Receptors In Human Endometrium Research Articles

Delta and kappa opioid receptors in human endometrium during the menstrual cycle: Expression and localization

ObjectiveEndogenous opioid peptides were reported to be involved in the regulation of reproductive physiology and their precursors and receptors were described in many of the male and female reproductive tissues. Mu opioid receptor (MOR) was described in human endometrial cells and its expression and localization changed during the menstrual cycle. However, there is no data from the distribution of the other opioid receptors: Delta (DOR) and Kappa (KOR). The objective of the present work was to analyze the dynamics of expression and localization of DOR and KOR in human endometrium throughout the menstrual cycle. Study designHuman endometrial samples from different menstrual cycle phases were analyzed by immunohistochemistry. ResultsDOR and KOR were present in all samples analyzed and the protein expression and localization changed throughout the menstrual cycle. Both receptor expression increased during the late proliferative phase and decreased during the late secretory-one, especially in the luminal epithelium. DOR expression was generally higher than KOR expression in all cell compartments. ConclusionsThe presence of DOR and KOR in human endometrium and their dynamic changes during the menstrual cycle join the results previously obtained in MOR suggesting a possible role of opioids in reproduction events related to the human endometrium.

Evidence for expression and functionality of FSH and LH/hCG receptors in human endometrium

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) mediate intracellular functions by binding their specific protein G-coupled gonadotrophin receptor, respectively FSH receptor (FSHR) and LH/choriogonadotrophin receptor (LHCGR). Whereas the expression of FSHR and LHCGR in mammals was considered gonad-specific and cell-specific, studies identified gonadotrophin receptors in human female extragonadal reproductive tissues. This study aims to demonstrate that gonadotrophin receptors are expressed in endometrium and mediates intracellular functions. Collected endometria (n = 12) from healthy patients (mean age of 36 ± 6) were primary cultured for 24h. The presence of gonadotrophin receptors was evaluated by RT-PCR followed by the sequencing of the resulted amplicons and by immunohistochemistry in original samples. Endometrial primary cultures were treated with increasing concentration (range 0-100ng/ml) of either recombinant human LH (rhLH) or recombinant human FSH (rhFSH). Endometria controls had gonadotrophin replaced by the same volume of the culture medium. In gonadotrophin-treated samples, it was evaluated the intracellular cyclic adenosine monophosphate (cAMP) content by enzymatic immunoassay and the expression of steroidogenic genes by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). The sequencing of the RT-PCR amplicons confirmed the presence of both gonadotrophin receptors and immunohistochemistry localized them on the membrane of endometrial glands cells throughout the glandular epithelium. The gonadotrophin-receptor complex was able to increase the intracellular cAMP in a dose-response and time-course manner and to induce steroidogenic genes expression. This study demonstrates that both gonadotrophin receptors are expressed along the glandular epithelium of endometria and they mediate the effects of gonadotrophins on intracellular functions.

Mu opioid receptor in the human endometrium: dynamics of its expression and localization during the menstrual cycle

To study the dynamics of the expression and localization of the mu opioid receptor (MOR) in human endometrium throughout the menstrual cycle. Analysis of human endometrial samples from different menstrual cycle phases (menstrual, early/midproliferative, late proliferative/early secretory, midsecretory, and late secretory) by reverse transcription-polymerase chain reaction, Western blot, and immunohistochemistry. Academic research laboratory. Women from the Human Reproduction Unit of the Cruces University Hospital, fulfilling the following criteria: normal uterine vaginal ultrasound; absence of endometriosis, polycystic ovary syndrome, implantation failure, or recurrent miscarriage; and no history of opioid drug use. Endometrial samples of 86 women categorized into groups for the menstrual cycle phases: 12 menstrual, 21 early/midproliferative, 16 late proliferative/early secretory, 17 midsecretory, and 20 late secretory. MOR gene and protein expression and localization in the different compartments of the human endometrium at different stages of the menstrual cycle. The expression of MOR mRNA and protein changed throughout the cycle in human endometrium. MOR expression increased during the proliferative phase and decreased during the secretory one. Lower values were found at menstruation, and maximum values around the time of ovulation. Small variations for each endometrial compartment were found. The presence of MOR in human endometrium and the dynamic changes during the menstrual cycle suggest a possible role for opioids in reproduction events related to the human endometrium or endometriosis.

