir in the 9th week (170 ng/ml) then rose with increased gestation until the 39th week (190.4 ng/ml) followed by a slight and not significant drop. Single measurements of plasma 17--OHP from the 4th to the 6th week of pregnancy gave value between 2.8 and 3.6 ng/ml, but from the 7th week the mean plasma 17--OHP levels gradually declined, then from week 30 the 17-OHP concentration increased to reach a mean level of 7.63 ng/ml in the 41st week. The ratio P/20alpha--DHP increased from the 4th (3.5:1) to the 24th week (15.6:1) and then decreased from 25th week (7.9:1) towards term (3.2:1).     

Serum concentrations of delta 5C21 steroids during pregnancy and at delivery

In order to study the changes of C21-steroid levels which included Pregnenolone (P5), 20 alpha dihydropregnenolone (20P5), 16 alpha hydroxypregnenolone (16P5), progesterone (P4) and 20 alpha dihydroprogesterone (20P4) in maternal peripheral blood during pregnancy and at delivery, these steroids were measured by GC-MASS with application of deuterated steroids as internal standard. The accuracy of GC-MASS method of these steroids was satisfactory with C.V. value of less than 6%. Total delta 5C21 steroid concentrations in course of pregnancy and at delivery were as follows; P5 (mean +/- S.D. ng/ml): 66.6 +/- 36.2 (1st trimester), 80.9 +/- 24.6 (2nd trimester), 147.7 +/- 30.1 (3rd trimester) and 299.7 +/- 178.3 ng/ml (at delivery), 20Ps: 212.6 +/- 102.5, 143.4 +/- 53.9, 248.9 +/- 58.8, 563.4 +/- 198.2 ng/ml, 16P5: 8.6 +/- 8.6, 8.1 +/- 5.2, 124.3 +/- 40.3, 378.5 +/- 180.0 ng/ml, respectively. P4 (43.0 +/- 28.0 ng/ml) and 20P4 (8.0 +/- 4.0 ng/ml) in 1st trimester showed gradual increase to maximum level (P4: 138.2 +/- 30.1 ng/ml, 20P4: 105.4 +/- 21.6 ng/ml) at pre-pain period, afterward decreased rapidly (P4: 70.9 +/- 23.2 ng/ml, 20P4: 59.8 +/- 19.3 ng/ml) at delivery. P5, 20P5 and 16P5 levels were found to be significantly higher in umbilical artery (UA) as well as in umbilical vein (UV) than those in maternal vein (MV) regardless of labor pain. P4 and 20P4 did not show any differences in MV regardless of labor pain. P4 in UV (pain+) and 20P4 in UA (pain-), however, showed significantly higher than P4 in UV (pain-) and 20P4 in UA (pain+). P5, 20P5, 16P5 and 20P4 levels were significantly lower in the case of anencephalic pregnancy (ANC) at 3rd trimester than in normal pregnancy, especially 16P5 levels (22.2 +/- 5.0 ng/ml) showed 1/5 of those in normal pregnancy. From the results obtained above, it is suggested that these delta 5C21 steroids are actively produced in the feto-placental unit in the course of pregnancy. The levels of these steroids reached maximum at delivery, but the levels of P4, 20P4 decreased toward delivery after maximum levels were shown in the stage of pre-labor pain. No significant difference of P4 level in the case of ANC suggested that P4 production correlated with placenta as well as maternal and fetal precursor. Decreasing of 20P4 and P4 level after the stage of pre-labor pain suggested that activity of 3 beta hydroxysteroid dehydrogenase was reflected by uterine contraction during labor.     

