A role for steroid 5 alpha-reductase 1 in vascular remodeling during endometrial decidualization

Decidualization is the hormone-dependent process of endometrial remodeling that is essential for fertility and reproductive health. It is characterized by dynamic changes in the endometrial stromal compartment including differentiation of fibroblasts, immune cell trafficking and vascular remodeling. Deficits in decidualization are implicated in disorders of pregnancy such as implantation failure, intra-uterine growth restriction, and pre-eclampsia. Androgens are key regulators of decidualization that promote optimal differentiation of stromal fibroblasts and activation of downstream signaling pathways required for endometrial remodeling. We have shown that androgen biosynthesis, via 5α-reductase-dependent production of dihydrotestosterone, is required for optimal decidualization of human stromal fibroblasts in vitro, but whether this is required for decidualization in vivo has not been tested. In the current study we used steroid 5α-reductase type 1 (SRD5A1) deficient mice (Srd5a1-/- mice) and a validated model of induced decidualization to investigate the role of SRD5A1 and intracrine androgen signaling in endometrial decidualization. We measured decidualization response (weight/proportion), transcriptomic changes, and morphological and functional parameters of vascular development. These investigations revealed a striking effect of 5α-reductase deficiency on the decidualization response. Furthermore, vessel permeability and transcriptional regulation of angiogenesis signaling pathways, particularly those that involved vascular endothelial growth factor (VEGF), were disrupted in the absence of 5α-reductase. In Srd5a1-/- mice, injection of dihydrotestosterone co-incident with decidualization restored decidualization responses, vessel permeability, and expression of angiogenesis genes to wild type levels. Androgen availability declines with age which may contribute to age-related risk of pregnancy disorders. These findings show that intracrine androgen signaling is required for optimal decidualization in vivo and confirm a major role for androgens in the development of the vasculature during decidualization through regulation of the VEGF pathway. These findings highlight new opportunities for improving age-related deficits in fertility and pregnancy health by targeting androgen-dependent signaling in the endometrium.

Preclinical models of endometriosis and interstitial cystitis/bladder pain syndrome: an Innovative Medicines Initiative-PainCare initiative to improve their value for translational research in pelvic pain

ABSTRACT

Endometriosis (ENDO) and interstitial cystitis/bladder pain syndrome (IC/BPS) are chronic pain conditions for which better treatments are urgently needed. Development of new therapies with proven clinical benefit has been slow. We have conducted a review of existing preclinical in vivo models for ENDO and IC/BPS in rodents, discussed to what extent they replicate the phenotype and pain experience of patients, as well as their relevance for translational research. In 1009 publications detailing ENDO models, 41% used autologous, 26% syngeneic, 18% xenograft, and 11% allogeneic tissue in transplantation models. Intraperitoneal injection of endometrial tissue was the subcategory with the highest construct validity score for translational research. From 1055 IC/BPS publications, most interventions were bladder centric (85%), followed by complex mechanisms (8%) and stress-induced models (7%). Within these categories, the most frequently used models were instillation of irritants (92%), autoimmune (43%), and water avoidance stress (39%), respectively. Notably, although pelvic pain is a hallmark of both conditions and a key endpoint for development of novel therapies, only a small proportion of the studies (models of ENDO: 0.5%-12% and models of IC/BPS: 20%-44%) examined endpoints associated with pain. Moreover, only 2% and 3% of publications using models of ENDO and IC/BPS investigated nonevoked pain endpoints. This analysis highlights the wide variety of models used, limiting reproducibility and translation of results. We recommend refining models so that they better reflect clinical reality, sharing protocols, and using standardized endpoints to improve reproducibility. We are addressing this in our project Innovative Medicines Initiative-PainCare/Translational Research in Pelvic Pain.

Immune cell and transcriptomic analysis of the human decidua in term and preterm parturition

STUDY QUESTION

Is labour, both at term and preterm, associated with alterations in decidual lymphocyte densities and widespread changes to the decidual transcriptome?

SUMMARY ANSWER

The onset of parturition, both at term and preterm, is associated with widespread gene expression changes in the decidua, many of which are related to inflammatory signalling, but is not associated with changes in the number of any of the decidual lymphocyte populations examined.

WHAT IS KNOWN ALREADY

Given its location, directly at the maternal–foetal interface, the decidua is likely to play a pivotal role in the onset of parturition, however, the molecular events occurring in the decidua in association with the onset of labour, both at term and preterm, remain relatively poorly defined. Using flow cytometry and microarray analysis, the present study aimed to investigate changes to the immune cell milieu of the decidua in association with the onset of parturition and define the decidual gene signature associated with term and preterm labour (PTL).

STUDY DESIGN, SIZE, DURATION

This study used decidual samples collected from 36 women across four clinical groups: term (38–42 weeks of gestation) not in labour, TNL; term in labour, TL; preterm (<35 weeks of gestation)not in labour, PTNL; and preterm in labour, PTL.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Decidual lymphocytes were isolated from fresh decidual tissue collected from women in each of our four patient groups and stained with a panel of antibodies (CD45, CD3, CD19, CD56, CD4, CD8 and TCRVα24-Jα18) to investigate lymphocyte populations present in the decidua (TNL, n = 8; TL, n = 7; PTNL, n = 5; PTL, n = 5). RNA was extracted from decidual tissue and subjected to Illumina HT-12v4.0 BeadChip expression microarrays (TNL, n = 11; TL, n = 8; PTNL, n = 7; PTL, n = 10). Quantitative real-time PCR (qRT-PCR) was used to validate the microarray results.

MAIN RESULTS AND THE ROLE OF CHANCE

The relative proportions of decidual lymphocytes (T cells, NK cells, B cells and invariant natural killer (iNKT) cells) were unaffected by either gestation or labour status. However, we found elevated expression of the non-classical MHC-protein, CD1D, in PTL decidua samples (P < 0.05), suggesting the potential for increased activation of decidual invariant NKT (iNKT) cells in PTL. Both term and PTL were associated with widespread gene expression changes, particularly related to inflammatory signalling. Up-regulation of candidate genes in TL (IL-6, PTGS2, ATF3, IER3 and TNFAIP3) and PTL (CXCL8, MARCO, LILRA3 and PLAU) were confirmed by qRT-PCR analysis.

LARGE SCALE DATA

Microarray data are available at www.ebi.ac.uk/arrayexpress under accession number E-MTAB-5353.

LIMITATIONS REASONS FOR CAUTION

Whilst no changes in lymphocyte number were observed across our patient samples, we did not investigate the activation state of any of the immune cell sub-populations examined, therefore, it is possible that the function of these cells may be altered in association with labour onset. Additionally, the results of our transcriptomic analyses are descriptive and at this stage, we cannot prove direct causal link with the up-regulation of any of the genes examined and the onset of either term or PTL.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings demonstrate that the onset of parturition is associated with widespread changes to the decidual transcriptome, and there are distinct gene expression changes associated with term and PTL. We confirmed that an inflammatory signature is present within the decidua, and we also report the up-regulation of several genes involved in regulating the inflammatory response. The identification of genes involved in regulating the inflammatory response may provide novel molecular targets for the development of new, more effective therapies for the prevention of preterm birth (PTB). Such targets are urgently required.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by Medical Research Council (grant number MR/L002657/1) and Tommy's, the baby charity. Jane Norman has had research grants from the charity Tommy's and from the National Institute for Health Research on PTB during the lifetime of this project. Jane Norman also sits on a data monitoring committee for GSK for a study on PTB prevention and her institution receives financial recompense for this. The other authors do not have any conflicts of interest to declare.

Steroids Regulate CXCL4 in the Human Endometrium During Menstruation to Enable Efficient Endometrial Repair

Context

Repair of the endometrial surface at menstruation must be efficient to minimize blood loss and optimize reproductive function. The mechanism and regulation of endometrial repair remain undefined.

Objective

To determine the presence/regulation of CXCL4 in the human endometrium as a putative repair factor at menses.

Patients/Setting

Endometrial tissue was collected throughout the menstrual cycle from healthy women attending the gynecology department. Menstrual blood loss was objectively measured in a subset, and heavy menstrual bleeding (HMB) was defined as >80 mL per cycle. Monocytes were isolated from peripheral blood.

Design

CXCL4 messenger RNA (mRNA) and protein were identified by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The function/regulation of endometrial CXCL4 was explored by in vitro cell culture.

Results

CXCL4 mRNA concentrations were significantly increased during menstruation. Intense staining for CXCL4 was detected in late secretory and menstrual tissue, localized to stromal, epithelial and endothelial cells. Colocalization identified positive staining in CD68+ macrophages. Treatment of human endometrial stromal and endothelial cells (hESCs and HEECs, respectively) with steroids revealed differential regulation of CXCL4. Progesterone withdrawal resulted in significant increases in CXCL4 mRNA and protein in hESCs, whereas cortisol significantly increased CXCL4 in HEECs. In women with HMB, CXCL4 was reduced in endothelial cells during the menstrual phase compared with women with normal menstrual bleeding. Cortisol-exposed macrophages displayed increased chemotaxis toward CXCL4 compared with macrophages incubated with estrogen or progesterone.