Expression of Type 2 Orexin Receptor in Human Endometrium and Its Epigenetic Silencing in Endometrial Cancer

Orexins A and B are neuropeptides that bind and activate 2 types of receptors. In addition to direct action in the brain, the orexinergic system has broader implications in peripheral organs, and it has been proposed to have a role in the induction of apoptosis. There are very few data on the endometrium. The expression and epigenetic regulation of type 2 orexin receptor (OX2R) was investigated in the human endometrium as well as in endometrial endometrioid carcinoma (EEC). OX2R localization was studied by immunohistochemistry in normal endometrium (n = 24) and in EEC (n = 32). The DNA methylation status of a CpG island located in the first exon of OX2R was analyzed by bisulfite sequencing in normal (n = 18), EEC (n = 34), and 3 endometrial cell lines. On the latter, mRNA expression and Western blotting as well as in vitro induction with orexin were performed. Expression of the OX2R protein was detected in normal endometrial epithelia, whereas it was frequently lacking in EEC. This loss was associated with hypermethylation of OX2R in EEC in comparison with normal endometrium (median CpG methylation percentages of 48.85% and 5.85%, respectively). In cell lines, hypermethylation correlated with weak OX2R expression. Additionally, in vitro treatment of the 3 EEC cell lines with orexins A and B did not result in proliferation change Altogether our data provide evidence for the epigenetic silencing of OX2R in EEC. The implication of the OX2R loss in tumoral progression remains to be elucidated.

Endometrial LGR7 expression during menstrual cycle

In a prospective observational study, 50 healthy patients aged 18-39 years, with regular ovulatory cycle and normal hormone levels, underwent endometrial biopsy in the proliferative and secretory phase of the menstrual cycle for semiquantitative reverse-transcription polymerase chain reaction analysis of mRNA for LGR7, the classic relaxin receptor. LGR7 is constitutively expressed in human endometrium, and an increased LGR7 immunostaining is demonstrated in the secretory phase, confirming the involvement of relaxin in the physiology of endometrium and suggesting its role in implantation.

Gonadotropin‐releasing hormone (GnRH)‐I regulation of interleukin (IL)‐1b and IL‐1 receptor antagonist expression in cultured human endometrial stromal cells

Human endometrium is an active site of cytokine production and action. Among these cytokines, the interleukin-1 (IL-1) system seems to be relevant to the embryonic implantation process. We have previously reported the production of GnRH-I by human blastocyst, as well as the presence of GnRH-I receptor in human endometrium. This suggests a close interaction between the immune and endocrine systems through these cytokine mediators in embryonic implantation. To test the relevance of this interaction during embryonic implantation, we investigated GnRH-I regulation of IL-1b and IL-1ra mRNA and protein expression in human endometrial stromal cells using quantitative competitive polymerase chain reaction and ELISA. IL-1b mRNA and protein expression in cultured human endometrial stromal cells was significantly enhanced by GnRH-agonist in comparison to control groups. IL-1ra mRNA and protein was significantly decreased by GnRH-agonist in comparison to control groups. In contrast, the GnRH-antagonist ablated the regulatory effects of GnRH agonist in 1b and IL-1ra mRNA and protein levels in a dose-dependent manner. In conclusion, these results suggest a possible close interaction between the immune and endocrine systems in human embryonic implantation through the classical neuropeptide hormone GnRH and its receptor.

