Adrenomedullin expression in rat uterus is correlated with plasma estradiol

Modulation of neural gene networks by estradiol in old rhesus macaque females

The postmenopausal decrease in circulating estradiol (E2) levels has been shown to contribute to several adverse physiological and psychiatric effects. To elucidate the molecular effects of E2 on the brain, we examined differential gene expression and DNA methylation (DNAm) patterns in the nonhuman primate brain following ovariectomy (Ov) and subsequent subcutaneous bioidentical E2 chronic treatment. We identified several dysregulated molecular networks, including MAPK signaling and dopaminergic synapse response, that are associated with ovariectomy and shared across two different brain areas, the occipital cortex (OC) and prefrontal cortex (PFC). The finding that hypomethylation (p = 1.6 × 10-51) and upregulation (p = 3.8 × 10-3) of UBE2M across both brain regions provide strong evidence for molecular differences in the brain induced by E2 depletion. Additionally, differential expression (p = 1.9 × 10-4; interaction p = 3.5 × 10-2) of LTBR in the PFC provides further support for the role E2 plays in the brain, by demonstrating that the regulation of some genes that are altered by ovariectomy may also be modulated by Ov followed by hormone replacement therapy (HRT). These results present real opportunities to understand the specific biological mechanisms that are altered with depleted E2. Given E2's potential role in cognitive decline and neuroinflammation, our findings could lead to the discovery of novel therapeutics to slow cognitive decline. Together, this work represents a major step toward understanding molecular changes in the brain that are caused by ovariectomy and how E2 treatment may revert or protect against the negative neuro-related consequences caused by a depletion in estrogen as women approach menopause.

Modulation of neural gene networks by estradiol in old rhesus macaque females

The postmenopausal decrease in circulating estradiol (E2) levels has been shown to contribute to several adverse physiological and psychiatric effects. To elucidate the molecular effects of E2 on the brain, we examined differential gene expression and DNA methylation (DNAm) patterns in the nonhuman primate brain following ovariectomy (Ov) and subsequent E2 treatment. We identified several dysregulated molecular networks, including MAPK signaling and dopaminergic synapse response, that are associated with ovariectomy and shared across two different brain areas, the occipital cortex (OC) and prefrontal cortex (PFC). The finding that hypomethylation (p=1.6×10-51) and upregulation (p=3.8×10-3) of UBE2M across both brain regions, provide strong evidence for molecular differences in the brain induced by E2 depletion. Additionally, differential expression (p=1.9×10-4; interaction p=3.5×10-2) of LTBR in the PFC, provides further support for the role E2 plays in the brain, by demonstrating that the regulation of some genes that are altered by ovariectomy may also be modulated by Ov followed by hormone replacement therapy (HRT). These results present real opportunities to understand the specific biological mechanisms that are altered with depleted E2. Given E2's potential role in cognitive decline and neuroinflammation, our findings could lead to the discovery of novel therapeutics to slow cognitive decline. Together, this work represents a major step towards understanding molecular changes in the brain that are caused by ovariectomy and how E2 treatment may revert or protect against the negative neuro-related consequences caused by a depletion in estrogen as women approach menopause.

Sex Differences in Age-Associated Type 2 Diabetes in Rats-Role of Estrogens and Oxidative Stress

Females live longer than males, and the estrogens are one of the reasons for this difference. We reported some years ago that estrogens are able to protect rats against oxidative stress, by inducing antioxidant genes. Type 2 diabetes is an age-associated disease in which oxidative stress is involved, and moreover, some studies show that the prevalence is higher in men than in women, and therefore there are sex-associated differences. Thus, the aim of this study was to evaluate the role of estrogens in protecting against oxidative stress in type 2 diabetic males and females. For this purpose, we used Goto-Kakizaki rats, which develop type 2 diabetes with age. We found that female diabetic rats showed lower glycaemia levels with age than did diabetic males and that estrogens enhanced insulin sensitivity in diabetic females. Moreover, glucose uptake, measured by positron emission tomography, was higher in the female brain, cerebellum, and heart than in those from male diabetic rats. There were also sex-associated differences in the plasma metabolic profile as determined by metabolomics. The metabolic profile was similar between estrogen-replaced and control diabetic rats and different from ovariectomized diabetic rats. Oxidative stress is involved in these differences. We showed that hepatic mitochondria from females produced less hydrogen peroxide levels and exhibited lower xanthine oxidase activity. We also found that hepatic mitochondrial glutathione oxidation and lipid oxidation levels were lower in diabetic females when compared with diabetic males. Ovariectomy induced oxidative stress, and estrogen replacement therapy prevented it. These findings provide evidence for estrogen beneficial effects in type 2 diabetes and should be considered when prescribing estrogen replacement therapy to menopausal women.

Effects of cisplatin on the auditory function of ovariectomized rats with estrogen deficiency

CONCLUSION

The ovariectomy in rats does not change their auditory function. However, combining ovariectomy with Cisplatin treatment increases the risk of damaging the auditory function relative to the ototoxic effect caused by Cisplatin alone or ovariectomy alone.

OBJECTIVES

The auditory benefit from estrogen depends on a number of factors that make findings among studies controversial. The present study was to examine the impact of Cisplatin, a chemotherapy drug, on the auditory function of ovariectomized rats.

METHODS

Thirty-two female rats were assigned to three groups (OVX + C, OVX - C, Sham + C). The rats in the OVX + C and OVX - C groups received bilateral ovariectomy, and those in the Sham + C group received a sham surgery with intact ovaries. After 6 weeks the rats in the OVX + C and Sham + C groups were then treated with Cisplatin for 4 days, but not those in the OVX - C group (control). The auditory function was measured with DPOAE SNRs and ABR thresholds before the surgery and after the Cisplatin treatment.

