Cellular localization of chorionic gonadotropin in human fetal kidney and liver

Human Chorionic Gonadotropin-Mediated Immune Responses That Facilitate Embryo Implantation and Placentation

Human chorionic gonadotropin (hCG) serves as one of the first signals provided by the embryo to the mother. Exactly at the time when the first step of the implantation process is initiated and the blastocyst adheres to the maternal endometrium, the embryonic tissue starts to actively secrete hCG. Shortly thereafter, the hormone can be detected in the maternal circulation where its concentration steadily increases throughout early pregnancy as it is continuously released by the forming placenta. Accumulating evidence underlines the critical function of hCG for embryo implantation and placentation. hCG not only regulates biological aspects of these early pregnancy events but also supports maternal immune cells in their function as helpers in the establishment of an adequate embryo-endometrial relationship. In view of its early presence in the maternal circulation, hCG has the potential to influence both local uterine immune cell populations as well as peripheral ones. The current review aims to summarize recent literature on the participation of innate and adaptive immune cells in embryo implantation and placentation with a specific focus on their regulation by hCG.

Elimination of Signaling by the Luteinizing Hormone Receptor Reduces Ocular VEGF and Retinal Vascularization during Mouse Eye Development

Purpose/Aim: Vascular endothelial growth factor (VEGF) dysregulation is implicated in the pathogenesis of retinopathy of prematurity (ROP). Identifying the factors that contribute to VEGF regulation during normal retinal vascularization is the key to ROP prevention. Currently, physiologic hypoxia is thought to be responsible for retinal VEGF regulation in utero. However, a potential hormonal contribution to VEGF regulation during eye development has not been fully investigated. The placental hormone, human chorionic gonadotropin and the pituitary hormone, and luteinizing hormone (LH) induce VEGF expression in several tissue types. Both of these gonadotropins activate the same LH receptor (LHR) in the human body; LHRs are expressed in the retina. In this study, we aimed to show that LHR signaling participates in VEGF regulation in the developing eye.

METHODS

When offspring from breeding pairs of LHR knockout mice (lhrkos) reached 21 days old, eyes and serum were extracted from homozygote lhrkos and wildtype (WT) siblings. VEGF levels were measured using Mouse VEGF Quantikine immunoassay kit. Retinas were incubated with isolectin for endothelial cell staining, flat mounted and imaged by confocal microscopy. Retinal vascular density was quantified using Imaris software. Some eyes were sectioned and stained for histopathologic review.

RESULTS

Ocular VEGF and retinal vascular volumes were significantly reduced by ~ 15% in lhrko eyes. Serum VEGF was not changed. The lhrko retinas did not display any anomalies.

CONCLUSIONS

We provide evidence that LHR signaling plays a role in VEGF regulation and vascularization in the developing eye. Given that human preterm infants may have altered LHR-activity, the effect of gonadotropins on eye development should be further studied to identify novel strategies for ROP prevention.

Pretreatment with Human Chorionic Gonadotropin Protects the Neonatal Brain against the Effects of Hypoxic-Ischemic Injury

INTRODUCTION

Though the human fetus is exposed to placentally derived human chorionic gonadotropin (hCG) throughout gestation, the role of hCG on the fetal brain is unknown. Review of the available literature appears to indicate that groups of women with higher mean levels of hCG during pregnancy tend to have offspring with lower cerebral palsy (CP) risk. Given that newborn cerebral injury often precedes the development of CP, we aimed to determine whether hCG may protect against the neurodegenerative effects of neonatal brain injury.

METHODS

We utilized the Rice-Vannucci model of neonatal cerebral hypoxia-ischemia (HI) in postnatal day 7 mice to examine whether intraperitoneal administration of hCG 15-18 h prior, 1 h after or immediately following HI decrease brain tissue loss 7 days after injury. We next studied whether hCG has pro-survival and trophic properties in neurons by exposing immature cortical and hippocampal neurons to hCG in vitro and examining neurite sprouting and neuronal survival prior and after glutamate receptor-mediated excitotoxic injury.

