Testosterone signaling and the regulation of spermatogenesis

Characterisation of testicular function and spermatogenesis in transgender women

STUDY QUESTION

Does gender-affirming treatment prevent full spermatogenesis in transgender women (TW)?

SUMMARY ANSWER

Adequate hormonal therapy (HT) leads to complete suppression of spermatogenesis in most TW, if serum testosterone levels within female reference ranges are obtained.

WHAT IS KNOWN ALREADY

Gender-affirming treatment in transgender individuals may involve gender-affirming HT. The effects on spermatogenesis in TW remain unclear. In order to add information from a referral centre for transgender care, we wish to compare results of earlier studies with our population of TW who received a standard hormone treatment.

STUDY DESIGN, SIZE, DURATION

This was a prospective cohort study part of the European Network for the Investigation of Gender Incongruence (ENIGI), conducted between 15 February 2010 and 30 September 2015. There were 162 TW were included in the ENIGI study at the Ghent University Hospital in Belgium. Participants are included in ENIGI when they first start HT, and follow-up visits occur over the next 3 years.

PARTICIPANTS/MATERIALS, SETTING METHODS

The study included 97 TW who initiated HT with cyproterone acetate (CPA) plus oestrogens and proceeded with gonadectomy at the Ghent University Hospital. Testicular tissue retrieved during gonadectomy was processed and stained for four different germ cell markers by the Biology of the Testis lab at the Vrije Universiteit Brussel. Subsequent immunohistochemical staining was performed for melanoma-associated antigen A4 (MAGE-A4, marker for spermatogonia and early spermatocytes), boule homologue, RNA-binding protein (BOLL, marker for secondary spermatocytes and round spermatids), cAMP-responsive element modulator (CREM, marker for round spermatids) and acrosin (marker for acrosome visualization). Serum levels of sex steroids were measured prior to surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

Suppressed testosterone levels (<50 ng/dl) were found in 92% of the participants prior to surgery. The mean time between initiation of HT and surgery was 685 days. In 88% (85/97) of the sections, MAGE-A4 staining was positive. Further staining could not reveal complete spermatogenesis in any participant.

LIMITATIONS, REASONS FOR CAUTION

Testicular function of the participants prior to initiation of HT was not assessed, although all participants presented with cisgender male serum testosterone values before initiation of HT. The current study only reports on people using CPA at a fixed dose and may therefore not be applicable to all TW.

WIDER IMPLICATIONS OF THE FINDINGS

HT leads to complete suppression of spermatogenesis in most TW, if serum testosterone levels within female reference ranges are obtained. Serum testosterone levels are associated with the sperm maturation rate. It is important to discuss sperm preservation before the start of hormone therapy. If serum testosterone levels remain higher, spermatogenesis may still occur.

STUDY FUNDING/COMPETING INTEREST(S)

D.V.S. is a post-doctoral fellow of the Fonds Wetenschappelijk Onderzoek (FWO; 12M2819N). Processing of the testis specimens was funded by the Biology of The Testes (BITE) research group (Department of Reproduction, Genetics and Regenerative medicine at Vrije Universiteit Brussel (VUB)). There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Age-Related Alterations in the Testicular Proteome of a Non-Human Primate

Aging of human testis and associated cellular changes is difficult to assess. Therefore, we used a translational, non-human primate model to get insights into underlying cellular and biochemical processes. Using proteomics and immunohistochemistry, we analyzed testicular tissue of young (age 2 to 3) and old (age 10 to 12) common marmosets (Callithrix jacchus). Using a mass spectrometry-based proteomics approach, we identified 63,124 peptides, which could be assigned to 5924 proteins. Among them, we found proteins specific for germ cells and somatic cells, such as Leydig and Sertoli cells. Quantitative analysis showed 31 differentially abundant proteins, of which 29 proteins were more abundant in older animals. An increased abundance of anti-proliferative proteins, among them CDKN2A, indicate reduced cell proliferation in old testes. Additionally, an increased abundance of several small leucine rich repeat proteoglycans and other extracellular matrix proteins was observed, which may be related to impaired cell migration and fibrotic events. Furthermore, an increased abundance of proteins with inhibitory roles in smooth muscle cell contraction like CNN1 indicates functional alterations in testicular peritubular cells and may mirror a reduced capacity of these cells to contract in old testes.

Prebiotics mannan-oligosaccharides accelerate sexual maturity in rats: A randomized preclinical study

Background and Aim:

The prebiotics, mannan-oligosaccharides (MOS), demonstrate the ability to increase probiotic microorganisms and fixation and removal of pathogens associated with chronic systemic inflammation in the digestive system. Inflammatory processes play an important role in modulating the brain-intestinal axis, including maintaining male reproductive function and spermatogenesis and regulating stress. The aim of the present study was to evaluate the action of MOS on testosterone and corticosterone concentrations and the reproductive system development of rats in the growth phase as an animal model.

Materials and Methods:

In total, 128 male rats were used, randomly divided into four experimental groups (n=32): Control; MOS 1; MOS 2; and MOS 3. From each group, eight animals were sacrificed in four experimental moments (14, 28, 42, and 56 days, respectively, moments 1, 2, 3, and 4) and hormonal measurements and histological evaluations were performed.

Results:

The results revealed the effect of diet, MOS, and timing on testicle weight (p<0.05). At moments 3 and 4, the groups supplemented with MOS showed higher concentrations of testosterone and decreased corticosterone levels throughout the experimental period. Groups supplemented with MOS showed an increase in the frequency of relative sperm and sperm scores. The radii of the seminiferous tubules presented a significant statistical effect of the diet, moments, and diet + moment interaction.

Conclusion:

It was concluded that the three different MOS prebiotics brought forward sexual maturity.

Heat stress response of somatic cells in the testis

The testis is a temperature-sensitive organ that needs to be maintained 2-7 °C below core body temperature to ensure the production of normal sperm. Failure to maintain testicular temperature in mammals impairs spermatogenesis and leads to low sperm counts, poor sperm motility and abnormal sperm morphology in the ejaculate. This review discusses the recent knowledge on the response of testicular somatic cells to heat stress and, specifically, regarding the relevant contributions of heat, germ cell depletion and inflammatory reactions on the functions of Sertoli and Leydig cells. It also outlines mechanisms of testicular thermoregulation, as well as the thermogenic factors that impact testicular function.

Dose-Dependent Effect of Polystyrene Microplastics on the Testicular Tissues of the Male Sprague Dawley Rats

Due to the continuous increase in polystyrene microplastics (PS MPs) incorporation in the environment, growing number of adverse effects on living organisms and ecosystem have become a global concern. Therefore, current study was planned to elucidate the impacts of 5 different concentrations control, 2, 20, 200, and 2000 μgL-1 of PS MPs on testicular tissues of rats. PS MPs significantly reduced the activities of antioxidant enzymes (catalase, superoxide dismutase and peroxidase) as well as total protein contents, while elevated the level of lipid peroxidation and reactive oxygen species. Moreover, expressions of steroidogenic enzymes (3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein) as well as the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) in plasma, intra-testicular testosterone and plasma testosterone were reduced and a significant (P < 0.05) reduction was noticed in the sperm count, motility and viability. Furthermore, PS MPs significantly up-regulated the expressions of Bax and caspase-3, while down-regulated the Bcl-2 expression. The histomorphological assessment revealed significant damages in the testicles as well as decrease in the number of germ cells (spermatogenic, spermatocytes and spermatids). Collectively, PS MPs generated oxidative stress (OS) and caused potential damage to the testicles of rats in a dose-dependent manner.

