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

Sperm epigenetics and male infertility: unraveling the molecular puzzle

BACKGROUND

The prevalence of infertility among couples is estimated to range from 8 to 12%. A paradigm shift has occurred in understanding of infertility, challenging the notion that it predominantly affects women. It is now acknowledged that a significant proportion, if not the majority, of infertility cases can be attributed to male-related factors. Various elements contribute to male reproductive impairments, including aberrant sperm production caused by pituitary malfunction, testicular malignancies, aplastic germ cells, varicocele, and environmental factors.

MAIN BODY

The epigenetic profile of mammalian sperm is distinctive and specialized. Various epigenetic factors regulate genes across different levels in sperm, thereby affecting its function. Changes in sperm epigenetics, potentially influenced by factors such as environmental exposures, could contribute to the development of male infertility.

CONCLUSION

In conclusion, this review investigates the latest studies pertaining to the mechanisms of epigenetic changes that occur in sperm cells and their association with male reproductive issues.

APHRODITE criteria: addressing male patients with hypogonadism and/or infertility owing to altered idiopathic testicular function

RESEARCH QUESTION

Can a novel classification system of the infertile male - 'APHRODITE' (Addressing male Patients with Hypogonadism and/or infeRtility Owing to altereD, Idiopathic TEsticular function) - stratify different subgroups of male infertility to help scientists to design clinical trials on the hormonal treatment of male infertility, and clinicians to counsel and treat the endocrinological imbalances in men and, ultimately, increase the chances of natural and assisted conception?

DESIGN

A collaboration between andrologists, reproductive urologists and gynaecologists, with specialization in reproductive medicine and expertise in male infertility, led to the development of the APHRODITE criteria through an iterative consensus process based on clinical patient descriptions and the results of routine laboratory tests, including semen analysis and hormonal testing.

RESULTS

Five patient groups were delineated according to the APHRODITE criteria; (1) Hypogonadotrophic hypogonadism (acquired and congenital); (2) Idiopathic male infertility with lowered semen analysis parameters, normal serum FSH and normal serum total testosterone concentrations; (3) A hypogonadal state with lowered semen analysis parameters, normal FSH and reduced total testosterone concentrations; (4) Lowered semen analysis parameters, elevated FSH concentrations and reduced or normal total testosterone concentrations; and (5) Unexplained male infertility in the context of unexplained couple infertility.

CONCLUSION

The APHRODITE criteria offer a novel and standardized patient stratification system for male infertility independent of aetiology and/or altered spermatogenesis, facilitating communication among clinicians, researchers and patients to improve reproductive outcomes following hormonal therapy. APHRODITE is proposed as a basis for future trials of the hormonal treatment of male infertility.

Characterization and identification of extracellular vesicles-coupled miRNA profiles in seminal plasma of fertile and subfertile rabbit bucks

Seminal plasma (SP) provides essential nutrients, transport, and protection to the spermatozoa during their journey through the male and female reproductive tracts. Extracellular vesicles (EVs) are one of the main components of the SP with several biomolecular cargoes, including miRNAs, that can influence spermatozoa functions and interact with the cells of the female reproductive tract. This study aimed to isolate, characterize, and identify the miRNA expression profiles in the SP-EVs isolated from fertile (F) and subfertile (S) rabbit bucks that could serve as fertility biomarkers. In this study, the methods to isolate and identify EVs including exosomes, from SP of 3 F and S bucks have been developed. Ultracentrifugation and size exclusion chromatography analysis were using to isolate EVs from SP of F and S males that were qualitative and quantitively characterised using transmission electron microscopy, nanoparticle tracking analysis and western blotting. In addition, total RNA, including miRNA, was isolated, sequenced and identified from SP-EVs samples. Different SP-EVs concentrations (8.53 × 1011 ± 1.04 × 1011 and 1.84 × 1012 ± 1.75 × 1011 particles/mL of SP; P = 0.008), with a similar average size (143.9 ± 11.9 and 115.5 ± 2.4 nm; P = 0.7422) in F and S males, respectively was observed. Particle size was not significantly correlated with any kinetic parameter. The concentration of SP-EVs was positively correlated with the percentage of abnormal forms (r = 0.94; P < 0.05) and with the percentage of immotile spermatozoa (r = 0.88; P < 0.05). Small-RNA-seq analysis identified a total of 267 and 244 expressed miRNAs in the F and S groups, respectively. Two miRNAs (let-7b-5p and let-7a-5p) were the top most abundant miRNAs in both groups. Differential expression analysis revealed that 9 miRNAs including miR-190b-5p, miR-193b-5p, let-7b-3p, and miR-378-3p, and another 9 miRNAs including miR-7a-5p, miR-33a-5p, miR-449a-5p, and miR-146a-5p were significantly up- and downregulated in the F compared to the S group, respectively. The SP from F and S rabbit males contains EVs with different miRNA cargo correlated with spermatogenesis, homeostasis, and infertility, which could be used as biomarkers for male fertility and potential therapies for assisted reproductive technologies.

Transcriptomics-based analysis of sex-differentiated mechanisms of hepatotoxicity in zebrafish after long-term exposure to bisphenol AF

Bisphenol AF (BPAF) is an emerging endocrine-disrupting chemical (EDC) prevalent in the environment as one of the main substitutes for bisphenol A. Sex-specific effects of EDCs have been commonly reported and closely linked to sexually dimorphic patterns of hormone metabolism and related gene expression during different exposure windows, but our understanding of these mechanisms is still limited. Here, following 28-day exposure of adult zebrafish to an environmentally relevant concentration of BPAF at 10 μg/L, the global transcriptional networks applying RNA sequencing (RNA-seq) and Ingenuity Pathway Analysis (IPA) were respectively investigated in the male and female fish liver, connecting the sex-dependent toxicity of the long-term exposure of BPAF to molecular responses. As a result, more differentially expressed genes (DEGs) were detected in males (811) than in females (195), and spermatogenesis was the most enriched Gene Ontology (GO) functional classification in males, while circadian regulation of gene expression was the most enriched GO term in females. The expression levels of selected DEGs were routinely verified using qRT-PCR, which showed consistent alterations with the transcriptional changes in RNA-seq data. The causal network analysis by IPA suggested that the adverse outcomes of BPAF in males including liver damage, apoptosis, inflammation of organ, and liver carcinoma, associated with the regulation of several key DEGs detected in RNA-seq, could be linked to the activation of upstream regulatory molecules ifnα, yap1, and ptger2; while, the inhibition of upstream regulators hif1α, ifng, and igf1, leading to the down-regulated expression of several key DEGs, might be involved in BPAF's effects in females. Furthermore, BPAF exposure altered hepatic histological structure and inhibited antioxidant capability in both male and female livers. Overall, this study revealed different regulation networks involved in the sex-dependent effects of BPAF on the fish liver, and these detected DEGs upon BPAF exposure might be used as potential biomarkers for further assessing sex-specific hepatotoxicity following environmental EDC exposure.

Mating modifies the expression of crucial oxidative-reductive transcripts in the pig oviductal sperm reservoir: is the female ensuring sperm survival?

Background

Mating induces large changes in the female genital tract, warranting female homeostasis and immune preparation for pregnancy, including the preservation of crucial oxidative status among its pathways. Being highly susceptible to oxidative stress, sperm survival and preserved function depend on the seminal plasma, a protection that is removed during sperm handling but also after mating when spermatozoa enter the oviduct. Therefore, it is pertinent to consider that the female sperm reservoir takes up this protection, providing a suitable environment for sperm viability. These aspects have not been explored despite the increasing strategies in modulating the female status through diet control and nutritional supplementation.

Aims

To test the hypothesis that mating modifies the expression of crucial oxidative-reductive transcripts across the entire pig female genital tract (cervix to infundibulum) and, particularly in the sperm reservoir at the utero-tubal junction, before ovulation, a period dominated by estrogen stimulation of ovarian as well as of seminal origin.

