Urocortin 2 and urocortin 3 are expressed by the human placenta, deciduas, and fetal membranes

Urocortin3: Local inducer of somatostatin release and bellwether of beta cell maturity

Urocortin 3 (UCN3) is a peptide hormone expressed in pancreatic islets of Langerhans of both human alpha and human beta cells and solely in murine beta cells. UCN3 signaling acts locally within the islet to activate its cognate receptor, corticotropin releasing hormone receptor 2 (CRHR2), which is expressed by delta cells, to potentiate somatostatin (SST) negative feedback to reduce islet cell hormone output. The functional importance of UCN3 signaling in the islet is to modulate the amount of SST tone allowing for finely tuned regulation of insulin and glucagon secretion. UCN3 signaling is a hallmark of functional beta cell maturation, increasing the beta cell glucose threshold for insulin secretion. In doing so, UCN3 plays a relevant functional role in accurately maintaining blood glucose homeostasis. Additionally, UCN3 acts as an indicator of beta cell maturation and health, as UCN3 is not expressed in immature beta cells and is downregulated in dedifferentiated and dysfunctional beta cell states. Here, we review the mechanistic underpinnings of UCN3 signaling, its net effect on islet cell hormone output, as well as its value as a marker for beta cell maturation and functional status.

Corticotropin Releasing Factor Receptors in breast cancer: Expression and activity in hormone-dependent growth in vitro

Corticotropin Releasing Factor (CRF) neuropeptides coordinate the stress response via two distinct membrane receptors (CRF-Rs). We have previously shown expression of both CRF-Rs in human breast cancer tissues. In the present study, we examined in vitro using the MCF-7 cell line model, the regulation of CRF-Rs expression and their signaling in hormone-dependent breast cancer growth. Our findings show that similarly to breast cancer biopsies, the predominant receptor type expressed in the cell line is CRF-R2α. The transcription of CRF-R1 and CRF-R2 is up and down-regulated respectively by exposure to estradiol (E2); however this effect seems not to be exerted at the level of promoter gene methylation, although in human breast cancer specimens, CRF-R1 methylation was found to be positively associated with the presence of steroid hormone receptors. Finally, we showed that specific activation of CRF-R2 increased the migration of MCF-7 cells and potentiated an estrogen-inducing effect. Our data support an involvement of CRF-R signaling in breast cancer pathophysiology via a regulatory steroid-hormone interplay.

The Role of Urocortins in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) causes an accumulation of blood in the brain parenchyma that disrupts the normal neurological function of the brain. Despite extensive clinical trials, no medical or surgical therapy has shown to be effective in managing ICH, resulting in a poor prognosis for the patients. Urocortin (UCN) is a 40-amino-acid endogenous neuropeptide that belongs to the corticotropin-releasing hormone (CRH) family. The effect of UCN is activated by binding to two G-protein coupled receptors, CRH-R1 and CRH-R2, which are expressed in brain neurons and glial cells in various brain regions. Current research has shown that UCN exerts neuroprotective effects in ICH models via anti-inflammatory effects, which generally reduced brain edema and reduced blood-brain barrier disruption. These effects gradually help in the improvement of the neurological outcome, and thus, UCN may be a potential therapeutic target in the treatment of ICH. This review summarizes the data published to date on the role of UCN in ICH and the possible protective mechanisms underlined.

Progress in understanding the roles of Urocortin3 (UCN3) in the control of appetite from studies using animal models

Urocortin3 (UCN3), the newest member of corticotrophin releasing hormone (CRH) family polypeptides, is an anorexic factor discovered in 2001, which has a strong inhibitory effect on animal appetite regulation. UCN3 is widely distributed in various tissues of animals and has many biological functions. Based on the research progress of UCN3 on mammals and non-mammals, this paper summarized the discovery, tissue distribution, appetite regulation and mechanism of UCN3 in animals, in order to provide a reference for feeding regulation and growth in mammals and fish in further research and production.

Urocortins in the mammalian endocrine system

Urocortins (Ucns), peptides belonging to the corticotropin-releasing hormone (CRH) family, are classified into Ucn1, Ucn2, and Ucn3. They are involved in regulating several body functions by binding to two G protein-coupled receptors: receptor type 1 (CRHR1) and type 2 (CRHR2). In this review, we provide a historical overview of research on Ucns and their receptors in the mammalian endocrine system. Although the literature on the topic is limited, we focused our attention particularly on the main role of Ucns and their receptors in regulating the hypothalamic–pituitary–adrenal and thyroid axes, reproductive organs, pancreas, gastrointestinal tract, and other tissues characterized by “diffuse” endocrine cells in mammals. The prominent function of these peptides in health conditions led us to also hypothesize an action of Ucn agonists/antagonists in stress and in various diseases with its critical consequences on behavior and physiology. The potential role of the urocortinergic system is an intriguing topic that deserves further in-depth investigations to develop novel strategies for preventing stress-related conditions and treating endocrine diseases.

Second-trimester amniotic fluid corticotropin-releasing hormone and urocortin in relation to maternal stress and fetal growth in human pregnancy

This study explored the association between the acute psychobiological stress response, chronic social overload and amniotic fluid corticotropin-releasing hormone (CRH) and urocortin (UCN) in 34 healthy, second-trimester pregnant women undergoing amniocentesis. The study further examined the predictive value of second-trimester amniotic fluid CRH and UCN for fetal growth and neonatal birth outcome. The amniocentesis served as a naturalistic stressor, during which maternal state anxiety and salivary cortisol was measured repeatedly and an aliquot of amniotic fluid was collected. The pregnant women additionally completed a questionnaire on chronic social overload. Fetal growth parameters were obtained at amniocentesis using fetal ultrasound biometry and at birth from medical records. The statistical analyzes revealed that the acute maternal psychobiological stress response was unassociated with the amniotic fluid peptides, but that maternal chronic overload and amniotic CRH were positively correlated. Moreover, amniotic CRH was negatively associated with fetal size at amniocentesis and positively with growth in size from amniocentesis to birth. Hardly any studies have previously explored whether acute maternal psychological stress influences fetoplacental CRH or UCN levels significantly. Our findings suggest that (i) chronic, but not acute maternal stress may affect fetoplacental CRH secretion and that (ii) CRH is complexly involved in fetal growth processes as previously shown in animals.