Conclusions

These data implicate CXCL4 in endometrial repair after menses. Reduced cortisol at the time of menses may contribute to delayed endometrial repair and HMB, in part by mechanisms involving aberrant expression of CXCL4.

Immunoprofiling of human uterine mast cells identifies three phenotypes and expression of ERβ and glucocorticoid receptor

Background: Human mast cells (MCs) are long-lived tissue-resident immune cells characterised by granules containing the proteases chymase and/or tryptase. Their phenotype is modulated by their tissue microenvironment. The human uterus has an outer muscular layer (the myometrium) surrounding the endometrium, both of which play an important role in supporting a pregnancy. The endometrium is a sex steroid target tissue consisting of epithelial cells (luminal, glandular) surrounded by a multicellular stroma, with the latter containing an extensive vascular compartment as well as fluctuating populations of immune cells that play an important role in regulating tissue function. The role of MCs in the human uterus is poorly understood with little known about their regulation or the impact of steroids on their differentiation status. The current study had two aims: 1) To investigate the spatial and temporal location of uterine MCs and determine their phenotype; 2) To determine whether MCs express receptors for steroids implicated in uterine function, including oestrogen (ERα, ERβ), progesterone (PR) and glucocorticoids (GR). Methods: Tissue samples from women (n=46) were used for RNA extraction (n=26) or fixed (n=20) for immunohistochemistry. Results: Messenger RNAs encoded by TPSAB1 (tryptase) and CMA1 (chymase) were detected in endometrial tissue homogenates. Immunohistochemistry revealed the relative abundance of tryptase MCs was myometrium>basal endometrium>functional endometrium. We show for the first time that uterine MCs are predominantly of the classical MC subtypes: (positive, +; negative, -) tryptase+/chymase- and tryptase+/chymase+, but a third subtype was also identified (tryptase-/chymase+). Tryptase+ MCs were of an ERβ+/ERα-/PR-/GR+ phenotype mirroring other uterine immune cell populations, including natural killer cells. Conclusions: Endometrial tissue resident immune MCs have three protease-specific phenotypes. Expression of both ERβ and GR in MCs mirrors that of other immune cells in the endometrium and suggests that MC function may be altered by the local steroid microenvironment.

Immunoprofiling of human uterine mast cells identifies three phenotypes and expression of ERβ and glucocorticoid receptor

Background: Human mast cells (MCs) are long-lived tissue-resident immune cells characterised by granules containing the proteases chymase and/or tryptase. Their phenotype is modulated by their tissue microenvironment. The human uterus has an outer muscular layer (the myometrium) surrounding the endometrium, both of which play an important role in supporting a pregnancy. The endometrium is a sex steroid target tissue consisting of epithelial cells (luminal, glandular) surrounded by a multicellular stroma, with the latter containing an extensive vascular compartment as well as fluctuating populations of immune cells that play an important role in regulating tissue function. The role of MCs in the human uterus is poorly understood with little known about their regulation or the impact of steroids on their differentiation status. The current study had two aims: 1) To investigate the spatial and temporal location of uterine MCs and determine their phenotype; 2) To determine whether MCs express receptors for steroids implicated in uterine function, including oestrogen (ERα, ERβ), progesterone (PR) and glucocorticoids (GR). Methods: Tissue samples from women (n=46) were used for RNA extraction or fixed for immunohistochemistry. Results: Messenger RNAs encoded by TPSAB1 (tryptase) and CMA1 (chymase) were detected in endometrial tissue homogenates. Immunohistochemistry revealed the relative abundance of tryptase MCs was myometrium>basal endometrium>functional endometrium. We show for the first time that uterine MCs are predominantly of the classical MC subtypes: (positive, +; negative, -) tryptase+/chymase- and tryptase+/chymase+, but a third subtype was also identified (tryptase-/chymase+). Tryptase+ MCs were of an ERβ+/ERα-/PR-/GR+ phenotype mirroring other uterine immune cell populations, including natural killer cells. Conclusions: Endometrial tissue resident immune MCs have three protease-specific phenotypes. Expression of both ERβ and GR in MCs mirrors that of other immune cells in the endometrium and suggests that MC function may be altered by the local steroid microenvironment.

New concepts for an old problem: the diagnosis of endometrial hyperplasia

BACKGROUND

Endometrial hyperplasia (EH) is a uterine pathology representing a spectrum of morphological endometrial alterations. It is predominantly characterized by an increase in the endometrial gland-to-stroma ratio when compared to normal proliferative endometrium. The clinical significance of EH lies in the associated risk of progression to endometrioid endometrial cancer (EC) and 'atypical' forms of EH are regarded as premalignant lesions. Traditional histopathological classification systems for EH exhibit wide and varying degrees of diagnostic reproducibility and, as a consequence, standardized patient management can be challenging.

OBJECTIVE AND RATIONALE

EC is the most common gynaecological malignancy in developed countries. The incidence of EC is rising, with alarming increases described in the 40-44-year-old age group. This review appraises the current EH classification systems used to stratify women at risk of malignant progression to EC. In addition, we summarize the evidence base regarding the use of immunohistochemical biomarkers for EH and discuss an emerging role for genomic analysis.

SEARCH METHODS

PubMed, Medline and the Cochrane Database were searched for original peer-reviewed primary and review articles, from January 2000 to January 2016. The following search terms were used: 'endometrial hyperplasia', 'endometrial intraepithelial neoplasia', 'atypical hyperplasia', 'complex atypical hyperplasia', 'biomarker', 'immunohistochemistry', 'progression', 'genomic', 'classification' and 'stratification'.

OUTCOMES

Recent changes to EH classification reflect our current understanding of the genesis of endometrioid ECs. The concept of endometrial intraepithelial neoplasia (EIN) as a mutationally activated, monoclonal pre-malignancy represents a fundamental shift from the previously held notion that unopposed oestrogenic stimulation causes ever-increasing hyperplastic proliferation, with accumulating cytological atypia that imperceptibly leads to the development of endometrioid EC. Our review highlights several key biomarker candidates that have been described as both diagnostic tools for EH and markers of progression to EC. We propose that, moving forwards, a 'panel' approach of combinations of the immunohistochemical biomarkers described in this review may be more informative since no single candidate can currently fill the entire role.

WIDER IMPLICATIONS

EC has historically been considered a predominantly postmenopausal disease. Owing in part to the current unprecedented rates of obesity, we are starting to see signs of a shift towards a rising incidence of EC amongst pre- and peri-menopausal woman. This creates unique challenges both diagnostically and therapeutically. Furthering our understanding of the premalignant stages of EC development will allow us to pursue earlier diagnosis and facilitate appropriate stratification of women at risk of developing EC, permitting timely and appropriate therapeutic interventions.

A single, mild, transient scrotal heat stress causes hypoxia and oxidative stress in mouse testes, which induces germ cell death

Spermatogenesis is a temperature-dependent process, and increases in scrotal temperature can disrupt its progression. We previously showed that heat stress causes DNA damage in germ cells, an increase in germ cell death (as seen on TUNEL staining), and subfertility. The present study evaluated the stress response in mouse testes following a single mild transient scrotal heat exposure (40 degrees C or 42 degrees C for 30 min). We investigated markers of three types of stress response, namely, hypoxia, oxidative stress, and apoptosis. Heat stress caused an increase in expression of hypoxia-inducible factor 1 alpha (Hif1a) mRNA expression and translocation of HIF1A protein to the germ cell nucleus, consistent with hypoxic stress. Increased expression of heme oxygenase 1 (Hmox1) and the antioxidant enzymes glutathione peroxidase 1 (GPX1) and glutathione S-transferase alpha (GSTA) was consistent with a robust oxidative stress response. Germ cell death was associated with an increase in expression of the effector caspase cleaved caspase 3 and a decrease in expression of the protein inhibitor of caspase-activated DNase (ICAD). Reduced expression of ICAD contributes to increased activity of caspase-activated DNase and is consistent with the increased rates of DNA fragmentation that have been detected previously using TUNEL staining. These studies confirmed that transient mild testicular hyperthermia results in temperature-dependent germ cell death and demonstrated that elevated temperature results in a complex stress response, including induction of genes associated with oxidative stress and hypoxia.

Estrogen receptor related beta is expressed in human endometrium throughout the normal menstrual cycle

BACKGROUND

Estrogen receptor related beta (ERRbeta, ESRRB/NR3B2) is an orphan receptor that shares significant sequence homology with estrogen receptors ERalpha and ERbeta. ERR family members are reported to exhibit constitutive transcriptional activity; however, little is known about the biological function of ERRbeta. In an attempt to delineate its role, we examined expression of ERRbeta in normal human endometrium, a tissue that undergoes cyclic remodelling under the influence of estrogen and progesterone.

METHODS

Well-characterized endometrial tissue (n = 31), including full-thickness biopsies, was obtained from women with regular menstrual cycles. RT-PCR was used to measure mRNA encoding ERRbeta, the peroxisome proliferator activated receptor gamma coactivators (PGC)-1alpha and beta and to determine whether ERRbeta splice variant mRNAs were expressed. ERRbeta was immunolocalized using both single and double antibody immunohistochemistry.