Reproductive characteristics, semen quality, seminal oxidative status, steroid hormones, sperm production efficiency of rabbits fed herbal supplements

Today, orthodox medicine has almost exceeded its limits in resolving subfertility problems in animals, thus making phytomedicine a primary tool in the treatment of infertility. In this work, three herbal supplements obtained from freshly air-dried Moringa oleifera, Phyllanthus amarus and Viscum album leaves were evaluated to ascertain their comparative effect on the reproductive potentials of bucks. Sixty bucks were allotted four diets made up of standard grower rabbit ration without supplement and with 5% Moringa, Mistletoe and Phyllanthus supplementation for 84 days. Semen samples were collected from all bucks using artificial vagina, for semen quality and seminal oxidative stress markers. The organ weights, testicular and epididymal spermatozoa reserves were assessed to determine sperm production potentials using standard procedures. The result obtained revealed that spermatozoa concentration, progressive motility, curvilinear velocity, average path velocity and the amplitude of lateral head was significantly (p < 0.05) higher in the group fed with mistletoe supplemented diet compared to that recorded in the control groups. The inclusion of herbal supplements linearly (p < 0.05) increased the seminal total antioxidant activity with a corresponding decrease in the seminal lipid peroxidation across the herbal supplemented treatments compared to the control. The gonadal and extra-gonadal sperm reserves of bucks fed on the herbal supplements were depleted compared to bucks on control. Bucks on mistletoe supplementation rivalled the superior daily sperm production and testicular sperm reserve in bucks without herbal supplements. In conclusion, Viscum album supplements in bucks' diets encouraged daily sperm production, testicular sperm reserves, testosterone, as well as spermatozoa kinetics. The three herbal supplements did enhance semen oxidative stability.

The possible role of sirtuins in male reproduction

Global influence of male infertility is increasing in recent decades. Proper understanding of genetics, anatomy, physiology and the intricate interrelation of male reproductive system are much needed for explaining the etiology of male infertility; and a detailed study on the epigenetics, indeed, will reveal the molecular mechanism behind its etiology. Sirtuins, the molecular sensors, are NAD⁺ dependent histone deacetylases and ADP- ribosyl transferases, participate in the chief events of epigenetics. In mammals, sirtuin family comprises seven members (SIRT1-SIRT7), and they all possess a conserved NAD⁺ binding catalytic domain, termed the sirtuin core domain which is imperative for their activity. Sirtuins exert a pivotal role in cellular homeostasis, energy metabolism, apoptosis, age-related disorders and male reproductive system. However, their exact role in male reproduction is still obscure. This article specifically reviews the role of mammalian sirtuins in male reproductive function, thereby, prompting further research to discover the restorative methods and its implementation in reproductive medicine.

Melatonin promotes male reproductive performance and increases testosterone synthesis in mammalian Leydig cells†

Leydig cells play a critical role in male reproductive physiology, and their dysfunction is usually associated with male infertility. Melatonin has an important protective and regulatory role in these cells. However, the lack of suitable animal models impedes us from addressing the impact of endogenous melatonin on these cells. In the current study, by using arylalkylamine N-acetyltransferase (AANAT) overexpression transgenic sheep and AANAT knockout mice, we confirmed the regulatory effects of endogenously occurring melatonin on Leydig cells as well as its beneficial effects on male reproductive performance. The results showed that the endogenously elevated melatonin level was correlated with decreased Leydig cell apoptosis, increased testosterone production, and improved quality of sperm in melatonin-enriched transgenic mammals. Signal transduction analysis indicated that melatonin targeted the mitochondrial apoptotic Bax/Bcl2 pathway and thus suppressed Leydig cell apoptosis. In addition, melatonin upregulated the expression of testosterone synthesis-related genes of Steroidogenic Acute Regulatory Protein (StAR), Steroidogenic factor 1 (SF1), and Transcription factor GATA-4 (Gata4) in Leydig cells. This action was primarily mediated by the melatonin nuclear receptor RAR-related orphan receptor alpha (RORα) since blockade of this receptor suppressed the effect of melatonin on testosterone synthesis. All of these actions of melatonin cause Leydig cells to generate more testosterone, which is necessary for spermatogenesis in mammals. In contrast, AANAT knockout animals have dysfunctional Leydig cells and reduced reproductive performance.

Spermatogenesis in pre-pubertal boys with Leydig cell neoplasms suggests paracrine stimulation by testosterone

INTRODUCTION

Pediatric Leydig cell tumors (LCTs) represent approximately 4% of pre-pubertal testicular tumors and are known to cause precocious puberty secondary to testosterone production. While gonadotropins and testosterone are known to initiate spermatogenesis beginning in puberty, it is yet to be determined if a similar phenomenon is triggered by isolated testosterone production in prepubescent boys.

OBJECTIVE

To determine if testicular pathology in pre-pubertal pediatric patients with LCTs exhibit spermatogenesis secondary to paracrine testosterone stimulation.

STUDY DESIGN

We reviewed patients who underwent orchiectomy for a testicular tumor from 2003-17. We included patients with LCTs and compared them to children with non-LCT pathology (teratomas and epidermoid cysts). We excluded other pathologies and tumors in pubertal patients. Data were collected on the presence of spermatogenesis on pathology, tumor markers and serum hormone results.

RESULTS

Orchiectomy for testicular tumors were completed in 66 patients, of which 20 were included in the non-LCT group and 9 in the LCT group. Two of the 9 LCT patients had bilateral pathology. Age at presentation was 6.3 ± 5.8 years for the non-LCT group vs. 8.4 ± 1.6 years for LCTs (p = 0.261). Spermatogenesis was detected in 7 (64%) LCT specimens vs 2 (10%) non-LCT specimens (p = 0.002). Age of the spermatogenesis patients in the non-LCT group (11.08 ± 2.5 years) was older than LCT ones (8.3 ± 2.0 years), suggesting that spermatogenesis in the non-LCT group may be due to early pubertal development. The summary figure demonstrates spermatogenesis identified in a pre-pubertal LCT patient.

DISCUSSION

In this study, pre-pubertal males with LCTs were identified to have pathology evidence of spermatogenesis compared to controls with non-LCT pathology. This represents the first study assessing paracrine testosterone effects on spermatogenesis in pre-pubertal patients with LCTs. In contrast, adult literature on LCTs primarily report on resulting concerns for fertility, gynecomastia and testicular atrophy.

CONCLUSION

LCTs can induce spermatogenesis in prepubertal patients. This reinforces the hypothesis that paracrine testosterone signaling plays a role in spermatogenesis. Our findings could help explore novel fertility preservation opportunities in children.

Lead acetate induces apoptosis in Leydig cells by activating PPARγ/caspase-3/PARP pathway

This study was designed to investigate the cytotoxicity of lead acetate (Pb(AC)₂, a representative air pollutant) by focusing on PPARγ/caspase-3/PARP apoptotic signaling pathway and to explore the inhibitory effect of PPARγ antagonist on apoptosis of TM3 Leydig cells. MTT assay was utilized to examine cell viability. Cell apoptosis was analyzed using a flow cytometry by staining with Annexin V-PE/7AAD staining and a fluorescence microscope by staining with Hoechst 33,258. The levels of apoptosis-related proteins were examined using western blot. From the results, Pb reduced significantly TM3 cell proliferation in concentration- and time-dependent manner. It increased significantly apoptosis; increased the PPARγ, Bax, procaspase-3, cleaved caspase-3, proPARP, cleaved PARP levels; and decreased Bcl-2 level in Pb-treated TM3 cells as compared to control cells. Furthermore, pretreatment with PPARγ antagonist significantly attenuated the apoptosis and cleavage of caspase-3 and PARP induced by Pb. Our results suggested that Pb induced cytotoxicity on TM3 Leydig cells, at least in part, by increasing PPARγ expression, stimulating cleavage of caspase-3 and PARP, and then induced cell apoptosis.

The Good, the Bad and the Ugly of Testicular Immune Regulation: A Delicate Balance Between Immune Function and Immune Privilege

The testis is one of several immune privilege sites. These sites are necessary to decrease inflammation and immune responses that could be damaging to the host. For example, inflammation in the brain, eye or placenta could result in loss of cognitive function, vision or rejection of the semi-allogeneic fetus, respectively. In the testis, immune privilege is "good" as it is necessary for protection of the developing auto-immunogenic germ cells. However, there is also a downside or "bad" part of immune privilege, where pathogens and cancers can take advantage of this privilege and persist in the testis as a sanctuary site. Even worse, the "ugly" of privilege is how re-emerging viruses, such as Ebola and Zika viruses, can establish persistence in the testes and be sexually transmitted even months after they have been cleared from the bloodstream. In this review, we will discuss the delicate balance within the testis that provides immune privilege to protect the germ cells while still allowing for immune function to fight off pathogens and tumors.