High levels of corticotropin-releasing hormone immunoactivity in maternal and fetal plasma during pregnancy

Corticotropin-releasing hormone immunoactivity (CRHi) was measured in the plasma of 31 pregnant women and 6 nonpregnant women as well as in the umbilical cord plasma of 40 term fetuses. CRHi was not detectable (less than 44 pg/ml) in the plasma of 6 nonpregnant women or in 6 women in the first trimester of pregnancy. Mean plasma CRHi rose progressively to 58 +/- 18 and 270 +/- 68 pg/ml during the second and third trimesters, respectively, and again became undetectable within 24 h after delivery. Mean CRHi in 40 umbilical cord plasma samples was 136 +/- 16 pg/ml. Gel filtration of both fetal and maternal plasma showed that the majority of the CRHi eluted in the same position as synthetic human CRH. There was no significant correlation between CRHi and either beta-endorphin or ACTH in umbilical cord plasma, suggesting that this CRHi may not be primarily responsible for the release of beta-endorphin and ACTH into fetal plasma at delivery. A close correlation (r = 0.82) was found between simultaneously obtained maternal and umbilical cord plasma CRHi in 10 maternal-fetal pairs, supporting a common source for this peptide in maternal and fetal circulation. A placental source for fetal and maternal CRHi was suggested by the finding of a higher CRHi concentration in the umbilical vein than in the umbilical artery and by the disappearance of this peptide from maternal plasma after delivery. We conclude that a large amount of CRHi is secreted by the placenta into both the maternal and fetal circulation during pregnancy and suggest that this may be an important modulator of the maternal and fetal hypothalamic-pituitary-adrenal axis during gestation.     

Studies on 17 alpha, 20 alpha-dihydroxy-4-pregnen-3-one in non-pregnant and pregnant women by a new radioimmunoassay system

17 alpha, 20 alpha-dihydroxy-4-pregnen-3-one (17 alpha, 20 alpha-P) is reportedly a hyper-tensinogenic substance in a model of ACTH induced hypertension in sheep (Scoggins et al). This steroid has not previously been measured in Japan. We have developed a new radioimmunoassay (RIA) system for 17 alpha, 20 alpha-P, and measured this steroid in peripheral blood samples from non-pregnant and pregnant women. In this clinical investigation concentrations of 17 alpha-hydroxyprogesterone (17 alpha-OHP) and progesterone (P) were also measured in the same clinical samples. Specific anti-serum against 17 alpha, 20 alpha-P-3-carboxymethyloxime-BSA was generated in rabbits. Cross-reactions with 5-pregnen-3 beta, 17 alpha 20 alpha-triol (17 alpha, 20 alpha-P5) and 17 alpha-OHP were 42 and 2.4%, respectively. Other steroids showed cross-reactivity of less than 1%. As an internal standard dexamethasone (500 ng/100 microliter) was added to the samples which were extracted twice with 6 volumes of dichloromethane. Separation of the plasma extract was performed by high performance liquid chromatography (HPLC) with the ODS column in the solvent system, acetonitrile:water = 55:45. Eluates of the 17 alpha, 20 alpha-P and 17 alpha-OHP fractions were collected separately and the solvent was evaporated in vacuo. RIA was carried out on each extract with specific anti-sera. RIA of P was performed independently using the anti-P-3-CMO-BSA antiserum; 0.1 ml of serum was extracted with n-hexane and subjected to RIA without chromatography. The coefficient of variation for intra- and interassay (n = 10) were 8.5 and 11.7% for 17 alpha, 20 alpha-P; 7.2 and 12.1% for 17-OHP and 10.5 and 14.0% for P, respectively. The recovery rates of 17 alpha, 20 alpha-P, 17 alpha-OHP and P were 95 +/- 1.5, 93.2 +/- 3.5 and 97.5 +/- 4.2%, respectively. With the use of this method, 17 alpha, 20 alpha-P was measured in the blood samples from the menstrual cycle and normal pregnancy. The mean serum 17 alpha, 20 alpha-P concentrations +/- SD in the follicular, ovulatory and luteal phases, and in the first, second and third trimesters were; 76 +/- 6.0, 100 +/- 31, 101 +/- 6.4, 226 +/- 80, 151 +/- 48 and 367 +/- 99 pg/ml, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Immunoreactive adrenomedullin (AM) concentration in maternal plasma during human pregnancy and AM expression in placenta

