Androgen receptor roles in spermatogenesis and fertility: lessons from testicular cell-specific androgen receptor knockout mice

Environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin induces non-obstructive azoospermia: New insights from network toxicology, integrated machine learning, and biomolecular modeling

OBJECTIVE

As industrial pollution intensifies, global male semen quality has been declining at a rate of 2.64 % per year in the 21st century. Among the various types of infertility, non-obstructive azoospermia (NOA) is the most severe and is closely associated with exposure to environmental toxins. The molecular mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a typical persistent organic pollutant, induces NOA have yet to be systematically elucidated.

METHODS

This study employed the single-sample Gene Set Enrichment Analysis (ssGSEA) method to identify key toxicological pathways and constructed a diagnostic model based on 113 machine learning algorithms. By integrating Weighted Gene Co-expression Network Analysis (WGCNA) and single-cell analysis, we identified hub genes associated with the Sertoli Cell-Only Syndrome (SCOS) subtype. Finally, biomolecular modeling was conducted to validate the binding efficacy of the hub genes with TCDD.

RESULTS

Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis based on the ssGSEA method indicated that TCDD may disrupt spermatogenesis by activating the Tumor Necrosis Factor (TNF) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways while inhibiting the Vascular Endothelial Growth Factor (VEGF) signaling pathway, ultimately leading to NOA. Through the integration of machine learning techniques, 5 hub genes (AUC > 0.7) induced by TCDD and associated with NOA were identified: Androgen receptor (AR), Chromodomain Helicase DNA-Binding Protein 1 (CHD1), Discoidin Domain Receptor Tyrosine Kinase 2 (DDR2), Retinoic Acid Receptor-Related Orphan Receptor Alpha (RORA), and Glutamate Ionotropic Receptor AMPA Type Subunit 1 (GRIA1). WGCNA and single-cell analysis revealed that AR and DDR2 were specifically expressed in the testicular tissues of NOA patients and were closely associated with SCOS (p < 0.05). Immune infiltration analysis suggested that TCDD induces abnormal infiltration of various immune cells, indicating its close relationship with immune inflammatory responses (p < 0.05). Biomolecular modeling further demonstrated a strong binding affinity between AR and TCDD (∆G = -8.3 kcal·mol⁻¹, Etotal = -37.79 kcal·mol⁻¹), highlighting the critical role of AR in TCDD-induced NOA.

CONCLUSIONS

This study reveals the potential molecular mechanisms by which TCDD induces NOA, providing new targets for the development of diagnostic and therapeutic strategies.

Single-cell multiomic comparison of mouse and rat spermatogenesis reveals gene regulatory networks conserved for over 20 million years

Spermatogenesis is driven by dramatic changes in chromatin regulation, gene transcription, and protein expression. To assess the mechanistic bases for these developmental changes, we utilized multiomic single-cell/nucleus RNA sequencing (sc/snRNA-seq) and single-nucleus assay for transposase-accessible chromatin with sequencing (snATAC-seq) to identify chromatin changes associated with transcription in adult mouse and rat testes. We characterized the relationships between the transcriptomes and chromatin of both species, including the divergent expression of Id4 in spermatogonial stem cells between species. Promoter accessibility and gene expression showed the greatest association during meiosis in both species. We mapped the cross-species conservation of putative regulatory regions for key spermatogenic genes, including Cd9 and Spam1, and investigated correlations and disconnects in chromatin accessibility, gene expression, and protein expression via antibody-derived tags. Using a gene regulatory network (GRN) model, we identified 40 core regulons conserved between mouse and rat germ cells, highlighting the relevance of chromatin-related factors in regulating the transcription of canonical genes across spermatogenesis.