Role of urocortin in pregnancy: An update and future perspectives

The activities of corticotropin-releasing factor (CRF) and related peptides are mediated a number of receptors with seven transmembrane domains that are coupled to the Gs and Gq proteins. These receptors are known as CRF-Rs. In vitro studies have evidenced that urocortin (UCN) and CRF provoke an increase in the contractility of the uterus which is induced by endometrial prostaglandin F2a. Furthermore, through trophoblasts, it stimulates the secretion of adrenocorticotropic hormone (ACTH) and prostaglandin PGE2 and has a vasodilatory effect on the placenta. While it is well known that the placenta produces considerable quantities of CRF, several studies have, however, excluded that the placenta can generate significant quantities of UCN. In the short term, the human fetal adrenal gland produces more cortisol and dehydroepiandrosterone sulfate. The gestational tissues express UCN3 and UCN2 mRNA in cytotrophoblast and syncytiotrophoblast cells, while UCN2 is only to be found in the maternal and fetal vessels and amniotic cells. Nevertheless, gestational tissues express UCN2 and UCN3 differentially and do not stimulate placental ACTH secretion. In term pregnancies, maternal plasma levels of CRF and UCN are lower than at the beginning of pregnancy and are correlated to labor onset. Conversely, they do not decrease in post-term pregnancies. This evidence would seem to indicate that the fine-regulated expression of these neuropeptides is important in determining the duration of human gestation. In this scenario, low concentrations of UCN in the amniotic fluid at mid-term may be considered a sign of predisposition to preterm birth.

Corticotropin-releasing hormone family evolution: five ancestral genes remain in some lineages

The evolution of the peptide family consisting of corticotropin-releasing hormone (CRH) and the three urocortins (UCN1-3) has been puzzling due to uneven evolutionary rates. Distinct gene duplication scenarios have been proposed in relation to the two basal rounds of vertebrate genome doubling (2R) and the teleost fish-specific genome doubling (3R). By analyses of sequences and chromosomal regions, including many neighboring gene families, we show here that the vertebrate progenitor had two peptide genes that served as the founders of separate subfamilies. Then, 2R resulted in a total of five members: one subfamily consists of CRH1, CRH2, and UCN1. The other subfamily contains UCN2 and UCN3. All five peptide genes are present in the slowly evolving genomes of the coelacanth Latimeria chalumnae (a lobe-finned fish), the spotted gar Lepisosteus oculatus (a basal ray-finned fish), and the elephant shark Callorhinchus milii (a cartilaginous fish). The CRH2 gene has been lost independently in placental mammals and in teleost fish, but is present in birds (except chicken), anole lizard, and the nonplacental mammals platypus and opossum. Teleost 3R resulted in an additional surviving duplicate only for crh1 in some teleosts including zebrafish (crh1a and crh1b). We have previously reported that the two vertebrate CRH/UCN receptors arose in 2R and that CRHR1 was duplicated in 3R. Thus, we can now conclude that this peptide-receptor system was quite complex in the ancestor of the jawed vertebrates with five CRH/UCN peptides and two receptors, and that crh and crhr1 were duplicated in the teleost fish tetraploidization.

Hypothalamic-pituitary-adrenal axis function during perinatal depression

Abnormal function of the hypothalamic-pituitary-adrenal (HPA) axis is an important pathological finding in pregnant women exhibiting major depressive disorder. They show high levels of cortisol pro-inflammatory cytokines, hypothalamic-pituitary peptide hormones and catecholamines, along with low dehydroepiandrosterone levels in plasma. During pregnancy, the TH2 balance together with the immune system and placental factors play crucial roles in the development of the fetal allograft to full term. These factors, when altered, may generate a persistent dysfunction of the HPA axis that may lead to an overt transfer of cortisol and toxicity to the fetus at the expense of reduced activity of placental 11β-hydroxysteroid dehydrogenase type 2. Epigenetic modifications also may contribute to the dysregulation of the HPA axis. Affective disorders in pregnant women should be taken seriously, and therapies focused on preventing the deleterious effects of stressors should be implemented to promote the welfare of both mother and baby.

Urocortin 2 role in placental and myometrial inflammatory mechanisms at parturition

The purpose of the study was to investigate urocortin (Ucn)2 involvement in placental and myometrial inflammatory pathways associated with parturition by evaluating: 1) Ucn2 and its receptor, CRH-receptor type 2 (CRH-R2), expression in laboring/nonlaboring human gestational tissues and in mouse utero-placental tissues approaching delivery; and 2) Ucn2 effect on myometrial contractility and on the expression of inflammatory mediators (prostaglandin F2α receptor and cytokines) and regulation of Ucn2 by TNF-α in cultured myometrial cell line. Placenta (n = 16), fetal membranes (n = 16), and myometrium (n = 22) were obtained from healthy pregnant women delivering at term by vaginal/elective caesarean delivery and from timed-pregnant mice on days 16-19. Expression of Ucn2/CRH-R2 in human/mouse tissues and inflammatory mediators in myometrial cell lines were measured by RT-PCR or ELISA, mouse Ucn2/CRH-R2 protein localization by immunohistochemistry. Ucn2 but not CRH-R2 was up-regulated (P < .05) in all human tissues in labor (compared with before labor) and increased significantly (P < .01) in mouse placenta approaching delivery. Ucn2 was up-regulated by TNF-α via nuclear factor-κB (NF-kB) in myometrium cell lines (P < .05 or P < .01 on the basis of treatment doses) and increased proinflammatory mediators and prostaglandin F (PGF2α) receptor expression (P < .05) via CRH-R2, without a direct effect on contractility. Placental and myometrial Ucn2 may play a role in the endocrine-inflammatory processes of parturition, representing a potential target for treating inflammation-induced obstetric complications.

