Absence of estrogen receptor alpha leads to physiological alterations in the mouse epididymis and consequent defects in sperm function

Bovine Sperm Maturation

On completion of spermatogenesis, testicular spermatozoa appear structurally mature but are infertile and must undergo a sequential maturational process in the epididymis to become motile and acquire fertilizing potential. This chapter provides a cell biological overview of the endocytic and secretory activities, along the extratesticular duct system, that provide appropriate conditions for epididymal maturation of bull spermatozoa. The compartmentalization of the bovine epididymis is illustrated and discussed in terms of epithelial cell types and merocrine and apocrine protein secretions by principal cells that influence maturation. Sequential maturational events are followed with examples, first, of testicular proteins associated with spermatozoa that are endocytosed to form a 'clean slate' and then, of epididymal secretory proteins that recondition the sperm milieu and bind to spermatozoa in order to attain its full fertilization potential. Finally, an assessment is made of the potential contributions to epididymal maturation of some well-characterized and identified secretory proteins that interact with the cytoplasmic membrane of spermatozoa.

Metastasis-associated protein 1 participates in regulating luminal acidification of the epididymis via repressing estrogen receptor alpha transcription

BACKGROUND

As a component of the nucleosome remodeling and deacetylating (NuRD) complex, metastasis-associated protein 1 (MTA1) has been reported to be abundant in male reproductive system and might participate in spermatogenesis and sperm maturation, whereas the precise functional role of MTA1 in these processes is still undetermined.

OBJECTIVE

To investigate the effect and potential function of MTA1 in male fertility.

MATERIALS AND METHODS

Mta1 knockout mice (Mta1-/-) were employed to detect their reproductive phenotype. The pH value of Mta1-/- epididymal luminal fluid was measured, and the potential mechanism of MTA1 involved in regulating luminal acidification was detected in vivo and in vitro. A vasectomy model with abnormal pH of epididymal lumen was established to further detect the effect of MTA1 on epididymal luminal microenvironment.

RESULTS

Mta1-/- mice were fertile without any detectable defects in spermatogenesis or sperm motility while the deficiency of MTA1 could acidify the initial segment of epididymis to a certain extent. MTA1 could interact with estrogen receptor alpha (ERα) and inhibit the transcription of ERα target gene, hydrogen exchanger 3 (NHE3), and ultimately affect the epididymal luminal milieu. After vasectomy, the Mta1-/- mice presented a more acidic epididymal lumen which was closer to the normal state compared to the wild-type model.

DISCUSSION AND CONCLUSION

MTA1 is dispensable for male fertility in mice, but plays a potentially important function in regulating luminal acidification of the epididymis.

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

pH Homeodynamics and Male Fertility: A Coordinated Regulation of Acid-Based Balance during Sperm Journey to Fertilization

pH homeostasis is crucial for spermatogenesis, sperm maturation, sperm physiological function, and fertilization in mammals. HCO3- and H+ are the most significant factors involved in regulating pH homeostasis in the male reproductive system. Multiple pH-regulating transporters and ion channels localize in the testis, epididymis, and spermatozoa, such as HCO3- transporters (solute carrier family 4 and solute carrier family 26 transporters), carbonic anhydrases, and H+-transport channels and enzymes (e.g., Na+-H+ exchangers, monocarboxylate transporters, H+-ATPases, and voltage-gated proton channels). Hormone-mediated signals impose an influence on the production of some HCO3- or H+ transporters, such as NBCe1, SLC4A2, MCT4, etc. Additionally, ion channels including sperm-specific cationic channels for Ca2+ (CatSper) and K+ (SLO3) are directly or indirectly regulated by pH, exerting specific actions on spermatozoa. The slightly alkaline testicular pH is conducive to spermatogenesis, whereas the epididymis's low HCO3- concentration and acidic lumen are favorable for sperm maturation and storage. Spermatozoa pH increases substantially after being fused with seminal fluid to enhance motility. In the female reproductive tract, sperm are subjected to increasing concentrations of HCO3- in the uterine and fallopian tube, causing a rise in the intracellular pH (pHi) of spermatozoa, leading to hyperpolarization of sperm plasma membranes, capacitation, hyperactivation, acrosome reaction, and ultimately fertilization. The physiological regulation initiated by SLC26A3, SLC26A8, NHA1, sNHE, and CFTR localized in sperm is proven for certain to be involved in male fertility. This review intends to present the key factors and characteristics of pHi regulation in the testes, efferent duct, epididymis, seminal fluid, and female reproductive tract, as well as the associated mechanisms during the sperm journey to fertilization, proposing insights into outstanding subjects and future research trends.

Distinct actions of testicular endocrine and lumicrine signaling on the proximal epididymal transcriptome

The epididymal function and gene expression in mammals are under the control of the testis. Sex steroids are secreted from the testis and act on the epididymis in an endocrine manner. There is another, non-sex steroidal secreted signaling, named lumicrine signaling, in which testis-derived secreted proteins go through the male reproductive tract and act on the epididymis. The effects of such multiple regulations on the epididymis by the testis have been investigated for many genes. The recent development of high-throughput next-generation sequencing now enables us a further comparative survey of endocrine and lumicrine action-dependent gene expression. In the present study, testis-derived endocrine and lumicrine actions on epididymal gene expression were comparatively investigated by RNA-seq transcriptomic analyses. This investigation utilized experimental animal models in which testis-derived endocrine and/or lumicrine actions were interfered with, such as unilateral or bilateral orchidectomy. By bilateral orchidectomy, which interferes with both endocrine and lumicrine actions, 431 genes were downregulated. By unilateral orchidectomy, which also interferes with endocrine and lumicrine actions by the unilateral testis, but the endocrine action was compensated by the contralateral testis, 283 genes were downregulated. The content of such genes downregulated by unilateral orchidectomy was like those of lumicrine action-interfered efferent duct-ligation, W/Wv, and Nell2-/- mice. When genes affected by unilateral and bilateral orchidectomy were compared, 154 genes were commonly downregulated, whereas 217 genes were specifically downregulated only by bilateral orchidectomy, indicating the distinction between endocrine and lumicrine actions on the proximal epididymal transcriptome. Comparative transcriptome analyses also showed that the expressions of genes emerging since Amniota were notably impacted by bilateral orchidectomy, unilateral orchidectomy, and lumicrine action-interfering treatments; the degree of influence from these treatments varied based on the evolutionary stage beyond Amniota. These findings unveil an evolutional transition of regulated gene expression in the proximal epididymis by two different testis-derived signaling mechanisms.

Busulfan administration replicated the characteristics of the epididymal initial segment observed in mice lacking testis-epididymis lumicrine signaling

The physiological functions of the mammalian epididymis are typically regulated by the testes. In addition to sex steroids secreted by testicular Leydig cells, which act on the epididymis in an endocrine manner, there is a non-sex-steroidal signaling pathway known as the lumicrine pathway. This lumicrine signaling pathway involves ligand proteins secreted from germ cells within the testicular seminiferous tubules traversing the male reproductive tract, which induce epithelial differentiation in the epididymis. These findings prompted an inquiry into whether treatments influencing testis physiology can disrupt epididymal function by interfering with testis-epididymis communication. Busulfan, an alkylating agent commonly used to deplete testicular germ cells in reproductive biology, has not been sufficiently explored because of its effects on the epididymis. This study investigated the effects of busulfan administration on the proximal epididymis using histological and transcriptomic analyses. Notably, busulfan, as opposed to the vehicle dimethyl sulfoxide (DMSO), altered the morphology of the initial segment of the epididymis, leading to a reduction in the cell height of the luminal epithelium. RNA sequencing identified 185 significantly downregulated genes in the proximal epididymis of busulfan-administered mice compared to DMSO-administered mice. Comparative transcriptome analyses revealed similarities between the epididymal transcriptome of busulfan-administered mice and lumicrine-deficient mice, such as efferent-duct-ligated W/Wv and Nell2-/- mice. However, this differed from that of bilaterally orchidectomized mice, in which both the endocrine and lumicrine signaling pathways were simultaneously ablated. Collectively, these results suggested that the harmful effects of busulfan on the proximal epididymis are secondary consequences of the ablation of testis-epididymis lumicrine signaling.

Adverse outcome pathways of PBDEs inducing male reproductive toxicity

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants, they are easily released into environment and causing adverse effects to the ecosystem and human health. This review aims to summarize the research status of PBDEs-induced male reproductive toxicity and its mechanisms at various levels such as molecular/cellular, tissue/organ and individual/population. The Adverse Outcome Pathways (AOPs) diagram showed that PBDEs-induced reactive oxygen species (ROS) production, disruptions of estrogen receptor-α (ERα) and antagonism of androgen receptor (AR) were defined as critical molecular initiating events (MIEs). They caused key events (KEs) at the molecular and cellular levels, including oxidative stress, increased DNA damage, damaging mitochondria, increased glycolipid levels and apoptosis, depletion of ectoplasmic specialization and decreased Leydig cells numbers. These in turn lead to followed KEs at the tissue or organ levels, such as the impaired spermatogenesis, impaired blood-testis barrier and reduced testosterone synthesis and function. As a result, reproductive system-related adverse outcomes (AOs) were reported, such as the decreased sperm quantity or quality, shorten male anogenital distance and cryptorchidism in individual and reduced reproduction of the population. This review assembled information on the mechanisms of male reproductive toxicity induced by PBDEs, and constructed a causal mechanism relationship diagram from different levels using the an AOP framework to provide theoretical basis for ecological risk assessment and environmental management of PBDEs. The AOP framework makes it possible to develop risk management strategies based on toxicity mechanisms and support for development of Integrated Approach to Testing and Assessment (IATA) which are available for regulatory purposes.