Methods

The differential expression of estrogen (ER) and progesterone (PR) receptors and of 59 oxidative-reductive transcripts were studied using a species-specific microarray platform, in specific segments of the peri-ovulatory sow reproductive tract in response to mating.

Results

Mating induced changes along the entire tract, with a conspicuous downregulation of both ER and PR and an upregulation of superoxide dismutase 1 (SOD1), glutaredoxin (GLRX3), and peroxiredoxin 1 and 3 (PRDX1, PRDX3), among other NADH Dehydrogenase Ubiquinone Flavoproteins, in the distal uterus segment. These changes perhaps helped prevent oxidative stress in the area adjacent to the sperm reservoir at the utero-tubal junction. Concomitantly, there were a downregulation of catalase (CAT) and NADH dehydrogenase (ubiquinone) oxidoreductases 1 beta subcomplex, subunit 1 (NDUFB1) in the utero-tubal junction alongside an overall downregulation of CAT, SOD1, and PRDX3 in the ampullar and infundibulum segments.

Conclusions

Natural mating is an inducer of changes in the expression of female genes commanding antioxidant enzymes relevant for sperm survival during sperm transport, under predominant estrogen influence through the bloodstream and semen. The findings could contribute to the design of new therapeutics for the female to improve oxidative-reductive balance.

Quest for Biomarkers of Positive Health: A Review

The positive health of a person can be defined as the ability to live long in good health, possibly with no activity limitation. No method is yet available for its objective assessment in individuals, and we propose a framework in this communication that can operationalize this concept. Instead of distal factors, such as diet and lifestyle because these are subjective and difficult to measure, we concentrate on the objectively measurable biomarkers such as immunity level, endorphins, and handgrip strength. The focus is on the major parameters that may protect from diseases and infirmity and can be assessed by noninvasive methods. A combination of such parameters may signify positive health. This may be a novel way to measure positive health at the individual level. In this communication, we briefly review the literature and identify a few major biomarkers that provide a protective shield and could determine the status of positive health at the individual level. This exercise demonstrates that the assessment of the positive health of a person is feasible. A scale based on these and other relevant parameters can be developed later that could quantitatively measure the exact level of positive health. As the exact combination of the parameters that protects from ailments is not fully known yet, a framework such as this may help in identifying the data gaps that require attention in this context. The proposed framework may initiate a discussion on indicators of positive health and characterize the parameters for intervention that could increase a healthy life.

Follicle-stimulating hormone effectiveness in male idiopathic infertility: What happens in daily practice?

OBJECTIVES

To assess the effectiveness of follicle-stimulating hormone (FSH) administration in male idiopathic infertility in a clinical setting.

METHODS

A retrospective real-world study was carried out, including all consecutive FSH-treated infertile men attending the Andrology Unit of Modena (Italy) from June 2015 to May 2022. Medical history, physical and andrological examinations, hormonal and seminal parameters, therapeutic management and pregnancy data were collected. The primary endpoint was the number of pregnancies obtained after FSH administration, whereas semen parameters change was the secondary outcome.

RESULTS

A total of 194 of 362 (53.6%) infertile men, eligible according to the Italian Health System regulations, were treated with FSH (mean age 37.9 ± 6.1 years). Following FSH administration (mean therapy duration 9.1 ± 7.1 months), 43 pregnancies were recorded (27.6%), of which 22 occurred naturally and 21 after assisted reproduction. A significant increase in sperm concentration (9.9 ± 12.2 vs. 18.9 ± 38.9 million/mL, p = 0.045) was detected after treatment, together with a significant increase in normozoospermia (from 1.0% to 5.1%, p = .044) and a reduction in azoospermia rate (from 9.8% to 7%, p = 0.044). Dividing the cohort in FSH-responders and non-responders, in terms of pregnancy achieved, higher sperm concentrations (15.7 ± 26.6 vs. 22.2 ± 25.7 million/mL, p = 0.033) and progressive sperm motility (18.0 ± 18.2 vs. 27.3 ± 11.3, p = 0.044) were found in pregnancy group.

CONCLUSION

Our experience suggests that FSH, empirically administered to men with idiopathic infertility, leads to pregnancy in one out of four patients and increases sperm concentration. Although the expected limits because of a real-world data study, the number of FSH-treated patients required to achieve one pregnancy seems to be lower in clinical setting if compared to previously published data.

Estrogenic and Non-Estrogenic Disruptor Effect of Zearalenone on Male Reproduction: A Review

According to some estimates, at least 70% of feedstuffs and finished feeds are contaminated with one or more mycotoxins and, due to its significant prevalence, both animals and humans are highly likely to be exposed to these toxins. In addition to health risks, they also cause economic issues. From a healthcare point of view, zearalenone (ZEA) and its derivatives have been shown to exert many negative effects. Specifically, ZEA has hepatotoxicity, immunotoxicity, genotoxicity, carcinogenicity, intestinal toxicity, reproductive toxicity and endocrine disruption effects. Of these effects, male reproductive deterioration and processes that lead to this have been reviewed in this study. Papers are reviewed that demonstrate estrogenic effects of ZEA due to its analogy to estradiol and how these effects may influence male reproductive cells such as spermatozoa, Sertoli cells and Leydig cells. Data that employ epigenetic effects of ZEA are also discussed. We discuss literature data demonstrating that reactive oxygen species formation in ZEA-exposed cells plays a crucial role in diminished spermatogenesis; reduced sperm motility, viability and mitochondrial membrane potential; altered intracellular antioxidant enzyme activities; and increased rates of apoptosis and DNA fragmentation; thereby resulting in reduced pregnancy.

Expression of estrogen receptors, PELP1, and SRC in human spermatozoa and their associations with semen quality

Sperm cells are target cells for both estrogens and xenoestrogens. Due to the specific structure of spermatozoa, these hormonal compounds may act on sperm in a non-genomic mechanism only. However, the ESR-mediated signaling pathways are still poorly understood. In this study, we obtained 119 samples from male participants of Caucasian descent who donated semen for standard analysis. We analyzed gene expression of estrogen receptors (ESR1 and ESR2) and their coregulators-proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), and cellular kinase c-Src (SRC). RNA level was established using reverse-transcribed RNA as a template, followed by a polymerase chain reaction. Proteins' presence was confirmed by western blot and immunocytochemistry techniques. "Normal" values of semen parameters were defined as follows: > 32% sperm with progressive motility, > 4% sperm cells with normal morphology, > 15 × 10⁶ sperm per mL, > 58% live spermatozoa and leukocyte amount < 10⁶ cells per mL, according to WHO 2010 reference. Semen parameters that deviated from these "normal" values were labeled as "abnormal". Gene expression ratios revealed significant, moderate, and negative correlations for ESR1/ESR2 and weak, negative ESR2/PELP1 correlations in the subgroup of patients with abnormal values of semen parameters. In addition, SRC/PELP1 was moderately and positively correlated in the subgroup with parameters within the reference values established by WHO 2010. Our study showed that both PELP1 scaffolding protein and SRC kinase might influence semen quality via ESRs. It seems that not the expression of a single gene may affect the sperm quality, but more gene-to-gene mutual ratio. Characterization of estrogen-signaling pathway-related genes' modulated expression in sperm cells could aid in better understanding sperm biology and quality.

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.

Estrogen-related receptor is critical for testicular mitochondrial homeostasis and sperm motility: a Drosophila-based study

OBJECTIVE

To study the role of estrogen-related receptors (ERRs) in testicular function, with particular emphasis on mitochondrial homeostasis, testicular steroidogenesis, and sperm motility using Drosophila as a model.

DESIGN

Experimental study.

SETTING

Academic research laboratory.

ANIMAL(S)

Wild-type and transgenic strains of Drosophila melanogaster.

INTERVENTION(S)

Using a ribonucleic acid interference-based approach, ERR was knocked down specifically in the testes to generate Drosophila males with reduced ERR levels in their testes. Genetically matched sibling males without the knockdown formed the controls.