RESULTS

The OVX + C group had significantly decreased the DPOAE SNRs and increased the ABR thresholds relative to the Sham + C group at stimulus frequencies between 2-8 kHz, and the Sham + C group also had worse auditory function than the OVX - C group.

Equine endometrial gene expression changes during and after maternal recognition of pregnancy

The mechanism for maternal recognition of pregnancy (MRP) in horses is unknown. To maintain a pregnancy, a mobile conceptus must be recognized by the uterus before d 14 postovulation (PO). This recognition prevents endometrial secretion of PGF2α on d14 through 16, which would otherwise initiate luteolysis. The objective of this study was to evaluate gene expression in the endometrium of pregnant and nonpregnant mares during and after MRP to identify possible genes involved during this time. Twelve normally cycling mares were used in a crossover design and randomly assigned to a specific collection day. Endometrial samples were collected from a pregnant and nonpregnant (nonmated) mare on cycle d 12, 14, 16, and 18 (n = 3/d) PO. Microarray analysis comparing the endometrial gene expression in pregnant and nonpregnant mares revealed no differences at d 12. Ten genes were identified to have consistently higher or lower expression levels in the endometrium from pregnant versus nonpregnant mares on d 14, 16, and 18 (P < 0.001). The expression of these 10 genes was further analyzed with real-time PCR. d 14, 16, and 18 gene expression patterns were consistent with the microarray analysis, but on d 12, 4 of the 10 were identified as differentially expressed. Endometrial samples were then collected on d 13 PO (n = 3) and processed for western blot and immunohistochemical analysis of 2 proteins due to their reproductive significance. SPLA2 and DKK1 antibody specificity were confirmed via western blot analysis but were not different in samples from pregnant and nonpregnant mares (P = 0.114 and P = 0.514, respectively) and cellular localization was examined by immunohistochemical analysis. This is the first study to describe gene expression and cellular localization in the endometrium at the time of MRP for these genes and suggests that the uterus does not prepare to support a pregnancy until d 14. The function of these genes may be critical in the process of MRP.

The role of immunohistochemical adrenomedullin and Bcl-2 expression in development of type-1 endometrial adenocarcinoma: Adrenomedullin expression in endometrium

BACKGROUND

Adrenomedullin (AM) is a pluripotent peptide first discovered from human pheochromocytoma. AM expression has been shown in various cancer types including endometrium cancer. Bcl-2 is an antiapoptotic protein which might be regulated by AM in hypoxic conditions. The aim of the present study was to investigate the role of AM and Bcl-2 expressions in carcinogenesis of type-1 endometrium cancer.

MATERIALS AND METHOD

Study group consisted of 10 proliferative endometrium, 22 simple endometrial hyperplasia, 23 endometrial intraepithelial neoplasia (EIN) and 30 Grade 1 endometrioid adenocarcinoma patients. AM and Bcl-2 expressions were investigated by immunohistochemistry.

RESULTS

Mean AM Allred score was 3±2.6, 5.6±1.6 and 5.7±2.5 in benign, EIN and adenocarcinoma groups, respectively. AM expression was significantly higher in EIN and adenocarcinoma groups than in benign endometrium group (p<0.05). Mean Bcl-2 Allred score was 6.4±2.1, 5.2±2.6, 2.3±2 in benign endometrium, EIN and adenocarcinoma groups, respectively. Mean Bcl-2 Allred score was similar between benign endometrium and EIN groups (p>0.05). However, it was significantly lower in adenocarcinoma group (p<0.05). An inverse correlation between AM and Bcl-2 expressions was found (r: -0.4, p<0.001).

CONCLUSIONS

Our findings showed that AM expression increased in progression from benign endometrium to EIN and type-1 adenocarcinoma while expression of Bcl-2 decreased in transition from EIN to carcinoma.

Early, but not late onset estrogen replacement therapy prevents oxidative stress and metabolic alterations caused by ovariectomy

AIMS

The usefulness of estrogen replacement therapy (ERT) in preventing oxidative stress associated with menopause is controversial. We aimed to study if there is a critical time window for effective treatment of the effects of ovariectomy with estrogens at the molecular, metabolic, and cellular level.

RESULTS

Our main finding is that early, but not late onset of ERT prevents an ovariectomy-associated increase in mitochondrial hydrogen peroxide levels, oxidative damage to lipids and proteins, and a decrease in glutathione peroxidase and catalase activity in rats. This may be due to a change in the estrogen receptor (ER) expression profile: ovariectomy increases the ER α/β ratio and immediate estrogen replacement prevents it. Positron emission tomography analysis shows that ovariectomy decreases the brain glucose uptake in vivo and that estrogen administration is beneficial, but only if administered immediately after deprivation. Ovariectomy decreases GLUT-1 and 3 glucose transporters in the brain, and only early onset estrogen administration prevents it. Plasma from rats treated with estrogens immediately after ovariectomy show similar metabolomics profiles as controls.

INNOVATION

We provide molecular basis for the recommendation of early onset ERT and explain its lack of effectiveness if a significant time period elapses after ovariectomy and probably after the onset of menopause.

CONCLUSION

Only early, but not late onset administration of estrogens after ovariectomy has beneficial effects at molecular levels on oxidative stress, brain glucose uptake, and metabolomic profiles.