Neuroendocrinology of pregnancy and parturition

During pregnancy, the maternal brain drives a series of adaptive mechanisms that are fundamental for allowing fetal growth and development, protecting both mother and fetus from adverse programming and timing of parturition. This neuroendocrine concept is even more complex as fetal brain and placenta also participate as regulators of maternal-placental-fetal physiology. The placenta is now seen as a neuroendocrine organ, acting as a source of several neuroactive factors that may exert their biologic effects either locally or by entering maternal and fetal circulation, thus acting in an autocrine, paracrine, and endocrine manner. A variety of hypothalamic neurohormones (GnRH, GHRH, somatostatin, CRH, oxytocin) are expressed in the placenta. When stress occurs during pregnancy, the maternal, fetal, and placental hypothalamic-pituitary-adrenal (HPA) axes are activated to stimulate a series of responses contributing to maintain physiologic conditions while at the same time avoiding the adverse effects of stress on the mother and offspring. However, when stress is excessive, a number of obstetric complications may occur, such as preterm birth, pre-eclampsia and intrauterine growth restriction, related to an impairment of the placental adaptive response.

Early-life glucocorticoid exposure: the hypothalamic-pituitary-adrenal axis, placental function, and long-term disease risk

An adverse early-life environment is associated with long-term disease consequences. Adversity early in life is hypothesized to elicit developmental adaptations that serve to improve fetal and postnatal survival and prepare the organism for a particular range of postnatal environments. These processes, although adaptive in their nature, may later prove to be maladaptive or disadvantageous if the prenatal and postnatal environments are widely discrepant. The exposure of the fetus to elevated levels of either endogenous or synthetic glucocorticoids is one model of early-life adversity that contributes substantially to the propensity of developing disease. Moreover, early-life glucocorticoid exposure has direct clinical relevance because synthetic glucocorticoids are routinely used in the management of women at risk of early preterm birth. In this regard, reports of adverse events in human newborns have raised concerns about the safety of glucocorticoid treatment; synthetic glucocorticoids have detrimental effects on fetal growth and development, childhood cognition, and long-term behavioral outcomes. Experimental evidence supports a link between prenatal exposure to synthetic glucocorticoids and alterations in fetal development and changes in placental function, and many of these alterations appear to be permanent. Because the placenta is the conduit between the maternal and fetal environments, it is likely that placental function plays a key role in mediating effects of fetal glucocorticoid exposure on hypothalamic-pituitary-adrenal axis development and long-term disease risk. Here we review recent insights into how the placenta responds to changes in the intrauterine glucocorticoid environment and discuss possible mechanisms by which the placenta mediates fetal hypothalamic-pituitary-adrenal development, metabolism, cardiovascular function, and reproduction.

Corticotropin-releasing factor receptor 2 mediates sex-specific cellular stress responses

Although females suffer twice as much as males from stress-related disorders, sex-specific participating and pathogenic cellular stress mechanisms remain uncharacterized. Using corticotropin-releasing factor receptor 2-deficient (Crhr2-/-) and wild-type (WT) mice, we show that CRF receptor type 2 (CRF2) and its high-affinity ligand, urocortin 1 (Ucn1), are key mediators of the endoplasmic reticulum (ER) stress response in a murine model of acute pancreatic inflammation. Ucn1 was expressed de novo in acinar cells of male, but not female WT mice during acute inflammation. Upon insult, acinar Ucn1 induction was markedly attenuated in male but not female Crhr2-/- mice. Crhr2-/- mice of both sexes show exacerbated acinar cell inflammation and necrosis. Electron microscopy showed mild ER damage in WT male mice and markedly distorted ER structure in Crhr2-/- male mice during pancreatitis. WT and Crhr2-/- female mice showed similarly distorted ER ultrastructure that was less severe than distortion seen in Crhr2-/- male mice. Damage in ER structure was accompanied by increased ubiquitination, peIF2, and mistargeted localization of vimentin in WT mice that was further exacerbated in Crhr2-/- mice of both sexes during pancreatitis. Exogenous Ucn1 rescued many aspects of histological damage and cellular stress response, including restoration of ER structure in male WT and Crhr2-/- mice, but not in females. Instead, females often showed increased damage. Thus, specific cellular pathways involved in coping and resolution seem to be distinct to each sex. Our results demonstrate the importance of identifying sex-specific pathogenic mechanisms and their value in designing effective therapeutics.

Posttranslational processing of human and mouse urocortin 2: characterization and bioactivity of gene products

Mouse (m) and human (h) urocortin 2 (Ucn 2) were identified by molecular cloning strategies and the primary sequence of their mature forms postulated by analogy to closely related members of the corticotropin-releasing factor (CRF) neuropeptide family. Because of the paucity of Ucn 2 proteins in native tissues, skin, muscle, and pancreatic cell lines were transduced with lentiviral constructs and secretion media were used to isolate and characterize Ucn 2 products and study processing. Primary structures were assigned using a combination of Edman degradation sequencing and mass spectrometry. For mUcn 2, transduced cells secreted a 39 amino acid peptide and the glycosylated prohormone lacking signal peptide; both forms were C-terminally amidated and highly potent to activate the type 2 CRF receptor. Chromatographic profiles of murine tissue extracts were consistent with cleavage of mUcn 2 prohormone to a peptidic form. By contrast to mUcn 2, mammalian cell lines transduced with hUcn 2 constructs secreted significant amounts of an 88 amino acid glycosylated hUcn 2 prohormone but were unable to further process this molecule. Similarly, WM-266-4 melanoma cells that express endogenous hUcn 2 secreted only the glycosylated prohormone lacking the signal peptide and unmodified at the C terminus. Although not amidated, hUcn 2 prohormone purified from overexpressing lines activated CRF receptor 2. Hypoxia and glycosylation, paradigms that might influence secretion or processing of gene products, did not significantly impact hUcn 2 prohormone cleavage. Our findings identify probable Ucn 2 processing products and should expedite the characterization of these proteins in mammalian tissues.