Adrenomedullin (AM) is a novel vasorelaxant peptide, isolated from human pheochromocytoma. Although AM may be involved in the regulation of the cardiovascular system, a number of other mechanisms are also involved. The present study was undertaken to confirm the presence of AM in human maternal circulation and in placental function during pregnancy. Immunoreactive (ir) AM concentrations in maternal plasma were 3.4+/-0.7fmol/ml (mean+/-s.e. m.) in the first trimester, 3.3+/-1.1fmol/ml in the second trimester, 7.3+/-2.8fmol/ml in the third trimester, 4.1+/-1.9fmol/ml in early puerperium and 3.0+/-0.4fmol/ml in non-pregnant periods; the concentration in the third trimester was significantly greater than those in other periods. Plasma concentrations of estradiol (E(2)), progesterone, human placental lactogen (hPL) and human chorionic gonadotropin (hCG) were also measured, using RIA kits. Significant correlations have been demonstrated between the concentrations of irAM and those of E(2), progesterone and hPL. We therefore examined the expression of AM within the placental tissues using immunohistochemistry and northern blot analysis in order to demonstrate a correlation between the presence of AM in the placenta and maternal plasma. Using immunohistochemistry, we detected AM in the amnion at term and the expression of AM mRNA in human placental tissues using cloned human (h) AM complementary DNA as a probe. This study demonstrates the immunoreactivity of human hAM in maternal plasma during pregnancy, and suggests that hAM in maternal plasma is generated partly from placental tissue.     

Immunoreactive corticotropin-releasing factor is present in human maternal plasma during the third trimester of pregnancy

Immunoreactive (IR) corticotropin-releasing factor (CRF)-like activity was detectable in the majority of plasma samples obtained from women in the third trimester of pregnancy (68.7 +/- 23.6 pg/ml (14.4 +/- 4.9 fmol/ml); mean +/- SE, n = 15), but not in plasma (less than 10 pg/ml) from first (n = 9) or second (n = 11) trimester of pregnancy, 1 day post partum (n = 7), non-pregnant women (n = 10), or in plasma obtained from patients with Cushing's disease (n = 2) or Nelson's syndrome (n = 1), or in basal (n = 6) or ether-stressed (n = 6) rat plasma. Gel filtration of third trimester pooled plasma revealed that the majority of such material eluted with Kav of rat CRF (1-41). The IR CRF (1-41)-sized material eluted with the identical retention time as rat CRF in a reverse phase high performance liquid chromatography (HPLC) system. The detection of IR CRF exclusively in third trimester maternal plasma, together with our previous demonstration that material physicochemically indistinguishable from it is present in human term placental extracts, suggests that the placenta may be the source of plasma IR CRF.     

Serum immunoreactive erythropoietin during pregnancy and in the early postpartum

We studied 209 women during normal pregnancy, at delivery, or in the early postpartum, to determine whether erythropoietin (EPO) response was appropriate for the degree of anaemia. Serum immunoreactive EPO was measured in 74 nonpregnant women, including 33 normal subjects (16.4 +/- 4.1 mU/ml) and 41 women with hypoplastic, haemolytic, dyserythropoietic, or iron-deficient anaemia. An inverse linear relationship (R = -0.88, P less than 0.0001) between log(EPO) and Hct was observed. Predicted EPO values were derived for each Hct and an O/P ratio of observed/predicted log(EPO) was calculated for each sample (1.00 +/- 0.10, range 0.80-1.20). Serum EPO levels (mU/ml) were significantly higher during pregnancy (30 +/- 16, n = 142), at delivery (31 +/- 16, n = 41), and on day 7 postpartum (37 +/- 35, n = 26) than in normal women (P less than 0.001). EPO levels increased steadily from 18 +/- 6 mU/ml in the first, to 26 +/- 14 mU/ml in the second, and to 35 +/- 18 mU/ml in the third trimester (P less than 0.0001). The O/P ratio was normal on day 7 postpartum (1.01 +/- 0.16), at delivery (1.03 +/- 0.16), and in the third trimester (0.96 +/- 0.15), but was significantly reduced in the first two trimesters (0.88 +/- 0.15, P less than 0.001). A significant negative correlation between log(EPO) and Hct was lacking in the first two trimesters, was present but with a reduced slope during the third trimester and at delivery, and was normal postpartum. We conclude that EPO response to anaemia is impaired in early pregnancy, recovers in late pregnancy, and normalizes rapidly in the postpartum.     