Single-cell transcriptomic atlas of the human testis across the reproductive lifespan

Testicular aging is associated with declining reproductive health, but the molecular mechanisms are unclear. Here we generate a dataset of 214,369 single-cell transcriptomes from testicular cells of 35 individuals aged 21-69, offering a resource for studying testicular aging and physiology. Machine learning analysis reveals a stronger aging response in somatic cells compared to germ cells. Two waves of aging-related changes are identified: the first in peritubular cells of donors in their 30s, marked by increased basement membrane thickness, indicating a priming state for aging. In their 50s, testicular cells exhibit functional changes, including altered steroid metabolism in Leydig cells and immune responses in macrophages. Further analyses reveal the impact of body mass index on spermatogenic capacity as age progresses, particularly after age 45. Altogether, our findings illuminate molecular alterations during testis aging and their relationship with body mass index, providing a foundation for future research and offering potential diagnostic markers and therapeutic targets.

Targeted gene silencing in mouse testicular Sertoli and Leydig cells using adeno-associated virus vectors

ABSTRACT

Researchers commonly use cyclization recombination enzyme/locus of X-over P1 (Cre/loxP) technology-based conditional gene knockouts of model mice to investigate the functional roles of genes of interest in Sertoli and Leydig cells within the testis. However, the shortcomings of these genetic tools include high costs, lengthy experimental periods, and limited accessibility for researchers. Therefore, exploring alternative gene silencing techniques is of great practical value. In this study, we employed adeno-associated virus (AAV) as a vector for gene silencing in Sertoli and Leydig cells. Our findings demonstrated that AAV serotypes 1, 8, and 9 exhibited high infection efficiency in both types of testis cells. Importantly, we discovered that all three AAV serotypes exhibited exquisite specificity in targeting Sertoli cells via tubular injection while demonstrating remarkable selectivity in targeting Leydig cells via interstitial injection. We achieved cell-specific knockouts of the steroidogenic acute regulatory (Star) and luteinizing hormone/human chorionic gonadotropin receptor (Lhcgr) genes in Leydig cells, but not in Sertoli cells, using AAV9-single guide RNA (sgRNA)-mediated gene editing in Rosa26-LSL-Cas9 mice. Knockdown of androgen receptor (Ar) gene expression in Sertoli cells of wild-type mice was achieved via tubular injection of AAV9-short hairpin RNA (shRNA)-mediated targeting. Our findings offer technical approaches for investigating gene function in Sertoli and Leydig cells through AAV9-mediated gene silencing.

Androgen Receptor Expression Governs the Seasonal Inhibition of Testicular Development and Subsequent Recovery in Rattus norvegicus caraco

Commonly in seasonal breeding animals, testicular development is inhibited prior to Sertoli cell maturation when environmental conditions become unfavorable, with recovery occurring once conditions improve. However, the precise molecular mechanisms governing this process remain unclear. We investigated the role of androgen receptor (AR) in the seasonal regulation of testicular development in a wild population of Rattus norvegicus caraco, a subspecies of brown rats in Northeast China residing in high-latitude regions, known for its seasonal reproductive patterns. Our results revealed a significant increase in Ar mRNA expression in wild rats with small testes less than 0.2 g and body weights ranging between 80 and 100 g during the nonbreeding season. Further examinations of Ar expression in the testicular development of R. n. caraco in the laboratory under different day lengths and temperatures that simulating breeding and nonbreeding seasons suggest that the maturation of Sertoli cells depends on the upregulation of Ar expression around a testis weight of 0.07-0.18 g, regardless of age and conditions, synchronously accompanying the initiation of the meiotic phase. When Ar expression was suppressed, testicular development was impeded around the stage of Sertoli cell maturation, resulting in decreased spermatogenesis and hindered growth in testis weight. Our findings elucidate how animals control the seasonal inhibition and subsequent recovery of testicular development by regulating Ar expression in R. n. caraco.

Sustanon suppresses spermatogenesis and increases cell death

Background

Anabolic-androgenic steroids (AAS) are synthetic derivatives of testosterone. Sustanon, dissolved in peanut oil, is an AAS used by athletes to build muscle mass. This study aims to examine the effects of Sustanon on male reproductive health.