Regulation of estradiol and progesterone production by CRH-R1 and -R2 is through divergent signaling pathways in cultured human placental trophoblasts

CRH and its related peptides urocortins (UCN) have been identified in placenta and implicated to play pivotal roles in the regulation of pregnancy and parturition in humans. The objectives of present study were to investigate the effects of endogenous CRH and its related peptides in the regulation of steroid production in placenta. Placental trophoblasts were isolated from term placenta tissues and cultured for 72 h. Estradiol (E(2)) and progesterone (P(4)) contents in culture media were determined by radioimmunoassay. Treatment of cultured trophoblasts with CRH or UCNI antibody showed decreased E(2), whereas increased P(4) production. Treatment of cells with CRH receptor type 1 antagonist antalarmin or CRH receptor type 2 (CRH-R2) antagonist astressin-2b also decreased E(2) but increased P(4) production. Knockdown of CRH receptor type 1 or CRH-R2 cells showed a decrease in E(2) production and an increase in P(4) production. In CRH-R2 knockdown cells, CRH stimulated GTP-bound Gαs protein and phosphorylated phospholipase C-β3. Adenylyl cyclase and protein kinase A inhibitors blocked CRH-induced increased E(2) production but not decreased P(4) production. PLC inhibitor U73122 and protein kinase C inhibitor chelerythrine blocked the effects of CRH on E(2) and P(4) production in CRH-R2 knockdown cells. UCNIII, the specific CRH-R2 agonist, stimulated GTP-bound Gαi protein and phosphorylated phospholipase C-β3 expression. Both U73122 and chelerythrine blocked UCNIII-induced increased E(2) production and decreased P(4) production. We suggest that CRH and its related peptides might be involved in changes in the progesterone to estrogen ratio during human pregnancy.

Neuroendocrine aspects of placenta and pregnancy

Placenta plays a central role in the regulation of physiological mechanisms of pregnancy, and in particular is the organ of communication between mother and fetus. This action is also related to its ability to produce hormones, growth factors and cytokines during the progression of pregnancy, and in response to stimuli such as stress and inflammation/infection. In the last years the understanding of the physiological and pathological functions of human placenta revealed the hypersecretion of hormones in presence of gestational diseases and raised the question whether this mechanism is cause of disorders of pregnancy, or part of an adaptive response of placenta to resolve adverse conditions. However, there are evidences indicating that changes of placental hormone secretion may have clinical usefulness, since they are measurable in biological fluids, and may be used as predictive markers or prognostic tools. Of particular interest is the role of corticotropin releasing hormone, urocortins and activins in the maintaining physiological pregnancy and in the pathogenesis of diseases (preterm birth and preeclampsia).

Differential regulation of gonadotropin-releasing hormone by corticotropin-releasing factor family peptides in hypothalamic N39 cells

Corticotropin-releasing factor (CRF) is involved in a variety of physiological functions including regulation of hypothalamo-pituitary-adrenal axis activity during stressful periods. Urocortins (Ucns) are known to be members of the CRF family peptides. CRF has a high affinity for CRF receptor type 1 (CRF(1) receptor). Both Ucn2 and Ucn3 have very high affinity for CRF receptor type 2 (CRF(2) receptor) with little or no binding affinity for the CRF(1) receptor. Gonadotropin-releasing hormone (GnRH) is known to be involved in the regulation of the stress response. Gonadotropin-inhibitory hormone (GnIH) neurons interact directly with GnRH neurons, and the action of GnIH is mediated by a novel G-protein coupled receptor, Gpr147. This study aimed to explore the possible function of CRF family peptides and the regulation of GnRH mRNA in hypothalamic GnRH cells. Both mRNA and protein expression of the CRF(1) receptor and CRF(2) receptor were found in hypothalamic GnRH N39 cells. CRF suppressed GnRH mRNA levels via the CRF(1) receptor, while Ucn2 increased the levels via the CRF(2) receptor. Both CRF and Ucn2 increased Gpr147 mRNA levels. The results indicate that CRF and Ucn2 can modulate GnRH mRNA levels via each specific CRF receptor subtype. Finally, CRF suppressed GnRH protein levels, while Ucn2 increased the levels. Differential regulation of GnRH by CRF family peptides may contribute to the stress response and homeostasis in GnRH cells.

Distribution of urocortins and corticotropin-releasing factor receptors in the cardiovascular system

Urocortins are human homologues of urotensin I, a fish corticotropin-releasing-factor- (CRF-) like peptide secreted from the urophysis. There are three urocortins: urocortin 1, urocortin 2, and urocortin 3 in mammals. We have shown that urocortin 1 and urocortin 3 are endogenously synthesized in the myocardial cells of human heart and may act on CRF type 2 receptor (CRFR2) expressed in the heart. Expression levels of urocortin 1 in the heart and plasma urocortin 1 levels are elevated in patients with heart failure. Recent studies have shown that urocortins have various biological actions in the cardiovascular system, such as a vasodilator action, a positive inotropic action, a cardioprotective action against ischemia/reperfusion injury, and suppressive actions against the renin angiotensin system and the sympathetic nervous system. Urocortins and CRFR2 may therefore be a potential therapeutic target for cardiovascular diseases, such as congestive heart failure, hypertension, and myocardial infarction.