Free-to-total leptin ratio in maternal plasma is constant throughout human pregnancy

To clarify the mechanism of leptin resistance during pregnancy, we measured plasma leptin concentrations, free to total leptin ratio (percent free leptin) and soluble leptin receptor concentrations in pregnant women, and compared the results with those in non-pregnant women. We collected plasma samples from 23 non-pregnant and 31 pregnant women in the third trimester. Plasma samples from 5 pregnant women were collected longitudinally in each trimester. Plasma leptin concentrations in pregnant women in the second trimester (17.4 +/- 3.2 ng/ml) were higher than those in the first trimester of pregnancy (11.0 +/- 2.8 ng/ml, n = 5), as previously reported. However, percent free leptin did not change significantly throughout pregnancy. Percent free leptin correlated with total leptin concentrations (ng/ml) in non-pregnant women (r = 0.727, P < 0.0001), but not in women in the third trimester of pregnancy (r = 0.006). Constant percent free leptin during pregnancy despite increased leptin concentrations indicates increased leptin binding capacity in pregnant women, that might partly contribute to the establishment of leptin resistance. On the other hand, soluble leptin receptor concentrations showed significant negative correlation with BMI and plasma leptin concentrations in pregnant women (r = -0.470, P < 0.01 and r = -0.493, P < 0.01, respectively) but not in non-pregnant women. These data suggest the possibility that soluble leptin receptor is a minor component of leptin binding capacity in the plasma of pregnant women.     

Plasma concentrations of prostaglandins during late human pregnancy: influence of normal and preterm labor.

Highly sensitive and specific RIA procedures have been used to measure prostaglandin concentrations in the peripheral circulation of late pregnant and parturient women. The concentrations of prostaglandin E (PGE) and prostaglandin F (PGF) in plasma samples assayed within 4 weeks of collection were not significantly different among the groups studied, the levels (mean +/- SEM, picograms per ml) were: late pregnancy (n = 13): PGE, 4.8 +/- 1.0; PGF, 6.2 +/- 0.5; early term labor (n = 5): PGE, 6.8 +/- 1.5; PGF, 7.9 +/- 0.7; late term labor (n = 5): PGE, 5.4 +/- 2.2; PGF, 12.4 +/- 3.5; and preterm labor (n = 7): PGE, 4.4 +/- 0.4; PGF, 6.9 +/- 1.4. The concentration of 13,14-dihydro-15-keto-prostaglandin F (PGFM) in late pregnancy was 59.0 +/- 7.8 pg/ml. During spontaneous term labor, the concentration of PGFM was significantly elevated (P less than 0.01) to 142.8 +/- 32.3 pg/ml in early labor and 282.7 +/- 55.3 pg/ml in late labor. The concentration of PGFM in plasma from patients in preterm labor (62.7 +/- 17.4 pg/ml) was not significantly different from that found during late pregnancy, but was significantly lower than levels found at term during early labor (P less than 0.05). The concentration of PGE increased significantly in frozen plasma samples stored for more than 4 weeks in all groups studied; the concentration of PGF was significantly elevated after storage only in the late pregnancy group (P less than 0.01). The plasma concentration of PGFM in all groups studied was unaffected by storage. It is concluded that measurement of PGFM concentrations is the most reliable method available of monitoring prostaglandins in the peripheral circulation and that great care must be exercised in the assay and interpretation of prostaglandin levels in human plasma.     

Changing osteocalcin concentrations during pregnancy and lactation: implications for maternal mineral metabolism