BDE-209 disturbed proliferation and differentiation of spermatogonia during mitotic process through estrogen receptor α

Deca-bromodiphenyl ether (BDE-209) exposure caused spermatogenesis disorder resulting in poor sperm quality has become a public concern in recent years. Spermatogenesis refers to the process by which the division of spermatogonia stem cells (SSCs) produces haploid spermatozoa, including mitosis, meiosis, and spermiogenesis. However, the mechanism of mitosis including proliferation and differentiation of spermatogonia dysfunction induced by BDE-209 remains largely unclear. Here, our data showed that BDE-209 exposure caused a decline in sperm quality with seminiferous tubule structure disorder in rats. In addition, BDE-209 exposure damage spermatogonia proliferation and differentiation with decreasing level of PLZF and cKit in testis. Moreover, rats exposed to BDE-209 decreased the expression of ERα, whereas an elevated expression of Wnt3a and Wnt5a. Mechanistically, supplementation with propipyrazole triol (PPT, a selective ERα pathway agonist) rescued sperm quality and attenuated impairment of proliferation and differentiation of spermatogonia in BDE-209-induced rats. Therefore, ERα plays a crucial role in the proliferation and differentiation of spermatogonia during mitotic process. In conclusion, our study clarified the role of ERα in BDE-209-induced spermatogonia proliferation and differentiation in rats and provides a potential therapeutic application on poor sperm quality caused by BDE-209 exposure.

Venlafaxine increases aromatization, reduces apical V-ATPase in clear cells and induces increased number of mast cells and smooth muscle cells death in rat cauda epididymis

Depressive disorders (DD) have affected millions of people worldwide. Venlafaxine, antidepressant of the class of serotonin and norepinephrine reuptake inhibitors, has been prescribed for the treatment of DD. In rat testes, venlafaxine induces testosterone (T) aromatization and increases estrogen levels. Aromatase is a key enzyme for the formation of estrogen in the epididymis, an essential organ for male fertility. We investigated the impact of serotonergic/noradrenergic venlafaxine effect on the epididymal cauda region, focusing on aromatase, V-ATPase and EGF epithelial immunoexpression, smooth muscle (SM) integrity and mast cells number (MCN). Male rats were distributed into control (CG; n = 10) and venlafaxine (VFG, n = 10) groups. VFG received 30 mg/kg b.w. of venlafaxine for 35 days. The epididymal cauda was processed for light and transmission electron microscopy (TEM). The expression of connexin 43 (Cx43) and estrogen alpha (Esr1), adrenergic (Adra1a) and serotonergic (Htr1b) receptors were analyzed. Clear cells (CCs) area, SM thickness, viable spermatozoa (VS) and MCN were evaluated. Apoptosis was confirmed by TUNEL and TEM. The following immunoreactions were performed: T, aromatase, T/aromatase co-localization, V-ATPase, EGF, Cx43 and PCNA. The increased Adra1a and reduced Htr1b expressions confirmed the noradrenergic and serotonergic venlafaxine effects, respectively, corroborating the increased MCN, apoptosis and atrophy of SM. In VFG, the epithelial EGF increased, explaining Cx43 overexpression and basal cells mitotic activity. T aromatization and Esr1 downregulation indicate high estrogen levels, explaining CCs hypertrophy and changes in the V-ATPase localization, corroborating VS reduction. Thus, in addition to serotonergic/noradrenergic effects, T/estrogen imbalance, induced by venlafaxine, impairs epididymal structure and function.

Absence of Testicular Estrogen Leads to Defects in Spermatogenesis and Increased Semen Abnormalities in Male Rabbits

Estrogens are steroid hormones produced by the aromatization of androgens by the aromatase enzyme, encoded by the CYP19A1 gene. Although generally referred to as "female sex hormones", estrogen is also produced in the adult testes of many mammals, including humans. To better understand the function of estrogens in the male, we used the rabbit model which is an important biomedical model. First, the expression of CYP19A1 transcripts was localized mainly in meiotic germ cells. Thus, testicular estrogen appears to be produced inside the seminiferous tubules. Next, the cells expressing ESR1 and ESR2 were identified, showing that estrogens could exert their function on post-meiotic germ cells in the tubules and play a role during sperm maturation, since ESR1 and ESR2 were detected in the cauda epididymis. Then, CRISPR/Cas9 CYP19A1-/- genetically modified rabbits were analyzed. CYP19A1-/- males showed decreased fertility with lower sperm count associated with hypo-spermatogenesis and lower spermatid number. Germ/sperm cell DNA methylation was unchanged, while sperm parameters were affected as CYP19A1-/- males exhibited reduced sperm motility associated with increased flagellar defects. In conclusion, testicular estrogens could be involved in the spermatocyte-spermatid transition in the testis, and in the acquisition of sperm motility in the epididymis.

Emerging organoid models to study the epididymis in male reproductive toxicology

The importance of the epididymis on sperm maturation and consequently male fertility has been well documented. The pseudostratified epithelium of the epididymis is comprised of multiple cell types, including principal cells, which are the most abundant, and basal cells. The role of basal cells has been unclear and has been a source of discussion in the literature. However, the recent demonstration that these cells are multipotent or adult stem cells has opened new areas of research in epididymal biology. One such avenue is to understand the regulation of these stem cells, and to exploit their properties to develop tools for toxicological studies to elucidate the effects of chemicals on cell differentiation and epididymal function in vitro. Studies in both rat and mouse have shown that purified single epididymal basal cells cultured under 3D conditions can proliferate and differentiate to form organoids, or mini organs. Furthermore, these epididymal basal stem cells can self-renew and differentiate into other epididymal cell types. It is known that during epididymal development, basal cells are derived from undifferentiated columnar cells, which have been reported to share common properties to stem cells. Like basal cells, these undifferentiated columnar cells can also form organoids under 3D culture conditions and can differentiate into basal, principal and clear cells. Organoids derived from either basal cells or columnar cells offer unique models for toxicology studies and represent an exciting and emerging approach to understand the epididymis.

Identification of the TSSK4 Alternative Spliceosomes and Analysis of the Function of the TSSK4 Protein in Yak (Bos grunniens)

In mammals, the testis-specific serine/threonine kinase (TSSK) is essential for spermatogenesis and male fertility. TSSK4 belongs to the family of the testis-specific serine/threonine-protein kinase (TSSK), with a crucial role in spermatogenesis. This study aimed to analyze the variable spliceosome of the TSSK4 gene in the yak for understanding the regulatory function of the TSSK4 spliceosome in yak testis development using PCR amplification and cloning techniques. The GST pull-down was used for pulling down the protein interacting with TSSK4, and then the protein interacting with TSSK4 was identified using LC–MS/MS. The results of the PCR amplification demonstrated multiple bands of the TSSK4 gene in the yak. The cloning and sequencing yielded a total of six alternative spliceosomes, which included only two alternative spliceosomes before sexual maturity and four alternative spliceosomes after sexual maturity. The sub-cells of the alternative spliceosomes were found to localize in the nucleus before sexual maturity and in the cytoplasm after sexual maturity. The LC–MS/MS analysis of the alternative spliceosome with the highest expression after sexual maturity yielded a total of 223 interacting proteins. The enrichment analysis of the 223 interacting proteins revealed these proteins participate in biological processes, cell composition, and molecular functions. The KEGG analysis indicated that the TSSK4-interacting protein participates in the estrogen signaling pathways, tight junctions, endoplasmic reticulum protein processing, and other signaling pathways. This study cloned the six alternative spliceosomes of the TSSK4 gene laying the foundation for studying the function of each spliceosome in the future.

An Integrated Analysis of Network Pharmacology, Molecular Docking, and Experiment Validation to Explore the New Candidate Active Component and Mechanism of Cuscutae Semen-Mori Fructus Coupled-Herbs in Treating Oligoasthenozoospermia

PURPOSE

One of the most common types of male infertility is recognized as oligoasthenozoospermia (OA), characterized by low sperm count and quality in males. As a traditional Chinese medicine (TCM), Cuscutae Semen-Mori Fructus coupled-herbs (CSMFCH) has been known to act a curative effect on OA for thousands of years. Nevertheless, the substantial basis and molecular mechanism of CSMFCH in treating OA remain elusive.

METHODS

Herein, an integrated approach, including network pharmacology, molecular docking, and experiment validation, was utilized to reveal the new candidate active component and mechanism of CSMFCH in treating OA.