CRH acts on CRH-R1 and -R2 to differentially modulate the expression of large-conductance calcium-activated potassium channels in human pregnant myometrium

CRH has been implicated to play a key role in the control of human pregnancy and parturition. Large-conductance potassium channels (BKCa) play a pivotal role in the modulation of uterine contractility during pregnancy. The objectives of the present study were to investigate the effect of CRH on BKCa expression in human pregnant myometrial cells. Myometrial tissues were collected at cesarean section from pregnant women not-in-labor (TNL) or in-labor (TL) at term, and myocytes were isolated and cultured. CRH was identified in human pregnant myometrium and mainly expressed in myometrial myocytes. Cultured myometrial cells were able to secrete CRH. In TNL myometrial cells, CRH treatment increased the expression of BKCa α- and β-subunits. CRH receptor type 1 (CRH-R1) antagonist, antalarmin, decreased whereas CRH receptor type 2 (CRH-R2) antagonist, astressin2b, increased the expression of BKCa. CRH-R2 small interfering RNA (siRNA) caused an increase, but CRH-R1 siRNA resulted in a decrease, in BKCa expression. In contrast to TNL cells, CRH exhibited an opposite effect on BKCa expression in TL myometrial cells, i.e. decreased BKCa expression. Antalarmin enhanced but astressin2b reduced BKCa expression. CRH-R2 siRNA decreased whereas CRH-R1 siRNA increased BKCa expression. 1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one significantly inhibited the frequency of spontaneous contractions of myometrial strips, and this effect was significantly decreased in TL strips compared with TNL ones. Our data suggest that CRH-R1 and CRH-R2 show differential regulation of BKCa expression. These effects mediated by CRH-R1 and CRH-R2 are changed after the onset of labor. This leads us to suggest that CRH may fine-tune myometrial contractility by modulating the expression of BKCa during pregnancy and labor.

Expression of urocortin and corticotropin-releasing hormone receptors in the bovine adrenal gland

Urocortin (UCN), a 40 amino acid peptide, is a corticotrophin-releasing hormone (CRH)-related peptide. The biological actions of CRH family peptides are mediated via two types of G protein-coupled receptors, CRH type 1 receptor (CRHR1) and CRH type 2 receptor (CRHR2). The aim of the present study was to investigate the expression of UCN, CRHR1 and CRHR2 by immunohistochemistry, western blot and real-time RT-PCR in the bovine adrenal gland to clarify the mechanisms of the intra-adrenal CRH-based regulatory system. The results showed that UCN, CRHR1 and CRHR2 were expressed in both the cortex and medulla. Specifically, UCN-immunoreactivity (IR) was distributed in the outer part of the zona fasciculata and in the zona reticularis of the cortex and in the medulla. UCN and CRHR2 mRNA expression levels were higher in the cortex than in the medulla, while CRHR1 mRNA levels were undetectable in the cortex. These results suggest that UCN, CRHR1 and CRHR2 are expressed in the bovine adrenal gland and that UCN might play a role in the intra-adrenal CRH-based regulatory system through an autocrine mechanism.

Changes in placental CRH, urocortins, and CRH-receptor mRNA expression associated with preterm delivery and chorioamnionitis

CONTEXT

The pathogenesis of preterm delivery (PTD) is not clear, although inflammation/infection play a major role. Corticotropin releasing-hormone (CRH) and Urocortins (Ucns) are involved in the pathophysiology of PTD.

OBJECTIVE

This study evaluates trophoblast mRNA expression of CRH, Ucn, Ucn2, Ucn3, and their receptors [CRH-type 1 receptor (CRH-R1), CRH-R2] in infective conditions. To determine whether infection or glucocorticoids contribute to change their placental mRNA expression, the effects of lipopolysaccharide or dexamethasone was evaluated.

DESIGN

Placentas were obtained from spontaneous PTD; premature rupture of membranes (pPROM) and pPROM with chorioamnionitis.

SETTING

Placental specimens were collected from women receiving perinatal care at our Division of Obstetrics and Gynecology.

PATIENTS OR OTHER PARTICIPANTS

Pregnant women delivered preterm were enrolled.

INTERVENTIONS

mRNA expression was evaluated by RT-PCR.

MAIN OUTCOME MEASURE

Because CRH and Ucns are involved in immunological functions we evaluated their involvement in PTD with or without infection.

RESULTS

CRH, Ucn2, and CRH-R1 mRNA expression were higher, while Ucn and CRHR-2 were lower in pPROM with chorioamnionitis than in PTD and pPROM. Ucn3 mRNA expression was lower in pPROM with and without chorioamnionitis than in PTD. The addition of lipopolysaccharide in trophoblast explants decreased Ucn, Ucn3, and CRH-R2 and increased CRH, Ucn2, and CRH-R1 mRNA expression in a dose-dependent manner. Dexamethasone increased CRH and decreased Ucn2 mRNA expression in a dose dependent manner.

CONCLUSIONS

Our findings showed a significant impact of pPROM with chorioamnionitis on placental CRH peptides and receptors, suggesting that placental expression of stress-related pathways is activated in infective process.