PMCA4 gene expression is regulated by the androgen receptor in the mouse testis during spermatogenesis

The present study aimed to investigate the expression of ATPase Ca⁺⁺ transporting plasma membrane 4 (PMCA4) in mouse testis and to determine its role in spermatogenesis. Reverse transcription-quantitative PCR, western blotting and immunofluorescence were performed to evaluate the expression levels of PMCA4 in mouse testes at various weeks postnatal in wild type mice, and in testes from Sertoli cell-specific androgen receptor knockout and androgen receptor knockout (ARKO) mice. Luciferase assay, androgen receptor (AR) overexpression and AR antagonist experiments were used to confirm that AR regulated the expression of PMCA4. The results demonstrated that PMCA4 was highly expressed in mouse testes at 3–8 weeks postnatal. PMCA4 expression levels in ARKO mouse testes were decreased compared with wild type. In addition, activation of AR by testosterone administration resulted in an increase in the activity of the PMCA4 promoter. Cells transfected with an AR-overexpressing plasmid exhibited increased expression levels of the PMCA4 protein. Finally, the increase in PMCA4 protein levels induced by testosterone was prevented by pre-treatment with the AR antagonist flutamide. The present results confirmed that PMCA4 was upregulated during mouse testis development and that PMCA4 mRNA and protein expression levels were regulated by androgens and AR. The present findings suggest that PMCA4 may be involved in the regulation of spermatogenesis.

Low Testosterone and Semen Parameters in Male Partners of Infertile Couples Undergoing IVF with a Total Sperm Count Greater than 5 Million

Low serum testosterone is found in approximately 15% of subfertile men. Although testosterone is essential in spermatogenesis, it is unclear whether low testosterone levels may have a negative impact on the semen parameters of men belonging to infertile couples with a total sperm count greater than 5 million. Furthermore, it is debatable whether the initial evaluation of the subfertile male should include an endocrine assessment. This was a retrospective, single-center cohort study conducted at a tertiary fertility clinic. Male partners of infertile couples undergoing in vitro fertilization (IVF), with a total sperm count greater than 5 million, were included. All men provided morning blood samples, and none had been on exogenous testosterone or other relevant medications. Low total testosterone (TT) was defined as <264 ng/dL. Free T was calculated using TT and sex hormone-binding globulin (SHBG) levels (nmol/L) by a constant albumin concentration of 43 g/L. In total, 853 patients were included: 116 had low TT (<264 ng/dL) and 737 had normal TT (≥264 ng/dL). Semen volume, sperm cell count, progressive (A + B) motility and morphology (≥4% strict Kruger) were lower in the low TT group but not significantly different between low and normal TT groups (3.2 ± 1.79 vs. 3.23 ± 1.64, p = 0.87; 76.82 ± 83.18 vs. 67.55 ± 57.70, p = 0.7; 54.89 ± 19.45 vs. 56.25 ± 19.03, p = 0.6; 5.77 ± 3.23 vs. 6.89 ± 3.94, p = 0.23). The percentage of patients with below-reference sperm volume (<1.5 mL), cell count (<15 × 106/mL), motility (A + B) (<32%) and morphology (<4%) was higher in the low TT group but not statistically different compared to the normal TT group. Multivariable regression analysis revealed that low TT and free T levels had no significant effect on the aforementioned semen parameters (coefficient: 3.94, 0.88, 1.37, 0.39; p = 0.53, 0.8, 0.3, 0.2; coefficient: 0.001, 0.06, 0.007, 0.0002; p = 0.73, 0.52, 0.85, 0.98). Despite our robust methodological approach, the presence of biases related to retrospective design cannot be excluded. Our findings highlighted the lack of association between low TT levels and semen parameter alterations in male partners of infertile couples undergoing IVF, with a total sperm count greater than 5 million. However, it is important to emphasize that more patients in the low TT group had subnormal semen parameters, albeit the difference was not statistically significant. Larger, prospective studies are warranted in order to validate these findings, as well as to investigate the existence of a TT threshold below which semen parameters might be negatively affected.

Proton MR Spectroscopy in Assessing the Biochemical Milieu of Human Testes

Proton magnetic resonance spectroscopy (MRS), considered a connection between metabolism and anatomic and functional information provided by standard MRI, gives information on various tissue metabolites and their pathologic changes. Recently, proton MRS has been added as an adjunct tool to the multiparametric protocol of scrotal MRI, providing a new insight into the extremely complex biochemical milieu of normal and abnormal testes. This article reviews proton MR spectra of normal testes, showing age and bilateralism dependence. Disturbances of various metabolic pathways in testes of infertile men resulting in alterations of metabolite peaks are discussed. Preliminary data on proton MR spectra of testicular mass lesions are presented. LEVEL OF EVIDENCE: 5. TECHNICAL EFFICACY STAGE: 5.

5-Alfa reductase type 2 (SRD5A2) gene rs523349 polymorphism is not associated with non-obstructive azoospermia in Turkish patients

Spermatogenesis is an androgen-dependent event, and testosterone is the major androgen source. The enzyme 5-alpha reductase converts testosterone to dihydrotestosterone (DHT) in testicular and peripheral tissues. Polymorphisms in genes encoding 5-alpha reductase may be associated with impaired male fertility. The present study aimed to investigate the relationship between 5-alpha reductase type 2 (SRD5A2) gene rs523349 polymorphism and non-obstructive azoospermia (NOA) in Turkish patients. The study included 75 NOA patients and 43 fertile men from Turkey. No significant relationship was found between SRD5A2 gene rs523349 polymorphism and male infertility (P = 0.071). There was a statistically significant difference in total testosterone level and total testis volume between NOA patients and the control groups, however there was no significant difference between serum follicle-stimulating hormone and luteinizing hormone levels. Our results showed that SRD5A2 gene rs523349 polymorphism was not associated with NOA in Turkish patients.

The role of the microbiome in the neurobiology of social behaviour

Microbes colonise all multicellular life, and the gut microbiome has been shown to influence a range of host physiological and behavioural phenotypes. One of the most intriguing and least understood of these influences lies in the domain of the microbiome's interactions with host social behaviour, with new evidence revealing that the gut microbiome makes important contributions to animal sociality. However, little is known about the biological processes through which the microbiome might influence host social behaviour. Here, we synthesise evidence of the gut microbiome's interactions with various aspects of host sociality, including sociability, social cognition, social stress, and autism. We discuss evidence of microbial associations with the most likely physiological mediators of animal social interaction. These include the structure and function of regions of the 'social' brain (the amygdala, the prefrontal cortex, and the hippocampus) and the regulation of 'social' signalling molecules (glucocorticoids including corticosterone and cortisol, sex hormones including testosterone, oestrogens, and progestogens, neuropeptide hormones such as oxytocin and arginine vasopressin, and monoamine neurotransmitters such as serotonin and dopamine). We also discuss microbiome-associated host genetic and epigenetic processes relevant to social behaviour. We then review research on microbial interactions with olfaction in insects and mammals, which contribute to social signalling and communication. Following these discussions, we examine evidence of microbial associations with emotion and social behaviour in humans, focussing on psychobiotic studies, microbe-depression correlations, early human development, autism, and issues of statistical power, replication, and causality. We analyse how the putative physiological mediators of the microbiome-sociality connection may be investigated, and discuss issues relating to the interpretation of results. We also suggest that other candidate molecules should be studied, insofar as they exert effects on social behaviour and are known to interact with the microbiome. Finally, we consider different models of the sequence of microbial effects on host physiological development, and how these may contribute to host social behaviour.

Fertility Preservation in Childhood Cancer: Endocrine Activity in Prepubertal Human Testis Xenografts Exposed to a Pubertal Hormone Environment

Simple Summary

Substantial strides have been made in treating childhood cancers; however, as a result of chemotherapy and radiotherapy, young males experience long-term side effects, including impaired fertility. Whilst prepubertal testicular tissue can be cryopreserved prior to gonadotoxic treatments, it remains to be determined how to generate mature gametes from the immature human testis tissue. Development of immature germ cells into sperm is a complex process, which is supported by mature Sertoli cells and testosterone produced from Leydig cells. We used an established testicular xenotransplantation model to investigate the effect of puberty hormones, known as gonadotrophins, on functional maturation of the spermatogonial stem cell (SSC) niche. Limited testosterone production and partial maturation of Sertoli cells occurred in prepubertal testis grafts, suggesting that longer periods of grafting and/or identification of additional factors are required to develop testicular transplantation as a model for fertility preservation in male survivors of childhood cancer.