MAIN OUTCOME MEASURE(S)

Analysis of the testicular mitochondrial structure and function in relation to energy production, steroidogenesis, and sperm motility in Drosophila.

RESULT(S)

Depletion of ERR affects mitochondrial homeostasis (biogenesis, fission, fusion, mitophagy, and transport) and oxidative respiration in the testes. Consequently, ERR knockdown testes have significantly reduced mitochondrial size, mass, and depleted adenosine triphosphate levels resulting in testicular oxidative stress. Further, Halloween genes, associated with steroidogenesis in Drosophila, are misregulated in ERR knockdown testes, and knockdown of some of the steroidogenic genes in a testis-specific manner results in significantly reduced fertility. In addition, sperm from ERR knockdown testes have significantly reduced levels of glucose transporter, Na+K+ ATPase, Dynein heavy chain, and adenosine triphosphate-5α synthase essential for sperm function. Corroborating this, sperm from ERR knockdown males are significantly less motile compared with control.

CONCLUSION(S)

The ERR is crucial for meeting the cellular energy requirements of the testes and the generation of normal motile sperm and hormone synthesis/secretion in the testes. To our knowledge, this is the first report implicating ERR in these ultimate functions of the testes. These findings can potentially contribute to the etiologic understanding of asthenozoospermia or infertility at large in men.

Expression and Characterization of the Spats1 Gene and Its Response to E2/MT Treatment in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

Spats1 (spermatogenesis-associated, serinerich 1) has been characterized as a male-biased gene which acts an important role in the germ cell differentiation of mammals. Nevertheless, the function of Spats1 in the Chinese soft-shelled turtle (P. sinensis) has not yet been reported. To initially explore the expression of Spats1 in P. sinensis and its response to sex steroid treatment, we cloned the CDS of Spats1 for the first time and analyzed its expression profile in different tissues, including the testes in different seasons. The Spats1 cDNA fragment is 1201 base pairs (bp) in length and contains an open reading frame (ORF) of 849 bp, which codes for 283 amino acids. Spats1 mRNA was highly expressed in the testes (p < 0.01) and barely detectable in other tissues. In P. sinensis, the relative expression of Spats1 also responsive to seasonal changes in testis development. In summer (July) and autumn (October), Spats1 gene expression was significantly higher in the testes than in other seasons (p < 0.05). Spats1 mRNA was found to be specifically expressed in germ cells by chemical in situ hybridization (CISH), and it was mainly located in primary spermatocytes (Sc1), secondary spermatocytes (Sc2) and spermatozoa (St). Spats1 expression in embryos was not significantly changed after 17α-methyltestosterone (MT)and 17β-estradiol (E2) treatment. In adults, MT significantly induced Spats1 expression in male P. sinensis. However, the expression of Spats1 in testes was not responsive to E2 treatment. In addition, the expression of Spats1 in females was not affected by either MT or E2 treatment. These results imply that Spats1 is a male-specific expressed gene that is mainly regulated by MT and is closely linked to spermatogenesis and release in P. sinensis.

The association between serum estradiol levels and sperm DNA integrity

In men from the general population, BMI has been associated with a lower sperm DNA fragmentation index (DFI). We wondered whether this could be due to estradiol, which is associated with BMI and reported important for sperm function. Our objective was to investigate the association between estradiol and DFI. In 2008-2010, we recruited 284 young men from the general population to deliver samples of semen and blood and answer questionnaires. Serum concentrations of reproductive hormones and DFI were analyzed, the latter using the Sperm Chromatin Structure Assay. Associations were studied using general linear models. The first model utilized metric values of estradiol, whereas the second model compared men with high and low levels, dichotomized by the median value. A possible interaction between estradiol and testosterone was also examined. When investigating metric estradiol levels and DFI, an inverse association was seen without adjustments (p = .02), but the statistical significance was lost at adjustments for potential confounders (p = .08). Men with lower estradiol levels (<88 pmol/L, mean 71 pmol/L) had a statistically significantly higher DFI than men with higher levels of estradiol (≥88 pmol/L, mean 110 pmol/L). Mean ratio difference was 1.21 (p = .002) without adjustments and 1.18 (p = .01) with adjustments. A statistically significant difference in DFI was observed in men with testosterone levels below median when comparing high and low estradiol (p < .001). This study supports the idea that serum estradiol levels are protective for sperm DNA integrity, at least at lower testosterone levels.

Effects of prenatal and lactational bisphenol a and/or di(2-ethylhexyl) phthalate exposure on male reproductive system

Bisphenol A (BPA) and phthalates are abundantly used endocrine disrupting chemicals (EDCs). The aim of this study was to evaluate the effects of single and combined exposures to BPA and/or di(2-ethylhexyl) phthalate (DEHP) in prenatal and lactational period on rat male reproductive system in later stages of life. Pregnant Sprague-Dawley rats were divided randomly to four groups (n = 3/group): Control (corn oil); DEHP (30 mg/kg/day); BPA (50 mg/kg/day); and BPA+ DEHP (30 mg/kg/day DEHP and 50 mg/kg/day BPA). Groups exposed to EDCs through 6-21 gestational days and lactation period by intragastric lavage. Male offspring (n = 6/group) from each mother were fed till adulthood and were then euthanized. Later, reproductive hormones, sperm parameters, and oxidative stress parameters were determined. In conclusion, we can suggest that prenatal and lactational exposure to BPA and DEHP may cause adverse effects in male reproductive system in later stages of life especially after combined exposure.

Expression of G-Protein-Coupled Estrogen Receptor (GPER) in Whole Testicular Tissue and Laser-Capture Microdissected Testicular Compartments of Men with Normal and Aberrant Spermatogenesis

Simple Summary

Nowadays, there is no doubt that estrogens play an important role in male reproduction, affecting testicular cell differentiation, proliferation, apoptosis and metabolism. It is also widely believed that intratesticular balance of androgens and estrogens is crucial for the testicular development and function and that the increased testicular estrogen production may be associated with spermatogenic failure. There is also growing epidemiological evidence that the exposure of men to endocrine disruptors demonstrating estrogenic activity (xenoestrogens) may lead to impairment of male fertility via interference with estrogen signaling pathways. Besides the two classical nuclear estrogen receptors, the membrane-bound G protein-coupled estrogen receptor (GPER) was described in human testicular tissue. However, there are little data on its expression in testes with disturbed spermatogenesis. In this study, we investigated the GPER expression pattern in biopsies of azoospermic men with complete and aberrant spermatogenesis. Our results showed an increased expression of the GPER in testes with impaired spermatogenesis. Moreover, they indicate a possible involvement of estrogen signaling through GPER in disturbed function of Sertoli cells—the cells that support spermatogenic process.

Abstract

In this study, we retrospectively investigated GPER expression in biopsies of azoospermic men with complete (obstructive azoospermia—OA) and aberrant spermatogenesis (nonobstructive azoospermia—NOA). Each biopsy was histologically evaluated with morphometry. The testicular GPER expression was analyzed by the immunohistochemistry and RT-PCR technique in the whole testicular tissue and in seminiferous tubules and Leydig cells after laser-capture microdissection. In laser-microdissected compartments, we also analyzed transcriptional expression of selected Leydig (CYP17A1, HSD17B3, StAR) and Sertoli cell (AMH, SCF, BMP4) function markers. Immunohistochemical staining revealed expression of GPER in the cytoplasm of Leydig and Sertoli cells. Its stronger intensity was observed in Sertoli cells of NOA biopsies. The RT-PCR analysis of the GPER mRNA level unequivocally showed its increased expression in seminiferous tubules (i.e., Sertoli cells), not Leydig cells in NOA biopsies. This increased expression correlated positively with the transcriptional level of AMH—a marker of Sertoli cell immaturity, as well as FSH serum level in NOA but not in the OA group. Our results clearly demonstrate altered GPER expression in testes with primary spermatogenic impairment that might be related to Sertoli cell maturity/function.