RESULTS

Total ERRbeta mRNA appeared higher in proliferative phase samples but results did not reach significance. Transcripts corresponding to the long- and short-splice variants of ERRbeta as well as PGC1alpha and beta were detected but ERRbetaDelta10 was absent. ERRbeta protein was localized to cell nuclei within multiple endometrial cell types including the glands, stroma, endothelium and immune cells, including uterine natural killer (uNK) cells and macrophages. Fluorescent immunohistochemistry revealed that some cells co-expressed ERRbeta and ERalpha or ERbeta, for example, endothelial and uNK cells were ERRbeta+/ERbeta+.

CONCLUSIONS

ERRbeta mRNA and protein are expressed in healthy human endometrium. Further studies are warranted to characterize the functional impact of ERRbeta on endometrial biology.

Blastocyst oestrogen synthesis and the maternal recognition of pregnancy

The maternal recognition of pregnancy takes a number of forms in different species; among the eutherian mammals the maintenance of luteal function and cessation of oestrous or menstrual cycles is an important event in early pregnancy. In the pig the embryos signal their presence in the uterus between Days 10 and 12 post coitum; this time corresponds to the onset of blastocyst synthesis of oestrogens, which are luteotrophic in this species, and it has been suggested that oestrogens may constitute an embryonic signal responsible for maintained luteal function in pregnancy. Although oestrone sulphate, which is formed from oestrogens of embryonic origin by uterine sulphotransferase, has been found in the maternal circulation in high concentrations after Day 15 p.c., its appearance is late relative to the time of maternal recognition of pregnancy. Therefore an alternative mechanism has been sought. The recent finding that oestradiol is capable of reducing uterine prostaglandin F2 alpha secretion (i.e. acting as an antiluteolysin), and that it is present in uterine venous blood as early as Day 12 p.c. in pregnant pigs, suggests a mechanism whereby blastocyst oestrogens may be capable of influencing luteal function.

Relationship between expression of sex steroid receptors and structure of the seminal vesicles after neonatal treatment of rats with potent or weak estrogens

In this study we evaluated the effect of manipulating the estrogen and androgen environment of the neonatal male rat on subsequent immunoexpression of sex steroid receptors in the seminal vesicles (SVs) at age 18 days. The aim was to establish to what extent such changes were associated with and predictive of changes in SV structure/composition. Treatments were either diethylstilbestrol (DES; 10, 1, or 0.1 microg/injection), ethinyl estradiol (EE; 10 microg/injection), tamoxifen (2 mg/kg/day), flutamide (50 mg/kg), a gonadotropin-releasing hormone antagonist (GnRHa; 10 mg/kg), genistein (4 mg/kg/day), octylphenol (2 mg/injection), or bisphenol A (0.5 mg/injection). Compared with controls, treatment with DES (10 microg) induced loss of epithelial and stromal androgen receptor (AR) immunoexpression coincident with induction of stromal progesterone receptor (PR) immunoexpression and upregulation of stromal immunoexpression of estrogen receptor-alpha (ERalpha). These changes were associated with gross distortion (increase) of the normal stromal:epithelial tissue proportions in the SVs. DES (1 microg) and EE induced similar but less pronounced changes, and DES (0.1 microg) had no noticeable effect. Tamoxifen and flutamide induced PR and slightly upregulated ERalpha immunoexpression but had only a minor or no effect on AR expression and the stromal:epithelial ratio, though flutamide retarded normal development of the SVs. The latter was also evident in GnRHa-treated males, but otherwise this treatment had no effect on AR and PR immunoexpression. None of the foregoing treatments had any detectable effect on the immunoexpression of ERss in stromal or epithelial cells. The major treatment-induced changes in immunoexpression of AR, PR, and ERalpha and lack of change in ERss were confirmed by Western blots of SV protein extracts. None of the three weak (environmental) estrogens tested caused any detectable change in sex steroid receptor immunoexpression or SV tissue composition. We conclude that treatment-induced loss of AR is a prerequisite for altered stromal:epithelial proportions in the SVs and that such loss is always associated with induction of PR and upregulation of ERalpha; the latter two changes are insufficient on their own to bring about such a change. Nevertheless, induction of PR expression was always associated with altered SV development and is a potentially useful marker because it is not normally expressed in male reproductive tissues.

Nature of the spermatogenic arrest in Dazl -/- mice

Dazl encodes an RNA-binding protein essential for spermatogenesis. Mice that are deficient for Dazl are infertile, lacking any formation of spermatozoa, and the only germ cells present are spermatogonia and a few spermatocytes. To gain more insight regarding the timing of the spermatogenic arrest in Dazl -/- mice, we studied the spermatogonial cell types present in testis sections and in seminiferous tubular whole mounts. Most of the seminiferous tubular cross-sections contained A spermatogonia as the most advanced cell type, with only very few containing cells up to pachytene spermatocytes. Both 5-bromodeoxy-uridine incorporation and mitotic index indicated that the remaining A spermatogonia were actively proliferating. C-kit immunohistochemical studies showed that most of the A spermatogonia were positively stained for the c-Kit protein ( approximately 80%). The clonal composition of the A spermatogonia in tubular whole mounts indicated these cells to be A(single) (A(s)), A(paired) (A(pr)), and A(aligned) (A(al)) spermatogonia. It is concluded that the prime spermatogenic defect in the Dazl -/- mice is a failure of the great majority of the A(al) spermatogonia to differentiate into A(1) spermatogonia. As a result, most seminiferous tubules of Dazl -/- mice only contain actively proliferating A(s), A(pr), and A(al) spermatogonia, with cell production being equaled by apoptosis of these cells.

Comparison of androgen receptor and oestrogen receptor beta immunoexpression in the testes of the common marmoset (Callithrix jacchus) from birth to adulthood: low androgen receptor immunoexpression in Sertoli cells during the neonatal increase in testosterone concentrations

The aims of this study were: (i) to investigate the cellular immunoexpression of androgen receptor and oestrogen receptor beta in the testes of the common marmoset (Callithrix jacchus) during neonatal life compared with their expression at later ages; (ii) to establish whether neonatal marmoset Sertoli cells are targets for androgens or oestrogens or both; and (iii) to investigate the relationship between neonatal plasma testosterone concentrations and androgen receptor immunoexpression by abolishing the neonatal testosterone surge with a potent GnRH antagonist. Androgen receptor and oestrogen receptor beta immunoexpression were evaluated in neonatal animals aged 1-4 days, 4 weeks and 6 weeks, and compared with immunoexpression in animals aged 18-22 weeks (early infancy), 35 weeks (late infancy), 58-62 weeks (late pubertal) and > 100 weeks (adult). Immunoexpression of androgen receptor in the reproductive tract was also evaluated at each age. Sertoli cell immunoexpression of androgen receptor was weak or absent in neonatal animals, but increased substantially in infant animals, reaching adult levels by the end of infancy. In contrast, immunoexpression of androgen receptor during the neonatal period was strong in testicular interstitial cells and very strong in epithelial cell nuclei throughout the reproductive tract, and did not change greatly with age in these cells or tissues. Similarly, immunoexpression of oestrogen receptor beta was prominent in many Sertoli cells and in the germ cells of neonatal animals, and was relatively constant throughout life. Weak immunoexpression of androgen receptor in neonatal Sertoli cells was associated with high plasma testosterone concentrations (2.7-5.5 ng ml(-1)), whereas strong Sertoli cell immunoexpression was associated with baseline (approximately 0.12 ng ml(-1)) testosterone concentrations in infant animals and with > 10 ng ml(-1) in late pubertal and adult animals. Immunoexpression of androgen receptor and oestrogen receptor beta was also evaluated in co-twin males aged 4 and 35 weeks, after treatment from birth to 4 weeks or from week 25 to week 35, respectively, with either vehicle or with GnRH antagonist at a dose known to suppress the neonatal testosterone surge completely. Only GnRH antagonist treatment during weeks 25-35 reduced androgen receptor immunoexpression, whereas immunoexpression of oestrogen receptor beta was unaffected by treatment during either period. On the basis of these findings it is suggested that: (i) neonatal marmoset Sertoli cells may be targets primarily for oestrogens rather than androgens; (ii) androgen receptor expression in the testes of neonatal and infant marmosets is not regulated in a straightforward way by testosterone; and (iii) high neonatal concentrations of plasma testosterone are not absolutely necessary for expression of androgen receptor in marmoset testes at this time.

Germ cell specific expression of c-kit in the human fetal gonad

The proto-oncogene receptor, c-kit, and its ligand have been demonstrated to be essential to the processes of germ cell migration, proliferation and survival in the rodent. The aim of the present study was to investigate the expression of c-kit mRNA and protein in human fetal ovary and testis across the gestational period 13-21 weeks. In the ovary, this crucial period of development spans the transition from oogonial replication by mitosis to primordial follicle formation. In the testis, germ cells (gonocytes) are mitotically active. Expression of c-kit mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) in both ovary and testis at all gestational ages examined. Testicular germ cell specific expression of c-kit mRNA was confirmed by RT-PCR using specific cell types recovered by laser capture microscopy. The expression of c-kit protein by both male and female germ cells was demonstrated by immunohistochemistry at all gestational ages examined, and was confirmed by immunoblotting. In both, c-kit was localized to the cell membrane except in oocytes within primordial follicles where it was localized to the cytoplasm. These data demonstrate that the expression of c-kit mRNA and protein is germ cell specific in human fetal gonads and are consistent with an important role for the c-kit/kit ligand signalling system in germ cell proliferation and survival in the developing human gonad.