Expression and regulation of vascular endothelial growth factor ligands and receptors during menstruation and post-menstrual repair of human endometrium

Regeneration and growth of the human endometrium after shedding of the functional layer during menstruation depends on an adequate angiogenic response. We analysed the mRNA expression levels of all known vascular endothelial growth factor (VEGF) ligands and receptors in human endometrium collected in the menstrual and proliferative phases of the menstrual cycle. In addition, we evaluated the expression of VEGF-A, VEGF-R2 and NRP-1 at the protein level. Two periods of elevated mRNA expression of ligands and receptors were observed, separated by a distinct drop at cycle days (CDs) 9 and 10. Immunohistochemical staining showed that VEGF and VEGF-R2 were expressed in epithelial, stromal and endothelial cells. NRP-1 was mainly confined to stroma and blood vessels; only in late-proliferative endometrium, epithelial staining was also observed. Except for endothelial VEGF-R2 expression in CDs 6-8, there were no significant differences in the expression of VEGF, VEGF-R2 or NRP-1 in any of the cell compartments. In contrast, VEGF release by cultured human endometrium explants decreased during the proliferative phase. This output was significantly reduced in menstrual and early-proliferative endometrium by estradiol (E2) treatment. Western blot analysis indicated that part of the VEGF-A was trapped in the extracellular matrix (ECM). Changes in VEGF ligands and receptors were associated with elevated expression of the hypoxia markers HIF1alpha and CA-IX in the menstrual and early proliferative phases. HIF1alpha was also detected in late-proliferative phase endometrium. Our findings indicate that VEGF-A exerts its actions mostly during the first half of the proliferative phase. Furthermore, VEGF-A production appears to be triggered by hypoxia in the menstrual phase and subsequently suppressed by estrogen during the late proliferative phase.

Expression of vascular endothelial growth factors and their receptors in human endometrium from women experiencing abnormal bleeding patterns after prolonged use of a levonorgestrel-releasing intrauterine system

Menstrual bleeding disturbances are a common initial complaint among users of the levonorgestrel-releasing intrauterine system (LNG-IUS). In this study, women who experienced bleeding disturbances recurring after a previous period of problem-free use and who therefore wanted removal of their LNG-IUD were investigated. Vascular endothelial growth factors (VEGFs) and their receptors are thought to be involved in normal endometrial angiogenesis. The aim of the study was to elucidate the possible association of these VEGF and receptors with bleeding disturbances among users of LNG-IUS. Endometrial biopsies were obtained from users of the LNG-IUS who complained of bleeding disturbances (n = 17) and from women without such problems (n = 14). The endometrial expression of these VEGFs and their receptors was analysed using immunohistochemistry. Endometrial endothelial cells from LNG-IUS users with menstrual bleeding disturbances exhibited significantly higher immunoreactivity for VEGFR-1 and VEGFR-3 than those from women without bleeding disturbances. Stromal cells showed significantly lower immunoreactivity for VEGF-A in samples from LNG-IUS users with bleeding disturbances than in those without. Changes in the expression of these angiogenic growth factors and their receptors in LNG-IUS-exposed endometrium might be involved in the formation of fragile and dysfunctional blood vessels that subsequently give rise to bleeding disturbances.

Evidence for cycle-dependent expression of follicle-stimulating hormone receptor in human endometrium

Objective. It was the purpose of the present study to investigate whether human endometrium expresses follicle-stimulating hormone (FSH) receptor mRNA and peptide, and whether this expression is regulated in a cycle-dependent manner in endometrium derived from various phases of the menstrual cycle.Methods. FSH receptor mRNA and peptide expression were evaluated by reverse transcription–polymerase chain reaction and by immunohistochemistry in endometrium from 15 women undergoing hysteroscopy to evaluate the morphology of the uterine cavity or hysterectomy for leiomyomas.Results. FSH receptor mRNA was expressed by human endometrium, and its peptide was located immunohistochemically in both proliferative and secretory endometrial epithelial and stromal cells. A significant increase in immunoreactive FSH receptor was observed during the secretory phase.Conclusions. We have shown the presence of FSH receptor in human endometrium and demonstrated that FSH receptor immunostaining is upregulated in the secretory phase of the menstrual cycle. The dynamic pattern of receptor expression indicates that FSH may play a role in the regulation of endometrial function and possibly in the embryo–endometrium interaction.