Effects of electro-acupuncture on ovarian P450arom, P450c17α and mRNA expression induced by letrozole in PCOS rats

Hyperandrogenism is a core factor in the series of reproductive and endocrine metabolic disorders involved in polycystic ovary syndrome (PCOS). Abnormalities in enzymatic activity and the expression of ovarian granular cell layer P450arom and theca cell P450c17α can lead to an atypical environment of local ovarian hormones, including excessive androgen levels. Rat models prepared with letrozole exhibit similar endocrine and histological changes to those that occur in human PCOS. We used such a model to study the role of electro-acupuncture (EA) in regulating ovarian P450arom and P450c17α enzymatic activity and mRNA expression in PCOS rats. Female Sprague Dawley (SD) rats aged 42 days were randomly divided into 3 groups (control, PCOS, and PCOS EA) consisting of 10 rats each. The PCOS and PCOS EA groups were administered a gavage of 1.0 mg/kg(-1) of letrozole solution once daily for 21 consecutive days. Beginning in the ninth week, the PCOS EA group was administered low-frequency EA treatment daily for 14 consecutive days. After the treatment, we obtained the following results. The estrous cycles were restored in 8 of the 10 rats in the PCOS EA group, and their ovarian morphologies and ultrastructures normalized. The peripheral blood measurements (with ELISA) showed significantly decreased androgens (i.e., androstenedione and testosterone) with significantly increased estrogens (i.e., estrone, estradiol) and increased P450arom with decreased P450C17α. Immunohistochemistry and Western blotting methods showed enhanced expression of ovarian granular cell layer P450arom as well as decreased expression of theca cell layer P450C17α. Fluorescence quantitative PCR methods showed enhanced expression of ovarian granular cell layer P450arom mRNA as well as decreased expression of theca cell layer P450C17α mRNA. These results may help explain the effects of electro-acupuncture in changing the local ovarian hyperandrogenic environment and improving reproductive and endocrine metabolic disorders in PCOS.

Intermedin in rat uterus: changes in gene expression and peptide levels across the estrous cycle and its effects on uterine contraction

BACKGROUND

The present study demonstrates the expression of intermedin (IMD) and its receptor components in the uterus of the female rat during the estrous cycle and its effect on uterine contraction.

METHODS

The gene expression level of intermedin and its receptor components and the peptide level of intermedin were studied by real-time RT-PCR and enzyme immunoassay (EIA) respectively. The separation of precursor and mature IMD was studied by gel filtration chromatography and EIA. The localization of IMD in the uterus was investigated by immunohistochemistry. The effect of IMD on in vitro uterine contraction was studied by organ bath technique.

RESULTS

Uterine mRNAs of Imd and its receptor components and IMD levels displayed cyclic changes across the estrous cycle. Imd mRNA level was the highest at proestrus while the IMD level was the highest at diestrus. IMD was found in the luminal and glandular epithelia and IMD treatment significantly reduced the amplitude and frequency of uterine contraction but not the basal tone. Both calcitonin gene-related peptide (CGRP) receptor antagonist hCGRP8-37 and adrenomedullin (ADM) receptor antagonist hADM22-52 partially abolished the inhibitory effect of IMD on uterine contraction while the specific IMD receptor antagonist hIMD17-47 completely blocked the actions. The enzyme inhibitors of NO (L-NAME) and PI3K (Wortmannin) pathways diminished the IMD effects on uterine contraction while the cAMP/PKA blocker, KT5720, had no effect, indicating an involvement of NO and PI3K/Akt but not PKA.

CONCLUSIONS

IMD and the gene expression of its receptor components are differentially regulated in the uterus during the estrous cycle and IMD inhibits uterine contraction by decreasing the amplitude and frequency.

Possible role of adrenomedullin in the pathogenesis of tubal ectopic pregnancy

CONTEXT

Tubal ectopic pregnancy (tEP) is currently the leading cause of pregnancy-related deaths during the first trimester. Our current knowledge on the molecular pathogenesis is limited.

OBJECTIVE

The objective of the study was to find out the possible role of adrenomedullin (ADM) in the pathogenesis of tEP.

DESIGN

This was an experimental in vitro study on oviductal tissue.

SETTING

The study was conducted at a university teaching hospital.

PATIENTS AND INTERVENTIONS

Patients included those having oviducts removed surgically during salpingectomy for tEP or hysterectomy for benign gynecological conditions. Oviductal tissues were incubated in hormonal condition mimicking early pregnancy before used for in vitro experiments.

MAIN OUTCOME MEASURES

Plasma ADM concentration, oviductal expression of ADM and its receptors, ciliary beat frequency, smooth muscle contraction were measured.

RESULTS

The ciliary beat frequency and frequency of muscle contraction were lower in the oviducts from patients with tEP than those from simulated normal pregnancy. The plasma and oviductal tissue ADM levels were also lower. The decreases in ciliary beat and frequency of contraction were restored to normal after ADM treatment.

CONCLUSIONS

The results suggest that the lower ADM level in the oviducts of tEP may lead to the decrease in ciliary beating and muscle contraction, with the result that the embryo is retained and implanted in the oviduct. Our findings explain for the first time the etiology of tubal pregnancy on the basis of an impairment of the transport of the fertilized ovum resulting from an ADM deficiency and raise the possibility of using the plasma ADM level as a predictor for tubal ectopic pregnancy.