Abstract

Survivors of childhood cancer are at risk for long-term treatment-induced health sequelae, including gonadotoxicity and iatrogenic infertility. At present, for prepubertal boys there are no viable clinical options to preserve future reproductive potential. We investigated the effect of a pubertal induction regimen with gonadotrophins on prepubertal human testis xenograft development. Human testis tissue was obtained from patients with cancer and non-malignant haematological disorders (n = 6; aged 1–14 years) who underwent testis tissue cryopreservation for fertility preservation. Fresh and frozen-thawed testis fragments were transplanted subcutaneously or intratesticularly into immunocompromised mice. Graft-bearing mice received injections of vehicle or exogenous gonadotrophins, human chorionic gonadotrophin (hCG, 20 IU), and follicle-stimulating hormone (FSH, 12.5 IU) three times a week for 12 weeks. The gross morphology of vehicle and gonadotrophin-exposed grafts was similar for both transplantation sites. Exposure of prepubertal human testis tissue xenografts to exogenous gonadotrophins resulted in limited endocrine function of grafts, as demonstrated by the occasional expression of the steroidogenic cholesterol side-chain cleavage enzyme (CYP11A1). Plasma testosterone concentrations (0.13 vs. 0.25 ng/mL; p = 0.594) and seminal vesicle weights (10.02 vs. 13.93 mg; p = 0.431) in gonadotrophin-exposed recipient mice were comparable to vehicle-exposed controls. Regardless of the transplantation site and treatment, initiation and maintenance of androgen receptor (AR) expression were observed in Sertoli cells, indicating commitment towards a more differentiated status. However, neither exogenous gonadotrophins (in castrated host mice) nor endogenous testosterone (in intact host mice) were sufficient to repress the expression of markers associated with immature Sertoli cells, such as anti-Müllerian hormone (AMH) and Ki67, or to induce the redistribution of junctional proteins (connexin 43, CX43; claudin 11, CLDN11) to areas adjacent to the basement membrane. Spermatogonia did not progress developmentally but remained the most advanced germ cell type in testis xenografts. Overall, these findings demonstrate that exogenous gonadotrophins promote partial activation and maturation of the somatic environment in prepubertal testis xenografts. However, alternative hormone regimens or additional factors for pubertal induction are required to complete the functional maturation of the spermatogonial stem cell (SSC) niche.

Effects and Mechanisms of Phthalates' Action on Reproductive Processes and Reproductive Health: A Literature Review

The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and reproductive diseases, phthalates-induced reproductive disorders, and their possible endocrine and intracellular mechanisms. Phthalates may induce alterations in puberty, the development of testicular dysgenesis syndrome, cancer, and fertility disorders in both males and females. At the hormonal level, phthalates can modify the release of hypothalamic, pituitary, and peripheral hormones. At the intracellular level, phthalates can interfere with nuclear receptors, membrane receptors, intracellular signaling pathways, and modulate gene expression associated with reproduction. To understand and to treat the adverse effects of phthalates on human health, it is essential to expand the current knowledge concerning their mechanism of action in the organism.

Alu-repeat polymorphism in the tissue plasminogen activator (t-PA) gene, seminal t-PA concentration, and male fertility impairment: A case-control study

Background

Tissue plasminogen activator (t-PA) is a protein involved in the fibrinolytic system that catalyzes the conversion of plasminogen into the active plasmin. The activity of t-PA is controlled by plasminogen activator inhibitor-1. t-PA has crucial functions during spermatogenesis. One polymorphism was reported for t-PA gene, either the presence of a 300-bp Alu-repeat (Alu + ) or its absence (Alu - ).

Objective

The current work aimed at studying the association between Alu polymorphism in the t-PA gene and male infertility.

Materials and Methods

Using polymerase chain reaction on genomic DNA isolated from the blood of 79 participants, a region polymorphic for Alu element insertion in t-PA gene was amplified. In addition, total t-PA concentration, plasminogen activator inhibitor-1 /t-PA complex concentration, and t-PA activity in seminal plasma were measured by enzyme-linked immunosorbent assay.

Results

The results indicate that the percentage of infertile participants (n = 50) who were homozygous for t-PA Alu insertion (Alu + / + ), heterozygous Alu + / - or homozygous for t-PA Alu deletion (Alu - / - ) did not change significantly (p = 0.43, 0.81, and 0.85, respectively) when compared with the control participants (n = 29). On the other hand, a significant decrease (p = 0.0001) of t-PA total concentration in seminal plasma was observed in the infertile group in comparison with the control group. However, the results indicate that there is no association between the t-PA Alu different genotypes and the total t-PA seminal concentration in the infertile group when compared to the control group (p = 0.63).

Conclusion

Data obtained from the current study does not support an association between t-PA Alu polymorphism and t-PA seminal concentration or male infertility.

Marijuana smoking and markers of testicular function among men from a fertility centre

STUDY QUESTION

Is marijuana smoking associated with semen quality, sperm DNA integrity or serum concentrations of reproductive hormones among subfertile men?

SUMMARY ANSWER

Men who had ever smoked marijuana had higher sperm concentration and count and lower serum FSH concentrations than men who had never smoked marijuana; no differences were observed between current and past marijuana smokers.

WHAT IS KNOWN ALREADY

Studies of marijuana abuse in humans and animal models of exposure to marijuana suggest that marijuana smoking adversely impacts spermatogenesis. Data is less clear for moderate consumption levels and multiple studies have found higher serum testosterone concentrations among marijuana consumers.

STUDY DESIGN, SIZE, DURATION

This longitudinal study included 662 subfertile men enroled at the Massachusetts General Hospital Fertility Center between 2000 and 2017. The men provided a total of 1143 semen samples; 317 men also provided blood samples in which we measured reproductive hormones.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Use of marijuana and other drugs was self-reported at baseline. Standard protocols were followed for measuring semen quality, sex hormones and DNA integrity. We used linear mixed effect models with a random intercept to evaluate the associations of self-reported marijuana smoking at enrolment with semen parameters from subsequently collected samples, and linear regression models for sperm DNA integrity and serum reproductive hormones, while adjusting for confounders including smoking and cocaine use.

MAIN RESULTS AND THE ROLE OF CHANCE

Men who had ever smoked marijuana (N = 365) had significantly higher sperm concentration (62.7 (95% confidence interval: 56.0, 70.3) million/mL) than men who had never smoked marijuana (N = 297) (45.4 (38.6, 53.3) million/mL) after adjusting for potential confounders (P = 0.0003). There were no significant differences in sperm concentration between current (N = 74) (59.5 (47.3, 74.8) million/mL) and past marijuana smokers (N = 291) (63.5 (56.1, 72.0) million/mL; P = 0.60). A similar pattern was observed for total sperm count. Furthermore, the adjusted prevalence of sperm concentration and total sperm motility below WHO reference values among marijuana smokers was less than half that of never marijuana smokers. Marijuana smokers had significantly lower follicle stimulating hormone (FSH) concentrations than never marijuana smokers (-16% (-27%, -4%)) and there were no significant differences between current and past marijuana smokers (P = 0.53). Marijuana smoking was not associated with other semen parameters, with markers of sperm DNA integrity or with reproductive hormones other than FSH. Chance findings cannot be excluded due to the multiple comparisons.

LIMITATIONS, REASONS FOR CAUTION

Our results may not be generalisable to men from the general population. Marijuana smoking was self-reported and there may be misclassification of the exposure.

WIDER IMPLICATIONS OF THE FINDINGS

These findings are not consistent with a deleterious effect of marijuana on testicular function. Whether these findings are reflective of the previously described role of the endocannabinoid system in spermatogenesis or a spurious association requires confirmation in further studies.