Methods

Adult male rats were divided into four groups under standard conditions. The control group received an intramuscular injection of the Sustanon solvent. The second, third, and fourth groups were treated with different doses (10, 20, and 30 mg/kg body weight) of Sustanon for 8 weeks. Blood samples, testes, and spermatozoa were collected for laboratory tests. Complementary DNA (cDNA) was synthesized from total RNA, and the expression of deleted in azoospermia like (DAZL) and B-cell lymphoma 2 (BCL2) genes was measured by real-time polymerase chain reaction (PCR). Histopathological analysis was performed on the testes.

Results

The BCL2 gene had significantly lower expression in the treatment groups compared to the control group. There was no significant increase in the expression of DAZL. Significant reductions in testicular length, diameter, weight, sperm count, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) concentrations were observed in the treatment groups. Histological changes were evident in the testes of the treated groups.

Conclusions

Sustanon likely induces adverse effects on the male reproductive system, potentially decreasing fertility. The study provides critical insights into the negative impacts of Sustanon on spermatogenesis and cell survival.

Rosemary officinalis extract mitigates potassium dichromate-induced testicular degeneration in male rats: Insights from the Nrf2 and its target genes signaling pathway

This study aimed to investigate the protective effects of Rosemary ethanol extract (ROEE) on testicular damage induced by potassium Dichromate (PDC) in male rats regarding the signaling pathway of Nrf2 and its target genes and proteins. A total of 28 male rats were divided into four groups: control, PDC only (15 mg/kg b.w. orally), PDC + low dose ROEE (220 mg/kg b.w.), and PDC + high dose ROEE (440 mg/kg b.w.). After 28 days of consecutive treatment, the rats were sacrificed for histological, immunohistochemistry, and biochemical analyses. The results revealed that the ROEE treatment up-regulated the Nrf2 and its target genes (NQO1, HO-1) mRNA expressions compared to the PDC group. correspondingly, the protein levels of GCLM, GSH, SOD, and catalase were significantly increased in the ROEE-treated animals compared to the PDC-treated animals. Furthermore, ROEE administration led to increased serum levels of testosterone (T4) and decreased levels of estrogen (E2) compared to the PDC group. Semen analysis and histopathology demonstrated that ROEE administration significantly improved spermatological impairment caused by PDC. The immunoexpression of cytoplasmic HSP-90 was reduced in the ROEE-treated groups, while the expression of androgen receptor (AR) was markedly improved. ROEE exhibited protective effects against PDC-induced testicular damage, likely due to its antioxidant properties. However, further investigation is required to elucidate the underlying mechanisms of action.

Potential antiandrogenic effects of parabens and benzophenone-type UV-filters by inhibition of 3α-hydroxysteroid dehydrogenases

Parabens and UV-filters are frequently used additives in cosmetics and body care products that prolong shelf-life. They are assessed for potential endocrine disrupting properties. Antiandrogenic effects of parabens and benzophenone-type UV-filters by blocking androgen receptor (AR) activity have been reported. Effects on local androgen formation received little attention. Local 5α-dihydrotestosterone (DHT) production with subsequent AR activation is required for male external genitalia formation during embryogenesis. We investigated whether parabens and benzophenone-type UV-filters might cause potential antiandrogenic effects by inhibiting oxidative 3α-hydroxysteroid dehydrogenases (3α-HSDs) involved in the backdoor pathway of DHT formation. Five different 3α-HSDs were assessed for their efficiency to catalyze the 3α-oxidation reaction to form DHT and activate AR. 17β-hydroxysteroid dehydrogenase type 6 (HSD17B6), retinol dehydrogenases type 5 and 16 were further assessed using a radiometric in vitro activity assay to determine the conversion of 5α-androstane-3α-ol-17-one to 5α-androstane-3,17-dione in lysates of overexpressing HEK-293 cells. All parabens tested, except p-hydroxybenzoic acid (a main metabolite) inhibited HSD17B6 activity. Hexyl- and heptylparaben, as well as benzophenone (BP)-1 and BP-2, showed the highest inhibitory potencies, with nanomolar IC50 values. Molecular modeling predicted binding modes for the inhibitory parabens and BPs and provided an explanation for the observed structure-activity-relationship. Our results propose a novel mechanism of antiandrogenic action for commercially used parabens and BP UV-filters by inhibiting HSD17B6 and lowering DHT synthesis. Follow-up studies should assess BP-3 metabolism after topical application and whether the identified inhibitors reach concentrations in liver, testis, or prostate to inhibit HSD17B6, thereby causing antiandrogenic effects.