Adrenomedullin interacts with VEGF in endometrial cancer and has varied modulation in tumours of different grades

OBJECTIVE

Endometrial cancer, in developed countries, is the most common malignancy of the female genital tract. Surgery and radiotherapy are successful in many patients but systemic and recurrent diseases have no consistently effective treatments, and for high grade advanced disease the prognosis is poor. The study investigated characteristics of adrenomedullin in endometrial cancer to assist in identifying targets for developing treatments.

METHODS

Endometrial samples of women with and without cancer, and the Ishikawa cell line were used to investigate adrenomedullin mRNA regulation, peptide expression, adrenomedullin secretion and effects of adrenomedullin on VEGF secretion.

RESULTS

Expression of adrenomedullin mRNA was upregulated compared to that in healthy post-menopausal endometria. Adrenomedullin secretion was increased by cobalt chloride in this study. Secretion was reduced by the naturally-occurring compounds, (-)-epigallocatechin gallate (EGCG) and 3,4',5-trihydroxystilbene (resveratrol), which we have previously demonstrated to also suppress VEGF secretion in endometrial tumour tissue. We noted, for the first time, that adrenomedullin enhanced VEGF secretion from tumour cells.

CONCLUSIONS

Increased adrenomedullin expression may result in amplifying both tumorigenic and angiogenic activities. A substantial impact on growth of tumours may result in vivo as a consequence of the synergism between adrenomedullin and VEGF. Adrenomedullin, which has altered cellular characteristics in tumour compared to healthy tissue, offers an understudied target with potential to modify endometrial cancer behaviour, complementing other treatments.

Adrenomedullin Function in Vascular Endothelial Cells: Insights from Genetic Mouse Models

Adrenomedullin is a highly conserved peptide implicated in a variety of physiological processes ranging from pregnancy and embryonic development to tumor progression. This review highlights past and present studies that have contributed to our current appreciation of the important roles adrenomedullin plays in both normal and disease conditions. We provide a particular emphasis on the functions of adrenomedullin in vascular endothelial cells and how experimental approaches in genetic mouse models have helped to drive the field forward.

The expression and regulation of adrenomedullin in the human endometrium: a candidate for endometrial repair

After menstruation, the endometrium has a remarkable capacity for repair, but the factors involved remain undefined. We hypothesize adrenomedullin (AM) plays a role in this process. Premenstrually progesterone levels decline, stimulating prostaglandin (PG) synthesis, vasoconstriction, and hypoxia. This study aimed to determine 1) AM expression throughout the menstrual (M) cycle and 2) its regulation by PG and hypoxia. Human endometrial biopsies (n = 51) were collected with ethical approval and consent. AM mRNA expression was examined by quantitative RT-PCR and was found to be selectively elevated in endometrium from the menstrual (M) phase (P < 0.001). AM immunohistochemical staining was maximal in M and proliferative (P) endometrium. Culture of secretory, but not P, explants with 100 nm PGF(2α) or hypoxia (0.5% O2) increased AM mRNA (P < 0.05). P explants were induced to increase AM expression using in vitro progesterone withdrawal but required the presence of hypoxia (P < 0.05). Short hairpin sequences against hypoxia-inducible factor-1α (HIF-1α) inhibited AM hypoxic up-regulation but did not alter PGF(2α)-induced expression. The AM receptor was immunolocalized to endothelial cells in both lymphatic and blood vessels. Conditioned medium from PGF(2α)-treated cells increased endothelial cell proliferation and branching (P < 0.05). This was abolished by AM receptor antagonists. In conclusion, AM is elevated at the time of endometrial repair and induces both angiogenesis and lymphangiogenesis by stimulating endothelial cell proliferation and tube formation. In the human endometrium, AM expression is up-regulated by two mechanisms: a HIF-1α-mediated hypoxic induction and a HIF-1α-independent PGF(2α) pathway. These physiological mechanisms may provide novel therapeutic targets for disorders such as heavy menstrual bleeding.

Coexpression of adrenomedullin and its receptor component proteins in the reproductive system of the rat during gestation

BACKGROUND

Adrenomedullin (ADM), a novel vasorelaxant peptide, was found in human/rat ovaries and uteri. Plasma ADM level increases in pregnant women and pregnant rats.

METHODS

The gene expression levels of Adm and its receptor components - Crlr, Ramp1, Ramp2 and Ramp3, the ADM peptide concentration and localization in the rat female reproductive system during gestation were studied by real-time RT-PCR, EIA and immunohistochemical techniques.

RESULTS

The mRNAs of Adm and its receptor component and ADM were differentially distributed between implantation sites and inter-implantation sites of the pregnant uterus. The day on which vaginal sperm were found was taken to be pregnancy day 1. The Adm mRNA levels in the implantation sites of the uteri in mid- (day 12) and late pregnancy (day 17) were more than 10-fold higher than those in nonpregnancy, pre-implantation (day 3) or early (day 7) pregnancy. ADM was localized in the endometrial stroma with increased immunoreactivity from nonpregnancy to pregnancy. The ADM level and the mRNA levels of Adm, Crlr, Ramp2 and Ramp3 in the corpus luteum all increased in late pregnancy compared with early pregnancy. The gene expression of Adm and it receptor components and intense immunostaining of ADM were also found in the oviduct during pregnancy.

CONCLUSIONS

The gene expressions levels of Adm and its receptor components - Crlr, Ramp1, Ramp2 and Ramp3, and ADM peptide concentration exhibited a spatio-temporal pattern in the rat female reproductive system during gestation and this suggests that ADM may play important roles in gestation.

Expression of adrenomedullin in human oviduct, its regulation by the hormonal cycle and contact with spermatozoa, and its effect on ciliary beat frequency of the oviductal epithelium

CONTEXT

Adrenomedullin (ADM) has been found expressed in the mouse oviduct and might play a role in reproduction.