STUDY FUNDING/COMPETING INTEREST(S)

The project was funded by grants R01ES009718 and P30ES000002 from the National Institute of Environmental Health Sciences (NIEHS). None of the authors has any conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

In vitro supplementation of testosterone or prolactin affects spermatozoa freezability in small ruminants

In small ruminants, testosterone and prolactin plasma concentrations show circannual fluctuations as an adaptation mechanism to their seasonal breeding behavior. Sperm resistance to the freezing-thawing process shows seasonal fluctuation throughout the year, with lower sperm freezability at the beginning of the breeding season when prolactin and testosterone levels reach their maximum concentration. Nevertheless, whether these hormones directly affect post-thaw sperm quality parameters is still unclear. The objective was to study the effect of testosterone or prolactin added in vitro on sperm freezability in domestic ram (Ovis aries) and buck (Capra hircus). Sperm samples were incubated for 1 h with a range of testosterone (0, 2, 4, or 6 ng/mL; Exp. 1) or prolactin (0, 20, 100, 200, or 400 ng/mL; Exp. 2) concentrations. Samples were cryopreserved by slow freezing in straws at 0 h and after 1 h incubation. Sperm viability, acrosome integrity, motility, and kinetic parameters were assessed at 0 and 1 h in fresh and frozen-thawed samples. Results showed no hormone effect in fresh sperm, whereas these hormones affected post-thaw sperm parameters. In Exp. 1, in vitro incubation with testosterone decreased the post-thaw acrosome integrity of ram sperm (from 68.1 ± 6.3% to 49.6 ± 3.9%; P < 0.05). In Exp. 2, in vitro incubation with prolactin decreased the post-thaw acrosome integrity of ram (from 78.2 ± 3.4% to 66.3 ± 3.5%; P < 0.05) and buck sperm (from 81.7 ± 2.5% to 67.6 ± 3.5%; P < 0.05). Moreover, prolactin increased the post-thaw amplitude of lateral head displacement in ram sperm (from 3.3 ± 0.1 μm to 3.8 ± 0.2 μm; P < 0.05). In conclusion, either testosterone or prolactin added in vitro decreased the post-thaw acrosome integrity of ram and buck sperm. This suggests a destabilization process that could be decreasing sperm freezability when physiological levels of these hormones are high in vivo.

Essential roles of interstitial cells in testicular development and function

BACKGROUND

Testicular architecture and sperm production are supported by a complex network of communication between various cell types. These signals ensure fertility by: regulating spermatogonial stem/progenitor cells; promoting steroidogenesis; and driving male-specific differentiation of the gonad. Sertoli cells have long been assumed to be the major cellular player in testis organogenesis and spermatogenesis. However, cells in the interstitial compartment, such as Leydig, vascular, immune, and peritubular cells, also play prominent roles in the testis but are less well understood.

OBJECTIVES

Here, we aim to outline our current knowledge of the cellular and molecular mechanisms by which interstitial cell types contribute to spermatogenesis and testicular development, and how these diverse constituents of the testis play essential roles in ensuring male sexual differentiation and fertility.

METHODS

We surveyed scientific literature and summarized findings in the field that address how interstitial cells interact with other interstitial cell populations and seminiferous tubules (i.e., Sertoli and germ cells) to support spermatogenesis, male-specific differentiation, and testicular function. These studies focused on 4 major cell types: Leydig cells, vascular cells, immune cells, and peritubular cells.

RESULTS AND DISCUSSION

A growing number of studies have demonstrated that interstitial cells play a wide range of functions in the fetal and adult testis. Leydig cells, through secretion of hormones and growth factors, are responsible for steroidogenesis and progression of spermatogenesis. Vascular, immune, and peritubular cells, apart from their traditionally acknowledged physiological roles, have a broader importance than previously appreciated and are emerging as essential players in stem/progenitor cell biology.

CONCLUSION

Interstitial cells take part in complex signaling interactions with both interstitial and tubular cell populations, which are required for several biological processes, such as steroidogenesis, Sertoli cell function, spermatogenesis, and immune regulation. These various processes are essential for testicular function and demonstrate how interstitial cells are indispensable for male fertility.

Chestnut polysaccharides benefit spermatogenesis through improvement in the expression of important genes

Recently there has been a continuing worldwide decrease in the quality of human spermatozoa, especially in spermatozoa motility and concentration. Many factors are involved in this decline, and great efforts have been made to rescue spermatogenesis; however, there has been little progress in the improvement of sperm quality. Chestnuts are used in traditional Chinese medicine; their major active components are chestnut polysaccharides (CPs). CPs have many biological activities but their effects on spermatogenesis are unknown. The current investigation was designed to explore the impact of CPs on spermatogenesis and the underlying mechanisms. We demonstrated that CPs significantly increased sperm motility and concentration (4-fold and 12-fold, respectively), and improved seminiferous tubule development by increasing the number of germ cells after busulfan treatment. CPs dramatically rescued the expression of important genes and proteins (STRA8, DAZL, SYCP1, SYCP3, TNP1 etc.) in spermatogenesis. Furthermore, CPs increased the levels of hormone synthesis proteins such as CYP17A1 and HSD17β1. All the data suggested that CPs improved the testicular microenvironment to rescue spermatogenesis. With CPs being natural products, they may be an attractive alternative for treating infertile patients in the future. At the same time, the deep underlying mechanisms of their action need to be explored.

Chronic Copper Exposure Induces Hypospermatogenesis in Mice by Increasing Apoptosis Without Affecting Testosterone Secretion

Chronic copper exposure impaired spermatogenesis in adult male mice. The aim of this study was to determine whether chronic copper exposure can induce apoptosis of testicular cell and hypospermatogenesis via disturbing testosterone synthesis in adult male mice. In the present study, sixty CD-1 male mice were randomly divided into four groups, and were continuously administered for 8 weeks by oral gavage with copper sulfate at a dose of 0, 25, 100, and 150 mg/kg/day, respectively. We determined the content of serum and testicular copper, testicular coefficient, testicular histopathology, sperm count and motility, the mRNA and protein levels of Caspase-3, Bax, and Bcl-2, Leydig cell count, testosterone content, testosterone synthetase, and testosterone synthesis-related genes. The results showed that the copper levels in serum increased in a dose-dependent manner, and the copper levels in testes were significantly related to serum copper levels. Male mice given copper sulfate 100 and 150 dosage groups showed significant decreased in sperm motility and sperm number as well as increased in testes damage, and there was no significant change in testicular coefficient in the four groups. The mRNA levels of Bcl-2 decreased and Caspase-3 increased in 150 dosage group, and Bax increased in two higher dosage groups. Meanwhile, Caspase-3 and Bax proteins increased in 150 dosage group, and Bcl-2 protein decreased in three copper treatment groups. Nevertheless, there were no differences on the levels of testosterone content and testosterone synthetase of 3β-HSD, 17β-HSD, 17α-Hyd, and 20α-Hyd, mRNA levels of Cyp11a1, Cyp17a1, and Star, and quantity of Leydig cells in four groups. Overall, these data showed that chronic copper exposure led to copper residues in the testes, and the doses of 100 and 150 mg/kg/day copper sulfate may induce hypospermatogenesis by increasing apoptosis without affecting testosterone secretion.

Reviewing the Evidence on Vitamin D Supplementation in the Management of Testosterone Status and Its Effects on Male Reproductive System (Testis and Prostate): Mechanistically Dazzling but Clinically Disappointing

PURPOSE

Vitamin D supplementation has been suggested to increase testosterone levels. The primary purpose of this literature review was to critically assess the physiologic effects of vitamin D supplementation on serum testosterone concentrations in men and the secondary purpose was to evaluate the feasibility of vitamin D status toward urologic health (testis and prostate).

METHODS

A structured literature review was performed using the Cochrane, MEDLINE, and Web of Science databases. The literature search encompassed studies published between 2011 and 2019.

FINDINGS

Observational studies suggest an association between higher testosterone and serum vitamin D concentrations. Conversely, most randomized clinical trials that investigated the effect of vitamin D administration on testosterone levels have failed to detect any significant effect. Physiologically, vitamin D is engaging in spermatogenesis, but it remains unclear whether vitamin D is a determinant of fertility. With prostate support, the management of vitamin D status has been associated with a decreased prevalence of benign prostatic hyperplasia and symptoms (ie, lower urinary tract symptoms). However, with prostate cancer, there is a paucity of evidence pertaining to vitamin D supplementation.