Improvement of Late-Onset Hypogonadism Symptoms of Fermented Morinda citrifolia Extract in TM3 Leydig and TM4 Sertoli Cells

BACKGROUND/OBJECTIVES

Late-onset hypogonadism (LOH), characterized by declining testosterone levels with age, negatively affects the health of men, causing physical, psychological, and sexual dysfunction. Conventional testosterone replacement therapies have side effects, which has led to interest in natural alternatives. We investigated the effects of a standardized fermented Morinda citrifolia extract (FME) on oxidative stress-induced damage in TM3 Leydig and TM4 Sertoli cells. The cells were treated with H2O2 to simulate oxidative stress, followed by the FME treatment.

METHODS

Cytotoxicity assays, testosterone measurements, and gene and protein expression analyses were conducted to evaluate the restorative properties of FME.

RESULTS

The H2O2 treatment significantly decreased the cell viability, testosterone production, and the expression of proteins involved in testosterone synthesis and spermatogenesis, and the FME treatment improved testosterone production and restored the luteinizing hormone receptor, steroidogenic acute regulatory protein, CYP11A1, 3β-hydroxysteroid dehydrogenase, 17,20 desmolase, and 17β-hydroxysteroid dehydrogenase levels in the TM3 Leydig cells. It also reduced the expression of testosterone-degrading enzymes, aromatase and 5α-reductase. The FME treatment restored the levels of the androgen receptor and follicle-stimulating hormone receptor in the TM4 Sertoli cells.

CONCLUSIONS

FME alleviates oxidative stress-induced damage in Leydig and Sertoli cells by promoting testosterone synthesis and spermatogenesis while regulating testosterone metabolism. These findings suggest that FME could be a promising candidate for the management of LOH symptoms.

Guijiajiao-Lujiaojiao Synergistically Promote Spermatogenesis in Tripterygium Wilfordii Polyglycoside-Induced Oligoasthenozoospermia Rats via PI3K/AKT Signaling Pathway

Guijiajiao-Lujiaojiao (GL) is a combination of Traditional Chinese Medicine (TCM) that can be used to treat oligoasthenozoospermia (OAS). However, its mechanistic role in OAS needs to be better understood and necessitates more studies. This study was planned to investigate GL's therapeutic effects and its mechanistic role in the tripterygium wilfordii polyglycoside (GTW)-induced OAS rat model. In total, 60 Sprague-Dawley (SD) rats at 8 weeks of age were assigned to six groups: blank (NC), model (GTW), GL low-dose (GL-L, 0.3 g/kg/day), GL medium-dose (GL-M, 0.6 g/kg/day), GL high-dose (GL-H, 1.2 g/kg/day), and GL high-dose + PI3K inhibitor LY294002 (GL-H 1.2 g/kg/day + LY 1.2 mg/kg/day) groups. The model was characterized after 8 weeks to examine sperm concentration and viability, serum hormone levels, testes histopathology, and specific protein markers. The treatment efficacy was evaluated by mRNA and protein expression levels, among other parameters. Compared with the GTW group, the viability and concentration of rat spermatozoa were significantly increased after GL intervention (p < .01). Meanwhile, the serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and T hormones in rats in the GL-M and GL-H groups were significantly higher than those in the GTW group (p < .05). Furthermore, GL enhanced the proliferation of spermatogenic cells by modulating the PI3K/AKT signaling pathway, increasing and decreasing the levels of Bcl-2 and Bax proteins, respectively. It is concluded that the mechanism by which GL effectively enhanced the spermatogenic function of the GTW-induced OAS model may be attributed to the PI3K/AKT signaling pathway activation and the elevation of serum LH, FSH, and T hormone levels.