We measured serum osteocalcin concentrations in 82 pregnant and 21 nonpregnant women. Osteocalcin values declined in the second trimester, but returned to nonpregnant levels late in the third trimester. The mean serum osteocalcin concentration in 36 women during pregnancy (mean gestation, 26 weeks) of 2.8 ng/mL was significantly lower than that in nonpregnant women (6.4 ng/mL; P less than 0.001) or term pregnant women at delivery (6.1 ng/mL; n = 46). Serum immunoreactive PTH (iPTH) levels were significantly higher during pregnancy than in nonpregnant women [97 +/- 5 vs. 56 +/- 4 ng/L (mean +/- SE); P less than 0.001]. No significant correlations were found between maternal osteocalcin concentrations and serum phosphorus, alkaline phosphatase, or iPTH, but significant negative correlations were found between osteocalcin and total calcium or total protein. Osteocalcin concentrations in midtrimester amniotic fluid were very low (mean, 0.3 +/- 0.1 ng/mL; n = 11). In 29 lactating mothers, the mean serum osteocalcin level was 9.5 +/- 1.5 ng/mL, significantly higher than in any of the other groups (P less than 0.05), but their serum calcium and iPTH levels were normal. There was no correlation between serum osteocalcin and calcium or iPTH concentrations in lactating women. These changes are compatible with a sequence in which bone turnover is reduced during early pregnancy, rebounds in the third trimester, and increases in postpartum lactating women.     

Brain beta-endorphin during pregnancy, parturition, and the postpartum period

Brain beta-endorphin (beta-EP) was measured in the rat during pregnancy, parturition, and the postpartum period. beta-EP increased in the hypothalamus, midbrain, and amygdala during gestation and remained elevated through delivery until 1-2 days postpartum. The concentration of beta-EP increased in the hypothalamus from 31.8 +/- 1.4 (+/- SE) ng/mg protein in nonpregnant controls to 41.4 +/- 1.8 and 39.2 +/- 1.9 during early (8-10 days) and late (18-20 days) pregnancy, respectively, and in the midbrain from 3.20 +/- 0.17 to 5.21 +/- 0.30 and 5.25 +/- 0.64 ng/mg protein (P less than 0.01). In another experiment, the brain content of beta-EP expressed as nanograms per region, increased from 12.6 +/- 0.29 to 14.7 +/- 0.33 in the hypothalamus, from 4.09 +/- 0.44 to 6.03 +/- 0.34 in the midbrain, and from 0.93 +/- 0.11 to 1.32 +/- 0.06 ng in the amygdala at 16-17 days of gestation compared with that in nonpregnant controls (P less than 0.01). When hypothalamic beta-EP was measured 1 week postpartum in lactating and nonlactating rats, a significant decline in the beta-EP concentration of both groups was noted compared with that measured during pregnancy; beta-EP levels were similar in the lactating and nonlactating rats. We conclude that pregnancy and parturition are associated with significant changes in brain beta-EP and suggest that beta-EP of central rather than peripheral origin may mediate changes in pain perception and maternal behavior during pregnancy.     

Ovine placental steroid 17 alpha-hydroxylase/C-17,20-lyase, aromatase and sulphatase in dexamethasone-induced and natural parturition

Parturition in the sheep is preceded by an abrupt alteration in placental steroid metabolism causing a shift from progesterone to oestrogen production. This change is believed to be a consequence of the preparatum rise in cortisol in the fetal circulation and involves increases in activities of the enzymes steroid 17 alpha-hydroxylase (cytochrome P-450(17) alpha), steroid C-17,20-lyase, and possibly aromatase and steroid sulphatase. The activity levels have been determined of steroid 17 alpha-hydroxylase, aromatase and steroid sulphatase in placental microsomes in late pregnancy, dexamethasone-induced labour and in natural labour at term. Over the gestational period of 118-140 days, basal levels of placental aromatase were relatively constant (mean value (+/- S.E.M.) of 5.6 +/- 0.5 pmol/min per mg microsomal protein (n = 10]. Pregnenolone and progesterone 17 alpha-hydroxylase activities were undetectable (less than 0.5 pmol/min per mg microsomal protein (n = 7]. In six animals in labour induced with infusion of dexamethasone into the fetus, placental aromatase activity increased to a value of 14.0 +/- 1.0 pmol/min per mg protein; placental pregnenolone 17 alpha-hydroxylase, measured in four of the animals, also increased to 453 +/- 77 pmol/min per mg microsomal protein. In five animals in natural spontaneous labour with vaginal delivery, aromatase activity was 26.7 +/- 5.2 pmol/min per mg microsomal protein and pregnenolone 17 alpha-hydroxylase activity was 141 +/- 14 pmol/min per mg microsomal protein. Steroid sulphatase activity was barely detectable (less than 1.5 pmol/min per mg microsomal protein) during late pregnancy, dexamethasone-induced labour or natural parturition.(ABSTRACT TRUNCATED AT 250 WORDS)     