Neuroendocrine mechanisms in pregnancy and parturition

The complex mechanisms controlling human parturition involves mother, fetus, and placenta, and stress is a key element activating a series of physiological adaptive responses. Preterm birth is a clinical syndrome that shares several characteristics with term birth. A major role for the neuroendocrine mechanisms has been proposed, and placenta/membranes are sources for neurohormones and peptides. Oxytocin (OT) is the neurohormone whose major target is uterine contractility and placenta represents a novel source that contributes to the mechanisms of parturition. The CRH/urocortin (Ucn) family is another important neuroendocrine pathway involved in term and preterm birth. The CRH/Ucn family consists of four ligands: CRH, Ucn, Ucn2, and Ucn3. These peptides have a pleyotropic function and are expressed by human placenta and fetal membranes. Uterine contractility, blood vessel tone, and immune function are influenced by CRH/Ucns during pregnancy and undergo major changes at parturition. Among the others, neurohormones, relaxin, parathyroid hormone-related protein, opioids, neurosteroids, and monoamines are expressed and secreted from placental tissues at parturition. Preterm birth is the consequence of a premature and sustained activation of endocrine and immune responses. A preterm birth evidence for a premature activation of OT secretion as well as increased maternal plasma CRH levels suggests a pathogenic role of these neurohormones. A decrease of maternal serum CRH-binding protein is a concurrent event. At midgestation, placental hypersecretion of CRH or Ucn has been proposed as a predictive marker of subsequent preterm delivery. While placenta represents the major source for CRH, fetus abundantly secretes Ucn and adrenal dehydroepiandrosterone in women with preterm birth. The relevant role of neuroendocrine mechanisms in preterm birth is sustained by basic and clinic implications.

Distinct distribution of corticotropin releasing factor receptors in human breast cancer

The hypothalamic neuropeptide corticotropin releasing factor (CRF) has been found in several types of human cancer, where its biological role is not clarified. In experimental models of breast cancer CRF has been shown to exert anti-proliferative and other actions. Aim of the present study was to describe the expression of the two types of CRF receptors CRF(1) and CRF(2) in human breast tumors. Receptor expression was studied in breast biopsies from patients diagnosed for primary breast adenocarcinoma, obtained from the tumor and the adjacent benign tissue. Gene expression levels were evaluated by real-time PCR following reverse transcription of total RNA extracts. CRF(1) transcripts were found in 23.1% of benign and in 23.1% of malignant biopsies. CRF(2(a)) was found in 22.2% of benign and 36.0% of malignant biopsies. Transcript levels of both receptors did not differ significantly between cancer and benign biopsies from the same tumor. No correlation was found between CRF receptor expression and patient histo/clinicopathological characteristics. Histological mapping using immunohistochemistry revealed positive CRF(1) immunostaining in the cancerous implants and breast ducts, whereas CRF(2) immunoreactivity was localized mainly in the perineural invasions. In conclusion, both CRF receptors were found in breast cancer and the respective benign adjacent tissue. The two CRF receptor proteins presented distinct distribution and subcellular localization, pointing into differing biological roles. CRF receptors could serve as targets of endogenous ligands expressed in the tumor microenvironment, regulating cancer growth.

Hypoxia and preeclampsia: increased expression of urocortin 2 and urocortin 3

OBJECTIVE

Urocortin 2 (Ucn2) and urocortin 3 (Ucn3) are new members of the corticotrophin-releasing hormone (CRH) family of peptides expressed and localized in human placenta. In the current study, we aimed to asses whether hypoxia affects placental Ucn2/Ucn3 messenger RNA (mRNA) expression and protein localization in physiological or pathological hypoxia and to evaluate whether the effect is modulated by the hypoxia-inducible factor 1alpha (HIF-1alpha).

METHODS

Early first-trimester placental specimens from elective termination of pregnancy were used for villous explants and term placental tissue were used for primary cell cultures. The samples were incubated under different oxygen conditions; parallel sets exposed to hypoxia re-oxygenation (HR). Dimethyloxalylglycine (DMOG), an HIF-1alpha stabilizer, was used to mimic the effects of hypoxia in villous explants. Real-time polymerase chain reaction (PCR) and immunohystochemistry were performed on early pregnancy and preeclamptic (PE) placentae. mRNA levels were measured on villous explants and cell cultures incubated under different oxygen and reagent conditions.

RESULTS

Both Ucn2 and Ucn3 mRNA expression was significantly higher at 6 to 9 weeks of gestation than 10 to 12 wks and in primary trophoblast cell cultures and explants exposed to low O(2) tension (3%) compared to 20% O(2). Strong Ucn2/Ucn3 immunoreactivity was present in trophoblast villi from 6 weeks placentae. Ucn2 immunostaining was stronger in early PE (E-PE) samples relative to controls whereas Ucn3 showed stronger immunoreactivity in late-PE (L-PE) placentae. Only Ucn2 transcript levels increased in HR explants. Ucn2 and Ucn3 expression by first-trimester explants was significantly greater in the presence of DMOG. All PE placentae expressed significantly higher Ucn2 and Ucn3 mRNA compared to controls.

DISCUSSION

Placental Ucn2 and Ucn3 expression is sensitive to O(2) tensions and mediated by HIF-1alpha. During early pregnancy, Ucn2/Ucn3 may influence trophoblast proliferation and establishment of pregnancy. In PE placentae, the increased expression of both peptides may reflect a response to the oxidative stress.

Differential regulation and roles of urocortins in human adrenal H295R cells

Three urocortins (Ucns) are known as members of the corticotropin-releasing factor (CRF) family of peptides and serve as natural ligands for CRF receptors. Ucn1 and Ucn3 exhibit potent effects on the adrenal system via the CRF receptors. This study aimed to explore the regulation and roles of Ucns in the adrenal system using human adrenal carcinoma H295R cells, which express Ucn1, Ucn2, Ucn3, CRF receptor type 1 (CRF(1) receptor), and CRF receptor type 2a (CRF(2a) receptor) mRNA. Forskolin, which stimulates adenylate cyclase and then increases intracellular cAMP production, was shown to transiently decrease Ucn1 and Ucn2 mRNA levels, but increase Ucns 1-3 mRNA levels in H295R cells. Steroidogenic acute regulatory protein, Cyp11beta1, and Cyp11beta2 mRNA levels, and both cortisol and aldosterone secretions were elevated by Ucn1. Cell viability was reduced by both Ucn1 and Ucn3 via the CRF(2) receptor in H295R cells. Ucn1 and Ucn3 increased the expression of the cAMP-response element binding protein and extracellular signal-related kinase (ERK) phosphorylations. The ERK and protein kinase A pathways were involved in Ucn3-decreased cell viability.