Long-term exposure to environmental levels of phenanthrene disrupts spermatogenesis in male mice

Phenanthrene (Phe) is a tricyclic polycyclic aromatic hydrocarbon with high bioavailability under natural exposure. However, there are few studies on the reproductive toxicity of Phe in mammals. In this study, male Kunming mice were gavaged once every two days with Phe (5, 50, and 500 ng/kg) for 28 weeks. The accumulation levels of Phe in the testis were dose-dependently increased. Histopathological staining showed that Phe exposure reduced the number of spermatogonia, sperm and Sertoli cells. The percentage of testicular apoptotic cells was significantly increased, which was further verified by the upregulated BAX protein. The expression of the GDNF/PI3K/AKT signaling pathway was downregulated, which might suppress the self-renewal and differentiation of spermatogonial stem cells. Meanwhile, Phe exposure inhibited the expression of Sertoli cell markers (Fshr, WT1, Sox9) and the Leydig cell marker Cyp11a1, indicating damage to the function of Sertoli cells and Leydig cells. Serum estrogen and testicular estrogen receptor alpha were significantly upregulated, while androgen receptor expression was downregulated. These alterations might be responsible for impaired spermatogenesis. This study provides new insights for evaluating the reproductive toxicity and potential mechanisms of Phe in mammals.

Female sperm storage in the bonnethead Sphyrna tiburo oviducal gland: Immunolocalization of steroid hormone receptors in sperm storage tubules

Female sperm storage (FSS) has been demonstrated to occur in representatives from all major vertebrate groups and has been hypothesized to have several possible adaptive benefits that may maximize reproductive success of its practitioners. However, while the range of taxa that exhibit FSS and its possible evolutionary benefits have received significant attention in past years, the physiological mechanisms by which FSS occurs in vertebrates have only recently been explored. In this study, we examined the potential role of gonadal steroid hormones in regulating FSS in the bonnethead Sphyrna tiburo, a small hammerhead species in which females have been shown to be capable of storing male spermatozoa for up to 6 - 7 months following copulation. Like past studies on this species, we observed associations between plasma concentrations of the gonadal steroids 17β-estradiol, testosterone, and progesterone with FSS in female bonnetheads, suggesting roles for these hormones in regulating this process. Using immunohistochemistry, we also observed presence of androgen receptor, estrogen receptor alpha (ERα), and progesterone receptor in epithelial cells of sperm storage tubules in the bonnethead oviducal gland, as well as occurrence of ERα in stored spermatozoa, specifically during the sperm storage period. These results suggest that E₂, T, and P₄ may regulate certain aspects of FSS in bonnethead indirectly through actions on the female reproductive tract, whereas E₂ may also have direct effects on sperm function. This is the first study on the regulation of FSS in sharks and has formed a basis for future work geared towards improving our understanding of this process in chondrichthyans.

Associations of serum estradiol level, serum estrogen receptor-alpha level, and estrogen receptor-alpha polymorphism with male infertility: A retrospective study

Estradiol regulates spermatogenesis partly via estrogen receptor-alpha (ESRα). This study aimed to analyze the associations of serum estradiol level, serum ESRα level, and ESRα gene polymorphisms with sperm quality.This retrospective study included infertile men attending the Reproductive Center, Affiliated Hospital of Youjiang Medical University for Nationalities, and a control group without a history of fertility (October, 2016 to March, 2017). Data regarding sperm quality, serum levels of estradiol and ESRα, and rs2234693C/T genotype were extracted from the medical records. Pearson/Spearman correlations (as appropriate) between estradiol level, ESRα level, and sperm quality parameters were evaluated.The analysis included 215 men with infertility and 83 healthy controls. The infertile group had higher serum levels of estradiol (147.57 ± 35.3 vs 129.62 ± 49.11 pg/mL, P < .05) and ESRα (3.02 ± 2.62 vs 1.33 ± 0.56 pg/mL, P < .05) than the control group. For the infertile group, serum estradiol level was negatively correlated with sperm concentration, percentage of progressively motile sperm, and percentage of sperm with normal morphology (r = 0.309, 0.211, and 0.246, respectively; all P < .05). Serum estradiol and ESRα levels were lower in infertile men with normozoospermia than in those with azoospermia, oligozoospermia, mild azoospermia, or malformed spermatozoa (all P < .05). Sperm concentration, percentage of progressively motile sperm, serum ESRα level, and serum estradiol level did not differ significantly among the rs2234693 CC, CT, and TT genotypes.Elevated serum levels of estradiol and possibly ESRα might have a negative impact on sperm quality and fertility, whereas single nucleotide polymorphisms at rs2234693 of the ESRα gene had little or no effect.

Perfluorooctane sulfonate interferes with non-genomic estrogen receptor signaling pathway, inhibits ERK1/2 activation and induces apoptosis in mouse spermatocyte-derived cells

Perfluorooctane sulfonate (PFOS) is a widespread persistent organic pollutant. Both epidemiological survey and our previous in vivo study have revealed the associations between PFOS exposure and spermatogenesis disorder, while the underlying mechanisms are far from clear. In the present study, GC-2 cells, a mouse spermatocyte-derived cell line, was used to investigate the toxic effects of PFOS and its hypothetical mechanism of action. GC-2 cells were treated with PFOS (0, 50, 100 and 150 μM) for 24 h or 48 h. Results demonstrated that PFOS dose-dependently inhibited cell viability, induced G0/G1 cell cycle arrest and triggered apoptosis, which might be partly explained by the decrease in cyclin D1, PCNA and Bcl-2 protein expression; increase in Bax protein expression; and activation of caspase-9, -3. In addition, PFOS did not directly transactivate or repress estrogen receptors (ERs) in gene reporter assays, whereas the protein levels of both ERα and ERβ were significantly altered and the downstream ERK1/2 phosphorylation was inhibited by PFOS. Furthermore, pretreatment with specific ERα agonist PPT (1 μM) significantly attenuated the above PFOS-induced effects while specific ERβ agonist DPN (1 μM) accelerated them. These results suggest that PFOS may induce growth inhibition and apoptosis via non-genomic estrogen receptor/ERK1/2 signaling pathway in GC-2 cells, which provides a novel insight regarding the potential role of ERs in mediating PFOS-triggered spermatocyte toxicity.

Impact of Estrogens Present in Environment on Health and Welfare of Animals

Simple Summary

Estrogens are a group of steroid hormones that recently have gained even more attention in the eyes of scientists. There is an ongoing discussion in the scientific community about their relevance as environmental contaminants and the danger they pose to animal health and welfare. In available literature we can find many examples of their negative effects and mechanisms that are involved with such phenomena.

Abstract

Nowadays, there is a growing interest in environmental pollution; however, knowledge about this aspect is growing at an insufficient pace. There are many potential sources of environmental contamination, including sex hormones—especially estrogens. The analyzed literature shows that estrone (E1), estradiol (E2), estriol (E3), and synthetic ethinyloestradiol (EE2) are the most significant in terms of environmental impact. Potential sources of contamination are, among others, livestock farms, slaughterhouses, and large urban agglomerations. Estrogens occurring in the environment can negatively affect the organisms, such as animals, through phenomena such as feminization, dysregulation of natural processes related to reproduction, lowering the physiological condition of the organisms, disturbances in the regulation of both proapoptotic and anti-apoptotic processes, and even the occurrence of neoplastic processes thus drastically decreasing animal welfare. Unfortunately, the amount of research conducted on the negative consequences of their impact on animal organisms is many times smaller than that of humans, despite the great richness and diversity of the fauna. Therefore, there is a need for further research to help fill the gaps in our knowledge.