High concentrations of plasma immunoreactive inhibin during normal pregnancy in women

The plasma inhibin concentrations in 190 normal pregnant women at 5-40 weeks gestation and in 4 puerperal women were measured by a specific RIA for human inhibin. The average plasma inhibin concentrations in pregnant women throughout pregnancy (minimum, 2.25 +/- 0.48 IU/mL at 17 weeks gestation; maximum, 24.15 +/- 6.99 IU/mL at 39 weeks gestation) were much higher than those in nonpregnant women with a normal menstrual cycle (0.46 +/- 0.04 IU/mL in the midfollicular phase and 2.02 +/- 0.47 IU/mL in the midluteal phase). The inhibin concentrations were already high at 5 weeks gestation (7.54 +/- 1.10 IU/mL) and rose to peak at 8-10 weeks gestation. The concentrations then decreased and remained relatively low during 14-30 weeks gestation, but rose again during the third trimester. The inhibin concentrations decreased to undetectable levels after delivery. Immunoreactive inhibin was demonstrated in the corpus luteum and term placental extracts, and the dose-response curves were parallel to an inhibin preparation from human follicular fluid. Immunoreactive inhibin concentrations were also high in both the umbilical vein and artery (7.77 +/- 0.80 and 7.84 +/- 0.78 IU/mL, respectively). These observations suggest that both the corpus luteum and placenta are likely sources of inhibin.     

Longitudinal study of progestins, mineralocorticoids, and glucocorticoids throughout human pregnancy

The maternal adrenal cortex seems to be involved in the adaptation to pregnancy. To study in detail adrenocortical secretion during pregnancy, we measured plasma aldosterone, corticosterone, 11-deoxycorticosterone, progesterone, 17-hydroxyprogesterone, 11-deoxycortisol, cortisol, and cortisone simultaneously by RIA after extraction and automated Sephadex LH-20 chromatography of 10 normal pregnant women longitudinally throughout pregnancy at weeks 8-10, 14-17, 21-24, 28-32, and 38 as well as at the time of admission to the delivery room. The mean plasma progesterone and 17-hydroxy-progesterone concentrations increased from 37.2 +/- 6.5 (+/- SE) and 8.2 +/- 1.0 nmol/L, respectively, in early gestation to maximum levels of 138.0 +/- 25.7 and 22.8 +/- 2.2 nmol/L at week 38 (P less than 0.01). Plasma glucocorticoid levels rose 2- to 3-fold (P less than 0.01) from weeks 8-10 (corticosterone, 18.5 +/- 5.4; 11-deoxycortisol, 1.9 +/- 0.2; cortisone, 24.2 +/- 4.2; cortisol, 195.5 +/- 37.6 nmol/L) to week 38 (corticosterone, 42.9 +/- 11.2; 11-deoxycortisol, 4.6 +/- 0.5; cortisone, 71.5 +/- 13.6; cortisol, 420 +/- 63 nmol/L). Similarly, plasma mineralocorticoid levels increased 5- to 7-fold (P less than 0.01) from weeks 8-10 (11-deoxycorticosterone, 0.69 +/- 0.12; aldosterone, 0.41 +/- 0.08 nmol/L) to maximum levels at week 38 (5.3 +/- 0.9 and 2.1 +/- 0.3 nmol/L, respectively). At the time of admission to the delivery room, plasma 11-deoxycortisol, corticosterone, and cortisol concentrations were higher (P less than 0.02) than at 38 weeks, but plasma progestin and mineralocorticoid concentrations were not. We conclude that the source of the elevated maternal corticosteroid levels in pregnancy in addition to the estrogen-mediated rise in corticosteroid-binding globulin is the maternal adrenal cortex itself. The peak glucocorticoid levels at admission to the delivery room reflect increased maternal and fetal stress with the onset of labor.     