IMPLICATIONS

Mechanistically, vitamin D exhibits essential roles in the testis and prostate; otherwise, there is no apparent evidence to support the use of vitamin D supplementation to increase testosterone levels and to improve clinical outcomes related to the male reproductive system.

Phytochemical content, antioxidant activities and androgenic properties of four South African medicinal plants

Introduction:This study aimed to investigate the phytochemical contents, antioxidant activities, and androgenic properties ofPeltophorum africanumSond,Trichilia emeticaVahl,Terminalia sambesiaca, andXimenia caffra.Methods:The finely powdered leaves of the selected plants were extracted using acetone, aqueous, and methanol as solvents. The total phenolics and flavonoids contents were determined from gallic acid and quercetin standard curves. The antioxidant activities of these extracts were evaluated using 1, 1-Diphenyl-2-picrylhydrazyl ( DPPH) assay. The effect of plant extracts (100-1000 µg/mL) on TM3 Leydig cells was assessed using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay. Testosterone levels were measured using ELISA kit.Results:The methanol extracts ofT. sambesiacaandX. caffrarevealed higher total phenolic and flavonoid contents (102.13±2.32 mg/g GAE and 1.05±0.04 mg/g QE, respectively) than other plant extracts. The acetone and methanol extracts ofP. africanumrevealed the best IC50value (12.50 ± 0.052 µg/mL) against DPPH than the other plant extracts and ascorbic acid. The MTT assay results showed that all varying concentrations of plant extracts maintained cell viability and were not cytotoxic with IC50values of greater than 20 µg/mL. The methanol extract ofT. sambesiacahad the highest testosterone production at 500 µg/mL (0.399 ng/mL) when compared with the basal control while at the concentration of 500 µg/mL the acetone extracts ofP. africanumandT. sambesiacahad significantly high testosterone production 0.147 and 0.188 ng/mL respectively when compared with basal control.Conclusion:The results reveal that these plants possess antioxidants and androgenic property and suggest the potential use for the treatment of male infertility.

Saccharum officinarum juice alters reproductive functions in male Wistar rats

Infertility is a problem across almost all cultures and societies. Problems in the male partner, especially as a result of unhealthy dietary habits, are the commonest single group of course. Many populations, therefore, tend more toward the use of natural dietary substitutes opined to proffer less risk to reproductive functions and more health benefits. Saccharum officinarum juice (SOJ) is a widely consumed, energy-rich, nutritious substance that has many minerals and enzymes. Saccharum officinarum plant was reported to have anti-thrombosis, anti-inflammatory and immune-stimulatory activities. This study evaluated the reproductive effects of S. officinarum juice in male Wistar rats. A sugarcane press juicer was used to extract S. officinarum juice. Twenty male Wistar rats (100-120 g) grouped into four (n = 5) received 1.0 mL/kg/day distilled water (control), and 1.0, 3.2 and 10.0 mL/kg/day of fresh S. officinarum juice once daily for 8 weeks via gavage. Sperm analysis, histology of testes and epididymides were evaluated by microscopy. Enzyme-linked immunosorbent assay (ELISA) was used in assessing the serum levels of luteinizing hormone, follicle-stimulating hormone and testosterone. Data were analyzed using the analysis of variance at a significance of p < 0.05. SOJ increased fasting blood glucose levels in 3.2 and 10.0 mL/kg groups. The 10.0 mL/kg juice caused a significant increase in testosterone level and sperm count, and it also increased the percentage of aberrant sperm and decreased sperm viability. Saccharum officinarum juice impaired the histological integrity of the testes and epididymides. Thus, S. officinarum juice adversely altered the reproductive functions of male Wistar rats by reducing sperm quality and disrupting testicular architecture.

Effects and mechanisms of pyrethroids on male reproductive system

Synthetic pyrethroids are used as insecticides in agriculture and a variety of household applications worldwide. Pyrethroids are widely distributed in all environmental compartments and the general populations are exposed to pyrethroids through various routes. Pyrethroids have been identified as endocrine-disrupting chemicals (EDCs) which are responsible for the male reproductive impairments. The data confirm pyrethroids cause male reproductive damages. The insecticides exert the toxic effects on male reproductive system through various complex mechanisms including antagonizing androgen receptor (AR), inhibiting steroid synthesis, affecting the hypothalamic-pituitary-gonadal (HPG) axis, acting as estrogen receptor (ER) modulators and inducing oxidative stress. The mechanisms of male reproductive toxicity of pyrethroids involve multiple targets and pathways. The review will provide further insight into pyrethroid-induced male reproductive toxicity and mechanisms, which is crucial to preserve male reproductive health.

Glyphosate-based herbicide exposure during pregnancy and lactation malprograms the male reproductive morphofunction in F1 offspring

One of the most consumed pesticides in the world is glyphosate, the active ingredient in the herbicide ROUNDUP®. Studies demonstrate that glyphosate can act as an endocrine disruptor and that exposure to this substance at critical periods in the developmental period may program the fetus to induce reproductive damage in adulthood. Our hypothesis is that maternal exposure to glyphosate during pregnancy and lactation in mice will affect the development of male reproductive organs, impairing male fertility during adult life. Female mice consumed 0.5% glyphosate-ROUNDUP® in their drinking water [glyphosate-based herbicide (GBH) group] or filtered water [control (CTRL) group] from the fourth day of pregnancy until the end of the lactation period. Male F1 offspring were designated, according to their mother's treatment, as CTRL-F1 and GBH-F1. Female mice that drank glyphosate displayed reduced body weight (BW) gain during gestation, but no alterations in litter size. Although GBH male F1 offspring did not exhibit modifications in BW, they demonstrated delayed testicular descent. Furthermore, at PND150, GBH-F1 mice presented a lower number of spermatozoa in the cauda epididymis and reduced epithelial height of the seminiferous epithelium. Notably, intratesticular testosterone concentrations were enhanced in GBH-F1 mice; we show that it is an effect associated with increased plasma and pituitary concentrations of luteinizing hormone. Therefore, data indicate that maternal exposure to glyphosate-ROUNDUP® during pregnancy and lactation may lead to decreased spermatogenesis and disruptions in hypothalamus-pituitary-testicular axis regulation in F1 offspring.

The dynamics and regulation of microfilament during spermatogenesis

Spermatogenesis is a highly complex physiological process which contains spermatogonia proliferation, spermatocyte meiosis and spermatid morphogenesis. In the past decade, actin binding proteins and signaling pathways which are critical for regulating the actin cytoskeleton in testis had been found. In this review, we summarized 5 actin-binding proteins that have been proven to play important roles in the seminiferous epithelium. Lack of them perturbs spermatids polarity and the transport of spermatids. The loss of Arp2/3 complex, Formin1, Eps8, Palladin and Plastin3 cause sperm release failure suggesting their irreplaceable role in spermatogenesis. Actin regulation relies on multiple signal pathways. The PI3K/Akt signaling pathway positively regulate the mTOR pathway to promote actin reorganization in seminiferous epithelium. Conversely, TSC1/TSC2 complex, the upstream of mTOR, is activated by the LKB1/AMPK pathway to inhibit cell proliferation, differentiation and migration. The increasing researches focus on the function of actin binding proteins (ABPs), however, their collaborative regulation of actin patterns and potential regulatory signaling networks remains unclear. We reviewed ABPs that play important roles in mammalian spermatogenesis and signal pathways involved in the regulation of microfilaments. We suggest that more relevant studies should be performed in the future.

New frontiers in fertility preservation: a hypothesis on fertility optimization in men with hypergonadotrophic hypogonadism

Strategies exist that can mitigate the risk of causing iatrogenic infertility when men require testosterone replacement therapy (TRT). This article reviews the current medical therapies that preserve spermatogenesis when TRT is indicated. Furthermore, we highlight the re-emerging concept of hypothalamic-pituitary-gonadal (HPG) axis reset in hypergonadotrophic, hypogonadal infertile men who are planning sperm retrieval procedures. Finally, we present our hypothesis for a novel protocol to optimize hypergonadotrophic hypogonadal men before sperm extraction surgeries hormonally.