RESULTS

The results show that kaempferol is the most significant bioactive component of CSMFCH on OA. The mechanism and targets of CSMFCH against OA are relevant to hormone regulation, oxidant stress, and reproductive promotion. In order to validate network pharmacology results, molecular docking and experiment validation were conducted. In detail, molecular docking was employed to verify the strong binding interactions between kaempferol and the core targets. UHPLC-Q-Orbitrap-MS was used to identify kaempferol in the CSMFCH extract. In vitro and in vivo experiments further proved CSMFCH and kaempferol could enhance the mouse Leydig (TM3) and mouse Sertoli (TM4) cell viability, improve the male reproductive organ weights, sperm quality, and decrease testis tissue damage in the OA mouse model induced by CP.

CONCLUSION

Our results not only identify the new candidate active component of CSMFCH in treating OA but also provide new insights into the mechanisms of CSMFCH against OA.

Estrogens and development of the rete testis, efferent ductules, epididymis and vas deferens

Estrogen has always been considered the female hormone and testosterone the male hormone. However, estrogen's presence in the testis and deleterious effects of estrogen treatment during development have been known for nearly 90 years, long before estrogen receptors (ESRs) were discovered. Eventually it was learned that testes actually synthesize high levels of estradiol (E2) and sequester high concentrations in the reproductive tract lumen, which seems contradictory to the overwhelming number of studies showing reproductive pathology following exogenous estrogen exposures. For too long, the developmental pathology of estrogen has dominated our thinking, even resulting in the "estrogen hypothesis" as related to the testicular dysgenesis syndrome. However, these early studies and the development of an Esr1 knockout mouse led to a deluge of research into estrogen's potential role in and disruption of development and function of the male reproductive system. What is new is that estrogen action in the male cannot be divorced from that of androgen. This paper presents what is known about components of the estrogen pathway, including its synthesis and target receptors, and the need to achieve a balance between androgen- and estrogen-action in male reproductive tract differentiation and adult functions. The review focuses on what is known regarding development of the male reproductive tract, from the rete testis to the vas deferens, and examines the expression of estrogen receptors and presence of aromatase in the male reproductive system, traces the evidence provided by estrogen-associated knockout and transgenic animal models and discusses the effects of fetal and postnatal exposures to estrogens. Hopefully, there will be enough here to stimulate discussions and new investigations of the androgen:estrogen balance that seems to be essential for development of the male reproductive tract.

Androgen and estrogen receptors immunolocalization in the sand rat (Psammomys Obesus) cauda epididymis

Both androgens and estrogens play key, albeit incompletely described, roles in the functioning of the epididymis. Because this tightly-coiled tubular structure is compartmented, precise mapping of the distribution of sex steroid's receptors is important. Such receptors have been located in the first segments (caput, corpus), but the last part (cauda) remains poorly explored. We used immunochemistry to localize androgen (AR) and estrogen (ESR1 and ESR2) receptors in the cauda in the fat sand rat (Psammomys obesus). We compared results obtained during the breeding versus resting seasons. We also used individuals castrated, or castrated then treated with testosterone, or subjected to the ligation of their efferent ducts. During the breeding season, in principal cells, we found strong staining both for AR and ESR1 in the apical cytoplasm, and strong staining for ESR2 in the nucleus. During the resting season, principal cells were positive for AR and ESR1, but negative for ESR2. In castrated animals, staining was null for ESR2 and AR, and weak for ESR1. In castrated then treated animals, immuno-expression was restored but only for AR and ESR1. Following efferent duct ligation, AR reactivity decreased while ESR1 and ESR2 provided strong staining. Broadly similar, but not fully identical patterns were observed in basal cells. They were positive for ESR2 and AR during the breeding season, but not for ESR1. During the resting season, staining was modest for ESR1 and AR and negative for ESR2. In all experimentally treated animals, we observed weak staining for AR and ESR1, and a lack of signal for ESR2. Overall, this study provides strong evidence that androgens and estrogens are involved in the seasonal regulation of the whole epididymis in the fat sand rat, with marked differences between caput and cauda (the corpus is highly reduced in rodent).

Network pharmacology integrated molecular docking reveals the bioactive components and potential targets of Morinda officinalis-Lycium barbarum coupled-herbs against oligoasthenozoospermia

Oligoasthenozoospermia (OA) is one of the most common types of male infertility affecting sperm count and sperm motility. Unfortunately, it is difficult for existing drugs to fundamentally improve the sperm quality of OA patients, because the pathological mechanism of OA has not been fully elucidated yet. Morinda officinalis-Lycium barbarum coupled-herbs (MOLBCH), as traditional Chinese Medicines, has been widely used for treating OA over thousands of years, but its molecular mechanism is still unclear. For this purpose, we adopted a comprehensive approach integrated network pharmacology and molecular docking to reveal the bioactive components and potential targets of MOLBCH against OA. The results showed that MOLBCH alleviated apoptosis, promoted male reproductive function, and reduced oxidant stress in the treatment of OA. Ohioensin-A, quercetin, beta-sitosterol and sitosterol were the key bioactive components. Androgen receptor (AR), Estrogen receptor (ESR1), Mitogen-activated protein kinase 3 (MAPK3), RAC-alpha serine/threonine-protein kinase (AKT1), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were the core potential targets. PI3K/Akt signaling pathway, prostate cancer, AGE-RAGE signaling pathway in diabetic complications were the most representative pathways. Moreover, molecular docking was performed to validate the strong binding interactions between the obtained core components and targets. These observations provide deeper insight into the pathogenesis of OA and can be used to design new drugs and develop new therapeutic instructions to treat OA.

Venlafaxine-induced damage to seminiferous epithelium, spermiation, and sperm parameters in rats: A correlation with high estrogen levels

BACKGROUND

Venlafaxine (selective serotonin and norepinephrine reuptake inhibitor) use has increased worldwide. However, the impact of venlafaxine on testes and sperm parameters has not been investigated.

OBJECTIVES

We evaluated venlafaxine impact on testicular and sperm parameters and verified whether the changes are reversible.

METHODS

Animals from venlafaxine-35 days and venlafaxine-65 days groups received 30 mg/kg of venlafaxine for 35 days. Control-35 days and control-65 days received distilled water. In control-65 days and venlafaxine-65 days, the treatment was interrupted for 30 days. Sperm concentration, morphology, motility, and mitochondrial activity were analyzed. Number of step 19 spermatids (NLS), frequency of tubules with spermiation failure, Sertoli cells number, and TUNEL-positive germ cells were quantified. Testicular aromatase, connexin 43 (Cx43) immunoexpression, Cx43 protein levels, and Cx43 expression were evaluated. Either intratesticular testosterone or estrogen levels were measured.

RESULTS

Venlafaxine impaired sperm morphology, reduced sperm concentration, mitochondrial activity, and sperm motility. The frequency of tubules with spermiation failure and NLS increased in parallel to increased Cx43 immunoexpression; mRNA and protein levels; and aromatase, testosterone, and estrogen levels. An increase in germ cell death and decreased Sertoli cells number were observed. In venlafaxine-65 days, except for sperm motility, mitochondrial activity, Sertoli cells number, and germ cell death, all other parameters were partially or totally recovered.

CONCLUSION

Venlafaxine increases testosterone aromatization and Cx43. This drug, via high estrogen levels, disturbs Sertoli cells, induces germ cell death, and impairs spermiation and sperm parameters. The restoration of spermiation associated with the decreased Cx43 and hormonal levels in venlafaxine-65 days reinforces that high estrogen levels are related to venlafaxine-induced changes. The presence of damaged Sertoli cells, germ cell death, and low sperm motility in venlafaxine-65 days indicates that interruption of treatment for 30 days was insufficient for testicular recovery and points to a long-term estrogen impact on the seminiferous epithelium.

Ontogeny of estrogen receptors in human male and female fetal reproductive tracts

This paper reviews and provides new observations on the ontogeny of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in developing human male and female internal and external genitalia. Included in this study are observations on the human fetal uterine tube, the uterotubal junction, uterus, cervix, vagina, penis and clitoris. We also summarize and report on the ontogeny of estrogen receptors in the human fetal prostate, prostatic urethra and epididymis. The ontogeny of ESR1 and ESR2, which spans from 8 to 21 weeks correlates well with the known "window of susceptibility" (7-15 weeks) for diethylstilbestrol (DES)-induced malformations of the human female reproductive tract as determined through examination of DES daughters exposed in utero to this potent estrogen. Our fairly complete mapping of the ontogeny of ESR1 and ESR2 in developing human male and female internal and external genitalia provides a mechanistic framework for further investigation of the role of estrogen in normal development and of abnormalities elicited by exogenous estrogens.

Canine spermatozoa-What do we know about their morphology and physiology? An overview

Spermatozoa are unique cells because of their morphological and physiological characteristics. They are produced during the process called spermatogenesis. Spermatogenesis consists of three phases: spermatocytogenesis, spermiogenesis and spermiation, during which spermatozoa undergo several changes. Spermatogenesis takes place within the seminiferous tubules containing two types of cells-the germ cells and the Sertoli cells-that alongside the Leydig cells, which play an important role when it comes to normal fertility. Everything is regulated by the hypothalamic-pituitary-gonadal axis and specific hormones due to multi-hormonal feedback systems. Spermatozoa possess morphological and physiological features, which are sometimes completely different from what is observed in various somatic cells. What is more, canine spermatozoa have specific characteristics making them special compared to the spermatozoa of other mammalian species. The metabolic energy production, which is crucial for the appropriate functioning of spermatozoa, can be fuelled by different metabolic pathways utilizing different chemical substrates. Inseparable from the oxidative phosphorylation process is the production of reactive oxygen species, which are both essential and toxic to spermatozoa. Furthermore, epididymis is a very important structure, responsible for the transport and maturation of spermatozoa, which are then stored in the last segment of epididymis-the epididymal cauda. Moreover, the retrieval of spermatozoa from the epididymides is crucial for the development of assisted reproduction techniques and sperm cryopreservation methods. The information gained from the research on domestic dogs might be transferred to their wild relatives, especially those species categorized as endangered.