Angiogenesis during follicular development in the primate and its inhibition by treatment with truncated Flt-1-Fc (vascular endothelial growth factor Trap(A40))

The aims of this study were to 1) quantify changes in angiogenesis during follicular growth in a primate model; 2) investigate the molecular regulation using in situ hybridization of vascular endothelial growth factor (VEGF), its receptor, Flt-1, the angiopoietins (Ang-1 and Ang-2), and their receptor, Tie-2; 3) elucidate the role of VEGF in follicular angiogenesis by blocking its action by treatment with a soluble truncated form of the Flt-1 receptor, (VEGF Trap(A40)). Changes in angiogenesis were quantified using bromodeoxyuridine to obtain a proliferation index, and CD31 immunocytochemistry to visualize endothelial cell area. Percentage of proliferating endothelial cells was calculated by double labeling for bromodeoxyuridine and CD31. Vascularization was first observed in follicles containing four granulosa cell layers. A significant increase in proliferation in the thecal layer was observed from the early to late secondary stage, and dual staining showed that 25% of proliferating cells were of endothelial cell origin. VEGF messenger RNA (mRNA) was expressed in granulosa cells with an increase of grain density from late secondary to tertiary follicles. Ang-1 was weakly expressed in the theca of tertiary follicles. Ang-2 mRNA was not detected in any follicles. The mRNA for the Flt-1 and Tie-2 receptors was localized in endothelial cells of the theca. Unexpectedly, Tie-2 mRNA was also found in granulosa cells of early follicular stages and its translation was confirmed by immunocytochemistry. VEGF trap treatment for 3 days resulted in an 87% decrease of proliferation in the theca of secondary and tertiary follicles, a reduction in endothelial cell area and a marked decline in Flt-1 mRNA expression. Granulosa cell proliferation also decreased. These results show that onset and establishment of the follicle vasculature takes place early during follicular development. The ability of VEGF trap treatment to severely restrict follicular angiogenesis establishes that VEGF is the major regulator of this process in the primate ovary.

Modulation of gene expression by androgen and oestrogens in the testis and prostate of the adult rat following androgen withdrawal

Androgens are important for the structural and functional integrity of the testis and the prostate and this may in part be mediated by the aromatisation of testosterone to oestradiol. The aim of the present study was to establish an in vivo model that would allow the identification of genes, the expression of which was regulated acutely by androgen and/or oestrogen in the male reproductive system. In rats in which the Leydig cells were ablated by administration of ethane dimethane sulfonate (EDS) 6 days earlier, testosterone esters (T) were administered from day 0 (To), and additional animals were administered either T, 17beta-oestradiol benzoate (EB) or diethylstilbestrol (DES) for 1 or 4 h on day 6 after EDS-treatment. Nuclear immunoexpression of the androgen receptor (AR) was reduced or absent from the testis but unaffected in the ventral prostate following these treatments. ERbeta immunoexpression in these tissues was unchanged. Northern blot analysis showed that EB and DES as well as T administration 4 h earlier could modulate mRNA expression of two androgen-responsive genes, C3 and SGP-2, in the prostate. The co-administration of T or EB with the AR antagonist, flutamide, or with the ER antagonist, ICI 182,780 (ICI), did not block the suppression of SGP-2 mRNA expression by T or EB. In contrast, the upregulation of C3 mRNA expression by T was successfully antagonised by both flutamide and by ICI. A preliminary evaluation of the expression of three Sertoli cell and five germ cell mRNAs revealed that their expression was not steroid regulated. Our results support the hypothesis that the action of testosterone in the male reproductive system may in part be mediated by its conversion to oestradiol. This in vivo model should prove of value in future studies to identify androgen and oestrogen regulated genes in the male reproductive system.

Estrogen receptor-alpha and beta- immunoreactivity and mRNA in neurons of sensory and autonomic ganglia and spinal cord

Estrogen receptor-alpha immunoreactivity and mRNAs are present in neurons in locales that innervate genital organs, e.g., parasympathetic pelvic autonomic ganglia, sensory dorsal root and nodose ganglia, and autonomic areas of the lumbosacral spinal cord. With the availability of probes for the beta-isoform of the estrogen receptor, we studied this receptor in autonomic, sensory, and spinal cord neurons and compared it with the distribution of the alpha-receptor. Estrogen receptor-alpha and -beta immunoreactivity were located in the nuclei of neurons, were in subpopulations of parasympathetic neurons in pelvic ganglia, and sensory neurons of dorsal root and nodose ganglia. Both receptor subtypes were present in the lumbosacral spinal cord: in neurons of the outer laminae of the dorsal horn, lateral collateral and medial collateral pathways, sacral parasympathetic nucleus, dorsal intermediate gray, and lamina X. Similar numbers of spinal cord neurons were immunoreactive for estrogen receptor-beta and estrogen receptor-alpha. However, estrogen receptor-beta-immunoreactive neurons appeared less numerous in the outer dorsal horn, but more numerous in the deeper layers of the spinal cord than estrogen receptor-alpha neurons. Retrograde tracing from the uterus revealed "uterine-related" neurons in dorsal root and pelvic ganglia that contained estrogen receptor-alpha and -beta. In situ hybridization revealed both estrogen receptor-alpha and -beta mRNA transcripts in sensory neurons of the dorsal root and nodose ganglia, parasympathetic neurons of pelvic ganglia, and spinal cord neurons in the dorsal horn, sacral parasympathetic nucleus, and dorsal intermediate gray of L6-S1 segments. These studies show that both estrogen receptor-alpha and -beta are synthesized by autonomic and sensory neurons in parts of the nervous system that have connections with the female reproductive system. Such neurons contain neurotransmitters that have important functions in the female reproductive organs; thus, it is likely that estrogen can influence the activity of such neurons and consequently, through them, the activities of the reproductive organs.

Neonatal exposure to potent and environmental oestrogens and abnormalities of the male reproductive system in the rat: evidence for importance of the androgen-oestrogen balance and assessment of the relevance to man

The effects on reproductive tract development in male rats, of neonatal exposure to potent (reference) oestrogens, diethylstilboestrol (DES) and ethinyl oestradiol (EE), with those of two environmental oestrogens, octylphenol and hisphenol A were systematically compared. Other treatments, such as administration of a gonadotrophin-releasing hormone antagonist (GnRHa) or the anti-oestrogen tamoxifen or the anti-androgen flutamide, were used to aid interpretation of the pathways involved. All treatments were administered in the neonatal period before onset of puberty. The cellular sites of expression of androgen receptors (AR) and of oestrogen receptor-alpha (ERalpha) and ERbeta were also established throughout development of the reproductive system. The main findings were as follows: (i) all cell types that express AR also express one or both ERs at all stages of development; (ii) Sertoli cell expression of ERbeta occurs considerably earlier in development than does expression of AR; (iii) most germ cells, including fetal gonocytes, express ERbeta but not AR; (iv) treatment with high, but not low, doses of potent oestrogens such as DES and EE, induces widespread structural and cellular abnormalities of the testis and reproductive tract before puberty; (v) the latter changes are associated with loss of immunoexpression of AR in all affected tissues and a reduction in Leydig cell volume per testis; (vi) none of the effects in (iv) and (v) can be duplicated by treating with high-dose octylphenol or bisphenol A; (vi) none of the reproductive tract changes in (iv) and (v) can be induced by simply suppressing androgen production (GnRHa treatment) or action (flutamide treatment); and (vii) the adverse changes induced by high-dose DES (iv and v) can be largely prevented by co-administration of testosterone. Thus, it is suggested that many of the adverse changes to the testis and reproductive tract induced by exposure to oestrogens result from a combination of high oestrogen and low androgen action. High oestrogen action or low androgen action on their own are unable to induce the same changes.

Estrogen receptor beta, but not estrogen receptor alpha, is present in the vascular endothelium of the human and nonhuman primate endometrium

Estrogen action is dependent upon the presence of specific ligand-activated receptors in target tissues. The aim of the present experiments was to compare the spatial and temporal pattern of expression of estrogen receptor beta (ERbeta) with that of ERalpha in full thickness endometrial samples (from the superficial to the basal zone) obtained from both women and rhesus macaques. Immunohistochemical localization with specific antibodies revealed that ERalpha and ERbeta were both expressed in nuclei of the glands and stroma. Consistent with previous studies, expression of ERalpha declined in the glands and stroma of the functionalis during the secretory phase. The luminal epithelium also displayed positive immunoreactivity for ERbeta. Expression of ERbeta declined in glandular cell nuclei, but not stroma, within the functionalis during the late secretory phase. Levels of expression of ERalpha and ERbeta in all cellular compartments remained unchanged in the basalis. Both receptor subtypes were detected on Western blots using proteins extracted from uterine samples obtained throughout the menstrual cycle. There was a striking contrast between the pattern of expression of ERalpha and ERbeta in the vascular endothelium and the perivascular cells surrounding endometrial blood vessels; only ERbeta was present in the endothelial cell population, although both forms of ER were expressed in perivascular cells. We conclude that estrogen action(s) within the vascular endothelium in the endometrium may be mediated via direct binding to the ERbeta isoform and that these cells could therefore be a target for agonists or antagonists that selectively target the beta form of the ER.