Neuropeptide and sigma receptors as novel therapeutic targets for the pharmacotherapy of depression

Among the most prevalent of mental illnesses, depression is increasing in incidence in the Western world. It presents with a wide variety of symptoms that involve both the CNS and the periphery. Multiple pharmacological observations led to the development of the monoamine theory as a biological basis for depression, according to which diminished neurotransmission within the CNS, including that of the dopamine, noradrenaline (norepinephrine) and serotonin systems, is the leading cause of the disorder. Current conventional pharmacological antidepressant therapies, using selective monoamine reuptake inhibitors, tricyclic antidepressants and monoamine oxidase inhibitors, aim to enhance monoaminergic neurotransmission. However, the use of these agents presents severe disadvantages, including a delay in the alleviation of depressive symptoms, significant adverse effects and high frequencies of non-responding patients. Neuroendocrinological data of recent decades reveal that depression and anxiety disorders may occur simultaneously due to hypothalamus-pituitary-adrenal (HPA) axis hyperactivity. As a result, the stress-diathesis model was developed, which attempts to associate genetic and environmental influences in the aetiology of depression. The amygdala and the hippocampus control the activity of the HPA axis in a counter-balancing way, and a plethora of regulatory neuropeptide signalling pathways are involved. Intervention at these molecular targets may lead to alternative antidepressant therapeutic solutions that are expected to overcome the limitations of existing antidepressants. This prospect is based on preclinical evidence from pharmacological and genetic modifications of the action of neuropeptides such as corticotropin-releasing factor, substance P, galanin, vasopressin and neuropeptide Y. The recent synthesis of orally potent non-peptide micromolecules that can selectively bind to various neuropeptide receptors permits the onset of clinical trials to evaluate their efficacy against depression.

Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour

BACKGROUND

Corticotropin-releasing hormone (CRH) and CRH-related peptide are shown to modulate uterine contractility through two CRH receptor subtype, CRH-R1 and CRH-R2 during pregnancy. Through different signaling pathways, CRH-R1 maintains myometrial quiescence whereas CRH-R2 promotes smooth muscle contractility. We hypothesized that the expression of CRH receptors in myometrium might be changed during pregnancy and labour.

METHOD

Immunohistochemistry, Western blot and RT-PCR were used to quantify the cellular localization, the protein levels and the mRNA variants of both CRH-R1 and CRH-R2 in upper segment (US) and lower segment (LS) myometrium from nonpregnant and pregnant women at term before or after labour.

RESULTS

CRH-R1 and CRH-R2 were predominately localized to myometrial smooth muscle cells in US and LS. The protein level of CRH-R1 in US was significantly down-regulated in pregnancy, with a further decrease at the onset of labour. However, the expression of CRH-R1 in LS remained unchanged during pregnancy and labour. No significant changes in CRH-R2 expression were observed in US or LS. Six variants of CRH-R1, CRH-R1alpha,-R1beta,-R1c, -R1e,-R1f and -R1g, were identified in nonpregnant and pregnant myometrium. CRH-R2alpha was identified in pregnant myometrium, whereas CRH-R2beta was identified in nonpregnant myometrium

CONCLUSION

CRH-R1 and CRH-R2 are expressed in nonpregnant and pregnant US and LS myometrium. Changed expression of CRH receptors during labour may underlie the initiation of uterine contractility during parturition.

Differential regulation of prostaglandin production mediated by corticotropin-releasing hormone receptor type 1 and type 2 in cultured human placental trophoblasts

Prostaglandin (PG) production by intrauterine tissues plays a key part in the control of pregnancy and parturition. The present study was to investigate the role of placenta-derived CRH and CRH-related peptides in the regulation of PG synthesis and metabolism. We found that placental trophoblasts expressed both CRH-R1 and CRH-R2. Treatment of cultured placental cells with either a CRH or urocortin I (UCNI) antibody resulted in a significant decrease in PGE2 release. Both CRH and UCNI antibodies significantly decreased mRNA and protein expression of synthetic enzymes cytosolic phospholipase A2 (cPLA2) and cyclooxygenase (COX)-2 and increased mRNA and protein expression of 15-hydroxyprostaglandin dehydrogenase (PGDH), the key enzyme of PG metabolism. CRH-R1/-R2 antagonist astressin and CRH-R1 antagonist antalarmin significantly inhibited PGE2 release, whereas CRH-R2 antagonist astressin-2b had no effect on PGE(2) release. Administration of astressin decreased expression of cPLA2 but had no effect on COX-2 expression. Antalarmin reduced cPLA2 and COX-2 expression, whereas astressin-2b did not alter cPLA2 expression but increased COX-2 expression. PGDH expression was enhanced by these three antagonists. Cells treated with exogenous CRH and UCNI showed an increase in PGE(2) release and expression of cPLA2 and COX-2 but a decrease in PGDH expression. UCNII and UCNIII had no effect on PGE2 release but decreased COX-2 and PGDH expression. Our results suggested CRH and CRH-related peptides act on CRH-R1 and CRH-R2 to exert different effects on PG biosynthetic enzymes cPLA2 and COX-2 and thereby modulate output of PGs from placenta, which would be important for controlling pregnancy and parturition.