Freeze-Dried Royal Jelly Proteins Enhanced the Testicular Development and Spermatogenesis in Pubescent Male Mice

Simple Summary

Spermatogenesis and hormones secretions are serious life-threating and complicated process, which can be improve through science-based approaches. Royal jelly is a thick white milky fluid secreted by the hypopharyngeal and mandibular glands of young nurse worker bees (Apis mellifera) and used to feed their queen to expand their life. The results of the study revealed that, the growth performance of testis in exposed mice to freeze-dried Royal Jelly for 35 consecutive days were significantly enhanced in moderate dose among other treated doses. However, at Post Natal Days (PNDs 14 and PNDs 21), obviously changes were observed in histological examination of the testis while at PNDs-07 no major changes were observed. The Tunnel assay showed that, less apoptotic cells were detected in the testis of mice in high dose of freeze-dried RJ and oral administration of freeze-dried royal jelly can aggravate adverse effects via tempestuous on sexual hormone secretion at both PNDs 21 and PNDs 35 respectively.

Abstract

Spermatogenesis and hormones secretions are crucial endocrine and physiological process for maintaining the life. Royal Jelly (RJ) bioactive components are Major Royal Jelly Proteins (MRJPs), owing exceptional biological properties. However, the effects of RJ on pup’s testicular development during neonatal and pubertal period exposure hasn’t been adequately studied. The aim of the study was to detect neonatal sexual hormones concentration and histopathological changes on testicular development of the male progeny after oral exposure to freeze-dried RJ for 35 consecutive days. After mice give birth, male pups were collected together, separated by sex, and randomly standardized to seven (7) male pups per dam. Male pups were assigned to control diet (CON group), low dose RJ (L-RJ group) diet (control diet + 125 mg/kg/day RJ), moderate dose RJ (M-RJ group) diet (control diet + 250 mg/kg/day RJ) and high dose of RJ (H-RJ group) diet (control diet + 500 mg/kg/day RJ). After weaning, male pups were continuously fed with freeze-dried RJ until the age of PNDs 35. The results revealed that, oral M-RJ (250 mg/kg/day) administration significantly (p < 0.05) increased the testis weight, the diameter of seminiferous tubule and the height of seminiferous epithelium of offspring mice at PNDs 14. However, high-dose RJ (500 mg/kg/day) decreased the diameter of seminiferous tubule but increased the height of seminiferous epithelium of male offspring (p < 0.05) at the same time point. Furthermore, oral M-RJ treatment significantly (p < 0.05) increased the testis weight and spermatogenesis at PNDs 21. Whereas, oral H-RJ treatment significantly (p < 0.05) reduced the diameter of seminiferous tubule and the height of seminiferous epithelium at PNDs 21. At PNDs 35, oral M-RJ treatment increased the testis weight, the diameter of seminiferous tubule and the level of FSH. While, high-dose of RJ reduced testis weight and size (diameter of seminiferous tubule and height of seminiferous epithelium), ratio of apoptotic germ cells and incomplete spermatogenesis collectively. In addition, sexual hormone secretions (FSH, LH, E2) were decreased after RJs treatment (L-RJ, M-RJ, H-RJ) at PNDs 21 respectively. In conclusion, the results concluded that oral administration of low and moderate doses of RJ could enhance the development of testis at neonate period until pubescent, whereas unfavorable adverse effects induced by high dose of RJ might remain.

Seasonal expressions of androgen receptor, estrogen receptors, 5α-reductases and P450arom in the epididymis of the male muskrat (Ondatra zibethicus)

The steroid hormones not only exert various endocrine functions but also act as the autocrine or paracrine factors in different tissues of mammals. In the present study, the seasonal expressions of androgen receptor (AR), estrogen receptors alpha and beta (ERα and ERβ), aromatase cytochrome P450 (P450arom) and 5α-reductase 1, 2 were investigated in the epididymis of the muskrat. HE staining showed enlarged lumen and abundant sperm in the breeding season while reduced lumen with no sperm in the non-breeding season. The staining of AR was presented in nuclei of epithelial cells of the epididymis in both seasons. The immunostaining of ERα was localized in both nuclei and cytoplasm of epithelial cells of the epididymis during the breeding season, while the weak staining of ERα was only in the nuclei of epithelial cells during the non-breeding season. In contrast, ERβ signal was negative in the epididymis of the muskrat in both seasons. The positive signals for P450arom and 5α-reductase 1, 2 were found in the cytoplasm of epithelial and smooth muscle cells during both seasons. Moreover, the protein and mRNA expression levels of AR, ERα, P450arom and 5α-reductase 1, 2 were significantly higher in the epididymis during the breeding season than those of the non-breeding season, and the expression level of 5α-reductase 1 was higher when compared with 5α-reductase 2. In addition, the levels of testosterone (T) and dihydrotestosterone (DHT) in the epididymis and serum were remarkably higher during the breeding season. Taken together, these findings suggested androgen and estrogen might play an important endocrine or autocrine/paracrine role to regulate the epididymal functions of the muskrat.

NCOA5 Haplo-insufficiency Results in Male Mouse Infertility through Increased IL-6 Expression in the Epididymis

Male infertility might be caused by genetic and/or environmental factors that impair spermatogenesis and epididymal sperm maturation. Here we report that heterozygous deletion of the nuclear receptor coactivator-5 (Ncoa5) gene resulted in decreased motility and progression of spermatozoa in the cauda epididymis, leading to infertility in male mice. Light microscopic and ultrastructural analysis revealed morphological defects in the spermatozoa collected from the cauda epididymis of Ncoa5^+/− mice. Immunohistochemistry showed that interleukin-6 (IL-6) expression in epithelial cells of Ncoa5^+/− epididymis was higher than wild type counterparts. Furthermore, heterozygous deletion of Il-6 gene in Ncoa5^+/− male mice partially improved spermatozoa motility and moderately rescued infertility phenotype. Our results uncover a previously unknown physiological role of NCOA5 in the regulation of epididymal sperm maturation and suggest that NCOA5 deficiency could cause male infertility through increased IL-6 expression in epididymis.

pH and male fertility: making sense on pH homeodynamics throughout the male reproductive tract

In the male reproductive tract, ionic equilibrium is essential to maintain normal spermatozoa production and, hence, the reproductive potential. Among the several ions, HCO3- and H+ have a central role, mainly due to their role on pH homeostasis. In the male reproductive tract, the major players in pH regulation and homeodynamics are carbonic anhydrases (CAs), HCO3- membrane transporters (solute carrier 4-SLC4 and solute carrier 26-SLC26 family transporters), Na+-H+ exchangers (NHEs), monocarboxylate transporters (MCTs) and voltage-gated proton channels (Hv1). CAs and these membrane transporters are widely distributed throughout the male reproductive tract, where they play essential roles in the ionic balance of tubular fluids. CAs are the enzymes responsible for the production of HCO3- which is then transported by membrane transporters to ensure the maturation, storage, and capacitation of the spermatozoa. The transport of H+ is carried out by NHEs, Hv1, and MCTs and is essential for the electrochemical balance and for the maintenance of the pH within the physiological limits along the male reproductive tract. Alterations in HCO3- production and transport of ions have been associated with some male reproductive dysfunctions. Herein, we present an up-to-date review on the distribution and role of the main intervenient on pH homeodynamics in the fluids throughout the male reproductive tract. In addition, we discuss their relevance for the establishment of the male reproductive potential.

Estrogen in the male: a historical perspective

Estrogens have traditionally been considered female hormones. Nevertheless, the presence of estrogen in males has been known for over 90 years. Initial studies suggested that estrogen was deleterious to male reproduction because exogenous treatments induced developmental abnormalities. However, demonstrations of estrogen synthesis in the testis and high concentrations of 17β-estradiol in rete testis fluid suggested that the female hormone might have a function in normal male reproduction. Identification of estrogen receptors and development of biological radioisotope methods to assess estradiol binding revealed that the male reproductive tract expresses estrogen receptor extensively from the neonatal period to adulthood. This indicated a role for estrogens in normal development, especially in efferent ductules, whose epithelium is the first in the male reproductive tract to express estrogen receptor during development and a site of exceedingly high expression. In the 1990s, a paradigm shift occurred in our understanding of estrogen function in the male, ushered in by knockout mouse models where estrogen production or expression of its receptors was not present. These knockout animals revealed that estrogen's main receptor (estrogen receptor 1 [ESR1]) is essential for male fertility and development of efferent ductules, epididymis, and prostate, and that loss of only the membrane fraction of ESR1 was sufficient to induce extensive male reproductive abnormalities and infertility. This review provides perspectives on the major discoveries and developments that led to our current knowledge of estrogen's importance in the male reproductive tract and shaped our evolving concept of estrogen's physiological role in the male.

