P. Florio

Activin A, corticotropin-releasing factor and prostaglandin F2α increase immunoreactive oxytocin release from cultured human placental cells☆

The aim of the present study was to investigate the presence of the immunoreactive oxytocin in human placental extracts and putative factors regulating the release of immunoreactive oxytocin from cultured human placental cells. Fresh placental tissue was collected from pregnant women at term and dissected of membranes (n = 5). Presence of immunoreactive oxytocin in trophoblast tissue was evaluated by a specific radio-immunoassay after acidic extraction and high-pressure liquid chromatography. In a second set of experiments, primary cultures of placental cells were performed and, 48-72 h after dissociation, the effect of arginine vasopressin, corticotropin-releasing factor, neuropeptide Y, activin A, inhibin A, noradrenaline or prostaglandins on immunoreactive oxytocin level in culture medium was investigated. The presence of immunoreactive oxytocin was shown in the acidic extract of trophoblast at term, and in the culture medium of human placental cells, and it was identical to the native peptide. The addition of corticotropin-releasing factor or arginine vasopressin, but not of neuropeptide Y, increased the release of immunoreactive oxytocin three- to fourfold from placental cells, with a dose-dependent effect (P < 0.01). A significantly increased release of immunoreactive oxytocin was shown in presence of noradrenaline (P < 0.01), which was reversed by prazosin, an antagonist of alpha-adrenergic receptors. Recombinant human activin A (P < 0.01), but not inhibin A, stimulated the release of immunoreactive oxytocin three- to fourfold from placental cells. Prostaglandin F2 alpha was a potent secretagogue of immunoreactive oxytocin, whereas a partial or no effect was observed when prostaglandin E2 or prostaglandin I2 was added. Thus, the present findings showed that human placenta contains immunoreactive oxytocin, and that its release from cultured placental cells is regulated by neurohormones, growth factors or prostaglandins.

Hypertension in pregnancy: Changes in activin a maternal serum concentration

Human placenta is the major source of activin A in maternal circulation. The aim of the present study was to evaluate maternal activin A serum concentration in pregnant women with chronic hypertension (n = 14), pregnancy-induced hypertension (n = 10) or pre-eclampsia (n = 16). In the group of pregnant women with chronic hypertension and of healthy pregnant women (n = 10) activin A was measured in samples collected longitudinally throughout gestation. Using a specific two-site enzyme-linked immunosorbent assay, it has been possible to measure maternal serum activin A concentration. In addition, the effect of recombinant human activin A administration on mean arterial pressure and heart rate in female rats have been also investigated. Mean +/- SEM of maternal serum activin A concentration in pre-eclamptic women (57.4 +/- 28.3 ng/ml), was significantly higher than in women with pregnancy-induced hypertension (14.8 +/- 10.5 ng/ml), chronic hypertension (10.3 +/- 5.4 ng/ml) or healthy control women (9.2 +/- 9.4 ng/ml) (P < 0.01). Serum activin A levels evaluated 2 weeks after anti-hypertensive treatment were not significantly different in pre-eclamptic women. Moreover, when exogenous recombinant human activin A was administered in female rats arterial pressure or frequency of heart rate did not change. The present study showed that maternal serum activin A concentration is abnormally high in patients with pre-eclampsia. Thus, since the patients with chronic hypertension or pregnancy-induced hypertension have activin A concentration in the normal range of values, activin A may be a prognostic marker of hypertension in pregnancy.

Activin A stimulates insulin secretion in cultured human pancreatic islets.

Activin A is a dimeric glycoprotein showing a high sequence homology with transforming growth factor-ß (TGF-ß) and playing autocrine/ paracrine actions in reproductive tissues. However, since the synthesis of activin is ubiquitous it may have a role in regulating cell growth and differentiation in several tissues. Previous studies showed that activin A is expressed by insulin-positive B cells of human pancreatic islets, and women with gestational diabetes have higher serum activin A levels than healthy pregnant women at the same gestational age. The present study aimed to evaluate the effect of activin A on insulin secretion from cultured human pancreatic islets. With this purpose human pancreatic islets were incubated with varying concentrations of activin A (0.1 to 10.0 nM). In absence of glucose, activin A did not modify insulin secretion at the different concentrations used. In absence of activin A, 8.3 mM and 16.7 mM glucose significantly increased insulin secretion, with a dosedependent pattern. In presence of a non stimulatory concentration of glucose (3.3 mM), activin A significantly increased insulin secretion starting from low concentration (0.1 nM). Furthermore, the addition of activin A to 8.3 mM and 16.7 mM glucose induced an additional effect of the dose-dependent glucose-mediated insulin secretion (p<0.001). The present data could support a role for activin A in human endocrine pancreas in modulating insulin response to different glucose concentrations.