RESULTS

We found that intraperitoneal injection of hCG 15 h prior to HI, but not at or 1 h after HI induction, resulted in a significant decrease in hippocampal and striatal tissue loss 7 days following brain injury. Furthermore, hCG reduced N-methyl-d-aspartate (NMDA)-mediated neuronal excitotoxicity in vitro when neurons were continuously exposed to this hormone for 10 days or when given at the time and following neuronal injury. In addition, continuous in vitro administration of hCG for 6-9 days increased neurite sprouting and basal neuronal survival as assessed by at least a 1-fold increase in MAP2 immunoreactivity and a 2.5-fold increase in NeuN + immunoreactivity.

CONCLUSION

Our findings suggest that hCG can decrease HI-associated immature neural degeneration. The mechanism of action for this neuroprotective effect may partly involve inhibition of NMDA-dependent excitotoxic injury. This study supports the hypothesis that hCG during pregnancy has the potential for protecting the developing brain against HI, an important CP risk factor.

hCG, the wonder of today's science

BACKGROUND

hCG is a wonder. Firstly, because hCG is such an extreme molecule. hCG is the most acidic glycoprotein containing the highest proportion of sugars. Secondly, hCG exists in 5 common forms. Finally, it has so many functions ranging from control of human pregnancy to human cancer. This review examines these molecules in detail.

CONTENT

These 5 molecules, hCG, sulfated hCG, hyperglycosylated hCG, hCG free beta and hyperglycosylated free beta are produced by placental syncytiotrophoblast cells and pituitary gonadotrope cells (group 1), and by placental cytotrophoblast cells and human malignancies (group 2). Group 1 molecules are both hormones that act on the hCG/LH receptor. These molecules are central to human menstrual cycle and human pregnancy. Group 2 molecules are autocrines, that act by antagonizing a TGF beta receptor. These molecules are critical to all advanced malignancies.

CONCLUSIONS

The hCG groups are molecules critical to both the molecules of pregnancy or human life, and to the advancement of cancer, or human death.

hCG, five independent molecules

INTRODUCTION

The hCG amino acid sequence supports 5 glycoproteins. All are called hCG forms. This review examines all 5 molecules, the hormone as produced by the placental syncytiotrophoblast cells, the sulfated hormone produced by the pituitary gonadotrope cells, the hyperglycosylated hCG autocrine made by placental cytotrophoblast cells, and the autocrine cancer promoters hyperglycosylated hCG, hCGß and hyperglycosylated hCGß as made by all malignancies. This review examines all the molecules and multiple proven functions, ranging from evolution to cancer promotion to hormone action.

RESULTS AND DISCUSSION

hCG forms are critical super-growth factors in humans, with an exceptional wide range of functions.

Biological functions of hCG and hCG-related molecules

BACKGROUND

hCG is a term referring to 4 independent molecules, each produced by separate cells and each having completely separate functions. These are hCG produced by villous syncytiotrophoblast cells, hyperglycosylated hCG produced by cytotrophoblast cells, free beta-subunit made by multiple primary non-trophoblastic malignancies, and pituitary hCG made by the gonadotrope cells of the anterior pituitary.

RESULTS AND DISCUSSION

hCG has numerous functions. hCG promotes progesterone production by corpus luteal cells; promotes angiogenesis in uterine vasculature; promoted the fusion of cytotrophoblast cell and differentiation to make syncytiotrophoblast cells; causes the blockage of any immune or macrophage action by mother on foreign invading placental cells; causes uterine growth parallel to fetal growth; suppresses any myometrial contractions during the course of pregnancy; causes growth and differentiation of the umbilical cord; signals the endometrium about forthcoming implantation; acts on receptor in mother's brain causing hyperemesis gravidarum, and seemingly promotes growth of fetal organs during pregnancy. Hyperglycosylated hCG functions to promote growth of cytotrophoblast cells and invasion by these cells, as occurs in implantation of pregnancy, and growth and invasion by choriocarcinoma cells. hCG free beta-subunit is produced by numerous non-trophoblastic malignancies of different primaries. The detection of free beta-subunit in these malignancies is generally considered a sign of poor prognosis. The free beta-subunit blocks apoptosis in cancer cells and promotes the growth and malignancy of the cancer. Pituitary hCG is a sulfated variant of hCG produced at low levels during the menstrual cycle. Pituitary hCG seems to mimic luteinizing hormone actions during the menstrual cycle.