Morphological changes of telocytes in camel efferent ductules in response to seasonal variations during the reproductive cycle

Telocytes (TCs) are a distinct stromal cell type described in many organs. The present study investigated the existence of TCs within the efferent ductules in camel and the changes that occur in their morphology and activity during active and inactive reproductive seasons. TCs in the camel had a cell body and multiple telopodes (TPs), and most TCs had indented nuclei that exhibited prominent intranucleolar chromatin. TCs exhibited seasonal differences which were evaluated by histochemistry, immunohistochemistry (IHC), Transimition electron microscopy (TEM) and scanning electron microscopy (SEM). The presence of TCs in camel efferent ductules has been confirmed by CD34 positive immunostaing. In addition to the expression of the vascular endothelial growth factor (VEGF) which was stronger in the summer season. TCs exhibited stronger immunoreactivity for progesterone and oestrogen alpha receptors (ESR1) in the spring than in the summer. In addition, TCs showed strong positive immunostaining for both vimentin and androgen receptor (AR). Several ultrastructural changes were observed in TCs during the two seasons. TPs in the summer season had delicate ramifications whereas, in the spring, TPs displayed fine arborization and became more corrugated. TCs acquired signs of exaggerated secretory activities in the spring; TPs became expanded and packed with secretory vesicles. Thus, we conclude that, hormonal alterations during the reproductive cycle impact the morphology and secretory behavior of TCs.

An increase of estrogen receptor α protein level regulates BDE-209-mediated blood-testis barrier disruption during spermatogenesis in F1 mice

Deca-bromodiphenyl ether (BDE-209) regulates various aspects of spermatogenesis and male fertility through its effect on estrogen receptor α (ERα), but the underlying mechanism remains unclear. Because molecular mechanisms such as remodeling of the blood-testis barrier (BTB) play crucial roles in spermatogenesis, we investigated the disruptive effects of ERα agonists on the BTB in spermatogenesis. In this study, 0, 300, and 500 mg/kg/day of BDE-209 were administered to pregnant adult mice by oral gavage from gestation day 7 to postnatal day 21. SerW3 cells were treated with methylpiperidino pyrazole (MPP) for 30 min before being treated with 50 μg/mL of BDE-209. BDE-209 increases ERα in time- and dose-dependent manners and decreases formin 1 and BTB-associated protein in F1 male mice. Furthermore, BDE-209 impairs the structure and function of the BTB. Activation of ERα signaling could disrupt the BTB, leading to spermatogenesis dysfunction. The results identified the role of ERα in BTB disruption during spermatogenesis and suggested that BTB disruption occurs because of exposure to BDE-209, which could potentially affect spermatogenesis. In conclusion, Sertoli cells seem to be the primary target of BDE-209 in the perinatal period, and this period constitutes a critical window of susceptibility to BDE-209. Also, the SerW3 cell model may not be a particularly useful cell model for studying the function of the cytoskeleton.

Ethylene dimethane sulfonate (EDS) ablation of Leydig cells in adult rat depletes testosterone resulting in epididymal sperm granuloma: Testosterone replacement prevents granuloma formation

Sperm granuloma may develop in the epididymis following vasectomy or chemical insults. Inflammation due to sperm granuloma causes abdominal and scrotal pain. Prolonged and persistent inflammation in the epididymis due to sperm granuloma may lead to infertility. Extravasation of germ cells into the interstitium of epididymis following damage of the epididymal epithelium is one of the primary reasons for sperm granuloma-associated pathology. Since testosterone is vital for the maintenance of epididymal epithelium, we investigated the pathology of sperm granuloma and its relationship with testosterone. Adult rats were treated with a Leydig cell-specific toxicant ethylene dimethane sulfonate (EDS) to eliminate testosterone. At 7 days post-EDS, disrupted epididymal epithelium and sperm granuloma were observed in the caput epididymis. Sperm granuloma and caput were collagen-filled indicating fibrosis. Numerous round apoptotic cells were localized inside the caput lumen and dispersed through the sperm granuloma. Tnp1 (round spermatid marker) was significantly higher in the epididymis of the EDS-treated group compared to controls suggesting the apoptotic cells were round spermatids. Increases in CD68⁺ macrophages and T cells (CD4 and CD8) support an inflammatory immune infiltration in post-EDS epididymis. However, testosterone replacement following EDS prevented the sperm granuloma-associated pathology. We suggest that the immune response in the sperm granuloma may be due to the increased numbers of apoptotic round spermatids or other testicular tissue components that may be released, in addition to the regression of epididymal epithelium due to testosterone loss. Thus, testosterone replacement prevents EDS-induced sperm granuloma and ameliorates sperm granuloma-associated pathology.

Effects of Estrogen Treatment on Aging in the Rat Epididymis

Previous studies from our laboratory demonstrated that estrogen signaling in the testis contributes to maintaining spermatogenesis in adult rats, and that estrogen treatment attenuated the age-associated decline in sperm production. The purpose of this study was to determine if epididymal function is also altered with age, and what effects estrogen treatment may have on the epididymis during aging. We compared untreated rats at 3 and 15 months of age to 18-month-old vehicle-treated and estrogen treated rats. In all four groups, tubule and lumen diameter of the cauda was significantly larger than more proximal regions of the epididymis. In the 3-, 15-, and 18-month-old treated animals, the epithelial cell height of the cauda was significantly shorter than that of more proximal regions. The caput cell height was shorter at 18 months compared to 3 months but this was not seen in estrogen treated animals. Thus, estrogen appears able to prevent some age related changes in epididymal morphology. Sperm transit time through the distal cauda was significantly delayed with aging. Estrogen treatment prevented this delay, indicating that sperm transit through the epididymis is an estrogen regulated function. Differences in estradiol and testosterone concentrations were observed between 3- and 15-month-old animals, but no further differences were noted between treated or untreated animals at 18 months. Interestingly, expression of androgen receptor and estrogen receptor alpha were similar between ages and treatments. Collectively, these results suggest epididymal morphology and function are affected by aging and estrogen treatment. Anat Rec, 302:1447-1457, 2019. © 2018 Wiley Periodicals, Inc.

Relative contribution of clear cells and principal cells to luminal pH in the mouse epididymis

While spermatozoa undergo epididymal maturation, they remain quiescent thanks to the establishment of a low luminal pH. This study is aimed at determining how epithelial cells lining the epididymal lumen work together to maintain and regulate this acidic milieu. In particular, we examined the relative contribution of clear cells (CCs) and principal cells (PCs) to this process. Functional analysis in the mouse cauda epididymidis (Cd) perfused in vivo showed that the pH of a control solution remained constant at pH 6.6 after perfusion through the Cd lumen. In contrast, the pH of both an acidic (pH 5.8) and alkaline (pH 7.8) perfusate was progressively restored toward the control acidic pH. Pharmacological studies indicated the contribution of cystic fibrosis transmembrane regulator, previously shown to be present in the apical membrane of PCs, to the recovery from an acidic pH of 5.8. In addition, we found that CCs and PCs equally contribute to the recovery from an alkaline of 7.8, via the H+ pumping vacuolar ATPase (V-ATPase) located in CCs, and the Na+/H+ exchanger type 3 (NHE3) located in PCs. Immunofluorescence labeling showed apical membrane accumulation of the V-ATPase in CCs at pH 7.8, and its internalization at pH 5.8 compared to pH 6.6. Immunofluorescence showed expression of NHE3, but absence of NHE2, in PCs located in the Cd. RT-PCR and western blotting showed expression of NHE3 in all epididymal regions. Luminal 8-(4-chlorophenylthio)adenosine 3΄,5΄-cyclic monophosphate (cpt-cAMP) partially inhibited luminal pH recovery from pH 7.8. However, cpt-cAMP induced an increase in V-ATPase apical membrane accumulation at this pH. Cell fractionation studies showed the apical accumulation of NHE3 from intracellular vesicles at pH 7.8 versus 6.6, and prevention of this effect by cpt-cAMP. These results indicate the participation of both CCs and PCs in the regulation of luminal pH in the epididymis. Our study also shows the dual role of PCs in HCO3− and H+ secretion, and that this switch from base to acid secretion depends on the luminal environment. Characterization of the respective roles of CCs and PCs in the regulation of the optimal luminal condition for epididymal sperm maturation should provide new frameworks for the evaluation and treatment of male infertility.

Peripubertal serum dioxin concentrations and subsequent sperm methylome profiles of young Russian adults

BACKGROUND

The association of exposure to endocrine disrupting chemicals in the peripubertal period with subsequent sperm DNA methylation is unknown.

OBJECTIVE

We examined the association of peripubertal serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations with whole-genome bisulfite sequencing (WGBS) of sperm collected in young adulthood.

METHODS

The Russian Children's Study is a prospective cohort of 516 boys who were enrolled at 8-9 years of age and provided semen samples at 18-19 years of age. WGBS of sperm was conducted to identify differentially methylated regions (DMR) between highest (n = 4) and lowest (n = 4) peripubertal TCDD groups.