Plasma GHRH, CRH, ACTH, beta-endorphin, human placental lactogen, GH and cortisol concentrations at the third trimester of pregnancy

The aim of the study was to determine the concentration of GHRH and CRH in maternal plasma during the 3rd trimester of pregnancy and to search for the possible correlations with related hormones such as ACTH, beta-endorphin, cortisol, GH and human placental lactogen. Patients consisted of 31 healthy pregnant women (20-39 years) divided according to duration of pregnancy into 2 groups: I. from 26 to 32 pregnancy week N = 13), II. from 33 to 39 week (N = 18), and of 7 women evaluated 3 days after delivery. All listed hormones except ACTH were measured by RIA (GHRH, CRH and beta-endorphin-like immunoreactivity after extraction with silic acid) and ACTH by IRMA. In the late 3rd trimester plasma levels of CRH (P less than 0.001), ACTH (P less than 0.02), beta-endorphin (P less than 0.05), cortisol (P less than 0.025), as well as GHRH (P less than 0.002) and human placental lactogen (hPL) (P less than 0.001) were increased in comparison to early 3rd trimester, whereas 3 days after delivery CRH and GHRH became undetectable and those of ACTH and cortisol decreased significantly. The CRH plasma concentrations were found to be strongly correlated with gestational age (r = 0.86, P less than 0.001) but not with ACTH and cortisol. GHRH levels correlated mainly with human placental lactogen concentrations (r = 0.64, P less than 0.001). CONCLUSION: In maternal plasma at the 3rd trimester of pregnancy, apart from the known markedly elevated CRH, the GHRH level was also raised. Strong correlations between CRH and gestational age and those between GHRH and human placental lactogen suggest that there is a relationship between these neurohormones and the placental function.     

Beta-endrophin immunoreactivity during human pregnancy.

The human placenta has been implicated as a source of numerous peptide hormones during pregnancy. Since the immunoassay detection of the proopiomelanocortin derived peptide beta-endorphin (beta E) in placental extracts in 1978, it has remained uncertain whether placental beta E immunoreactivity (IR) is 1) secreted into the maternal circulation and 2) opiate receptor active during pregnancy. To elucidate the nature of beta E IR in the placenta, both beta E IR and N-alpha-acetylated beta E (Ac beta E) IR were simultaneously measured in extracts of human pituitaries, placentas, and plasma by two homologous RIAs. Pituitary extracts (n = 6) contained 38 +/- 7 nmol beta E IR per g wet wt tissue (mean +/- SEM), of which only 20 +/- 4 pmol/g were Ac beta E IR. Term placental extracts (n = 19) had 201 +/- 30 fmol/g wet wt total beta E IR and 30 +/- 3 fmol/g wet wt total Ac beta E IR, which comprised 15% of total beta E IR in placental extracts. Total plasma beta E IR rose from 28 weeks gestation (8.5 +/- 0.3 fmol/mL, n = 159) to peak at labor (50 +/- 4 fmol/mL, n = 98; P < 0.01) but total Ac beta E IR was found in only four 28-week (1.7 +/- 0.9 fmol/mL) and 42 labor plasma samples (0.9 +/- 0.1 fmol/mL). Gel filtration chromatography of placental and pituitary extracts showed that while less than 1% of the beta E31-size material was acetylated in the pituitary, up to 60% of the beta E31-size material in placental extracts was acetylated. In pooled third trimester plasma extracts, however, only 4% of the beta E31-size material was acetylated. Furthermore, the ratio of beta E31:beta-lipotropin in pituitary extracts (n = 3) was 0.5; pooled plasma-0.5, and placental extracts (n = 5)-1.2. These data indicate that 1) the placenta extensively N-alpha-acetylates beta E31 destroying its opiate bioactivity while the pituitary does not; 2) beta E IR in pregnant women's plasma is similar to pituitary beta E IR, being mostly nonacetylated and similar in size to beta-lipotropin. These findings are consistent with a pituitary source for the elevated plasma beta E IR found during late pregnancy which may, in turn, be a consequence of elevated plasma concentrations of placentally secreted plasma corticotropin-releasing factor IR present during the third trimester.