Expression of corticotropin-releasing hormone receptor type 1 and type 2 in human pregnant myometrium

It has been suggested that corticotropin-releasing hormone (CRH) receptors CRH-R1 and CRH-R2 might be involved in the modulation of uterine activity during pregnancy. The authors determine the localization, concentrations, and variants of CRH-R1 and CRH-R2 in the human pregnant myometrium from patients undergoing labor and patients not undergoing labor. Biopsies were taken from 40 patients undergoing either elective or emergency cesarean delivery after spontaneous labor. The localization of CRH-R1 and CRH-R2 was examined by immunohistochemistry. The mRNA and protein levels of CRH-R1 and CRH-R2 were measured by quantitative reverse-transcriptase polymerase chain reaction (PCR) and Western blot analysis, respectively. The variants of CRH-R1 and CRH-R2 were determined by PCR analysis followed by sequencing. Both CRH-R1 and CRH-R2 were found by immunohistochemistry to be expressed by smooth muscle cells in the pregnant myometrium. There was no significant difference in mRNA and protein levels of CRH-R1 and CRH-R2 in myometria between the labor and nonlabor groups. Levels of CRH-R1 alpha , R1 beta, R1c, R1e, R1f, and R2 alpha were identified in the pregnant myometrium, and levels of CRH-R1 alpha, R1c, and R2 alpha were detected in both the term labor and nonlabor myometrium. A heterogeneous distribution of other CRH-R1 variants in term labor and nonlabor myometrium was observed. Human myometrium expresses both CRH-R1 and CRH-R2 during pregnancy. A heterogeneous distribution of CRH-R1 variants in term labor and nonlabor myometrium might be related to the effects of CRH on contractile phenotype of myometrium at the term.

Corticotropin-releasing hormone receptor type 1 and type 2 mediate differential effects on 15-hydroxy prostaglandin dehydrogenase expression in cultured human chorion trophoblasts

Throughout gestation, the chorion laeve controls the levels of biologically active prostaglandins (PGs) by its high level of nicotinamide adenine dinucleotide-dependent 15-hydroxy PG dehydrogenase (PGDH). In this study, we investigate the effects mediated by CRH receptors on the expression of PGDH in the chorion. We found that both CRHR1 and CRHR2 were localized in cultured chorion trophoblast cells, with CRH-R1alpha, R1beta, R1c, R1e, and R1f and CRHR2beta isoforms identified in these cells. To block the actions of endogenous CRH and its related peptides, cultured chorion trophoblasts were treated with an increasing concentration of alpha-helical CRH 9-41, the nonselective CRH receptor antagonist, which resulted in decreased mRNA and protein expression as well as the activity of PGDH. To investigate the individual role of CRHR1 and CRHR2, cell cultures were treated with the specific CRHR1 antagonist antalarmin and CRHR2 antagonist astressin2B, respectively. The results showed that antalarmin increased whereas astressin2B decreased mRNA and protein expression as well as the activity of PGDH in chorion cells. When the cells were treated with an exclusive CRHR2 agonist, urocortin II, elevated expression and activity of PGDH was exhibited. However, cells treated with either exogenous CRH or urocortin I showed significantly increased PGDH expression, and these effects could be blocked by astressin2B but not by antalarmin. We suggest that, in chorion trophoblast cells, CRHR1 and CRHR2 mediate divergent effects on PGDH expression, and this may provide a precise regulation of PGs levels from chorion to myometrium during pregnancy.

Expression of molecular equivalent of hypothalamic-pituitary-adrenal axis in adult retinal pigment epithelium

We have investigated expression of molecular elements of the hypothalamic-pituitary-adrenal (HPA) axis in the human retinal pigment epithelium (RPE) cells. The presence of corticotropin-releasing factor (CRF); urocortins I, II and III; CRF receptor type 1 (CRFR1); POMC and prohormone convertases 1 and 2 (PC1 and PC2) mRNAs were shown by RT-PCR; the protein products were detected by ELISA, western blot or immunocytochemical methods in an ARPE-19 cell line derived from an adult human donor. CRFR2 was below the level of detectability. The CRFR1 was functional as evidenced by CRF stimulation of cAMP and inositol triphosphate production as well as by ligand induction of transcriptional activity of inducible cis-elements cAMP responsive element (CRE), activator protein 1 responsive element (AP-1) and POMC promoter) in ARPE-19 using luciferase reporter assay. Immunoreactivities representative of CRF, pre-urocortin, CRFR1 receptor and ACTH were also detected in mouse retina by in situ immunocytochemistry. Finally, using RT-PCR, we detected expression of genes encoding four key enzymes participating in steroids synthesis (CYP11A1, CYP11B1, CYP17 and CYP21A2) and showed transformation of progesterone into cortisol-immunoreactivity in cultured ARPE-19 cells. Therefore, we suggest that ocular tissue expresses CRF-driven signalling system that follows organisational structure of the HPA axis.

Physiology, pharmacology, and therapeutic relevance of urocortins in mammals: ancient CRF paralogs

Urocortins, three paralogs of the stress-related peptide corticotropin-releasing factor (CRF) found in bony fish, amphibians, birds, and mammals, have unique phylogenies, pharmacologies, and tissue distributions. As a result and despite a structural family resemblance, the natural functions of urocortins and CRF in mammalian homeostatic responses differ substantially. Endogenous urocortins are neither simply counterpoints nor mimics of endogenous CRF action. In their own right, urocortins may be clinically relevant molecules in the pathogenesis or management of many conditions, including congestive heart failure, hypertension, gastrointestinal and inflammatory disorders (irritable bowel syndrome, active gastritis, gastroparesis, and rheumatoid arthritis), atopic/allergic disorders (dermatitis, urticaria, and asthma), pregnancy and parturition (preeclampsia, spontaneous abortion, onset, and maintenance of effective labor), major depression and obesity. Safety trials for intravenous urocortin treatment have already begun for the treatment of congestive heart failure. Further understanding the unique functions of urocortin 1, urocortin 2, and urocortin 3 action may uncover other therapeutic opportunities.