FOXO4-DRI improves spermatogenesis in aged mice through reducing senescence-associated secretory phenotype secretion from Leydig cells

Male ageing is always accompanied by decreased fertility. The forkhead O (FOXO) transcription factor FOXO4 is reported to be highly expressed in senescent cells. Upon activation, it binds p53 in the nucleus, preventing senescent cell apoptosis and maintaining senescent cells in situ. Leydig cells play key roles in assisting spermatogenesis. Leydig cell senescence leads to deterioration of the microenvironment of the testes and impairs spermatogenesis. In this study, we observed that FOXO4-DRI, a specific FOXO4- p53 binding blocker, induced apoptosis in senescent Leydig cells, reduced the secretion of certain Senescence-Associated Secretory Phenotype and improved the proliferation of cocultured GC-1 SPG cells. In naturally aged mice, FOXO4-DRI-treated aged mice exhibited increased sperm quality and improved spermatogenesis.

Assessing the Risks of Pesticide Exposure: Implications for Endocrine Disruption and Male Fertility

Pesticides serve as essential tools in agriculture and public health, aiding in pest control and disease management. However, their widespread use has prompted concerns regarding their adverse effects on humans and animals. This review offers a comprehensive examination of the toxicity profile of pesticides, focusing on their detrimental impacts on the nervous, hepatic, cardiac, and pulmonary systems, and their impact on reproductive functions. Additionally, it discusses how pesticides mimic hormones, thereby inducing dysfunction in the endocrine system. Pesticides disrupt the endocrine system, leading to neurological impairments, hepatocellular abnormalities, cardiac dysfunction, and respiratory issues. Furthermore, they also exert adverse effects on reproductive organs, disrupting hormone levels and causing reproductive dysfunction. Mechanistically, pesticides interfere with neurotransmitter function, enzyme activity, and hormone regulation. This review highlights the effects of pesticides on male reproduction, particularly sperm capacitation, the process wherein ejaculated sperm undergo physiological changes within the female reproductive tract, acquiring the ability to fertilize an oocyte. Pesticides have been reported to inhibit the morphological changes crucial for sperm capacitation, resulting in poor sperm capacitation and eventual male infertility. Understanding the toxic effects of pesticides is crucial for mitigating their impact on human and animal health, and in guiding future research endeavors.

Reproductive Outcomes of Infertile Males With Novel Genetic Defects

Various chromosomal structural aberrations and genetic mutations have been discovered in infertile couples. Some have no obvious loss of genetic material; they are usually phenotypically normal people with reproductive issues. Males with these illnesses may have infertility and abnormal sperm analysis. However, positive sperm have also been detected in the ejaculation of some patients. As a result, knowing about these problems and how common they are can influence the fertility treatment that couples receive to achieve pregnancy and the birth of healthy newborns.

Interaction between Chromodomain Y-like Protein and Androgen Receptor Signaling in Sertoli Cells Accounts for Spermatogenesis

Spermatogenesis is a highly regulated process dependent on androgen receptor (AR) signaling in Sertoli cells. However, the pathogenic mechanisms of spermatogenic failure, by which loss of AR impairs downstream target genes to affect Sertoli cell function, remain incompletely understood. By using microarray analysis, we identified several AR-regulated genes involved in the maturation of spermatogenesis, including chromodomain Y-like protein (CDYL) and transition proteins 1 (TNP-1), that were significantly decreased in ARKO mouse testes. AR and CDYL were found to co-localize and interact in Sertoli cells. The AR-CDYL complex bound to the promoter regions of TNP1 and modulated their transcriptional activity. CDYL acts as a co-regulator of AR transactivation, and its expression is decreased in the Sertoli cells of human testes from patients with azoospermia. The androgen receptor-chromodomain Y-like protein axis plays a crucial role in regulating a network of genes essential for spermatogenesis in Sertoli cells. Disruption of this AR-CDYL regulatory axis may contribute to spermatogenic failure. These findings provide insights into novel molecular mechanisms targeting the AR-CDYL signaling pathway, which may have implications for developing new therapeutic strategies for male infertility.