Zebrafish gonadotropins and their receptors: II. Cloning and characterization of zebrafish follicle-stimulating hormone and luteinizing hormone subunits--their spatial-temporal expression patterns and receptor specificity

Gonadotropins, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) play critical roles in vertebrate reproduction. In the present study, we cloned and characterized zebrafish FSHbeta (fshb), LHbeta (lhb), and GTHalpha (cga) subunits. Compared with the molecules of other teleosts, the cysteine residues and potential glycosylation sites are fully conserved in zebrafish Lhb and Cga but not in Fshb, whose cysteines exhibit unique distribution. Interestingly, in addition to the pituitary, fshbeta, lhbeta, and cga were also expressed in some extrapituitary tissues, particularly the gonads and brain. In situ hybridization showed that zebrafish fshbeta and lhbeta were expressed in two distinct populations of gonadotrophs in the pituitary. Real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that all the three subunits increased expression before ovulation (0100-0400) when the germinal vesicles in the full-grown follicles were migrating toward the periphery, but the levels dropped at 0700, when ovulation occurred. Recombinant zebrafish FSH (zfFSH) and LH (zfLH) were produced in the Chinese hamster ovary (CHO) cells and their effects on the cognate receptors (zebrafish Fshr and Lhr) tested. Interestingly, zfFSH specifically activated zebrafish Fshr expressed together with a cAMP-responsive reporter gene in the CHO cells, whereas zfLH could stimulate both Fshr and Lhr. In conclusion, the present study systematically investigated gonadotropins in the zebrafish in terms of their structure, spatial-temporal expression patterns, and receptor specificity. These results, together with the availability of recombinant zfFSH and zfLH, provide a solid foundation for further studies on the physiological relevance of FSH and LH in the zebrafish, one of the top biological models in vertebrates.

Extraplacental human fetal tissues express mRNA transcripts encoding the human chorionic gonadotropin-beta subunit protein

The glycoprotein hormone human chorionic gonadotropin (hCG) is synthesized in large quantities by the developing placenta, reaching peak concentrations in maternal blood during the late first trimester and early midtrimester of pregnancy. In general it is believed that the alpha-subunit of this dimeric hormone is expressed in pituitary gonadotropes, thyrotropes, and trophoblasts, while the beta-subunit is expressed exclusively by trophoblasts. Studies from our laboratory and other laboratories have shown that some midtrimester human fetal tissues, in addition to the placenta, can synthesize proteins that appear to be very similar to the beta-subunit of hCG. To define precisely the nature of this putative hCG-beta-subunit in extraplacental fetal tissues, we have examined the mRNA from a variety of human fetal and adult tissues using nucleic acid hybridization and reverse transcription-polymerase chain reaction (PCR) methods. Our results demonstrate that midtrimester fetal kidney and adrenal tissues contain hCG-beta mRNA transcripts at concentrations comparable to that of placenta, while fetal lung, brain, muscle, and adult adrenal contain only trace to undetectable levels of hCG-beta mRNA. By restriction endonuclease mapping of PCR fragments from fetal tissue cDNAs, we show that the hCG-beta transcript expressed in midtrimester human fetal organs is a bone fide copy of hCG-beta gene No. 5 of the beta-subunit gene family located on chromosome 19.

The unique endocrine milieu of the fetus

Table II summarizes in tabular form the major features of the fetal endocrine milieu discussed in the foregoing pages. The mammalian fetus develops in an environment where respiration, alimentation, and excretory functions are provided by the placenta. Fetal tissue metabolism is oriented largely to anabolism; body temperature is modulated by maternal metabolism, and fetal tissue thermogenesis is maintained at a basal level. Tissue and organ growth appear to be regulated by growth factors which probably function by autocrine or paracrine mechanisms during most of gestation (72, 146-148). In this milieu conventional endocrine control systems are largely redundant, and other transient systems more appropriate to the intrauterine environment have evolved. We have developed some insights into these systems, but much more information is necessary before we can truly understand this fascinating environment.