OBJECTIVE

The objective of the study was to demonstrate the expression of ADM in the human oviduct, investigate its regulation by steroidal hormones and spermatozoa contact, and study its effect on ciliary beat frequency (CBF) in the human oviduct. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS: Oviducts from women undergoing hysterectomy for benign diseases in a university hospital were collected. The oviducts were treated with estradiol and/or progesterone to simulate different phases of the ovarian cycle. ADM expression was studied at the peptide and mRNA levels by immunohistochemistry and RT-PCR, respectively. CBF was measured after treatment with graded concentrations of ADM and its antagonists. Cells from OE-E6/E7, an immortalized oviductal cell line, as well as oviductal tissue were cocultured with and without direct contact with capacitated human spermatozoa to compare oviductal cell ADM expression levels. CBF was also analyzed in oviductal tissue after spermatozoa-oviduct coincubation.

RESULTS

ADM expression was the highest in the isthmic region and in a hormonal environment simulating the early luteal phase. CBF was increased by ADM in a dose-dependent manner, which was blocked by ADM and calcitonin-gene-related peptide receptor antagonists. Direct contact with spermatozoa in coculture resulted in higher ADM expression in OE-E6/E7 cell line and oviductal tissue and higher CBF in oviductal epithelium.

CONCLUSIONS

ADM expression in the human oviduct is hormone dependent and is up-regulated by sperm contact. ADM stimulates ciliary motility of the human oviduct.

Measurement of sex steroids in murine blood and reproductive tissues by liquid chromatography-tandem mass spectrometry

Accurate measurement of sex steroids is essential to evaluate mouse models for human reproductive development and disorders. The recent advent of liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays that match the sensitivity of steroid immunoassay could overcome problems arising from the limited specificity of steroid immunoassay. In this current study we validate a LC-MS/MS assay for the measurement of key sex steroids from murine serum and reproductive tissues. The assay gave excellent dilutional linearity (r(2)> or =0.98) and reproducibility (CV< or =10% of replicate samples) in serum and reproductive tissues with sensitive quantitation limits; testosterone (T; 2pg), dihydrotestosterone (DHT; 10pg), 5alpha-androstane-3alpha,17beta-diol (3alphaDiol; 40pg), 5alpha-androstane-3beta,17beta-diol (3betaDiol; 40pg), estradiol (E2; 0.5pg) and estrone (E1; 0.3pg). Using 0.1mL sample, T was the only consistently detectable steroid (detection limit 20pg/ml) in both male and female mouse serum. In the testis, T and DHT were quantifiable as were both diols at relatively high levels. Prostatic T levels were low and DHT was determined to be the most abundant androgen in this tissue. Uterine and ovarian levels of E2, E1 and T were measurable, with levels varying according to estrous cycle stage. Hence, we demonstrate that this LC-MS/MS method has the sensitivity, specificity and multi-analyte capability to offer accurate steroid profiling in mouse serum and reproductive tissues.

Inhibition of oxygen-induced hypoxia-inducible factor-1alpha degradation unmasks estradiol induction of vascular endothelial growth factor expression in ECC-1 cancer cells in vitro

Estradiol (E(2)) rapidly and strongly induces vascular endothelial growth factor (VEGF) transcription in uterine endometrial epithelial cells in vivo. We have shown that this is mediated by both the estrogen receptor-alpha and hypoxia-inducible factor (HIF)-1alpha. By contrast, E(2) induces little or no VEGF expression in cultured breast or endometrial cancer cells, which lack HIF-1alpha due to the abnormally high concentration of oxygen ( approximately 20%) to which they are exposed. To test the hypothesis that restoring HIF-1alpha in cultured cells would restore the ability of E(2) to induce VEGF expression, we treated human endometrial cancer cells (ECC-1) with cobalt chloride (CoCl(2);100 microm), which prevents oxygen-induced HIF-1alpha degradation. HIF-1alpha was absent in untreated ECC-1 cells but detectable by 4 h after treatment with CoCl(2) alone, as was a significant increase in VEGF mRNA. E(2) plus CoCl(2) induced detectable HIF-1alpha expression at 2 h and an even higher level than that induced by CoCl(2) alone at 4 h; this HIF-1alpha was localized in the nuclei. This was accompanied by increasing VEGF expression, with the increase at 4 h severalfold higher than that induced by CoCl(2) alone and was concurrent with recruitment of both HIF-1alpha and estrogen receptor-alpha to the VEGF promoter. These results confirm that HIF-1alpha plays an essential role in E(2)-induced expression of VEGF. Through the induction of increased microvascular permeability and the consequent exudation of plasma growth factors, VEGF in turn may play an essential role in cancer cell proliferation in vivo.