Effects of Qilin pills on spermatogenesis, reproductive hormones, oxidative stress, and the TSSK2 gene in a rat model of oligoasthenospermia

BACKGROUND

Qilin pills (QLPs), a classic Traditional Chinese Medicine (TCM) formula for treating male infertility, effectively improve semen quality in clinical trials. This study was designed to evaluate the effects of QLPs on spermatogenesis, reproductive hormones, oxidative stress, and the testis-specific serinekinase-2 (TSSK2) gene in a rat model of oligoasthenospermia.

METHODS

Forty adult male Sprague-Dawley (SD) rats were randomly divided into four groups. The rat model with oligoasthenospermia was generated by intragastric administration of tripterygium glycosides (TGs) once daily for 4 weeks. Then, two treatment groups were given different doses (1.62 g/kg and 3.24 g/kg) of QLPs once daily for 60 days. Sperm parameters, testicular histology and reproductive hormone measurements, oxidative stress tests, and TSSK2 expression tests were carried out.

RESULTS

QLPs effectively improved semen parameters and testicular histology; restored the levels of FSH, LH, PRL, fT, and SHBG; reduced the levels of oxidative stress products (ROS and MDA); increased testicular SOD activity; and restored the expression of spermatogenesis-related gene TSSK2.

CONCLUSION

QLPs have a therapeutic effect on a rat model of oligoasthenospermia, and this effect is manifested as improvement of semen quality and testis histology, gonadal axis stability, decreased oxidative stress, and the regulation of testis-specific spermatogenesis-related gene TSSK2.

The Dynamic Transcriptional Cell Atlas of Testis Development during Human Puberty

The human testis undergoes dramatic developmental and structural changes during puberty, including proliferation and maturation of somatic niche cells, and the onset of spermatogenesis. To characterize this understudied process, we profiled and analyzed single-cell transcriptomes of ∼10,000 testicular cells from four boys spanning puberty and compared them to those of infants and adults. During puberty, undifferentiated spermatogonia sequentially expand and differentiate prior to the initiation of gametogenesis. Notably, we identify a common pre-pubertal progenitor for Leydig and myoid cells and delineate candidate factors controlling pubertal differentiation. Furthermore, pre-pubertal Sertoli cells exhibit two distinct transcriptional states differing in metabolic profiles before converging to an alternative single mature population during puberty. Roles for testosterone in Sertoli cell maturation, antimicrobial peptide secretion, and spermatogonial differentiation are further highlighted through single-cell analysis of testosterone-suppressed transfemale testes. Taken together, our transcriptional atlas of the developing human testis provides multiple insights into developmental changes and key factors accompanying male puberty.

Adenosine accumulation causes metabolic disorders in testes and associates with lower testosterone level in obese mice

Overweight and obese men face numerous health problems, including type 2 diabetes, subfertility, and even infertility. However, few studies have focused on the effects of nutritional status and obesity-related regulatory signals on fertility deficiency. Our previous observations have shown that the elevation of plasma 5'-adenosine monophosphate (5'-AMP) and the accumulation of adenosine in liver and muscle of obese diabetic db/db mice are related to insulin resistance. Here, we found that adenosine accumulation in testis is a common marker of both genetic obesity and high-fat-diet induced obese mice. An messenger RNA sequencing analysis indicated that 78 upregulated genes and 155 downregulated genes in the testis of 5'-AMP-treated mice overlapped with the same genes in the testis of ob/ob mice, and these genes belonged to the clusters of steroid metabolic process and regulation of hormone levels, respectively. Serum testosterone was reduced in ob/ob and 5'-AMP-treated mice. Metabolomic analysis based on ¹ H nuclear magnetic resonance showed that the testicular metabolic profiles of ob/ob mice were similar to those of 5'-AMP treated mice. Exogenous 5'-AMP inhibited the phosphorylation of AKT and mammalian target of rapamycin signal transduction and reduced the proliferating cell nuclear antigen expressions in testes. Our results suggest that the accumulation of adenosine causes metabolic disorders in testes and associates lower testosterone level in obese mice.

Gestational and lactational exposure to triclosan causes impaired fertility of F1 male offspring and developmental defects in F2 generation

Triclosan (5-chloro-2-(2, 4-dichlorophenoxy) phenol, TCS), is a broad-spectrum antimicrobial agent and extensively used in household and daily daycare products. Recently, several reports have demonstrated the endocrine disruptive action of TCS to alter the testicular steroidogenesis. However, the gestational and lactational effects of TCS exposure on F1 offspring has not been studied. Present study aimed to investigate the effect of gestational and lactational exposure to TCS on F1 male progeny and its effect on fertility. Pregnant dams (F0) were administered with different doses of TCS (0.1, 4, 40 and 150 mg/kg b. wt./day) and Diethylstilbestrol (1 μg/kg b. wt./day), as a positive control daily by subcutaneous injection during Gestation Day 6 to Postnatal Day 21. Delayed testicular descent was observed at 150 mg/kg b. wt./day dose group. Dose-dependent decrease in testosterone level, sperm count and motility was observed. Significantly decreased expression of steroid hormone receptors (AR, ERα and ERβ), StAR and aromatase were observed in F1 male rats; indicating its prolonged effect on spermatogenesis and steroidogenesis in adulthood and poor development in F2 fetuses. Further, gestational and lactational exposure to TCS has negative impact on the fertility of F1 male rats. The F1 male rats were found sub-fertile with increased (%) pre- and post-implantation loss (at 40 and 150 mg/kg b.wt./day dose) with a simultaneous decrease in litter size. The significant decrease in mean fetal weight and crown-rump length (CRL) of F2 fetuses were observed at 0.1, 4, 40 and 150 dose groups indicating impaired development of F2 fetuses caused by TCS exposure. Present study emphasizes for the first time that TCS exposure during the vulnerable developmental time point (gestation and lactation) adversely affects reproductive functions and fertility of F1 male rats, which were transmitted to F2 generations leading to reduced CRLs and weights of F2 fetuses.

Downregulation of testosterone production through luteinizing hormone receptor regulation in male rats exposed to 17α-ethynylestradiol

The pharmaceutical 17α-ethynylestradiol (EE2) is considered as an endocrine-disrupting chemical that interferes with male reproduction and hormonal activation. In this study, we investigated the molecular mechanism underlying EE2-regulatory testosterone release in vitro and in vivo. The results show that EE2 treatment decreased testosterone release from rat Leydig cells. Treatment of rats with EE2 reduced plasma testosterone levels and decreased the sensitivity of human chorionic gonadotropin (hCG). EE2 reduced luteinizing hormone receptor (LHR) expression associated with decreased cAMP generation by downregulation of adenylyl cyclase activity and decreased intracellular calcium-mediated pathways. The expression levels of StAR and P450scc were decreased in Leydig cells by treatment of rats with EE2 for 7 days. The sperm motility in the vas deferens and epididymis was reduced, but the histopathological features of the testis and the total sperm number of the vas deferens were not affected. Moreover, the serum dihydrotestosterone (DHT) level was decreased by treatment with EE2. The prostate gland and seminal vesicle atrophied significantly, and their expression level of 5α-reductase type II was reduced after EE2 exposure. Taken together, these results demonstrate an underlying mechanism of EE2 to downregulate testosterone production in Leydig cells, explaining the damaging effects of EE2 on male reproduction.

In-vitro spermatogenesis through testis modelling: Toward the generation of testicular organoids

Background

The testicular organoid concept has recently been introduced in tissue engineering to refer to testicular cell organizations modeling testicular architecture and function. The testicular organoid approach gives control over which and how cells reaggregate, which is not possible in organotypic cultures, thereby extending the applicability of in‐vitro spermatogenesis (IVS) systems. However, it remains unclear which culture method and medium allow reassociation of testicular cells into a functional testicular surrogate in‐vitro.

Objective

The aim of this paper is to review the different strategies that have been used in an attempt to create testicular organoids and generate spermatozoa. We want to provide an up‐to‐date list on culture methodologies and media compositions that have been used and determine their role in regulating tubulogenesis and differentiation of testicular cells.