Exposure to fine particulate matter-bound polycyclic aromatic hydrocarbons, male semen quality, and reproductive hormones: The MARCHS study

Exposure to outdoor fine particulate matter (PM_2.5)-bound polycyclic aromatic hydrocarbons (PAHs) is linked to reproductive dysfunction. However, it is unclear which component of PAHs is responsible for the adverse outcomes. In the Male Reproductive Health in Chongqing College Students (MARHCS) cohort study, we measured the exposure levels of 16 PAHs by collecting air PM_2.5 particles and assessed eight PAHs metabolites from four parent PAHs, including naphthalene, fluorene, phenanthrene, and pyrene in urine samples. We investigated compositional profiles and variation characteristics for 16 PAHs in PM_2.5, and then assessed the association between PAHs exposure and semen routine parameters, sperm chromatin structure, and serum hormone levels in 1452 samples. The results showed that naphthalene (95% CI: -17.989, -8.101), chrysene (95% CI: -64.894, -47.575), benzo[a]anthracene (95% CI: -63.227, -45.936) and all the high molecular weight (HMW) PAHs in PM_2.5 were negatively associated with sperm normal morphology. Most of the low molecular weight (LMW) PAHs, such as acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, ∑LMW PAHs and ∑16 PAHs, were correlated with increased sperm motility (all corrected P < 0.05). On the other hand, sperm normal morphology was all negatively associated with urinary metabolites of ∑OH-Nap (95% CI: -5.611, -0.536), ∑OH-Phe (95% CI: -5.741, -0.957), and ∑OH-PAHs (95% CI: -5.274, -0.361). Urinary concentrations of ∑OH-PAHs were found to be negatively associated with sperm high DNA stainability (HDS) (P = 0.023), while ∑OH-Phe were negatively associated with serum testosterone level and sperm HDS (P = 0.004). Spearman correlation analysis showed that except for the urinary OH-Nap metabolites, the rest of the urinary OH-PAHs metabolites were negatively correlated with their parent PAHs in air. The results of this study suggest that various PAHs' components may affect reproductive parameters differently. Inhalation of PAHs in air, especially HMW PAHs, may be a potential risk factor for male reproductive health.

Acute effects of short-term exposure to ambient air pollution on reproductive hormones in young males of the MARHCS study in China

Air pollution, which is associated with male reproductive health. However, it is unknown the acute effects of ambient air pollutants exposure on male reproductive hormones. The current study, we measured serum levels of reproductive hormone in 2030 blood samples gathered from The Male Reproductive Health in Chongqing College Students (MARHCS) cohort study. We derived a full coverage of ambient air pollutant (PM₁₀, PM_2.5, SO₂, NO₂, CO and O₃) concentrations by employing machine learning algorithms, and used a mixed-effect model to estimate single-day and cumulative effects of air pollutants exposure on serum reproductive hormones. Our results showed that (1) PM₁₀ and PM_2.5 concentrations were positively associated with estradiol (E₂) in both single and cumulative lag days, but were negatively associated with the ratio of Testosterone/E₂ (the T/E₂ ratio). NO₂ was positively associated with estradiol at lag day 2 (95% CI: 0.290, 0.881; corrected P = 0.048) and lag 0-2 days (95% CI: 0.523, 1.337; corrected P = 0.003), with progesterone (P) at lag day 2 and lag day 3 (corrected P < 0.05). There was also a positive association between CO exposure and progesterone at lag day 2. (2) SO₂ was inversely associated with E₂ at lag day 3, 4 and lag 0-4 days, and progesterone at lag day 0, 1, 2 and lag 0-1, 0-2, 0-4 days, but positively associated with the T/E₂ ratio at lag day 3, 4 and lag 0-4 days (corrected P < 0.05). O₃ exposure was negatively associated with E₂ at lag day 3 (95% CI: -0.216, -0.074, corrected P = 0.03). (3) No significant associations were found between the cumulative daily average air pollutant exposure of CO, O₃ and hormone outcomes. This study suggests that short-term exposure to air pollutants may thus alter reproductive hormone levels, especially on serum estradiol, progesterone levels and the T/E₂ ratio.

Kinetic Study of 17α-Estradiol Activity in Comparison with 17β-Estradiol and 17α-Ethynylestradiol

17α-estradiol (αE2), an endogenous stereoisomer of the hormone 17β-estradiol (E2), is capable of binding to estrogen receptors (ER). We aimed to mathematically describe, using experimental data, the possible interactions between αE2 and sperm ER during the process of sperm capacitation and to develop a kinetic model. The goal was to compare the suggested kinetic model with previously published results of ER interactions with E2 and 17α-ethynylestradiol (EE2). The HPLC-MS/MS method was developed to monitor the changes of αE2 concentration during capacitation. The calculated relative concentrations Bt were used for kinetic analysis. Rate constants k and molar ratio n were optimized and used for the construction of theoretical B(t) curves. Modifications in αE2–ER interactions were discovered during comparison with models for E2 and EE2. These new interactions displayed autocatalytic formation of an unstable adduct between the hormone and the cytoplasmic receptors. αE2 accumulates between the plasma membrane lipid bilayer with increasing potential, and when the critical level is reached, αE2 penetrates through the inner layer of the plasma membrane into the cytoplasm. It then rapidly reacts with the ER and creates an unstable adduct. The revealed dynamics of αE2–ER action may contribute to understanding tissue rejuvenation and the cancer-related physiology of αE2 signaling.

A Potential Relationship Between Estrogen Receptors Polymorphisms, Sperm Function and in vitro Fertilization Success: A Preliminary Study*

Background: Estrogen receptor 1 (ESR1) and 2 (ESR2) play an important role in regulating fertility in the human reproductive system. Polymorphisms of these receptor genes have been implicated in male infertility in both Chinese and Caucasian populations. However, studies have produced inconsistent results. Spermatozoa defects that result in conception deficiencies could be related to estrogens, their receptors, or genes involved in estrogen-related pathways. This study aims to explore the potential association between the ESR1 and the ESR2 polymorphisms in relation to semen parameters of Caucasian males as well as fertilization success. Materials/Methods: A total of 116 males were included in this study. Forty couples underwent conventional in vitro fertilization, while 76 couples were treated by intracytoplasmic sperm injection. Standard semen analyses were performed according to the World Health Organization criteria. Polymerase chain reaction and restriction fragment length polymorphisms were used to determine genotype and allele distributions. Results: A strong association between the ESR1 rs2234693 recognized by PvuII enzyme, genotype/allele distribution and fertilization success was shown. The T allele occurrence was significantly lower in the case of fertilization failure (p = 0.02). Additionally, the TT genotype was absent in the same group (p=0.02). In the case of the remaining analyzed polymorphisms, little to no interdependence of genotype/allele distribution and fertilization success was noted. Conclusions: Apart from ESR1 rs2234693, the study failed to demonstrate that fertilization success was associated with the selected polymorphisms. In most cases, we did not discover a relationship between both estrogen receptors polymorphisms and sperm function.

Unraveling the Balance between Genes, Microbes, Lifestyle and the Environment to Improve Healthy Reproduction

Humans’ health is the result of a complex and balanced interplay between genetic factors, environmental stimuli, lifestyle habits, and the microbiota composition. The knowledge about their single contributions, as well as the complex network linking each to the others, is pivotal to understand the mechanisms underlying the onset of many diseases and can provide key information for their prevention, diagnosis and therapy. This applies also to reproduction. Reproduction, involving almost 10% of our genetic code, is one of the most critical human’s functions and is a key element to assess the well-being of a population. The last decades revealed a progressive decline of reproductive outcomes worldwide. As a consequence, there is a growing interest in unveiling the role of the different factors involved in human reproduction and great efforts have been carried out to improve its outcomes. As for many other diseases, it is now clear that the interplay between the underlying genetics, our commensal microbiome, the lifestyle habits and the environment we live in can either exacerbate the outcome or mitigate the adverse effects. Here, we aim to analyze how each of these factors contribute to reproduction highlighting their individual contribution and providing supporting evidence of how to modify their impact and overall contribution to a healthy reproductive status.