Activin A, inhibin A, inhibin B and parturition: changes of maternal and cord serum levels according to the mode of delivery

Objective To evaluate whether activin A, inhibin A, and inhibin B levels in maternal and umbilical artery serum change according to the mode of delivery.

Effect of acute corticotropin releasing factor on pituitary-adrenocortical responsiveness in elderly women and men

Aging is related to critical changes of the hypothalamo-pituitary-adrenal function. A decline in serum DHEA levels has been demonstrated in healthy elderly subjects, while ACTH and Cortisol concentrations remain at normal values. The purpose of the present study was to investigate the effect of aging on pituitary-adrenal responsiveness to hCRF in subjects of both sexes. A group of 12 physically and mentally healthy elderly subjects and a group of 12 young controls of both sexes have been selected. Blood samples were collected before and after iv bolus injection of hCRF; ACTH, Cortisol and DHEA levels were then determined by RIA. Basal ACTH and cortisol levels did not result statistically different between controls and elderly subjects, while DHEA showed a clear and significant age-related decrease (p<0.01). Following the hCRF injection, the responses of ACTH, Cortisol and DHEA in aged subjects were higher than in young controls; ACTH (p<0.03) and Cortisol (p<0.01) were higher in aged women than in men. The present study demonstrated that aging is associated with an increased responsiveness of ACTH, Cortisol and DHEA to exogenous hCRF supply. A hyperactivation of the pituitary-adrenal secretory activity may explain the age-related of the same axis. Gender probably has a significant influence on basal and stimulated hormonal secretion. In conclusion, hCRF test may become a useful clinical tool in establishing a neuroendocrine correlation with central disturbances associated to aging.

Corticotropin releasing hormone: a diagnostic marker for behavioral and reproductive disorders?

Corticotropin-releasing hormone (CRH) is a key mediator of endocrine, autonomic, behavioral, and immune responses to stress. The ability of CRH to induce hormonal stress responses has been used to investigate the functionality of the hypothalamus-pituitary-adrenal axis, and consequently the activity of hypothalamic CRH neuronal systems. Indeed, CRH administration to humans causes prompt release of ACTH, followed by secretion of cortisol, aldosterone and other adrenal steroids. CRH hypersecretion/hyperactivity has been associated to major depression, anxiety-related disorders, anorexia nervosa, Alzheimers and Parkinsons diseases and progressive supranuclear palsy. During pregnancy the human placenta and its accessory membranes are the major sites of CRH synthesis and secretion. Placental CRH secretion is autonomous, but increasing evidence indicates that maternal or fetal conditions may influence such secretion. Therefore, the emerging concept is that in the event of acute or chronic metabolic, physical or infectious stress, the placenta takes part in a stress syndrome by releasing CRH, which may contribute to restore local blood flow and to influence the timing of delivery. The CRH released by the placenta is measurable in maternal plasma and other biological fluids and may be used to diagnose subclinical processes anteceding pregnancy complications such as pre-eclampsia and preterm delivery.

Cord plasma corticotropin-releasing factor-binding protein (CRF-BP) in term and preterm labour

Corticotropin-releasing factor-binding protein (CRF-BP) in pregnant women is measurable in maternal and fetal plasma as well as in amniotic fluid. The concentration of CRF-BP in maternal plasma and amniotic fluid changes significantly at the time of parturition. The aim of the present study was to evaluate fetal plasma CRF-BP levels in women delivering at term or with preterm labour. CRF-BP levels were measured the in umbilical cord plasma of women subdivided into two groups: (1) healthy pregnant women throughout the last 5 weeks of pregnancy either (a) out of labour (n = 21) or (b) at delivery after spontaneous labour (n = 64); and (2) patients with preterm labour (a) gone to delivery (n = 12) or (b) responding to tocolysis (n = 10). In the group of healthy women at term, CRF-BP levels were also measured in maternal plasma. CRF-BP was measurable in all specimens of umbilical cord plasma. Mean values +/- SEM at 40 weeks (5.85 +/- 0.65 nmol/l) were significantly lower than those obtained at 37 (6.48 +/- 0.47 nmol/l) or 38 (6.95 +/- 1.16 nmol/l) weeks of pregnancy. Similarly, mean +/- SEM maternal plasma CRF-BP levels in women at term out of labour were lowest at 40 weeks (3.57 +/- 0.22 nmol/l). In these women, mean +/- SEM CRF-BP levels in cord plasma (37 weeks: 6.47 +/- 0.47; 38 weeks: 6.95 +/- 1.16; 40 weeks: 5.85 +/- 0.65 nmol/l) were significantly higher than in maternal plasma at the same gestational age (37 weeks: 4.29 +/- 0.2; 38 weeks: 4.35 +/- 0.205; 40 weeks: 3.57 +/- 0.22 nmol/l). Mean +/- SEM levels of cord blood collected at delivery at term (4.93 +/- 0.14 nmol/l) showed lower CRF-BP levels than in women out of labour (6.18 +/- 0.55 nmol/l). Patients with preterm labour, with delivery within 48 h, showed significantly lower levels of cord plasma CRF-BP (4.21 +/- 0.29 nmol/l) than women at term out of labour (6.18 +/- 0.55 nmol/l) and than those at term with labour (4.93 +/- 0.14 nmol/l). Cord plasma CRF-BP levels decreased in the last 5 weeks of pregnancy, similar to maternal plasma CRF-BP levels, the lowest values resulting in women at labour or with preterm labour, thus suggesting that changes of CRF-BP in cord plasma are associated with the events of parturition.