Gene expression pattern and immunoreactive protein localization of LGR7 receptor in human endometrium throughout the menstrual cycle.

Relaxin (RLX) is a pregnancy-associated polypeptide hormone. In non-pregnant women, the peak of circulating relaxin coincides with the window of endometrial receptivity and both in vivo and in vitro experiments showed that it plays a role in the decidualization process. Recently, two receptors, LGR7 and LGR8, have been identified as high affinity receptors for relaxin. Here we describe LGR7 mRNA and protein expression in human endometrium using semi-quantitative and quantitative fluorescent PCR (Q-PCR) and immunohistochemical analyses. Three different experimental designs were used. First, endometrial biopsies from five different phases of the menstrual cycle were analysed. Secondly, we assessed the early luteal phase in more detail. Finally we analysed the expression at LH+2 (2 days after the natural LH surge, pre-receptive endometrium) versus LH+7 (receptive endometrium) within the same menstrual cycle from the same patient to avoid inter-cycle or inter-person variations in gene expression. Our results indicate that there is no consistent regulation of LGR7 mRNA expression, neither during the menstrual cycle nor during the early-mid-luteal phase. In general, we observed a large degree of variation in LGR7 mRNA expression levels between patients. LGR7 immunoreactive protein was identified in all stages of the menstrual cycle. LGR7 protein was localized in both the epithelial and the stromal compartments, except for the mid-luteal phase when the expression was restricted to the endometrial epithelium. We conclude that no consistent regulation of LGR7 mRNA expression can be detected in human endometrium during the menstrual cycle.

85. Co-expression of fractalkine and its receptor in human endometrium supports a role for fractalkine in leukocyte recruitment and endometrial remodelling

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Expression of the vascular endothelial growth factors B and C and their receptors in human endometrium during the menstrual cycle.

Endometrial angiogenesis is important for bleeding control and fertility, and is believed to be regulated by angiogenic growth factors under the influence of ovarian steroids. To document the pattern of expression of the two angiogenic growth factors, vascular endothelial growth factor (VEGF)-B and VEGF-C, and of their receptors, VEGFR-1, VEGFR-2, and VEGFR-3, in order to investigate their possible role in the regulation of angiogenesis in normal cycling human endometrium. Cryosections of endometrial biopsy specimens obtained from 17 healthy women before laparoscopic sterilization were examined by immunohistochemistry. Vascular endothelial growth factor and VEGF-C and their receptors were all expressed in and around endometrial blood vessels, with no obvious menstrual cycle-dependent changes in expression except for VEGFR-2, which showed stronger expression during the early secretary phase. Stromal blood vessel density did not change significantly during the menstrual cycle. The presence and pattern of expression of these angiogenic growth factors and their receptors suggest that they participate in the regulation of normal endometrial angiogenesis.

Expression of vascular endothelial growth factor (VEGF) and its receptors in human endometrium throughout the menstrual cycle and in early pregnancy.

Immunohistochemistry for vascular endothelial growth factor (VEGF) and its receptors, fms-like tyrosine kinase (flt-1) and kinase insert domain-containing region (KDR), was performed on human endometrium obtained from patients with normal menstrual cycles, patients given oestrogen and progesterone, and women in early pregnancy. Intense immunostaining of VEGF was observed in both glandular epithelial and stromal cells during the mid-secretory phase; the immunostaining intensity was increased by administration of oestrogen plus progesterone and strong immunostaining was observed in decidual cells of early pregnancy. In addition to the immunostaining in vascular endothelial cells, strong KDR immunostaining was observed in glandular epithelial cells and in decidualized stromal cells induced by administration of oestrogen plus progesterone, whereas flt-1 immunostaining was negligible. Strong immunostaining for flt-1 and KDR was found in both vascular endothelial cells and decidual cells in early pregnancy. Endometrial stromal cells isolated from proliferative phase endometrium were incubated with oestrogen (10(-8) mol l-1) and medroxyprogesterone acetate (MPA; 10(-6) mol l-1) for 18 days to study the regulation of VEGF, flt-1 and KDR in endometrial stromal cells by oestrogen and progesterone. Expression of VEGF and KDR mRNAs was increased significantly by oestrogen and MPA, accompanied by decidualization, whereas flt-1 mRNA expression was not affected. In conclusion, VEGF and its receptors may play important roles in implantation and maintenance of pregnancy.