Differential expression of oestrogen receptor alpha and beta proteins in the testes and male reproductive system of human and non-human primates

The role(s) oestrogens play in male adult reproductive function remains uncertain. We have used antibodies specific for oestrogen receptor- alpha (ERalpha) and - beta (ERbeta) to investigate their distribution within the male. In testes from adult human, macaque and marmoset, ERbeta protein was detected in Sertoli cells, Leydig cells and peritubular myoid cells. In germ cells, the intensity of immunostaining for ERbeta was variable between species. Immunoexpression in preleptotene, leptotene and zygotene spermatocytes was low/absent in all species. Elongated spermatids were consistently immunonegative. No ERalpha immunoexpression was detected in testes. ERbeta was detected in epithelial and stromal cell nuclei throughout the male reproductive system [efferent ductules (ED), epididymis, vas deferens, seminal vesicles] and in the bladder. ERalpha was detected in non-ciliated epithelial cells in the ED, but rarely in epithelial and basal cells within the epididymis. Epithelial cells from seminal vesicles and bladder were immunonegative for ERalpha. Expression of ERalpha in stromal cells was rare in the ED, epididymis and bladder but more frequent in seminal vesicles. Expression of ERalpha, and long and short forms of ERbeta, was confirmed by Western blotting. The widespread expression of ERbeta suggests that it is the primary target for modulation of tissue function via oestrogenic ligands in the male reproductive system.

Age-, cell- and region-specific immunoexpression of estrogen receptor alpha (but not estrogen receptor beta) during postnatal development of the epididymis and vas deferens of the rat and disruption of this pattern by neonatal treatment with diethylstilbestrol

This study in rats sought to 1) characterize immunoexpression of estrogen receptor alpha (ERalpha) and ERss in the efferent ducts, epididymis, and vas deferens during postnatal development; 2) establish whether ER expression changed after neonatal treatment with diethylstilbestrol (DES); and 3) determine whether ER changes coincided with abnormal epididymal/vas development. Rats were administered 10 microg DES or vehicle on days 2, 4, 6, 8, 10, and 12 and were sampled on days 10, 18, 25, 35, and 90+. At all ages, ERalpha was immunoexpressed intensely in the efferent ducts. On day 10, immunoexpression of ERalpha was absent from the epididymis and vas, but was detectable on day 18 in epithelial cells in the caput, corpus, and proximal cauda. Epithelial expression of ERalpha was absent from the distal cauda and in the proximal and distal vas was confined to a band of periductal stromal cells. Thus, on day 18, the site of ERalpha expression delineated the epididymis-vas boundary. On days 25-35, epithelial expression of ERalpha was absent, but stromal expression persisted in the vas and distal cauda. In adults, immunoexpression of ERalpha in the epididymis and vas was absent. In contrast, ERbeta was immunoexpressed in epithelial cells and some stromal cells in the efferent ducts, epididymis, and vas at all ages. In the vas, stromal expression of ERalpha and ERbeta was in different layers. DES treatment caused 1) underdevelopment of the epididymal duct and reduced epithelial height in epididymis and vas; 2) coiling of the extraepididymal vas; 3) thickening of the periductal actin-free stromal layer in the distal cauda and vas; and 4) reduced cell proliferation on day 18 in the epididymis and vas, based on incorporation of bromodeoxyuridine, especially in the epithelium. These changes coincided with abnormalities in cell- and region-specific immunoexpression of ERalpha, but not ERbeta. Thus, in DES-treated rats on day 18, epithelial expression of ERalpha occurred in all regions of the epididymis and vas instead of being confined to the caput, corpus, and proximal cauda as in controls. Similarly, stromal ERalpha expression in the vas of DES-treated rats was not confined to a periductal layer as in controls, but occurred diffusely in the muscle layer. It is suggested that 1) estrogens play a role in peripubertal development of the epididymis and vas; 2) the cellular site of expression of ERalpha either plays a role in or reflects demarcation of the epididymal/vas boundary; and 3) blurring of this boundary in DES-treated rats coincides with altered ERalpha immunoexpression.

Localization of estrogen receptor beta protein expression in adult human bone

Evidence suggests that the newly described estrogen receptor beta (ER-beta) may be important for estrogen (17beta-estradiol) action on the skeleton, but its cellular localization in adult human bone requires clarification. We addressed this by using indirect immunoperoxidase with a novel affinity purified polyclonal antibody to human ER-beta, raised to hinge domain (D) sequences from the human receptor. Bone was demineralized in 20% EDTA and all biopsy specimens were formalin-fixed and wax-embedded. Vigorous retrieval was essential for ER-beta detection. In sections (5 microm) of benign prostate hyperplasia, used as positive control, clear nuclear immunoreactivity was seen in glandular epithelial cells, with a 1:500 dilution of ER-beta40. For bone sections, optimal antibody dilutions were 1:100-1:250. We found that in normal bone (from graft operations), in fracture callus from both men and women (>25 years old), pagetic bone, osteophytes, and secondary hyperparathyroid bone, all from older patients, ER-beta was expressed clearly in osteoclast nuclei, with little cytoplasmic immunoreactivity. Nuclear immunoreactivity was still prominent in osteoclasts, with antibody diluted 1:500, although it faded in other cells. Osteoblasts, in areas of active bone formation or bone remodeling, also expressed ER-beta, as did some osteocytes. However, hypertrophic chondrocytes were negative, unlike mesenchymal cells, adjacent to the osteogenesis. Megakaryocytes and some capillary blood vessels cells were receptor positive. All ER-beta expression was blocked totally by preincubation of antibody with antigen. We conclude that ER-beta is expressed in cells of osteoblast lineage and in osteoclasts. The latter appear relatively abundant in this receptor and this might provide a means for direct action of estrogen on osteoclasts.

Regulation of progesterone receptors and decidualization in uterine stroma of the estrogen receptor-alpha knockout mouse

Regulation of progesterone receptor (PR) in uterine stroma (endometrial stroma plus myometrium) by estrogen was investigated in estrogen receptor-alpha (ERalpha) knockout (alphaERKO) mice. 17 beta-Estradiol (E(2)) increased PR levels in uterine stroma of ovariectomized alphaERKO mice, and ICI 182 780 (ICI) inhibited this E(2)-induced PR expression. Estrogen receptor-beta(ER beta) was detected in both uterine epithelium and stroma of wild-type and alphaERKO mice by immunohistochemistry. In organ cultures of alphaERKO uterus, both E(2) and diethylstilbestrol induced stromal PR, and ICI inhibited this induction. These findings suggest that estrogen induces stromal PR via ERbeta in alphaERKO uterus. However, this process is not mediated exclusively by ERbeta+, because in ERbeta knockout mice, which express ERalpha, PR was up-regulated by E(2) in uterine stroma. In both wild-type and alphaERKO mice, progesterone and mechanical traumatization were essential and sufficient to induce decidual cells, even though E(2) and ERalpha were also required for increase in uterine weight. Progesterone receptor was strongly expressed in decidual cells in alphaERKO mice, and ICI did not inhibit decidualization or PR expression. This study suggests that up-regulation of PR in endometrial stroma is mediated through at least three mechanisms: 1) classical estrogen signaling through ERalpha, 2) estrogen signaling through ERbeta, and 3) as a result of mechanical stimulation plus progesterone, which induces stromal cells to differentiate into decidual cells. Each of these pathways can function independently of the others.

Mouse staufen genes are expressed in germ cells during oogenesis and spermatogenesis

The Drosophila melanogaster staufen gene encodes an RNA binding protein (Dm Stau) required for the localization and translational repression of mRNAs within the Drosophila oocyte. In mammals translational repression is important for normal spermatogenesis in males and storage of mRNAs in the oocytes of females. In the present study we identified two mouse cDNA expressed sequence tags (ESTs), encoding proteins with significant homology to Dm Stau and used these firstly to screen a mouse kidney cDNA library and secondly to determine whether staufen mRNAs are expressed in the ovaries and testes of mice and rats. Sequence analysis of the cDNAs revealed that they originated from two different genes. Using Northern blots of RNAs from kidneys, ovaries and testes, both cDNAs hybridized to mRNA species of approximately 3 kb in all three tissues. On sections of mouse ovaries, staufen mRNA was localized specifically to oocytes. On sections of mouse testes, staufen mRNA was expressed in spermatocytes found in seminiferous tubules at stages VI-XII of the spermatogenic cycle. In conclusion, we have shown that the mammalian homologues of Dm stau are expressed in germ cells in both male and female mice, consistent with a role for these RNA binding proteins in mammalian gametogenesis.