Haploinsufficiency for adrenomedullin reduces pinopodes and diminishes uterine receptivity in mice

Adrenomedullin (AM) is a multifunctional peptide vasodilator that signals through a G-protein-coupled receptor when the receptor, called calcitonin receptor-like receptor (CL), is associated with a receptor activity-modifying protein 2 (RAMP2). We demonstrated previously that haploinsufficieny for each of these genes led to reduced maternal fertility, and that even a modest genetic reduction of AM peptide caused maternal defects in implantation, placentation, and fetal growth. Here, we further demonstrate that Adm(+/-) female mice displayed reduced pregnancy success rates that were not caused by defects in folliculogenesis, ovulation, or fertilization. The poor fertility of Adm(+/-) female mice could not be rescued by transfer of wild-type blastocysts, which suggested an underlying defect in uterine receptivity. In fact, we found that Adm, Calcrl, and Ramp2 gene expressions are tightly and spatiotemporally regulated in the luminal epithelial cells of the uterus during the estrus cycle and the peri-implantation period. RAMP3, which also generates an AM receptor when associated with CL, had a diametrically opposite expression pattern than that of Adm, Calcrl, and Ramp2 and was most robustly induced in the stroma of the uterus. Finally, we discovered that Adm(+/-) female mice have a substantially reduced number of pinopodes on the uterine luminal epithelial surface, which is indicative and possibly causative of the poor uterine receptivity. Taken together, our studies identify a new class of pharmacologically tractable proteins that are involved in establishing uterine receptivity through the regulation of pinopode formation.

Ventilation and phrenic output following high cervical spinal hemisection in male vs. female rats

Female sex hormones influence the neural control of breathing and may impact neurologic recovery from spinal cord injury. We hypothesized that respiratory recovery after C2 spinal hemisection (C2HS) differs between males and females and is blunted by prior ovariectomy (OVX) in females. Inspiratory tidal volume (VT), frequency (fR), and ventilation (VE) were quantified during quiet breathing (baseline) and 7% CO2 challenge before and after C2HS in unanesthetized adult rats via plethysmography. Baseline breathing was similarly altered in all rats (reduced VT, elevated fR) but during hypercapnia females had relatively higher VT (i.e. compared to pre-injury) than male or OVX rats (p<0.05). Phrenic neurograms recorded in anesthetized rats indicated that normalized burst amplitude recorded ipsilateral to C2HS (i.e. the crossed phrenic phenomenon) is greater in females during respiratory challenge (p<0.05 vs. male and OVX). We conclude that sex differences in recovery of VT and phrenic output are present at 2 weeks post-C2HS. These differences are consistent with the hypothesis that ovarian sex hormones influence respiratory recovery after cervical spinal cord injury.

The level of adrenomedullin immunoreactivity in seminal fluid is higher in oligozoospermic subjects and correlates with semen biochemical parameters

OBJECTIVE

The newly discovered vasoactive peptide, adrenomedullin, and its receptors are widely distributed in various non-vascular tissues. Recent studies have suggested the possible regulatory role of adrenomedullin (AM) at several levels of the pituitary-gonadal axis. We determined the level of adrenomedullin-like immunoreactivity in the seminal fluid and examined its possible correlation with routine semen parameters, semen biochemical levels or plasma levels of FSH, LH, testosterone or prolactin.

MATERIALS AND METHODS

A total of 51 males were divided into three groups according to semen analysis: (i) normospermic (n=19); (ii) oligozoospermic (n=17); (iii) azoospermic (n=15). All the subjects were submitted to hormone analysis (LH, FSH, testosterone, prolactin), routine semen parameters and semen biochemical levels (fructosio, citric acid, L-carnitine, nitric oxide) evaluation. AM was determined in plasma and seminal fluid using a specific radioimmunoassay.

RESULTS

Mean AM concentration in seminal plasma was higher in oligozoospermic subjects than in normospermic males. In patients with non-obstructive azoospermia AM in semen was significantly lower than in patients with obstructive azoospermia. Semen AM levels correlated negatively with citric acid concentrations in oligozoospermic subjects. In patients with obstructive azoospermia AM in seminal fluid was correlated with citric acid levels. There was a relationship between plasma AM and prolactin.

CONCLUSIONS

We conclude that in human seminal fluid AM concentration is increased in infertile oligozoospermic patients and derives very likely from the prostate. Its role in the regulation of male fertility, however has to be understood.

Increased adrenomedullin protein content and mRNA expression in human fetal membranes but not placental tissue in pre-eclampsia

The relationship between Pre-eclampsia (PE) and placental production of Adrenomedullin (AdM) is not completely understood. This study measured placental and fetal membrane AdM protein concentrations by specific radioimmunoassay and mRNA expression by Northern blot analysis in samples obtained at either term or preterm gestation from women either in labour or not in labour. Samples were obtained from women with normotensive and pre-eclamptic pregnancies. There were significant increases in immunoreactive AdM protein concentration (pg/mg DNA) in choriodecidua and amnion of women with PE compared to normal pregnancy for the preterm not-in-labour group (choriodecidua: control 124 +/- 16, n = 10, PE 361 +/- 35, n = 10; amnion: control 94 +/- 12, n = 10, PE 153 +/- 19, n = 10) and for the term not-in-labour (choriodecidua: control 128 +/- 17, n = 14, PE 459 +/- 51, n = 8; amnion: control 112 +/- 15, n = 14, PE 253 +/- 57, n = 8) and in-labour (choriodecidua: control 531 +/- 74, n = 14, PE 881 +/- 188, n = 8; amnion: control 545 +/- 84, n = 14, PE 1008 +/- 230, n = 8) groups. AdM mRNA relative abundance was greater in preterm, not-in-labour choriodecidual samples in PE, but not in amnion. In addition, this study observed labour-associated increases in choriodecidual and amniotic irAdM in term pre-eclamptic and control patients. However, there were no significant changes in AdM protein or mRNA expressions between any of the groups for placental tissue. These results suggest that fetal membranes, but not placental, production of AdM is increased at the post-translational level during PE in preterm and term tissues and at the pre-translational level during PE in preterm tissues. Fetal membranes, AdM may play an important role in the regulation of feto-placental hemodynamics and fetal physiology during pre-eclampsia.