Expression of vascular endothelial growth factor (VEGF) and its receptors in human endometrium throughout the menstrual cycle and in early pregnancy

Immunohistochemistry for vascular endothelial growth factor (VEGF) and its receptors, fms-like tyrosine kinase (flt-1) and kinase insert domain-containing region (KDR), was performed on human endometrium obtained from patients with normal menstrual cycles, patients given oestrogen and progesterone, and women in early pregnancy. Intense immunostaining of VEGF was observed in both glandular epithelial and stromal cells during the mid-secretory phase; the immunostaining intensity was increased by administration of oestrogen plus progesterone and strong immunostaining was observed in decidual cells of early pregnancy. In addition to the immunostaining in vascular endothelial cells, strong KDR immunostaining was observed in glandular epithelial cells and in decidualized stromal cells induced by administration of oestrogen plus progesterone, whereas flt-1 immunostaining was negligible. Strong immunostaining for flt-1 and KDR was found in both vascular endothelial cells and decidual cells in early pregnancy. Endometrial stromal cells isolated from proliferative phase endometrium were incubated with oestrogen (10(-8) mol l-1) and medroxyprogesterone acetate (MPA; 10(-6) mol l-1) for 18 days to study the regulation of VEGF, flt-1 and KDR in endometrial stromal cells by oestrogen and progesterone. Expression of VEGF and KDR mRNAs was increased significantly by oestrogen and MPA, accompanied by decidualization, whereas flt-1 mRNA expression was not affected. In conclusion, VEGF and its receptors may play important roles in implantation and maintenance of pregnancy.

Expression of Leptin Receptor in Human Endometrium and Fluctuation during the Menstrual Cycle

Expression of Leptin Receptor in Human Endometrium and Fluctuation during the Menstrual Cycle

Expression of leptin receptor in human endometrium and fluctuation during the menstrual cycle.

Leptin is secreted by adipocytes and regulates appetite through interaction with hypothalamic leptin receptors (OB-R). Accumulated evidence shows that leptin is involved in the stimulation of reproductive functions and that local expression of leptin and OB-R in the ovary, oocyte, embryo, and placenta plays a role in early development. To investigate the role of leptin in implantation, we examined the expression of OB-R and leptin in the human endometrium. Northern and Western blot analyses and RT-PCR showed that the long form of OB-R (OB-R(L)) messenger ribonucleic acid (mRNA) and protein were expressed. In contrast, leptin mRNA or protein was not detected. All of the splice variants of OB-R (OB-R(T)) and OB-R(L) transcripts were expressed in 90% and 84% of the cases, respectively. OB-R mRNA expression peaked in the early secretory phase. Decidual tissue of early gestation also expressed OB-R(T) and OB-R(L). Their incidence and abundance were comparable among endometria with benign uterine diseases and disease-free endometria and were not related to a body mass index within the normal range. The present results indicate that OB-R, but not leptin, is expressed in the human endometrium.

Re: The Expression of Granulocyte Macrophage‐Colony Stimulating Factor (GM‐SCF) and Receptors in Human Endometrium. Am J Reprod Immunol 1999; 42:303–311

Re: The Expression of Granulocyte Macrophage‐Colony Stimulating Factor (GM‐SCF) and Receptors in Human Endometrium. Am J Reprod Immunol 1999; 42:303–311

The expression of granulocyte macrophage-colony stimulating factor (GM-CSF) and receptors in human endometrium.