Loss of oocytes in Dazl knockout mice results in maintained ovarian steroidogenic function but altered gonadotropin secretion in adult animals

Within 2 days of birth, the mouse ovary is mainly composed of oocytes surrounded by a few pregranulosa cells forming primordial follicles that remain quiescent until they are recruited by intraovarian or other unknown factors to initiate growth of the oocyte and proliferation of the attendant granulosa cells. However, the role of the oocyte in this early development and organization of the follicle is poorly understood. The Dazl knockout (-/-) mouse in which there is total ablation of oocytes in fetal life has allowed us to address this issue. Ovaries from -/- females lack any follicular structure and have no cells positive for either Mullerian inhibiting factor or sulfated glycoprotein-1, indicating a lack of small follicles or corpora lutea. However, by immunocytochemistry, there are cells positive for 3beta-hydroxysteroid dehydrogenase, 17alpha-hydroxylase, and aromatase, indicating the presence of steroidogenically active cells capable of producing estrogen. This was confirmed by the presence of hypertrophied uterine endometrium expressing both estrogen receptor alpha (ER alpha) and ER beta together with normal levels of plasma estradiol. In addition, these steroidogenically active cells contain ER beta, inhibin alpha, and betaB-subunits, and -/- mice have low measurable plasma inhibin A and B levels. The ovarian steroids and inhibins had no significant effect on either plasma or pituitary gonadotropin levels, with significantly (P < 0.01) lower LH and FSH in intact +/+ and +/- females. However, significantly (P < 0.05) increased plasma inhibin B together with significantly (P < 0.05) lower FSH were observed in the +/- females. In conclusion, our data showed that despite oocyte loss in fetal life, the adult ovaries contained steroidogenically active cells capable of producing estradiol and inhibin. Furthermore, in the +/- mice, the enhanced plasma inhibin B implies a role for Dazl protein within the oocyte either from more small follicles or increased inhibin B production from each follicle.

Marmoset spermatogenesis: organizational similarities to the human

The common marmoset (Callithrix jacchus), a small New World primate of high fecundity, is widely used in reproductive research. The aim of the present study was to determine the organization of the germ cells within the seminiferous epithelium, the duration of the spermatogenic cycle and the number of spermatogonial mitoses. Antibodies to cAMP response element modulator (CREM) and proliferating nuclear cell antigen (PCNA) and a cRNA directed against protamine P2 and morphological criteria were used to discriminate between stages of the spermatogenic cycle. Plastic sections were used to document the cell associations present in each of the nine stages of spermatogenesis. Up to five such stages could be observed within individual cross-sections of seminiferous tubules. Based on the pattern of incorporation of bromodeoxyuridine the length of the spermatogenic cycle was estimated to be 10 days and the duration of spermatogenesis to be 37 days. Four mitotic divisions were noted in spermatogonia. It is concluded that the organization of spermatogenesis in the marmoset has similarities to the human ('helical') and this makes the marmoset a suitable model for studies relevant to human testicular function.

Differential expression of estrogen receptor-alpha and -beta and androgen receptor in the ovaries of marmosets and humans

Estrogens and androgens are essential for the maturation of the ovarian follicle and normal fertility in the female. We have used antibodies specific for both forms of estrogen receptor (alpha [ERalpha] and beta [ERbeta]) and androgen receptor (AR) to investigate the pattern of receptor expression in ovaries obtained from women and from a New World primate, the Common marmoset (Callthrix jacchus). On Western blots, three antibodies directed against different peptides within human ERbeta all recognized recombinant human (h) ERbeta but did not bind to recombinant hERalpha. The ERbeta protein was extracted from human ovary and prostate and marmoset ovary. In marmoset and human ovaries, ERbeta protein was detected in the nuclei of granulosa cells in all sizes of follicle (both before and after formation of the antrum), and it was also detected in thecal cells, corpora lutea, surface epithelium, and stroma. In contrast, ERalpha protein was not detected in the nuclei of granulosa cells in preantral follicles, was low/absent from stromal and thecal cells, but was expressed in granulosa cells of antral follicles and in the surface epithelium. The pattern of expression of AR protein more closely resembled that of ERbeta than ERalpha. In conclusion, three independent antibodies have demonstrated convincingly that ERbeta is expressed in a wide range of cells in the primate ovary. Granulosa cells in preantral follicles could contain ERbeta:beta dimers. In antral follicles, however, ERalpha is also expressed, and the formation of homo- or heterodimers containing ERalpha may influence the pattern of gene activation within these cells.

Integral rein control in physiology II: a general model

We generalize the principle of integral rein control to include other systems which partition in such a way that the equilibrium values of some variables are not dependent on the equations governing those variables. Instead, they are determined by the dynamics of other, "regulator" variables. We improve our earlier model for the control of glucose by insulin and glucagon by relaxing the condition necessary for it to operate. The two hormones do not have to be inhibited in the same way; they need only respond to the same combination of their concentrations. We also present a model for the control of ionized calcium by PTH and calcitonin and suggest that the role of chromogranin A may be to stabilize an otherwise unstable system.

Induction of progesterone receptor immunoexpression in stromal tissue throughout the male reproductive tract after neonatal oestrogen treatment of rats

Oestrogen exposure of the male during fetal/neonatal life can fundamentally alter the structure and function of the reproductive system, though how is unknown. This study examined whether such treatment was able to induce a 'female' characteristic, namely immunoexpression of progesterone receptor (PR), in the reproductive system of the male. Rats were treated on postnatal days 2, 4, 6, 8, 10 and 12 with either 10, 1 or 0.1 microg diethystilbestrol (DES) or with the vehicle (20 microl corn oil). Groups of control and treated rats were killed on days 18, 25, 35 and 90 (= adults) and tissues fixed in Bouins for immunolocalisation studies using antisera to PR (recognises A and B forms) and oestrogen receptor-beta (ER beta). PR immunoexpression was absent from all tissues studied in control rats at all ages with the exception of the parasympathetic ganglia of the prostate. In rats treated with 10 microg DES, intense immunoexpression of PR was detected in the nuclei of stromal, but not epithelial, cells of the caput and cauda epididymis, the vas deferens, seminal vesicles and at the base of the dorsolateral prostatic complex (DLPC) at day 18, but was absent from the ventral prostate and from the testis. DES induction of PR immunoexpression was evident after a single injection (on day 3) and at 18-35 days the intensity of immunoexpression was DES dose-dependent; rats treated neonatally with 0.1 microg DES showed no detectable PR immunoexpression at any age. These findings were confirmed by Western analysis which indicated that most of the PR induced was probably the B form. Co-localisation studies, using confocal microscopy, demonstrated that PR and ER beta frequently co-localised to the same stromal cells in the DLPC, epididymis and seminal vesicles of DES-treated rats at day 18, whereas epithelial cells, which also expressed ER beta, did not express PR. In the tissues studied, only occasional stromal cells expressed ER alpha in comparison to the more widespread expression of ER beta, although epithelial cell expression of ER alpha was also detected in the epididymis on day 18 (but not on day 10). In DES-treated rats, immunoexpression of PR in the reproductive tract decreased progressively in intensity from days 18-35 and was non-detectable in adulthood. In conclusion, these findings are interpreted as evidence that neonatal oestrogen treatment exerts pervasive 'reprogramming' effects throughout the reproductive system of the developing male as indicated by the induction of PR immunoexpression. This induction was restricted to stromal tissue even though both stromal and epithelial cells at most sites expressed ER beta and/or ER alpha.

Effect of neonatal gonadotropin-releasing hormone antagonist administration on sertoli cell number and testicular development in the marmoset: comparison with the rat

The primary purpose of this study was to establish whether Sertoli cells proliferate in the neonatal period in the marmoset monkey (Callithrix jacchus) and whether administration of a long-acting GnRH antagonist (GnRHa) during this phase induced any transient or permanent effects on Sertoli cell number or on any other aspect of testicular development. Male marmoset co-twins (n = 9) were treated during Weeks 1-14 with either vehicle or GnRHa. Four sets of co-twins were examined at Weeks 18-22 (start of infancy) and 5 sets in adulthood (92+ wk), and Sertoli cell number was determined using either the nucleator or optical disector methods; other testicular morphometric analyses (e.g., germ cell volume, Leydig cell volume) used standard point-counting. Data for the marmoset were compared with that obtained in similarly treated rats. Sertoli cell number in marmosets treated neonatally with GnRHa was reduced by 35% compared with that of controls at Weeks 18-22 but was comparable to control values in adulthood. However, seminiferous epithelium volume was reduced significantly in adult marmosets treated neonatally with GnRHa, and there was a tendency for reduced germ cell volume per Sertoli cell. In the same animals, there was significant expansion of the interstitium and an increase in Leydig cell volume per testis when compared with co-twin controls; a similar increase in Leydig cell volume was evident in adult rats treated neonatally with GnRHa. Comparison of Sertoli cell numbers in 6 infantile (18-24 wk) and 10 adult marmosets showed that adult numbers of Sertoli cells were present by the start of infancy but, unlike rats, marmosets were still able to replicate Sertoli cells beyond this period. However, marmoset Sertoli cells supported only approximately 20% of the germ cell volume supported by rat Sertoli cells, indicative of poor efficiency of spermatogenesis, as shown previously in the human. This finding, together with the demonstration of a temporal pattern of Sertoli cell replication similar to that in the human, supports the use of marmosets as a model for human male testicular development and function.