Long-term stiripentol administration, an anticonvulsant drug, does not impair sperm parameters in rats

In this study, we investigated the influence of long-term administration of stiripentol on sex hormones and semen quality in young Wistar rats. Investigated animals received for 6 months either stiripentol or saline solution. After one month, stiripentol increased temporarily serum level of testosterone (p < 0.05) and FSH (p < 0.01). However, after 6 months levels of testosterone, FSH, LH, prolactin and SHBG were comparable in both groups. After 6 months, semen analysis did not reveal differences in sperm concentration, total sperm count and sperm motility between groups. However, stiripentol increased the rate of head defect (p < 0.001) and midpiece abnormalities (p < 0.05). Flow cytometry revealed higher percentage of live cells without lipid peroxidation (p < 0.00001) and higher percentage of live spermatozoa with intact acrosomes (p < 0.000001) in rats receiving stiripentol. There was no significant difference between groups in sperm mitochondrial activity and DNA fragmentation index. However, percentage of high DNA stainability cells was increased in stiripentol group (p < 0.001). The data showed that stiripentol does not cause obvious disturbances in young rat's semen. Detected changes in semen morphology and chromatin structure need further explanation, and their influence on rat's fertility should be evaluated.

The effects of sesame oil and different doses of estradiol on testicular structure, sperm parameters, and chromatin integrity in old mice

Objective

Studies of the effects of estrogens on the male reproductive system have emphasized the role of these hormones in male fertility. Sesame oil has many phytoestrogenic compounds and may improve male fertility. This study investigated the effects of sesame oil and different concentrations of estrogen on sperm parameters and DNA integrity in male mice.

Methods

Twenty old NMRI (The Naval Medical Research Institute) male mice (40 weeks; weight, 30–35 g) were treated with sesame oil or different concentrations of estrogen (estradiol, 1 and 10 μL/kg/day) or received no treatment (controls). After 35 days, sperm parameters and DNA integrity were assessed and analyzed.

Results

Sperm count, progressive motility, and morphology were decreased in the group that received 10 μL/kg of estradiol. A remarkably lower percentage of DNA fragmentation and protamine deficiency were detected in the group that received 1 μL/kg of estradiol. In the groups that received sesame oil and 1 μL/kg of estradiol, the numbers of spermatogonia and Leydig cells were higher than in controls. The combination of sesame oil and 1 μL/kg of estradiol led to improved sperm parameters and chromatin and testicular structure.

Conclusion

Based on this study, consumption of sesame oil and a low concentration of estradiol may improve testicular function in older mice.

Systematic Identification of Molecular Targets and Pathways Related to Human Organ Level Toxicity

The mechanisms leading to organ level toxicities are poorly understood. In this study, we applied an integrated approach to deduce the molecular targets and biological pathways involved in chemically induced toxicity for eight common human organ level toxicity end points (carcinogenicity, cardiotoxicity, developmental toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, reproductive toxicity, and skin toxicity). Integrated analysis of in vitro assay data, molecular targets and pathway annotations from the literature, and toxicity-molecular target associations derived from text mining, combined with machine learning techniques, were used to generate molecular targets for each of the organ level toxicity end points. A total of 1516 toxicity-related genes were identified and subsequently analyzed for biological pathway coverage, resulting in 206 significant pathways (p-value <0.05), ranging from 3 (e.g., developmental toxicity) to 101 (e.g., skin toxicity) for each toxicity end point. This study presents a systematic and comprehensive analysis of molecular targets and pathways related to various in vivo toxicity end points. These molecular targets and pathways could aid in understanding the biological mechanisms of toxicity and serve as a guide for the design of suitable in vitro assays for more efficient toxicity testing. In addition, these results are complementary to the existing adverse outcome pathway (AOP) framework and can be used to aid in the development of novel AOPs. Our results provide abundant testable hypotheses for further experimental validation.

Targeting Toll-like receptor 4 with CLI-095 (TAK-242) enhances the antimetastatic effect of the estrogen receptor antagonist fulvestrant on non-small cell lung cancer

PURPOSE

Estrogen plays a critical role in the invasiveness and metastasis of non-small cell lung cancer (NSCLC) through estrogen receptor β (ERβ). However, the antimetastatic effect of the ERβ antagonist fulvestrant was still limited in NSCLC patients. Recently, Toll-like receptor 4 (TLR4) signaling was implicated in NSCLC metastasis. Our present study aimed to evaluate the synergistic antimetastatic effect of a combination of fulvestrant and the TLR4-specific inhibitor CLI-095 (TAK-242) on human NSCLC cells.

METHODS

The expression levels of ERβ and TLR4 were detected by immunohistochemical (IHC) analysis of 180 primary NSCLC and 30 corresponding metastatic lymph node samples. The association between ERβ and TLR4 expression was analyzed. The aggressiveness of NSCLC cells treated with fulvestrant, CLI-095 or the drug combination and formation status of their invadopodia, invasion-associated structures, were investigated. The protein levels in NSCLC cells in different groups were determined by Western blot and immunofluorescence analyses.

RESULTS

Here, a positive correlation between ERβ and TLR4 expression was observed in both primary NSCLC tissue (Spearman's Rho correlation coefficient = 0.411, p < 0.001) and metastatic lymph node tissue (Spearman's Rho correlation coefficient = 0.374, p = 0.009). The protein levels of ERβ in NSCLC cell lines were decreased by fulvestrant, and this suppressive effect was significantly enhanced when fulvestrant was combined with CLI-095 (p < 0.05). Both the migration and invasion of NSCLC cells were suppressed by fulvestrant or CLI-095 alone, and the combination of fulvestrant + CLI-095 showed the strongest inhibitory effect (p < 0.05). In addition, the results demonstrated that CLI-095 also helped fulvestrant restrict the formation and function of invadopodia in NSCLC cells (p < 0.05).

CONCLUSIONS

Collectively, our study results suggested that CLI-095 enhances the antimetastatic effect of fulvestrant on NSCLC and provided support for further investigation of the antitumor activity of combined therapy with antiestrogen and anti-TLR4 agents in the clinic.

Gestational and pubertal exposure to low dose of di-(2-ethylhexyl) phthalate impairs sperm quality in adult mice

Di-(2-ethylhexyl)-phthalate (DEHP) is a compound widely used as a plasticizer, which can leach from plastics into the environment and thus influence human health. The aim of this study was to analyze whether exposure to an environmentally relevant dose of DEHP during mice fetal development or puberty can cause long-lasting changes detectable month/s after the last exposure. We used a DEHP concentration relevant to a daily human intake of 2.4-3 μg/kg of body weight/day. CD1 outbred mice were treated either in utero or postnatally during puberty and analyzed in adulthood. Analyzing fertility parameters using morphometric, histologic, genomic and proteomic methods we showed that DEHP exposure leads to decreased sperm concentration and quality, in both experimental groups. Moreover, the changes in anogenital distance, seminal vesicle weight, and testicular gene expression suggest a disturbance of androgen signaling in exposed animals. In conclusion, we hereby present, that the prenatal and pubertal exposure to a low dose of DEHP negatively influenced reproductive endpoints in male mice, and some of the effects were persistent until adulthood.

Gene X environment: the cellular environment governs the transcriptional response to environmental chemicals

Background

An individual’s response to environmental exposures varies depending on their genotype, which has been termed the gene-environment interaction. The phenotype of cell exposed can also be a key determinant in the response to physiological cues, indicating that a cell-gene-environment interaction may exist. We investigated whether the cellular environment could alter the transcriptional response to environmental chemicals. Publicly available gene expression array data permitted a targeted comparison of the transcriptional response to a unique subclass of environmental chemicals that alter the activity of the estrogen receptor, xenoestrogens.