To determine the temporal and spatial expression of granulocyte macrophage-colony stimulating factor (GM-CSF) and GM-CSF alpha and beta receptor mRNA and protein in human endometrium. The endometrial expression of GM-CSF and GM-CSF receptor mRNA and protein was determined using competitive quantitative reverse transcription polymerase chain reaction (Q-RT-PCR), in situ hybridization, and immunohistochemistry. Endometrium expresses GM-CSF and GM-CSF alpha receptor mRNA with maximal expression occurring during the mid-secretory phase (21.1 +/- 4.2 and 32.2 +/- 7.7 x 10(6) mRNA copies/microg total RNA) compared to the proliferative phase (1.46 +/- 0.4 and 7.5 +/- 0.5 x 10(6) copies) of the menstrual cycle, with a significant reduction (0.67 +/- 0.1 and 1.7 +/- 0.2 x 10(6) mRNA copies) during the post-menopausal period (P < 0.05). The endometrium expresses a significantly lower level of GM-CSF beta receptor mRNA (approximately 0.01 x 10(5) mRNA copies). Endometrial luminal and glandular epithelial cells are the primary site of GM-CSF mRNA and protein expression, while arteriole endothelial, stromal, and inflammatory cells are the primary site of GM-CSF alpha receptor protein. GM-CSF beta receptor protein has a similar cellular distribution as GM-CSF. Temporal and spatial expression of GM-CSF and GM-CSF receptors in human endometrium during the menstrual cycle suggests that epithelial-derived GM-CSF in an autocrine/paracrine manner may influence various endometrial biological activities, local inflammatory response, and macrophage survival.

Prolactin and its receptor in human endometrium.

Synthesis of prolactin (PRL) in human endometrium extends from the late luteal phase of the menstrual cycle throughout the pregnancy. We have studied the hormonal requirements for the sustained production of PRL and its receptor (PRL-R) in a long-term primary cell culture system. Progestin stimulates the production PRL and its receptor when stromal cells transform into decidual cells. The rise in PRL production rate correlates with an increase in steady-state PRL mRNA levels which are caused by increased transcription rate gene. Replacing progestin by the antiprogestin, RU 486, causes a transient superinduction of PRL production followed by reduction to basal level of expression. On the other hand, RU 486 exerts immediate inhibition of PRL-receptor mRNA expression. In addition, relaxin (RLX) enhances PRL synthesis. The transcription of the PRL gene in endometrium is dependent upon the promotor 6-kb upstream of the transcription start site in the pituitary. That biological functions of PRL and its receptor are critical to implantation and the maintenance of pregnancy is suggested by the impaired fertility of PRL and PRL-R knockout mice. PRL enhances endometrial cell growth at low concentrations and inhibits it at high concentrations. This dual action indicates an autocrine action of PRL-R-mediated signaling transduction pathways during reproductive cycles and pregnancy. During gestation, decidual-derived prolactin regulates the volume of amniotic and fetal extracellular fluid and electrolytes.

Arylhydrocarbon receptor expression in the human endometrium

Objective: To determine the expression and localization of the arylhydrocarbon (dioxin) receptor in human endometrium throughout the normal menstrual cycle. Design: Retrospective immunohistochemical and in situ hybridization study. Setting: Academic research unit. Patient(s): Premenopausal women (n = 86), aged 25 to 45 years, with histologically normal endometrium undergoing curettage or hysterectomy. Intervention(s): Endometrial samples were collected from days 3 to 26 of the cycle by superficial scrapings of the uterine cavity or by hysterectomy. Main Outcome Measure(s): Expression of arylhydrocarbon receptor mRNA and protein. Result(s): Arylhydrocarbon receptor was expressed in 43% of the endometria studied and was correlated with the day of the cycle. The maximum of immunopositive endometria was found around the time of ovulation. Immunostaining decreased with increasing age of the patients. The receptor protein was localized exclusively in the apical part of the cytoplasm in the epithelial cells of the endometrial glands. In women positive for arylhydrocarbon receptor, arylhydrocarbon receptor mRNA was expressed in the cytoplasm of endometrial epithelial cells. Conclusion(s): Our results describe the expression of the arylhydrocarbon receptor in human endometrium and indicate a possible involvement of this transcription factor in endometrial function in women during the reproductive phase.