Search method

A literature search was conducted in PubMed, Web of Science, and Scopus to select studies reporting the reorganization of testicular cell suspensions in‐vitro, using the keywords: three‐dimensional culture, in‐vitro spermatogenesis, testicular organoid, testicular scaffold, and tubulogenesis. Papers published before the August 1, 2019, were selected.

Outcome

Only a limited number of studies have concentrated on recreating the testicular architecture in‐vitro. While some advances have been made in the testicular organoid research in terms of cellular reorganization, none of the described culture systems is adequate for the reproduction of both the testicular architecture and IVS.

Conclusion

Further improvements in culture methodology and medium composition have to be made before being able to provide both testicular tubulogenesis and spermatogenesis in‐vitro.

Retinoid-related orphan nuclear receptor alpha (RORα)-deficient mice display morphological testicular defects

The role of retinoid-related orphan receptor, one of the transcription factors reported in testis, in testicular function is unclear, so this study was performed to evaluate the qualitative and quantitative changes in the testicular structure of RORα-deficient mice using light-, electron-microscopy, and immunohistochemistry. Among the most striking alterations observed in the testis of the mutant mice were hypospermatogenesis, marked reduction in volume proportions of interstitial tissues and number of Leydig cells, significant decrease in the diameter of seminiferous tubules and height of their epithelium, vacuolation in the epithelium of the seminiferous tubules with occurrence of mast cells, appearance of delay spermiation signs, and changes in sperm morphology. Moreover, the testis of mutant mice showed symplasts, in addition to appearance of multinucleated giant bromophenol-positive cells. ATPase activity was limited to spermatogonia and some primary spermatocytes, with higher alkaline phosphatase expression. Stronger vimentin reaction was immunolocalized to spermatogonia, spermatids, Leydig cells, and Sertoli cells. The expression of CD117 (C-kit, stem cell growth factor receptor) was limited to spermatogonia, primary spermatocytes, and Leydig cells. Seminiferous tubules showed overexpression of vascular endothelial growth factor (VEGF). Transmission electron microscopy examination of the mutant mice revealed abnormal Sertoli cells, hypertrophied spermatogonia, spermatocytes with degenerated mitochondria, and incompletely developed sperms. In conclusion, RORα is one of the essential proteins that regulate testicular structure.

Acute exposure to perfluorononanoic acid in prepubertal mice: Effect on germ cell dynamics and an insight into the possible mechanisms of its inhibitory action on testicular functions

Perfluoroalkyl acids (PFAAs) are anthropogenic compounds used globally in a variety of commercial products. Perfluorononanoic acid (PFNA), a member of PFAAs, is detected in human blood and this has been reported to cause hepatotoxic, immunotoxic, and developmental and testicular toxic effects in laboratory animals. We have recently shown that the acute exposure to PFNA in prepubertal Parkes (P) mice impairs spermatogenesis by inducing oxidative stress and inhibiting testosterone biosynthesis in the testis. The present study was aimed to examine the effect of acute exposure to PFNA in prepubertal P mice on germ cell dynamics and to understand the possible mechanisms of action of this compound on testicular functions. PFNA (2 and 5 mg/kg body weight) was orally administered to male mice for 14 days from postnatal day 25-38. The treatment caused a decrease in overall germ cell transformation. The results also reveal that impairment in testicular functions in treated mice is associated with alterations in cholesterol and glucose homeostasis; further, an inhibition in expressions of growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1), insulin-like growth factor-1 receptor (IGF-1R), androgen receptor (AR), phosphorylated mammalian target of rapamycin (p-mTOR) and peroxisome proliferator activated receptor α (PPAR α) in the testis is also implicated in this action. The findings thus suggest involvement of multiple factors which altogether contribute to the alterations in spermatogenic process and testosterone production following acute exposure to PFNA in prepubertal mice.

Reproductive, antioxidant and metabolic responses of Ossimi rams to kisspeptin

The aim of this study was to evaluate the potential reproductive, antioxidant and metabolic effects of kisspeptin-10 (KP-10) on Ossimi rams. Twelve Ossimi rams (1.5-2 years old) were divided randomly into two groups (six per group). The first one served as a control group, while the second one served as a treated group. Rams of the treated group were injected once weekly with KP-10 (5 μg/kg body weight) for one month. There were no significant differences in all measured parameters between rams of control group at pre-treatment period and those at post-treatment period. However, most examined parameters in the same rams in the treated group were affected by injection of KP-10 when comparing pre-treatment values in treated group with its post-treatment values. At the pre-treatment period, there were no significant differences between the treated and control groups regarding semen pH, mass motility, sperm concentration/mL, live and dead spermatozoa, total sperm abnormality, testosterone and oxidative stress and metabolic parameters. However, all semen characteristics were significantly improved in the treated group compared with the control group at the post-treatment period and in the treated group at the post-treatment period compared with that at the pre-treatment period. In addition, scrotal circumference, ejaculate volume and total sperm concentration/ejaculate showed higher significant improvements when comparing the treated group with the control one at the post-treatment period than when comparing the two groups at the pre-treatment period and also when comparing the treated group at the post-treatment period with that at the pre-treatment period. Serum testosterone, total antioxidant capacity, lipid peroxides, nitric oxide, total protein, albumin, glucose and high density lipoprotein-cholesterol levels significantly increased when comparing the treated group with the control one at the post-treatment period and also when comparing the treated group at the post-treatment period with that at the pre-treatment period. In conclusion, KP-10 led to potential improvement in the reproductive efficacy and metabolic capacity of Ossimi ram.

The current and future perspectives of zinc oxide nanoparticles in the treatment of diabetes mellitus

Diabetes mellitus (DM) is a multifaceted and costly disease, which requires serious attention. Finding a cheaper anti-diabetic alternative that can act on multiple disease-related targets and pathways is the ultimate treatment goal for DM. Nanotechnology has offered some exciting possibilities in biomedical and drug delivery applications. Zinc oxide nanoparticles (ZnO-NPs), a novel agent to deliver zinc, have great implications in many disease therapies including DM. This review summarizes the pharmacological mechanisms by which ZnO-NPs alleviate DM and diabetic complications. Research implications and future perspectives were also discussed.

Androgens downregulate anti-Müllerian hormone promoter activity in the Sertoli cell through the androgen receptor and intact steroidogenic factor 1 sites

Testicular anti-Müllerian hormone (AMH) production is inhibited by androgens around pubertal onset, as observed under normal physiological conditions and in patients with precocious puberty. In agreement, AMH downregulation is absent in patients with androgen insensitivity. The molecular mechanisms underlying the negative regulation of AMH by androgens remain unknown. Our aim was to elucidate the mechanisms through which androgens downregulate AMH expression in the testis. A direct negative effect of androgens on the transcriptional activity of the AMH promoter was found using luciferase reporter assays in the mouse prepubertal Sertoli cell line SMAT1. A strong inhibition of AMH promoter activity was seen in the presence of both testosterone and DHT and of the androgen receptor. By site-directed mutagenesis and chromatin immunoprecipitation assays, we showed that androgen-mediated inhibition involved the binding sites for steroidogenic factor 1 (SF1) present in the proximal promoter of the AMH gene. In this study, we describe for the first time the mechanism behind AMH inhibition by androgens, as seen in physiological and pathological conditions in males. Inhibition of AMH promoter activity by androgens could be due to protein-protein interactions between the ligand-bound androgen receptor and SF1 or by blockage of SF1 binding to its sites on the AMH promoter.

Warfarin-induced vitamin K deficiency affects spermatogenesis in Sprague-Dawley rats

Vitamin K is present in the testes though its actual function in male reproduction is poorly understood. This study investigated the harmful effect of extrahepatic vitamin K insufficiency on the testicular structure. Sprague-Dawley rats were fed with a diet containing warfarin for 2, 4 and 8 weeks; control animals received a standard diet without warfarin. It was found that extrahepatic vitamin K deficiency that is induced by warfarin results in histopathological features that range from delayed spermiation, presence of multinucleated giant cells in the seminiferous tubules, germ cells degeneration, asthenozoospermia, oligozoospermia and increase in the percentage of abnormal sperm morphology when compared to the controls. Data obtained from the two groups were analysed using the Student t test. It is concluded that warfarin-induced vitamin K deficiency has a negative impact on spermatogenesis.