RESULTS

We found 52 DMRs that distinguished lowest and highest peripubertal serum TCDD concentrations. One of the top scoring networks, "Cellular Assembly and Organization, Cellular Function and Maintenance, Carbohydrate Metabolism", identified estrogen receptor alpha as its central regulator.

CONCLUSION

Findings from our limited sample size suggest that peripubertal environmental exposures are associated with sperm DNA methylation in young adults.

Effects of MCLR exposure on sex hormone synthesis and reproduction-related genes expression of testis in male Rana nigromaculata

Microcystin-leucine-arginine (MCLR) is the most popular and toxic variant among microcystins, which can cause severe reproductive toxicity to animals. However, the mechanisms of reproductive toxicity induced by MCLR in amphibians are still not entirely clear. In the current study, toxicity mechanisms of MCLR on the reproductive system of male Rana nigromaculata followed by low concentration (0, 0.1, 1, and 10 μg/L) and short-term (0, 7, and 14 days) MCLR exposure were shown. It was observed that MCLR could be bioaccumulated in the testes of male frogs, and the theoretical bioaccumulation factor values were 0.24 and 0.19 exposed to 1 μg/L and 10 μg/L MCLR for 14 days, respectively. MCLR exposure significantly decreased testosterone (T) concentrations and increased estradiol (E2) concentrations exposed to 1 and 10 μg/L MCLR for 14 days. The mRNA levels of HSD17B3 were downregulated, and HSD17B1 and CYP19A1 mRNA expression levels were upregulated, respectively. Only 10 μg/L MCLR group showed significant induction of follicle-stimulating hormone (FSH) levels and cyclic adenosine monophosphate (cAMP) content. Moreover, AR and ESR1 mRNA expression levels were significantly upregulated exposed to 1 and 10 μg/L MCLR for 14 days, respectively. Our results suggested that low-concentration MCLR induced transcription changes of CYP19A1, HSD17B3, and HSD17B1 led to endocrine disorders, and caused interference of spermatogenesis by the decrease of T and abnormal gene expressions of AR and ESR1 in the testes of R. nigromaculata.

Colocalization of metastasis-associated proteins 1/2 and estrogen receptor alpha in rat epididymis

It has been suggested that metastasis-associated proteins 1 and 2 (MTA1 and MTA2) are capable of suppressing estrogen receptor alpha (ERα) transactivation activity in breast cancer cells. ERα, which is present in the epididymis, is a crucial mediator of maintaining the luminal environment necessary for proper sperm maturation and function. The present study was undertaken to analyze the expression profile of both MTA1 and MTA2 in the epididymis of rats and to ascertain whether MTA1/2 colocalizes with ERα in the epididymis and primary cultured epididymal epithelial cells. Reverse transcription polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry analyses were utilized to demonstrate that MTA1 and MTA2 are expressed in the epididymis. Furthermore, these analyses revealed that MTA1 and MTA2 are predominantly localized in the nuclei of almost all epididymal epithelial cells. Immunofluorescence staining revealed that MTA1/2 colocalizes with ERα in epididymal epithelial cells. In conclusion, MTA1 and MTA2 are expressed in the epididymis of rats; these proteins colocalize with ERα in epididymal epithelial cells, suggesting that MTA1 and MTA2 may be involved in the regulation of ERα transactivation activity in the epididymis of rats to facilitate a stable environment in the lumen.

Estrogens in Male Physiology

Estrogens have historically been associated with female reproduction, but work over the last two decades established that estrogens and their main nuclear receptors (ESR1 and ESR2) and G protein-coupled estrogen receptor (GPER) also regulate male reproductive and nonreproductive organs. 17β-Estradiol (E2) is measureable in blood of men and males of other species, but in rete testis fluids, E2 reaches concentrations normally found only in females and in some species nanomolar concentrations of estrone sulfate are found in semen. Aromatase, which converts androgens to estrogens, is expressed in Leydig cells, seminiferous epithelium, and other male organs. Early studies showed E2 binding in numerous male tissues, and ESR1 and ESR2 each show unique distributions and actions in males. Exogenous estrogen treatment produced male reproductive pathologies in laboratory animals and men, especially during development, and studies with transgenic mice with compromised estrogen signaling demonstrated an E2 role in normal male physiology. Efferent ductules and epididymal functions are dependent on estrogen signaling through ESR1, whose loss impaired ion transport and water reabsorption, resulting in abnormal sperm. Loss of ESR1 or aromatase also produces effects on nonreproductive targets such as brain, adipose, skeletal muscle, bone, cardiovascular, and immune tissues. Expression of GPER is extensive in male tracts, suggesting a possible role for E2 signaling through this receptor in male reproduction. Recent evidence also indicates that membrane ESR1 has critical roles in male reproduction. Thus estrogens are important physiological regulators in males, and future studies may reveal additional roles for estrogen signaling in various target tissues.

Membrane estrogen receptor 1 is required for normal reproduction in male and female mice

Steroid hormones, acting through their cognate nuclear receptors, are critical for many reproductive and non-reproductive functions. Over the past two decades, it has become increasingly clear that in addition to cytoplasmic/nuclear steroid receptors that alter gene transcription when liganded, a small fraction of cellular steroid receptors are localized to the cell membranes, where they mediate rapid steroid hormone effects. 17β-Estradiol (E2), a key steroid hormone for both male and female reproduction, acts predominately through its main receptor, estrogen receptor 1 (ESR1). Most ESR1 is nuclear; however, 5-10% of ESR1 is localized to the cell membrane after being palmitoylated at cysteine 451 in mice. This review discusses reproductive phenotypes of a newly-developed mouse model with a C451A point mutation that precludes membrane targeting of ESR1. This transgenic mouse, termed the nuclear-only ESR1 (NOER) mouse, shows extensive male and female reproductive abnormalities and infertility despite normally functional nuclear ESR1 (nESR1). These results provide the first in vivo evidence that membrane-initiated E2/ESR1 signaling is required for normal male and female reproductive functions and fertility. Signaling mechanisms for membrane ESR1 (mESR1), as well as how mESR1 works with nESR1 to mediate estrogen effects, are still being established. We discuss some possible mechanisms by which mESR1 might facilitate nESR1 signaling, as well as the emerging evidence that mESR1 might be a major mediator of epigenetic effects of estrogens, which are potentially linked to various adult-onset pathologies.

Interactions between oestrogen and 1α,25(OH)2-vitamin D3 signalling and their roles in spermatogenesis and spermatozoa functions

Oestrogens and 1α,25(OH)₂-vitamin D₃ (1,25-D₃) are steroids that can provide effects by binding to their receptors localised in the cytoplasm and in the nucleus or the plasma membrane respectively inducing genomic and non-genomic effects. As confirmed notably by invalidation of the genes, coding for their receptors as tested with mice with in vivo and in vitro treatments, oestrogens and 1,25-D₃ are regulators of spermatogenesis. Moreover, some functions of ejaculated spermatozoa as viability, DNA integrity, motility, capacitation, acrosome reaction and fertilizing ability are targets for these hormones. The studies conducted on their mechanisms of action, even though not completely elicited, have allowed the demonstration of putative interactions between their signalling pathways that are worth examining more closely. The present review focuses on the elements regulated by oestrogens and 1,25-D₃ in the testis and spermatozoa as well as the interactions between the signalling pathways of both hormones.

Of Oestrogens and Sperm: A Review of the Roles of Oestrogens and Oestrogen Receptors in Male Reproduction

The crucial role that oestrogens play in male reproduction has been generally accepted; however, the exact mechanism of their action is not entirely clear and there is still much more to be clarified. The oestrogen response is mediated through oestrogen receptors, as well as classical oestrogen receptors’ variants, and their specific co-expression plays a critical role. The importance of oestrogen signalling in male fertility is indicated by the adverse effects of selected oestrogen-like compounds, and their interaction with oestrogen receptors was proven to cause pathologies. The aims of this review are to summarise the current knowledge on oestrogen signalling during spermatogenesis and sperm maturation and discuss the available information on oestrogen receptors and their splice variants. An overview is given of species-specific differences including in humans, along with a detailed summary of the methodology outcome, including all the genetically manipulated models available to date. This review provides coherent information on the recently discovered mechanisms of oestrogens’ and oestrogen receptors’ effects and action in both testicular somatic and germ cells, as well as in mature sperm, available for mammals, including humans.