Results

Thirty xenoestrogens were included in the analysis, for which 426 human gene expression studies were identified. Comparisons were made for studies that met the predefined criteria for exposure length, concentration, and experimental replicates. The cellular response to the phytoestrogen genistein resulted in remarkably unique transcriptional profiles in breast, liver, and uterine cell-types. Analysis of gene regulatory networks and molecular pathways revealed that the cellular context mediated the activation or repression of functions important to cellular organization and survival, including opposing effects by genistein in breast vs. liver and uterine cell-types. When controlling for cell-type, xenoestrogens regulate unique gene networks and biological functions, despite belonging to the same class of environmental chemicals. Interestingly, the genetic sex of the cell-type also strongly influenced the transcriptional response to xenoestrogens in the liver, with only 22% of the genes significantly regulated by genistein common between male and female cells.

Conclusions

Our results demonstrate that the transcriptional response to environmental chemicals depends on a variety of factors, including the cellular context, the genetic sex of a cell, and the individual chemical. These findings highlight the importance of evaluating the impact of exposure across cell-types, as the effect is responsive to the cellular environment. These comparative genetic results support the concept of a cell-gene-environment interaction.

Imidacloprid disrupts the endocrine system by interacting with androgen receptor in male mice

In the current study, six-week-old male ICR mice were administered imidacloprid (IMI) at concentrations of 3, 10 and 30 mg/L for a duration of 10 weeks to investigate the toxicity of IMI on the endocrine system. We observed that testicular morphology was severely impaired and damaged, and the levels of serum testosterone (T) and the expression of androgen receptor (AR) decreased significantly. Molecular docking analysis suggested that IMI docks into the active site of AR successfully and that three key hydrogen bonds were formed with the active site residues Glu11, Gln41 and Lys138. The binding free energy value of the AR-IMI complex suggested a stable binding between IMI and AR. All these results indicated that IMI could interact with AR. In addition, major genes in the testis involved in the synthesis of cholesterol and T were generally inhibited, and the serum cholesterol sources were also reduced. Moreover, the aromatase in male mice was lacking after subchronic IMI exposure. The data acquired from the present study indicated that IMI could lead to endocrine disruption by interacting with AR and influence the expression of genes involved in the production of T in male mice.

Kinetic Model of the Action of 17α-Ethynylestradiol on the Capacitation of Mouse Sperm, Monitored by HPLC-MS/MS

17α-Ethynylestradiol (EE2), a synthetic estrogen used in contraceptive pills, is resistant to hepatic degradation and is excreted in the urine. It is chemically stable and has a negative impact on the endocrine system. The aim of this work was to mathematically describe the possible interaction of EE2 (200, 20, and 2 μg/L) with sperm estrogen receptors during sperm maturation, which is called capacitation. The concentrations of the unbound EE2 remaining in capacitating medium during 180 min of sperm capacitation were determined at 30 min intervals by high performance liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS) and the data obtained (relative concentrations Bt) were subjected to kinetic analysis. The suggested kinetic schema was described by the system of differential equations with the optimization of rate constants used to calculate the theoretical Bt values. Optimal parameters (overall rate constants K1–K5 and molar ratio n) were determined by searching the minimum of absolute values of the difference between theoretical and experimental Bt values. These values were used for the design of the theoretical B(t) curves which fit to experimental points. The proposed kinetic model assumes the formation of an unstable adduct between EE2 and the receptor in cytoplasm, which acts as an autocatalytic agent and gradually decomposes.

Multifactorial control of reproductive and growth axis in male goldfish: Influences of GnRH, GnIH and thyroid hormone

Reproduction and growth are under multifactorial control of neurohormones and peripheral hormones. This study investigated seasonally related effects of GnIH, GnRH, and T3 on the reproductive and growth axis in male goldfish at three stages of gonadal recrudescence. The effects of injection treatments with GnRH, GnIH and/or T3 were examined by measuring serum LH and GH levels, as well as peripheral transcript levels, using a factorial design. As expected, GnRH elevated serum LH and GH levels in a seasonally dependant manner, with maximal elevations of LH in late stages of gonadal recrudescence (Spring) and maximal increases in GH in the regressed gonadal stage (Summer). GnIH injection increased serum LH and GH levels only in fish at the regressed stage but exerted both stimulatory and inhibitory effects on GnRH-induced LH responses depending on season. T3 treatment mainly had stimulatory effects on circulating LH levels and inhibitory effects on serum GH concentrations. In the liver and testes, we observed seasonal differences in thyroid receptors, estrogen receptors, vitellogenin, follicle-stimulating hormone receptor, aromatase and IGF-I transcript levels that were tissue- and sex-specific. Generally, there were no clear correlation between circulating LH and GH levels and peripheral transcript levels, presumably due to time-related response and possible direct interaction of GnRH and GnIH at the level of liver and testis. The results support the hypothesis that GnRH and GnIH are important components of multifactorial mechanisms that work in concert with T3 to regulate reciprocal control of reproduction and growth in goldfish.

Missing Information from the Estrogen Receptor Puzzle: Where Are They Localized in Bull Reproductive Tissues and Spermatozoa?

Estrogens are steroid hormones that affect a wide range of physiological functions. The effect of estrogens on male reproductive tissues and sperm cells through specific receptors is essential for sperm development, maturation, and function. Although estrogen receptors (ERs) have been studied in several mammalian species, including humans, they have not yet been described in bull spermatozoa and reproductive tissues. In this study, we analyzed the presence of all types of ERs (ESR1, ESR2, and GPER1) in bull testicular and epididymal tissues and epididymal and ejaculated spermatozoa, and we characterize them here for the first time. We observed different localizations of each type of ER in the sperm head by immunofluorescent microscopy. Additionally, using a selected polyclonal antibody, we found that each type of ER in bull sperm extracts had two isoforms with different molecular masses. The detailed detection of ERs is a prerequisite not only for understanding the effect of estrogen on all reproductive events but also for further studying the negative effect of environmental estrogens (endocrine disruptors) on processes that lead to fertilization.

Increased expression of PELP1 in human sperm is correlated with decreased semen quality

Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) is a scaffolding protein involved in both genomic and nongenomic estrogen signal transduction pathways. To date, the role of PELP1 protein has yet to be characterized in human sperm and has not been associated with sperm parameters. To confirm the presence of PELP1 in human sperm, fresh semen samples were obtained from 178 donors. The study was designed to establish both mRNA and protein presence, and protein cellular localization. Additionally, the number of PELP1-positive spermatozoa was analyzed in men with normal and abnormal semen parameters. Sperm parameters were assessed according to the World Health Organization (WHO) 2010 standards. The presence of PELP1 in spermatozoa was investigated using four precise, independent techniques. The qualitative presence of transcripts and protein was assessed using reverse transcription-polymerase chain reaction (RT-PCR) and western blot protocols, respectively. The cellular localization of PELP1 was investigated by immunocytochemistry. Quantitative analysis of PELP1-positive cells was done by flow cytometry. PELP1 mRNA and protein was confirmed in spermatozoa. Immunocytochemical analysis identified the presence of PELP1 in the midpieces of human sperm irrespective of sperm parameters. Becton Dickinson fluorescence-activated cell sorting (FACSCalibur™) analysis revealed a significantly lower number of PELP1-positive cells in males with normal semen parameters versus abnormal samples (42.78% ± 11.77% vs 61.05% ± 21.70%, respectively; P = 0.014). The assessment of PELP1 may be a time-saving method used to obtain information about sperm quality. The results of our study suggest that PEPL1 may be utilized as an indicator of sperm quality; thereby, PELP1 may be an additional biomarker useful in the evaluation of male infertility.