Prenatal exposure to Di(2-ethylhexyl) phthalate and high-fat diet synergistically disrupts gonadal function in male mice†

Prenatal exposure to Di (2-ethylhexyl) phthalate (DEHP) impairs the reproductive system and causes fertility defects in male offspring. Additionally, high-fat (HF) diet is a risk factor for reproductive disorders in males. In this study, we tested the hypothesis that prenatal exposure to a physiologically relevant dose of DEHP in conjunction with HF diet synergistically impacts reproductive function and fertility in male offspring. Female mice were fed a control or HF diet 7 days prior to mating and until their litters were weaned on postnatal day 21. Pregnant dams were exposed to DEHP or vehicle from gestational day 10.5 until birth. The male offspring's gross phenotype, sperm quality, serum hormonal levels, testicular histopathology, and testicular gene expression pattern were analyzed. Male mice born to dams exposed to DEHP + HF had smaller testes, epididymides, and shorter anogenital distance compared with those exposed to HF or DEHP alone. DEHP + HF mice had lower sperm concentration and motility compared with DEHP mice. Moreover, DEHP + HF mice had more apoptotic germ cells, fewer Leydig cells, and lower serum testosterone levels than DEHP mice. Furthermore, testicular mRNA expression of Dnmt1 and Dnmt3a was two to eight-fold higher than in DEHP mice by qPCR, suggesting that maternal HF diet and prenatal DEHP exposure additively impact gonadal function by altering the degree of DNA methylation in the testis. These results suggest that the combined exposure to DEHP and high-fat synergistically impairs reproductive function in male offspring, greater than exposure to DEHP or HF diet alone.

Loss of PBX1 function in Leydig cells causes testicular dysgenesis and male sterility

Leydig cells are essential components of testicular interstitial tissue and serve as a primary source of androgen in males. A functional deficiency in Leydig cells often causes severe reproductive disorders; however, the transcriptional programs underlying the fate decisions and steroidogenesis of these cells have not been fully defined. In this study, we report that the homeodomain transcription factor PBX1 is a master regulator of Leydig cell differentiation and testosterone production in mice. PBX1 was highly expressed in Leydig cells and peritubular myoid cells in the adult testis. Conditional deletion of Pbx1 in Leydig cells caused spermatogenic defects and complete sterility. Histological examinations revealed that Pbx1 deletion impaired testicular structure and led to disorganization of the seminiferous tubules. Single-cell RNA-seq analysis revealed that loss of Pbx1 function affected the fate decisions of progenitor Leydig cells and altered the transcription of genes associated with testosterone synthesis in the adult testis. Pbx1 directly regulates the transcription of genes that play important roles in steroidogenesis (Prlr, Nr2f2 and Nedd4). Further analysis demonstrated that deletion of Pbx1 leads to a significant decrease in testosterone levels, accompanied by increases in pregnenolone, androstenedione and luteinizing hormone. Collectively, our data revealed that PBX1 is indispensable for maintaining Leydig cell function. These findings provide insights into testicular dysgenesis and the regulation of hormone secretion in Leydig cells.

The effect of gonadotropin-inhibitory hormone on steroidogenesis and spermatogenesis by acting through the hypothalamic-pituitary-testis axis in mice