Dynamic subcellular distribution of the DAZL protein is confined to primate male germ cells

We have examined the location of the DAZL protein in fetal and adult rodents and human specimens and found that there is a shift from a predominantly nuclear to a predominantly cytoplasmic distribution of the protein in human testis. In rat testis and human ovary, however, the protein is predominantly, if not exclusively, cytoplasmic throughout germ cell development. One possible explanation for this could be that the DAZ protein is responsible for the nuclear localization of DAZL in human males. We have tested this hypothesis by examining the testis of marmosets, which lack the Daz genes and have found that the DAZL protein is both nuclear and cytoplasmic in spermatogonia, and by analyzing testis sections from DAZ-deleted patients in whom the cytoplasmic location of DAZL is evident in remaining germ cells. Transfection experiments indicate that the differences in DAZL expression between rodents and humans are not caused by the amino acid differences between the 2 proteins, and that DAZL is a cytoplasmic protein per se. Variations in location seem to be independent of the presence of the DAZ protein are species specific and, as in Drosophila, may not have great functional significance.

A human DAZ transgene confers partial rescue of the mouse Dazl null phenotype

In a subset of infertile men, a spectrum of spermatogenic defects ranging from a complete absence of germ cells (sertoli cell only) to oligozoospermia is associated with microdeletions of the DAZ (deleted in azoospermia) gene cluster on human distal Yq. DAZ encodes a testis-specific protein with RNA-binding potential recently derived from a single-copy gene DAZL1 (DAZ-like) on chromosome 3. Y chromosomal DAZ homologues are confined to humans and higher primates. It remains unclear which function unique to higher primate spermatogenesis DAZ may serve, and the functional status of the gene recently has been questioned. To assess the extent of functional conservation we have tested the capacity of a human DAZ gene contained in a 225-kb yeast artificial chromosome to complement the sterile phenotype of the Dazl null mouse (Dazl-/-), which is characterized by severe germ-cell depletion and meiotic failure. Although Dazl-/- mice remained infertile when the DAZ transgene was introduced, histological examination revealed a partial and variable rescue of the mutant phenotype, manifest as a pronounced increase in the germ cell population of the seminiferous tubules and survival to the pachytene stage of meiosis. As well as constituting definitive proof of the spermatogenic role of the DAZ gene product, these findings confirm the high degree of functional conservation between the DAZ and DAZL1 genes, suggesting they may constitute a single target for contraceptive intervention and raising the possibility of therapeutic up-regulation of the DAZL1 gene in infertile men.

The chromogranins and the counter-regulatory hormones: do they make homeostatic sense?

1. The chromogranins are ubiquitous proteins which are co-stored and co-secreted with many peptide hormones. All appear to be powerful inhibitors of endocrine secretions. This poses a problem. 2. When endocrine glands are involved in the efferent limbs of homeostatic loops, they are message transmitters. The self-inhibition caused by the co-secretion of a chromogranin will, on the face of it, erase the message. 3. Pairs of counter-regulatory homeostatic hormones also present a problem. 4. If both members of the pair have clearly defined set points, as suggested by their 'time integral' (or 'growth with time') responsiveness to deviations from set point, then, if the two set points are not exactly the same, one or other member will always register an error, leading, eventually, to an overwhelmingly large and unnecessary response. 5. Our model eliminates both paradoxes, and emphasizes the importance of counter-regulation and the co-secretion of chromogranins in 'zero steady-state error' (ZSSE) homeostasis. 6. If hormone A is secreted into the blood in progressively increasing amounts when [Q], the plasma concentration of substance Q, is low, and in decreasing amounts when [Q] is high; and hormone B responds in the opposite manner, then there will be a [Q], designated [Q]p, at which the secretory rate increase, or decrease, of the two hormones is exactly the same. 7. If, in addition, the secretion of both hormones is stimulated by low plasma chromogranin levels, [Cg], but inhibited by high [Cg] then there will be a different [Q]p for every chromogranin concentration in the blood. 8. At one of these points (at a unique [Q] and [Cg]) the concentration of neither hormone will increase or decrease. This is the equilibrium point to which, according to our model, the system always returns regardless of disturbances within physiological limits. 9. This is robust ZSSE control.

Abnormalities in functional development of the Sertoli cells in rats treated neonatally with diethylstilbestrol: a possible role for estrogens in Sertoli cell development

Diethylstilbestrol (DES) was administered neonatally (Days 2-12; 10 microg on alternate days) to rats, and developmental changes in Sertoli cell function were evaluated at 18, 25, and 35 days of age and compared to those observed in rats administered a GnRH antagonist (GnRHa; Days 2 and 5; 10 mg/kg) or a vehicle (controls). DES and GnRHa treatments resulted in similar reductions in both Sertoli cell numbers (40% for DES, 48% for GnRHa) and suppression of testicular growth at 18 and 25 days, though by 35 days the suppression was more pronounced (p < 0.001) in DES-treated animals. Plasma FSH levels were suppressed markedly at 18 and 25 days, but not at 35 days, in GnRHa-treated rats, whereas in DES-treated rats the FSH levels were suppressed significantly only at 35 days. Both treatments suppressed plasma levels of inhibin B, though this was more pronounced (p < 0.05) in DES- than in GnRHa-treated rats. In controls, Sertoli cell immunoexpression of inhibin alpha, sulfated glycoprotein-1 (SGP-1), and androgen receptor (AR) increased in intensity and changed to an adult, stage-dependent pattern by 25 days. In GnRHa-treated rats these changes were reduced in intensity but were similar to those in controls at 35 days. In DES-treated rats, the increase in intensity and stage-dependent pattern of immunoexpression of inhibin alpha, SGP-1, and AR were virtually absent at 25 days but were present by 35 days. Germ cell volume per Sertoli cell was reduced in GnRHa- and DES-treated rats compared with controls at 18 and 25 days but was significantly greater (p < 0. 001) in DES- than in GnRHa-treated rats at 35 days. The proportion of apoptotic to viable germ cells was increased (p < 0.01) in GnRHa- and DES-treated rats compared with controls at 18 and 25 days; but at 35 days, values in GnRHa-treated rats had declined to control values whereas those for DES-treated rats remained 10-fold elevated (p < 0.001). In adulthood, testis weight and daily sperm production were reduced by 43% and 44%, respectively, in GnRHa-treated rats, but spermatogenesis was grossly normal. Comparable changes were observed in approximately 25% of DES-treated rats, but the majority exhibited > 60% reduction in testis weight with many Sertoli cell-only tubules and very low daily sperm production. Taken together, these data are interpreted as providing evidence for direct modulation of Sertoli cell (maturational) development by DES.

Integral rein control in physiology

We propose that blood glucose is regulated by a principle which we call integral rein control, in which under most conditions both glucagon and insulin are produced and control is achieved by altering the balance between the two. Like other integral control systems, the mechanism achieves zero steady-state error, which explains how the blood glucose level can remain very nearly constant over a wide range of input and demand. In addition, the use of two hormones makes the system stable against relatively large perturbations in either direction. An important feature of the model is that the set point is not fixed by an external reference but arises out of the dynamics, in particular out of the relation between the rates of production of the two hormones. The model therefore predicts that the consequence of an inability to produce insulin will be not just that the control will be less effective but that the set point will be shifted. This allows us to explain why patients with untreated Type I diabetes mellitus have high blood glucose levels even under conditions of low glucose input, and why it is difficult to maintain the normal level of 5 mmol/1 in patients who are being treated with insulin. It also explains why Type II diabetes is easier to treat.

Oestrogen receptor beta (ER beta)

Steroid action is mediated by specific intracellular receptors, which are shifted to a transcriptionally active state after ligand binding. In 1996, the cloning of a new member of the nuclear receptor superfamily from the rat prostate was reported. Ligand-binding experiments have shown that this receptor binds specifically to oestrogens and it has been named oestrogen receptor beta (ER beta) to distinguish it from the oestrogen receptor (ER alpha) cloned from uterus in 1986. The alpha and beta forms of the oestrogen receptor have identical numbers of exons, and the cDNAs cloned from humans, rats and mice all share significant sequence homologies especially within their DNA and ligand-binding domains. Splice variants of ER beta have been identified. ER beta mRNA and protein have been detected in a wide range of tissues including the vasculature, bone, brain, heart and the gonads and genital tracts in both males and females, and in some, but not all, tissues the pattern of expression is distinct from that of ER alpha. Studies in vitro have demonstrated that ER alpha and ER beta can exist as hetero- or homodimers and that these forms may interact differentially with response elements on genes. The identification of ER beta has made us rethink the potential sites of action of both endogenous oestrogens and exogenous natural and synthetic oestrogens and anti-oestrogens and is currently the subject of intensive research efforts.