Loss of SLC9A3 decreases CFTR protein and causes obstructed azoospermia in mice

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF) and are associated with congenital bilateral absence of the vas deferens (CBAVD), which is the major cause of infertility in male patients with CF. However, most Taiwanese patients with CBAVD do not carry major CFTR mutations. Some patients have a single copy deletion of the solute carrier family 9 isoform 3 (SLC9A3) gene. SLC9A3 is a Na⁺/H⁺ exchanger, and depleted Slc9a3 in male mice causes infertility due to the abnormal dilated lumen of the rete testis and efferent ductules. Furthermore, SLC9A3 interacts with CFTR in the pancreatic duct and functions as a genetic modifier of CF. However, SLC9A3 function and its relation to CFTR expression in the male reproductive tract in vivo remain elusive. In the present study, we found that CFTR expression was dramatically decreased in the epididymis and vas deferens of Slc9a3 knockout mice. Adult Slc9a3^-/- mice showed not only significantly decreased epididymis and vas deferens weight but also increased testis weight. Furthermore, Slc9a3^-/- mice developed obstructive azoospermia because of abnormal abundant secretions and calcification in the lumen of the reproductive tract. Ultrastructural analysis of the epithelium in Slc9a3^–/–epididymis and vas deferens displayed disorganized and reduced number of stereocilia and numerous secretory apparatuses. Our data revealed that interdependence between SLC9A3 and CFTR is critical for maintaining a precise microenvironment in the epithelial cytoarchitecture of the male reproductive tract. The Slc9a3-deficient mice with impaired male excurrent ducts in this study provide proof for our clinical findings that some Taiwanese of CBAVD carry SLC9A3 deletion but without major CFTR mutations.

Cystic fibrosis (CF) is the most common inherited life-threatening disease in Caucasians. The most well-known cause of CF is a genetic defect in CFTR, an apical membrane chloride and bicarbonate channel. The symptoms of CF include defects in the respiratory, digestive, and male reproductive systems. Most male patients with CF are infertile due to congenital bilateral absence of the vas deferens (CBAVD), which leads to obstructive azoospermia. Nevertheless, Taiwanese patients with CBAVD do not carry the common mutations of CFTR found in Caucasians. We have identified a potential candidate, SLC9A3, of which a single copy is lost in Taiwanese patients with CBAVD. In addition to the previously reported role of SLC9A3 in the digestive system and efferent ductules, we now report that the SLC9A3 deficiency causes obstructive azoospermia and impairs the epithelial structure of the reproductive tract. Loss of SLC9A3 also leads to dramatic reduced expression of CFTR in the reproductive tract. We suggest that the interplay between SLC9A3 and CFTR is responsible for CF-related infertility. Thus, we have characterized a potential critical player in the pathogenesis of CBAVD and provide a new diagnostic candidate for Asian patients with CBAVD.

Ectopic synthesis of vitellogenin in testis and epididymis of estrogen-treated lizard Podarcis sicula

In oviparous vertebrates, vitellogenin (VTG) is the major yolk precursor synthesized in the liver of sexually mature females during the reproductive period. In males, the VTG gene is silent, but it may be activated by estradiol-17β (E2) or estrogen-like substances. Until now, extra-hepatic expression and synthesis of VTG after estrogen exposure has been reported only for aquatic vertebrates. This study demonstrates the ability of testis and epididymis of the terrestrial oviparous lacertid Podarcis sicula to synthesize VTG following E2 exposure. The results of in situ hybridization and immunohistochemistry analysis show the presence of both VTG mRNA and protein in these districts besides the known induction in the liver. The possible contemporaneous uptake of the E2-induced hepatic VTG by means of the specific vitellogenin receptor has been also evaluated. Finally, histological analysis shows that the E2-treatment during the mating season impairs spermatogenesis.

Implication of the estrogen receptors GPER, ESR1, ESR2 in post-testicular maturations of equine spermatozoa

Estrogen receptors ESR1, ESR2 and GPER are present on mature ejaculated horse spermatozoa, suggesting these cells as putative targets for estrogens. Indeed, spermatozoa are exposed to high level of estrogens during the transit in the male and female genital tracts but their roles are not investigated. So, we evaluated in vitro the role of 17β-estradiol during post-testicular maturations: regulation of motility, capacitation and acrosome reaction. Moreover according to the pseudo-seasonal breeder status of the stallion, we analyzed the putative seasonal variations in the presence of ESRs in spermatozoa. We showed that ESRs are more present on stallion sperm during the breeding season. We showed that capacitation and acrosome reaction are independent of estradiol action in horse. Estradiol can weakly modulate the motility and this effect is strictly associated with GPER and not with ESR1 and ESR2. The subcellular localization of GPER in the neck on stallion sperm is coherent with this effect. It seems that estrogens are not major regulators of sperm maturations associated to mare genital tract, so they could act during the epididymal maturations.

Membrane-Localized Estrogen Receptor 1 Is Required for Normal Male Reproductive Development and Function in Mice

Estrogen receptor 1 (ESR1) mediates major reproductive functions of 17β-estradiol (E2). Male Esr1 knockout (Esr1KO) mice are infertile due to efferent ductule and epididymal abnormalities. The majority of ESR1 is nuclear/cytoplasmic; however, a small fraction is palmitoylated at cysteine 451 in mice and localized to cell membranes, in which it mediates rapid E2 actions. This study used an Esr1 knock-in mouse containing an altered palmitoylation site (C451A) in ESR1 that prevented cell membrane localization, although nuclear ESR1 was expressed. These nuclear-only estrogen receptor 1 (NOER) mice were used to determine the roles of membrane ESR1 in males. Epididymal sperm motility was reduced 85% in 8-month-old NOER mice compared with wild-type controls. The NOER mice had decreased epididymal sperm viability and greater than 95% of sperm had abnormalities, including coiled midpieces and tails, absent heads, and folded tails; this was comparable to 4-month Esr1KO males. At 8 months, daily sperm production in NOER males was reduced 62% compared with controls. The NOER mice had histological changes in the rete testes, efferent ductules, and seminiferous tubules that were comparable with those previously observed in Esr1KO males. Serum T was increased in NOER males, but FSH, LH, and E2 were unchanged. Critically, NOER males were initially subfertile, becoming infertile with advancing age. These findings identify a previously unknown role for membrane ESR1 in the development of normal sperm and providing an adequate environment for spermatogenesis.

Revisiting the neural role of estrogen receptor beta in male sexual behavior by conditional mutagenesis

Estradiol derived from neural aromatization of gonadal testosterone plays a key role in the perinatal organization of the neural circuitry underlying male sexual behavior. The aim of this study was to investigate the contribution of neural estrogen receptor (ER) β in estradiol-induced effects without interfering with its peripheral functions. For this purpose, male mice lacking ERβ in the nervous system were generated. Analyses of males in two consecutive tests with a time interval of two weeks showed an effect of experience, but not of genotype, on the latencies to the first mount, intromission, pelvic thrusting and ejaculation. Similarly, there was an effect of experience, but not of genotype, on the number of thrusts and mating length. Neural ERβ deletion had no effect on the ability of males to adopt a lordosis posture in response to male mounts, after castration and priming with estradiol and progesterone. Indeed, only low percentages of both genotypes exhibited a low lordosis quotient. It also did not affect their olfactory preference. Quantification of tyrosine hydroxylase- and kisspeptin-immunoreactive neurons in the preoptic area showed unaffected sexual dimorphism of both populations in mutants. By contrast, the number of androgen receptor- and ERα-immunoreactive cells was significantly increased in the bed nucleus of stria terminalis of mutant males. These data show that neural ERβ does not play a crucial role in the organization and activation of the neural circuitry underlying male sexual behavior. These discrepancies with the phenotype of global ERβ knockout models are discussed.

Estrogen receptor ESR1 mediates activation of ERK1/2, CREB, and ELK1 in the corpus of the epididymis

Expression of the estrogen receptor ESR1 is higher in the corpus than it is in the initial segment/caput and cauda of the epididymis. ESR1 immunostaining in the corpus has been localized not only in the nuclei but also in the cytoplasm and apical membrane, which indicates that ESR1 plays a role in membrane-initiated signaling. The present study investigated whether ESR1 mediates the activation of rapid signaling pathways by estradiol (E2) in the epididymis. We investigated the effect of E2 and the ESR1-selective agonist (4,4',4''-(4-propyl-(1H)-pyrazole-1,3,5-triyl)trisphenol (PPT) on the activation of extracellular signal-regulated protein kinases (ERK1/2), CREB protein, and ETS oncogene-related protein (ELK1). Treatment with PPT did not affect ERK1/2 phosphorylation in the cauda, but it rapidly increased ERK1/2 phosphorylation in the initial segment/caput and corpus of the epididymis. PPT also activated CREB and ELK1 in the corpus of the epididymis. The PPT-induced phosphorylation of ERK1/2, CREB, and ELK1 was blocked by the ESR1-selective antagonist MPP and by pretreatment with a non-receptor tyrosine kinase SRC inhibitor, an EGFR kinase inhibitor, an MEK1/2 inhibitor, and a phosphatidylinositol-3-kinase inhibitor. In conclusion, these results indicate that the corpus, which is a region with high expression of the estrogen receptor ESR1, is a major target in the epididymis for the activation of rapid signaling by E2. The sequence of events that follow E2 interaction with ESR1 includes the SRC-mediated transactivation of EGFR and the phosphorylation of ERK1/2, CREB, and ELK1. This rapid estrogen signaling may modulate gene expression in the corpus of the epididymis, and it may play a role in the dynamic microenvironment of the epididymal lumen.