Photostimulation and thermotaxis of sperm: Overview and practical implications in porcine reproduction

The journey of mammalian sperm through the female genital tract requires the existence of a myriad of mechanisms that allow cells to reach the oviduct in a timely manner from the place of semen deposition. Several biochemical mechanisms such as signaling through molecules like bicarbonate, neurotransmitters or even glycosaminoglycanes are known and have been studied by several relevant groups worldwide. However, biophysical mechanisms for sperm transport are much less studied and understood. Thermotaxis, for example, is a powerful, physical signaling system that is known to direct sperm inside the female genital tract, although the intimate mechanisms by which this effect is launched are yet to be elucidated. This review is focuses on the analysis of thermotaxis and its possible relationship with another phenomenon that has been observed in sperm from a variety of species, namely photostimulation. An overall review on sperm thermotaxis and putative mechanism/s that can be involved in this phenomenon is developed, followed by a description of the most recent findings on the mechanisms underlying sperm photostimulation, highlighting its possible relationship with thermotactic mechanisms. Finally, an overview regarding some practical implications of the phototactic/thermotactic phenomenon has been included in order to evaluate the possible use of techniques based on these phenomena as tools for improving pig reproduction.

Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)

Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E₂) in males of this species shows seasonal variations but, since testes of R. arenarum do not express aromatase, the source of plasma E₂ remained unknown for several years. However, the Bidder's organ (BO), a structure located at one pole of each testis, is proposed to be the main source of E₂ in male's toads since it expresses several steroidogenic enzymes and is able to produce E₂ from endogenous substrates throughout the year. In addition, there were significant correlations between plasma E₂ and total activity of BO aromatase, and between plasma E₂ and the amount of hormone produced by the BO in vitro. In the toad, apoptosis induced by in vitro treatment with E₂ was mostly detected in spermatocytes during the breeding and in spermatids during the post-reproductive season, suggesting that this steroid has an important role in controlling spermatogenesis. However, in vitro treatment with E₂ had no effect on proliferation. This evidence suggests that the mechanism of action of E₂ on amphibian spermatogenesis is complex and more studies are necessary to fully understand the role of estrogens regulating the balance between cellular proliferation and apoptosis. In addition, in R. arenarum in vitro studies suggested that E₂ has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) activity during the post reproductive season. As well, E₂ regulates FSHβ mRNA expression all over the year suggesting a down regulation process carried out by this steroid. The effect on LHβ mRNA is dual, since during the reproductive season estradiol increases the expression of LHβ mRNA while in the non-reproductive season it has no effect. In conclusion, the effect of E₂ on gonadotropins and testicular function is complex, not clearly understood and probably varies depending on the species. The aim of the current article is to review evidence on reproductive endocrinology and on the role of estradiol regulating reproduction in amphibians, with emphasis on the South American species Rhinella arenarum.

New Insight into Sperm Capacitation: A Novel Mechanism of 17β-Estradiol Signalling

17β-estradiol (estradiol) is a natural estrogen regulating reproduction including sperm and egg development, sperm maturation—called capacitation—and sperm–egg communication. High doses can increase germ cell apoptosis and decrease sperm count. Our aim was to answer the biological relevance of estradiol in sperm capacitation and its effect on motility and acrosome reaction to quantify its interaction with estrogen receptors and propose a model of estradiol action during capacitation using kinetic analysis. Estradiol increased protein tyrosine phosphorylation, elevated rate of spontaneous acrosome reaction, and altered motility parameters measured Hamilton-Thorne Computer Assisted Semen Analyzer (CASA) in capacitating sperm. To monitor time and concentration dependent binding dynamics of extracellular estradiol, high-performance liquid chromatography with tandem mass spectrometry was used to measure sperm response and data was subjected to kinetic analysis. The kinetic model of estradiol action during sperm maturation shows that estradiol adsorption onto a plasma membrane surface is controlled by Langmuir isotherm. After, when estradiol passes into the cytoplasm, it forms an unstable adduct with cytoplasmic receptors, which display a signalling autocatalytic pattern. This autocatalytic reaction suggests crosstalk between receptor and non-receptor pathways utilized by sperm prior to fertilization.

Differences in aromatase expression and steroid hormone concentrations in the reproductive tissues of male domestic turkeys (Meleagris gallopavo) with white and yellow semen

1. To show hormonal differences between male turkeys with yellow semen syndrome (YSS) and white, normal semen (WNS), the expression of aromatase, oestrogen receptor α (ERα), and oestrogen receptor β (ERβ) as well as testosterone and oestradiol concentrations in YSS and WNS testes, epididymis, and ductus deferens were examined. 2. To measure gene expression levels of aromatase and oestrogen receptors (ERs), three complementary techniques (real-time PCR, Western blot, and immunohistochemistry) were used, whereas steroid hormone levels were determined radio-immunologically. 3. Upregulation of aromatase and ERα mRNAs in YSS testes (P < 0.05; P < 0.01), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.05; P < 0.01) compared to those of WNS tissues was detected. Significant increases in the levels of aromatase and ERα proteins were detected in YSS testes (P < 0.001; P < 0.05), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.001; P < 0.05). The expression of ERβ mRNA and protein level was upregulated in the testes (P < 0.05; P < 0.01) and epididymis (P < 0.001; P < 0.01) but not in ductus deferens where it was downregulated (P < 0.01; P < 0.01). Increased intensity of immunoreactive proteins in YSS versus WNS reproductive tissues corroborated gene expression results. 4. Testosterone concentration diminished in YSS epididymis (P < 0.05) and ductus deferens (P < 0.05), but not in the testes, remaining at high level (P < 0.05) compared to WNS values. Concomitantly, increased oestradiol concentration was found in YSS testes (P < 0.05) and epididymis (P < 0.05) but decreased in the ductus deferens (P < 0.05). 5. From the published literature, this study is the first to demonstrate the ability for androgen aromatisation in the turkey reproductive tissues and to show the cellular targets for locally produced oestrogens. The data suggested that the androgen/oestrogen ratio is a mechanistic basis for amplification of differences between turkeys with white and yellow semen and that these results can have a relevance in applied sciences to widen the knowledge on domestic bird reproduction.

G protein-coupled estrogen receptor (GPER) in adult boar testes, epididymis and spermatozoa during epididymal maturation

The G protein-coupled estrogen receptor (GPER) is a transmembrane receptor considered as a mediator of rapid non-genomic responses. GPER has been found in the male reproductive tract of many mammalian species. However, in adult boars, GPER has been reported only in ejaculated spermatozoa. Therefore, we focused on GPER detection in testicular and epididymal tissues and sperm cells in adult boars. We found GPER in Leydig cells and seminiferous tubules of boar testes and in the secretory epithelium of epididymis. A weaker signal was visible in smooth muscle cells and spermatozoa in the epididymal tubule. In spermatozoa isolated from epididymal parts, GPER was found to localize mainly in the sperm acrosome and flagellum. We immunodetected several protein bands in the extracts of the tissues and epididymal spermatozoa. A significantly higher amount of GPER mRNA was detected in the spermatozoa from caput epididymis, whereas the mRNA expression was lower in tissues of testes and caput epididymal. Our results showed the first evidence of GPER in boar epididymal spermatozoa. Moreover, the GPER localization in adult boar testes, epididymis, and mature spermatozoa suggests the involvement of estrogens via transmembrane receptor and rapid non-genomic signaling in both the sperm development and post-testicular maturation.

Estrogen, Estrogen Receptor and Lung Cancer

Estrogen has been postulated as a contributor for lung cancer development and progression. We reviewed the current knowledge about the expression and prognostic implications of the estrogen receptors (ER) in lung cancer, the effect and signaling pathway of estrogen on lung cancer, the hormone replacement therapy and lung cancer risk and survival, the mechanistic relationship between the ER and the epidermal growth factor receptor (EGFR), and the relevant clinical trials combining the ER antagonist and the EGFR antagonist, to investigate the role of estrogen in lung cancer. Estrogen and its receptor have the potential to become a prognosticator and a therapeutic target in lung cancer. On the other hand, tobacco smoking aggravates the effect of estrogen and endocrine disruptive chemicals from the environment targeting ER may well contribute to the lung carcinogenesis. They have gradually become important issues in the course of preventive medicine.