Immunoexpression of aquaporin-1 in the efferent ducts of the rat and marmoset monkey during development, its modulation by estrogens, and its possible role in fluid resorption

Recent data suggest that estrogens play a role in regulating fluid resorption from the efferent ducts, though the biochemical mechanisms involved are unknown. The present study has used immunocytochemistry to localize a water channel protein, Aquaporin-1 (AQP-1), to the efferent ducts of male rats and marmoset monkeys from perinatal life through to adulthood and has then investigated its potential hormonal regulation in neonatal/peripubertal life, via administration of a GnRH antagonist (GnRHa) or diethylstilbestrol (DES) to rats. AQP-1 was immunoexpressed intensely in the apical brush border of the epithelium lining the efferent ducts at all ages studied, from late fetal life through puberty to adulthood. In the marmoset, but not the rat, AQP-1 was also expressed in the epithelium of the rete testis. Once the cell types within the efferent duct epithelium had differentiated, it was clear that only nonciliated cells of the rat localized AQP-1. When gonadotropin secretion was suppressed in rats by neonatal administration of GnRHa, immunoexpression of AQP-1 at age 18 and 25 days was virtually unchanged in intensity, though the efferent ducts were reduced in size. In contrast, when DES was administered neonatally to rats (up to day 12), immunoexpression of AQP-1 was reduced at day 10, virtually abolished at day 18, reduced markedly at day 25 and to a small extent at day 35; these findings were confirmed by Western blot analysis at day 18. The DES-induced decrease in immunoexpression of AQP-1 was accompanied by pronounced distension of the efferent ducts and rete, consistent with reduced fluid resorption. The epithelial cells of the efferent ducts in DES-treated rats were cuboidal rather than columnar in shape as in controls and were reduced significantly in height compared with controls at all ages through to adulthood. These findings suggest that estrogens may play a role in regulating fluid resorption from the efferent ducts during fetal/neonatal development and/or a role in the gross and functional development of the efferent ducts and rete testis. The present data also suggest that AQP-1 is one of the elements involved in the regulation of fluid resorption in the efferent ducts. The importance of fluid flow in fetal/neonatal development of the excurrent duct system of the male is also suggested by these observations.

Expression of oestrogen receptor beta (ER beta) occurs in multiple cell types, including some germ cells, in the rat testis

The identification of a second oestrogen receptor (beta) has prompted a re-evaluation of the potential sites of action of oestrogens. The aim of the present study was to characterize immunoexpression of ER beta expression in the testis to complement earlier data which had demonstrated that expression of ER alpha is confined to testicular interstitial Leydig cells. In all testes studied, including those from both fetal (day 20.5 p.c.) and adult rats, ER beta was found to be expressed in multiple cell types. Sertoli cell nuclei were immunopositive at all ages. In adult testes expression in Sertoli cells was not stage dependent and was unaffected by ablation of Leydig cells. In fetal testes ER beta was also expressed in peritubular cells, fetal Leydig cells and gonocytes. In the pubertal and adult testis ER beta was detected in the nuclei of spermatogonia and most pachytene spermatocytes. Weak immunopositive staining was present in the cytoplasm of spermatocytes undergoing the second meiotic division. In conclusion the widespread expression of ER beta in the testis is consistent with a role for oestrogens in modulating spermatogenesis, and hence fertility, in the male.

Immunoexpression of the steroidogenic enzymes 3-beta hydroxysteroid dehydrogenase and 17 alpha-hydroxylase, C17,20 lyase and the receptor for luteinizing hormone (LH) in the fetal rat testis suggests that the onset of Leydig cell steroid production is independent of LH action

The production of testosterone in the adult testis is mainly regulated by LH. Testosterone is essential for normal development of the male fetus. The regulation of testosterone production in the fetal testis is less clear than in the adult testis, and there are indications that at least the onset of androgen production in the fetal testis takes place in an LH-independent way. The aim of the present study was to compare the onset of synthesis and pattern of expression of LH receptors and two important steroidogenic enzymes, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17alpha-hydroxylase/17,20-lyase (P450c17), in fetal rat gonads. Whole fetuses (13.5 and 14.0 postcoitum (p.c.), testes, and ovaries dissected from fetuses on Days 14.5 p.c. to 20.5 p.c. and testes obtained on Days 3, 5, and 7 postpartum were fixed in Bouin's solution and processed for immunocytochemistry. In all samples of fetal testis, 3beta-HSD was detected on Day 14.5 p.c., and immunoexpression of P450c17 appeared one day later on Day 15.5 p.c. Thereafter, immunoexpression of both enzymes remained intense throughout gestation and postnatally. In contrast, immunoexpression of LH receptors was detectable only from Day 16.5, when a few weakly positive cells were present, but it became more intense one and two days later. Similar to the immunostaining for 3beta-HSD and P450c17, immunostaining for LH receptor remained strong throughout gestation and during the first 7 days of postnatal life. No immunoexpression of any of the three proteins studied was detected in the fetal ovary at any age. These data show very early immunoexpression of 3beta-HSD, which was detected one day before the reported start of steroid production by the fetal Leydig cells. In contrast, immunoexpression of LH receptors was evident only after immunoexpression of both the steroidogenic enzymes studied had became apparent and after the reported start of steroidogenesis, which is consistent with the theory that onset of steroidogenesis in the fetal rat testis is an LH-independent process.

Fetal and perinatal influence of xenoestrogens on testis gene expression

The incidence of reproductive abnormalities in the male has been reported to have increased during the past 50 years. It has been suggested that these changes may be attributable to the presence of chemicals with oestrogenic activity in our environment. The aim of the experiments described in this chapter was to investigate the effects of acute exposure to high levels of xenoestrogens either indirectly during fetal life, or directly during neonatal life, on gene expression in the testis and pituitary. Fetal treatment involved administration of diethylstilbestrol (DES), 4-octylphenol (OP) or vehicle (oil, control) to pregnant rats on days 11.5 and 15.5 post coitum; fetuses were recovered on day 17.5. There was no difference between fetuses from control and treated mothers in either the overall histology of the testes or numbers of Leydig cells as determined by immunohistochemistry with an antibody directed against 3 beta-HSD. However there was a consistent and striking reduction in the amount of P450 17-a hydroxylase C17, 20 lyase (P450c17) and steroidogenic factor 1 (SF-1) detected by immunocytochemistry in testes from treatment groups given the higher doses of OP and DES. Oestrogen receptors (ER alpha) were present in the fetal leydig cells of all animals. Neonatal treatment involved direct injection of oil (control), DES, OP or Bisphenol A (Bis A) on days 2, 4, 6, 8, 10 and 12; pituitaries and testes were recovered on day 18. Testis weights and seminiferous tubule diameters were significantly reduced in animals treated with DES. In these same animals immunocytochemical localisation revealed that the amounts of FSH beta subunit and inhibin alpha subunit were reduced in their pituitaries and testes respectively. OP did not appear to have an acute, measurable effect on testis gene expression but a reduction in testis weight was noted in adult animals given the same treatment regime. The effects observed are consistent with negative feedback by oestrogens on pituitary production of FSH resulting in retarded maturation of seminiferous tubules and reduced Sertoli cell numbers. These studies have demonstrated that administration of high levels of oestrogens can affect gene expression in the testis early in life. However, the relevance of these findings to observations in man await a) a greater understanding of the physiological role(s) of oestrogens in normal males, b) an evaluation of the sources, routes of exposure, concentrations in vivo and bioavailability of xenoestrogens.

Preliminary investigations on androgen receptor gene mutations in infertile men

A total of 50 men were selected from all patients attending an infertility clinic on the basis of oligozoospermia or azoospermia with concentrations of luteinizing hormone >6 IU/l and testosterone >30 nmol/l. Six of these men responded to written invitation and DNA was extracted from blood leukocytes. Individual exons of the androgen receptor gene were amplified by polymerase chain reaction and screened for the presence of mutations by denaturing gradient gel electrophoresis. The glutamine rich portion of exon 1 was sequenced directly. All of the coding sequence of the gene was examined except the glycine rich portion of exon 1 in all patients. No mutations or deletions were identified. Androgen receptor gene mutations do not appear to be present in infertile men with biochemical disturbances compatible with androgen resistance. It is therefore unlikely that such mutations are a major factor in the pathogenesis of oligozoospermia/azoospermia and infertility.

Expression cloning of a rat testicular transcript abundant in germ cells, which contains two leucine zipper motifs

The aim of the present study was to identify specific, novel germ cell markers that could be used to monitor normal and abnormal spermatogenesis. Of several cloned cDNAs isolated from an adult rat testis cDNA library using an expression screening strategy, clone 813B4 (700 base pairs) hybridized exclusively to three mRNA transcripts in samples isolated from rat testes on and after Day 21 of life and to epididymides from some, but not all, adult rats. After further screening, two identical clones encoding a 2.2-kilobase cDNA (KTT4) were isolated and found to contain an open reading frame of 578 amino acids including two leucine zipper motifs. On Northern blots, KTT4 mRNA was abundant in samples from round spermatids, and homologous mRNAs were present in testes from mice and marmosets. A zoo blot revealed that the KTT4 gene is conserved in humans, monkeys, mice, dogs, and cattle. On sections of rat testes, KTT4 mRNA was first detectable in pachytene spermatocytes at stage VII and thereafter was abundant in round and elongating spermatids until step 15. Expression of KTT4 was not altered by ethane dimethane sulphonate-induced androgen withdrawal, but in rats treated 14 days previously with methoxyacetic acid, a marked reduction in KTT4 was noted associated with the depletion of round spermatids. In conclusion, the present study identified a conserved gene expressed in meiotic and post-meiotic germ cells; database searches have shown it to be homologous to recently published sequences for an outer dense fiber protein of the sperm tail (Odf2/Odf84).