High maternal and fetal plasma urocortin levels in pregnancies complicated by hypertension.

Objective We evaluated maternal and fetal plasma levels and placental mRNA expression of urocortin, a placental vasoactive neuropeptide, in singleton pregnancies (n = 70) complicated by hypertensive disorders classified as gestational hypertension (n = 36), pre-eclampsia (n = 19), and pre-eclampsia complicated by intrauterine growth restriction (PE/IUGR, n = 15), and in 70 healthy normotensive singleton pregnancies. Methods Plasma levels were assayed by radioimmunoassay, fetal biometry by ultrasound scans, utero-placental and fetal perfusion by Doppler velocimetry, and placental urocortin mRNA expression by quantitative real time reverse transcriptase-polymerase chain reaction. The main outcome measures were the correlation of urocortin concentrations with patterns of the utero-placental and fetal circulation, and the early prediction of a poor neonatal outcome such as the occurrence of perinatal death and intraventricular hemorrhage. Results Maternal and fetal urocortin levels were significantly (both P < 0.001) higher in gestational hypertension, pre-eclampsia and PE/IUGR women than in controls, and correlated with Doppler velocimetry patterns. Fetal concentrations were significantly (P < 0.0001) higher than and significantly (P < 0.0001) correlated to maternal levels. Placental mRNA expression did not change. Ten out of 140 newborns had a poor neonatal outcome, with an overall prevalence of 7.14% (pretest probability). Using the receiver operator characteristics curve analysis cut-off values, the probability of a poor neonatal outcome was 66.7% when urocortin was used, and was 0% if levels were unaltered. Conclusions Maternal and fetal urocortin levels are increased in hypertensive disorders of pregnancy. Since urocortin has vasoactive properties, the evidence of increased urocortin levels in hypertensive disorders may represent an adaptive fetal response.

Human placenta and fetal membranes express nerve growth factor mRNA and protein.

The present study investigated whether trophoblast, decidua and fetal membranes express nerve growth factor (NGF) mRNA and peptide. Tissue specimens were collected in the first and third trimester of pregnancy from women undergoing voluntary pregnancy interruption (no.= 6; from 8 to 12 gestational weeks) and from women having an elective caesarean section at term (no.= 6; week 39–40 of pregnancy). Using reverse transcriptase-polymerase chain reaction (RT-PCR), trophoblast, amnion/chorion and maternal decidua showed the expression of NGF mRNA both in early gestation and at term. By immunohistochemistry, the immunoreactive NGF was found in the cyto and syncytial trophoblast cells, chorionic mesodermic cells and in decidua. Vessel endothelial cells were stained in maternal compartments, while fetal vessels were unstained. These results, showing the expression and localization of NGF, support the current concept that human placenta is a potent neuroendocrine organ throughout gestation.

Activin A and inhibin B in extra-embryonic coelomic and amniotic fluids, and maternal serum in early pregnancy

Activin A and inhibin B levels were measured, using a two-site enzyme immunoassay, in extra-embryonic coelomic fluid, amniotic fluid and maternal serum samples retrieved from 23 healthy pregnant women, at 8 (n=8), 9 (n=8), and 10 (n=7) weeks of gestation. Dimeric activin A and inhibin B were measurable in all samples. Median (+/-SEM) activin A concentrations in coelomic fluid (0.98+/-0.34 ng/ml) were significantly higher than in maternal serum (0.68+/-0.05 ng/ml) and in amniotic fluid (0.09+/-0.04 ng/ml) (P<0.05). Maternal serum activin A levels were significantly higher than amniotic fluid concentrations. Median (+/-SEM) inhibin B concentrations in coelomic fluid (24.32+/-6.02 pg/ml) were significantly higher than in maternal serum (5.94+/-0.97 pg/ml) and in amniotic fluid (6.31+/-1.53 pg/ml) (P<0.05), while no significant difference between maternal serum levels and amniotic fluid concentrations was found. No significant difference in activin A and inhibin B levels in extra-coelomic fluid, amniotic fluid, and maternal serum throughout the 3 weeks of pregnancy was found. The present study showed that coelomic fluid is an important reservoir of activin A and inhibin B, supporting the hypothesis that the extra-embryonic coelom may have a secretory role during the first 11 weeks of gestation.