Disruption of estrogen receptor signaling and similar pathways in the efferent ductules and initial segment of the epididymis

Seminiferous tubular atrophy may involve indirectly the disruption of estrogen receptor-α (ESR1) function in efferent ductules of the testis. ESR1 helps to maintain fluid resorption by the ductal epithelium and the inhibition or stimulation of this activity in rodent species will lead to fluid accumulation in the lumen. If not resolved, the abnormal buildup of fluid in the head of the epididymis and efferent ductules becomes a serious problem for the testis, as it leads to an increase in testis weight, tubular dilation and seminiferous epithelial degeneration, as well as testicular atrophy. The same sequence of pathogenesis occurs if the efferent ductule lumen becomes occluded. This review provides an introduction to the role of estrogen in the male reproductive tract but focuses on the various overlapping mechanisms that could induce efferent ductule dysfunction and fluid backpressure histopathology. Although efferent ductules are difficult to find, their inclusion in routine histological evaluations is recommended, as morphological images of these delicate tubules may be essential for understanding the mechanism of testicular injury, especially if dilations are observed in the rete testis and/or seminiferous tubules.

Signature Lesion:

The rete testis and efferent ductules can appear dilated, as if the lumens were greatly expanded with excess fluid or the accumulation of sperm. Because the efferent ductules resorb most of the fluid arriving from the rete testis lumen, one of two mechanisms is likely to be involved: a) reduced fluid uptake, which has been caused by the disruption in estrogen receptor signaling or associated pathways; or b) an increased rate of fluid resorption, which results in luminal occlusion. Both mechanisms can lead to a temporary increase in testicular weight, tubular dilation and atrophy of the seminiferous tubules.

Urinary bisphenol A levels in young men: association with reproductive hormones and semen quality

BACKGROUND

Few human studies have examined bisphenol A (BPA) exposure in relation to semen quality and reproductive hormones in men, and results are divergent.

OBJECTIVES

We examined associations between urinary BPA concentration and reproductive hormones, as well as semen quality, in young men from the general population.

METHODS

Our study population consisted of 308 young men from the general population. Urinary BPA concentration was measured by isotope dilution TurboFlow-liquid chromatography-tandem mass spectrometry. We used multiple linear regression analysis to estimate associations between BPA concentration and reproductive hormones and semen quality, adjusting for confounding factors.

RESULTS

We found that 98% of the men had detectable urinary levels of BPA. Median (5th-95th percentiles) BPA concentration was 3.25 ng/mL (0.59-14.89 ng/mL). Men with BPA concentrations above the lowest quartile had higher concentrations of serum testosterone, luteinizing hormone (LH), estradiol, and free testosterone compared with the lowest quartile (p trend ≤ 0.02). Men in the highest quartile of BPA excretion had on average 18% higher total testosterone (95% CI: 8, 28%), 22% higher LH (95% CI: 6, 39%), and 13% higher estradiol (95% CI: 4, 24%) compared with lowest quartile. Men in the highest quartile of BPA also had significantly lower percentage progressive motile spermatozoa compared with men in the lowest quartile (-6.7 percentage points, 95% CI: -11.76, -1.63). BPA was not associated with other semen parameters. Adjusting for dietary patterns did not influence the results.

CONCLUSIONS

The pattern of associations between BPA and reproductive hormones could indicate an antiandrogenic or antiestrogenic effect, or both, of BPA on the hypothalamic-pituitary-gonadal hormone feedback system, possibly through a competitive inhibition at the receptor level. However, additional research is needed to confirm our findings and to further test the suggested potential mechanisms.

Effects of the oestrogen receptor antagonist Fulvestrant on expression of genes that affect organization of the epididymal epithelium

The role of oestrogens in epididymal function is still unclear. Knockout of the oestrogen receptor ESR1 (Esr1(-/-) ) or treatment with the anti-oestrogen Fulvestrant affect epididymal milieu and sperm motility. We investigated the effect of in vivo treatment of rats with Fulvestrant on: (i) expression of genes that may be important for the architecture and function of the epididymal epithelium: prominins 1 and 2, metalloproteinase 7, claudin 7, beta-catenin and cadherin 13, and (ii) levels of oestradiol and testosterone, and expression of oestrogen and androgen receptors, in the initial segment (IS), caput, corpus and cauda epididymis. Fulvestrant (i) reduced gene expression of prominin 1 (variant 1) in the caput, reduced prominin 1 protein content in the caput epididymis and in the efferent ductules, and increased the localization of prominin 1 in microvilli of the caput and corpus; (ii) reduced gene expression of prominin 2 in the corpus and cauda epididymis; (iii) increased the metalloproteinase 7 content in the apical region of principal cells from IS/caput; (iv) reduced in the corpus epididymis, but increased in the efferent ductules, the cadherin 13 mRNA level; (v) reduced testosterone but increased oestradiol levels in the corpus and cauda; (vi) increased the androgen receptor protein content in all regions of the epididymis, and the oestrogen receptor GPER in the corpus and cauda epididymis. In conclusion, treatment with Fulvestrant induced regional-specific changes in hormonal and steroid receptor content, and affected expression of proteins important for epithelial organization and absorption/secretion. The mechanisms of oestrogen action may differ among epididymal regions, which may contribute to determine region-specific sperm functions.

Vitamin D and male reproduction

Vitamin D is a versatile signalling molecule with a well-established role in the regulation of calcium homeostasis and bone health. The spectrum of vitamin D target organs has expanded and the reproductive role of vitamin D is highlighted by expression of the vitamin D receptor (VDR) and enzymes that metabolize vitamin D in testis, male reproductive tract and human spermatozoa. The expression levels of VDR and CYP24A1 in human spermatozoa serve as positive predictive markers of semen quality, and VDR mediates a nongenomic increase in intracellular calcium concentration that induces sperm motility. Interestingly, functional animal models show that vitamin D is important for estrogen signalling and sperm motility, while cross-sectional studies support the positive association between serum 25-hydroxyvitamin D level and sperm motility in both fertile and infertile men. Expression of VDR and enzymes that metabolize vitamin D in fetal testis indicates a yet unknown role during development, which may be extrapolated from invasive testicular germ cell tumours where 1α,25-dihydroxyvitamin D induces a mesodermal differentiation of the pluripotent testicular cancer cells. Taken together, vitamin D signalling has a positive effect on semen quality, increases estrogen responsiveness and differentiates germ cell tumours. Future studies are needed to determine when 1α,25-dihydroxyvitamin D acts in a paracrine manner and whether systemic changes, which are subject to pharmacological modulation, could influence male reproductive function.

Characterization of the testicular, epididymal and endocrine phenotypes in the Leuven Vdr-deficient mouse model: targeting estrogen signalling

Vitamin D is a key factor for calcium and bone homeostasis, but signalling through the vitamin D receptor (VDR) seems also to be important for testicular function. To test the functional role of vitamin D signalling we examined the male reproductive system of the Leuven Vdr-ablated (Vdr(-/-)) mice, previously established as a model for hereditary vitamin D-resistant rickets. We investigated reproductive hormones, changes in gene expression and histological phenotype of eleven Vdr(-/-), eight Vdr(+/-) and nine Vdr(+/+) mice. Testicular and epididymal histology were grossly normal in Vdr(-/-) mice. Accordingly, no differences were found in serum concentrations of testosterone, estradiol, LH, and FSH or testicular expression of Cyp19a1, Ersα, Cyp17a1, Star, Insl3, Inhbb, and Amh. However, a significantly lower ERβ expression was found in testis of Vdr(+/-) and Vdr(-/-) mice, conversely epididymal expressions of ERα and the estrogen-target gene Aqp9 were higher. In conclusion, vitamin D seems dispensable for murine spermatogenesis and sex hormone production, but aberrant estrogen-signalling may elicit some of the VDR-mediated effects on male reproduction.

Classical estrogen receptors and ERα splice variants in the mouse

Estrogens exert a variety of effects in both reproductive and non-reproductive tissues. With the discovery of ERα splice variants, prior assumptions concerning tissue-specific estrogen signaling need to be re-evaluated. Accordingly, we sought to determine the expression of the classical estrogen receptors and ERα splice variants across reproductive and non-reproductive tissues of male and female mice. Western blotting revealed that the full-length ERα66 was mainly present in female reproductive tissues but was also found in non-reproductive tissues at lower levels. ERα46 was most highly expressed in the heart of both sexes. ERα36 was highly expressed in the kidneys and liver of female mice but not in the kidneys of males. ERβ was most abundant in non-reproductive tissues and in the ovaries. Because the kidney has been reported to be the most estrogenic non-reproductive organ, we sought to elucidate ER renal expression and localization. Immunofluorescence studies revealed ERα66 in the vasculature and the glomerulus. It was also found in the brush border of the proximal tubule and in the cortical collecting duct of female mice. ERα36 was evident in mesangial cells and tubular epithelial cells of both sexes, as well as podocytes of females but not males. ERβ was found primarily in the podocytes in female mice but was also present in the mesangial cells in both sexes. Within the renal cortex, ERα46 and ERα36 were mainly located in the membrane fraction although they were also present in the cytosolic fraction. Given the variability of expression patterns demonstrated herein, identification of the specific estrogen receptors expressed in a tissue is necessary for interpreting estrogenic effects. As this study revealed expression of the ERα splice variants at multiple sites within the kidney, further studies are warranted in order to elucidate the contribution of these receptors to renal estrogen responsiveness.