New insight into the transcriptional regulation of vascular endothelial growth factor expression in the endometrium by estrogen and relaxin

Increased uterine capillary permeability, which can be induced by both estrogen and relaxin, is required for endometrial growth and implantation. This effect is mediated in both cases by estrogen receptors (ERs), via stimulation of vascular endothelial growth factor (VEGF) expression. The sites on the VEGF promoter through which induction occurs, however, are completely unclear. We have used the technique of chromatin immunoprecipitation in vivo to localize the site of ER action and identify other transcription factors that are involved. We have found that ERa associates with Sp1/Sp3 at a GC-rich region of the promoter. More interesting, however, is the observation that estrogen also induces rapid, transient binding of hypoxia-inducible factor 1 (HIF-1), which mediates VEGF transcription in response to hypoxia, to the promoter. The estrogen-induced HIF-1 binding closely matches the estrogen-induced pattern of VEGF expression in the uterus, suggesting that HIF-1 is involved in that induction, and probably that of many other genes as well (HIF-1 is now known to regulate the expression of more than 40 genes). It is likely that studies now under way will also link relaxin-induced VEGF expression to HIF-1. This is based on the similarities in the effects of the two hormones on VEGF expression and on their shared ability to activate the PI3K and MAPK pathways, both of which can activate HIF-1.

Changes in the distribution of ZO-1, occludin, and claudins in the rat uterine epithelium during the estrous cycle

During the estrous cycle, the endometrium epithelium experiences marked cellular structural changes. For fertilization to proceed, maintenance of an adequate uterine environment by ovarian hormones is essential. Epithelial cells lining the uterine lumen are associated with each other by tight junctions (TJs), which regulate the passage of ions and molecules through the paracellular pathway. The aim of the present study was to assess by confocal immunofluorescence the distribution pattern of the TJ proteins ZO-1, occludin, and claudins 1-7 in the rat uterus during the estrous cycle. Our results reveal that on proestrus, the day when mating takes place, ZO-1, occludin, and claudins 1 and 5 are located in the TJs, while claudins 3 and 7 display a basolateral distribution. In contrast, on metestrus day, when no sexual mating occurs and the uterine lumen is devoid of secretions, none of these proteins were detected in the TJ region, and only a diffuse cytosolic staining was observed for some of the proteins. On estrus and diestrus days, an intermediate situation was encountered, since ZO-1 localized in the TJs, whereas occludin was no longer detectable in the TJs. The distribution of claudins during these stages varied from the lowermost portion of the basolateral membrane to its apex. In conclusion, the results show that the protein composition of TJs present in the luminal epithelial cells of the uterus changes during the different days of the estrous cycle, and suggest that the expression of TJ proteins participates in providing an adequate environment for a successful fertilization.

Estrogen and phytoestrogen regulate the mRNA expression of adrenomedullin and adrenomedullin receptor components in the rat uterus

The serum estrogen surge in the uterus triggers precisely-timed physiological and biochemical responses required establishing and maintaining pregnancy. Previous reports have shown that consumption of phytoestrogen-containing plants may disrupt the precise control of pregnancy. To evaluate the effects of phytoestrogens in the uterus, we screened for estradiol (E2)-inducible genes in immature rat uteri. We identified the gene for receptor-activity-modifying protein 2 (Ramp2), known to be a component of the adrenomedullin (ADM) receptor, as responsive to both E2 and the phytoestrogen coumestrol (Cou). We further examined the expression of ADM and ADM signaling components Ramp2, Ramp3, and CRLR in the immature rat uterus and found that both E2 and Cou regulated these genes expression. In addition, treatment with ADM increased uterine weight and edema similar to that observed after Cou treatment. Our findings indicated that the phytoestrogen caused the abnormal induction of vasoactive factors in the uterus.

Angiogenic role of adrenomedullin through activation of Akt, mitogen-activated protein kinase, and focal adhesion kinase in endothelial cells

Adrenomedullin (AM) is a multifunctional peptide in human pheochromocytoma. To evaluate whether AM could be an angiogenic factor, we examined its effect on kinases and angiogenic processes. AM induced tyrosine phosphorylation of Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase1/2 (ERK1/2) by using distinct signaling pathways in human umbilical vein endothelial cells (HUVECs). AM also phosphorylated focal adhesion kinase, and phosphatidylinositol 3'-kinase inhibitor inhibited AM-induced focal adhesion kinase phosphorylation. Pretreatment with high concentrations of AM22-52, a putative AM receptor antagonist, partially suppressed AM-induced phosphorylation of Akt, ERK1/2, and focal adhesion kinase. AM and vascular endothelial growth factor produced increases in DNA synthesis and migration in HUVECs. AM induced tube formation in HUVECs, and its effect was inhibited by pretreatment with phosphatidylinositol 3'-kinase inhibitor or ERK1/2 inhibitor. AM induced sprouting in porcine pulmonary arterial endothelial cells and promoted neovessel formation in a mouse Matrigel plug assay. Inhibitors of phosphatidylinositol 3'-kinase and ERK1/2 inhibited AM-induced endothelial sprouting in vitro and angiogenesis in vivo. AM exerts angiogenic activity through activation of Akt, MAPK, and focal adhesion kinase in endothelial cells.

Distribution of adrenomedullin and proadrenomedullin N-terminal 20 peptide immunoreactivity in the pituitary gland of the frog Rana perezi

Adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) are two multifunctional peptides processed from a common precursor which have been described in numerous mammalian organs, including the pituitary gland. Previous studies have found AM immunoreactivity in neurohypophysis nerve fibers of amphibian pituitary. In the present study, immunocytochemical and Western blot analysis in the pituitary gland of the amphibian Rana perezi demonstrated in the adenohypophysis both AM and PAMP. AM-like immunoreactivity was found in a moderate number of endocrine cells of the pars distalis. In the neurohypophysis, AM was observed not only in nerve fibers of pars nervosa and axonal projections innervating the pars intermedia, but also in the outer zone of the median eminence. PAMP staining was observed in numerous endocrine cells scattered all over the pars distalis and in some cells of the pars tuberalis, but not in the neurohypophysis. In order to compare the quantity of AM and PAMP immunoreactivity between pars distalis of female and male specimens, an image analysis study was done. Significant differences for AM immunoreactivity (p<0.001) between sexes was found, the males showing higher immunostained area percentage. Differences of PAMP immunoreactivity were not significant (p=0.599). Western blot analysis detected bands presumably corresponding to precursor and/or intermediate species in the propeptide processing.

Adrenomedullin in perinatal medicine

This review will consider whether adrenomedullin (AM) plays a role in the different aspects of perinatal medicine: contributing to maternal systemic vasodilatation during pregnancy, regulating uterine and placental blood flow, being involved in the process of implantation and participating in uterine quiescence prior to parturition. In addition, this will also consider whether a modification of AM secretion contributes to some pathological conditions in pregnancy such as preeclampsia and impairment of fetal growth. The biosynthesis of AM increases in gravid rats and in pregnant women, and the placenta represents an important site of AM production during pregnancy. Both the peptide and its receptors have been found in the uterus, placenta, fetal membranes and cord vessels, and fetal membranes and placental tissues in culture secrete AM. AM contributes to maternal systemic vasodilatation, the placental vessels are relaxed by AM in a dose-dependent manner and AM is expressed in the fetoplacental and umbilical vascular endothelium where basal production of AM contributes to low fetoplacental vascular resistances. Controversy exists over the status of circulating and placental AM in preeclampsia and of the relative contribution of AM to impaired fetoplacental circulation and fetal growth. Moreover, the uterus expresses AM mRNA and exogenous AM relaxes the myometrium in a dose-dependent manner; however, clinical studies have shown that AM does not decrease before the onset of parturition. Rather, AM secretion increases during spontaneous labor and in preterm delivery.

c-fos and estrogen receptor gene expression pattern in the rat uterine epithelium during the estrous cycle

Different studies in ovariectomized estrogen treated animals support the idea that c-fos plays a role in the proliferation of uterine epithelial cells. However, these studies invite us to reassess the role played by c-fos in epithelial cell types of the endometrium during the estrous cycle. The present study was undertaken to determine the c-fos and estrogen receptor (ER) gene expression pattern in the rat uterine epithelium during the estrous cycle in which natural and cyclic changes of steroid hormones occur, and correlate these changes with the proliferation status of this cellular types. Proliferation was assessed during the estrous cycle using bromodeoxyuridine incorporation to DNA. ERalpha and beta proteins were assessed by immunohistochemistry. The regulation of c-fos gene expression in the uterus of intact animals during the estrous cycle was evaluated using both in situ hybridization and immunohistochemistry. Estradiol (E(2)) and progesterone (P(4)) plasma levels were assessed by radioimmunoassay. The results indicated that luminal (LE) and glandular epithelia (GE) presented maximal proliferation during the metestrus (M) and the diestrus (D) days. However, during the proestrus (P) day only LE presented proliferation, and during the estrus (E) day only the stromal cells proliferated. A marked immunostaining for ERalpha was detected in both LE and GE cells during the early phases of the cycle but diminished on the P and the E day. In contrast, ERbeta was undetectable in both epithelia during all stages of the cycle. The highest c-fos mRNA level was detected in both epithelia on the M day, followed by a significant reduction during the other days of the cycle. The highest protein content was observed on the M and D days, and the minimal value was detected on the E day. The c-Fos protein level in LE was increased during M and D days, presenting a high correlation with the cellular proliferation pattern of this cell type. In conclusion, the overall results indicate that c-Fos protein presented a good correlation with uterine epithelial cell proliferation of LE. In the case of GE, the same tendency was observed, although no significant correlation was found. Both in LE and GE, c-fos mRNA did not strictly correlate with its protein levels. c-fos seems to have a postranscriptional regulation in uterine epithelial cells during the rat's estrous cycle.

Mitochondria from females exhibit higher antioxidant gene expression and lower oxidative damage than males

We have investigated the differential mitochondrial oxidative stress between males and females to understand the molecular mechanisms enabling females to live longer than males. Mitochondria are a major source of free radicals in cells. Those from female rats generate half the amount of peroxides than those of males. This does not occur in ovariectomized animals. Estrogen replacement therapy prevents the effect of ovariectomy. Mitochondria from females have higher levels of reduced glutathione than those from males. Those from ovariectomized rats have similar levels to males, and estrogen therapy prevents the fall in glutathione levels that occurs in ovariectomized animals. Oxidative damage to mitochondrial DNA in males is 4-fold higher than that in females. This is due to higher expression and activities of Mn-superoxide dismutase and of glutathione peroxidase in females, which behave as double transgenics overexpressing superoxide dismutase and glutathione peroxidase, conferring protection against free-radical-mediated damage in aging. Moreover, 16S rRNA expression, which decreases significantly with aging, is four times higher in mitochondria from females than in those from males of the same chronological age. The facts reported here provide molecular evidence to explain the different life span in males and females.