Gonadotropin inhibitory hormone (GnIH) is essential for regulating the reproduction of mammals and inhibiting testicular activities in mice. This study aimed to explore the mechanism of GnIH on spermatogenesis and steroidogenesis by acting through the hypothalamus-pituitary-testis axis of mice. Mice were subcutaneously injected with different doses of GnIH (1 μg/150 μL, 3 μg/150 μL, 6 μg/150 μL, 150 μL saline, twice daily) for 11 days. Subsequently, luteinizing hormone (LH), testosterone (T), and inhibin B (INH B) levels of peripheral blood were determined, and the expression of GnRH synthesis-related genes (GnRH-1, Kiss-1, NPY) and gonadotropin synthesis-related genes (FSH β, LH β, GnRH receptor) in the hypothalamus and pituitary gland were respectively detected. Additionally, the expression of steroidogenesis-related genes/proteins (P450scc, StAR and 3β-HSD) and spermatogenesis-related proteins/genes including LH receptor (LHR), androgen receptor (AR), heat shock factor-2 (HSF-2) and INH B were analyzed using western blot and q-PCR. Results showed that GnIH treatment significantly reduced the concentration of LH in the peripheral blood. Further analysis revealed that GnIH treatment markedly reduced the expression of GnRHImRNA and Kiss-1 mRNA in the hypothalamus, and mRNA levels of FSH β, LH β, and GnRHR genes in the pituitary. We also observed that GnIH treatment significantly decreased T levels and expression of the P450scc, StAR, and 3β-HSD proteins in the testis. Furthermore, GnIH treatment down-regulated LHR, AR proteins, and HSF-2 gene in the testis. Importantly, the INH B concentration of and INH βb mRNA levels significantly declined following GnIH treatment. Additionally, GnIH treatment may induce germ cell apoptosis in the testis of mice. In conclusion, GnIH may suppress spermatogenesis and steroidogenesis by acting through the hypothalamus-pituitary-testis axis in mice.

Dichloroacetic acid and trichloroacetic acid as disinfection by-products in drinking water are endocrine-disrupting chemicals

Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are two typical non-volatile disinfection by-products (DBPs) found in drinking water. Increasing evidence has demonstrated that they show reproductive toxicity. However, whether they might have endocrine disrupting properties remains largely unknown. To discover this, we treated male mice or pregnant mice with 0, 1-, 102-, 103-, 104-, or 5 × 104-fold maximal concentration level (MCL) of DCAA or TCAA in drinking water. In male mice, the levels of testosterone in serum and androgen receptor (AR) in testis were declined with ≥ 103-fold MCL of DCAA (26.4 mg/kg/d) or TCAA (52.7 mg/kg/d). In pregnant mice, miscarriage rates were increased with ≥ 104-fold MCL of DCAA (264 mg/kg/d) or ≥ 103-fold MCL of TCAA. The levels of FSH in serum were increased and those of estradiol and progesterone were reduced with ≥ 103-fold MCL of DCAA or TCAA. The protein levels of estrogen receptors (ERα and ERβ) in ovary were reduced with ≥ 102-fold MCL of DCAA (2.64 mg/kg/d) or TCAA (5.27 mg/kg/d). Exposure to some certain fold MCL of DCAA or TCAA also altered the protein levels of ERα and ERβ in uterus and placenta. Exposure to 5 × 104-fold MCL of both DCAA and TCAA showed the combined effects. Therefore, both DCAA and TCAA could be considered as novel reproductive endocrine disrupting chemicals, which might be helpful for further assessment of the toxicological effects of DCAA and TCAA and the awareness of reproductive endocrine disrupting properties caused by DCAA and TCAA in drinking water.

Ursonic acid attenuates spermatogenesis in oligozoospermia mice through inhibiting ferroptosis

Ursonic acid (UNA) is a natural pentacyclic triterpene found in some medicinal plants and foods. The reproductive protective effect of UNA was evaluated in a mouse model of oligozoospermia induced by busulfan (BUS) at 30 mg/kg b.w.. The mice were initially divided into groups with UNA concentrations of 10, 30, 50, 100 mg/kg. Subsequently, based on sperm parameters, the optimal concentration of 50 mg/kg was identified. As a control, an additional group was supplemented with ursolic acid at a concentration of 50 mg/kg. The results indicated that BUS caused the loss of spermatogenic cells in testis, the decrease of sperm in epididymis, the disorder of testicular cytoskeleton, the decrease of serum sex hormones such as testosterone which induced an increase in feedback of androgen receptor and other testosterone-related proteins, the increase of malondialdehyde and reactive oxygen species levels and the increase of ferroptosis in testis while UNA successfully reversed these injuries. High-throughput sequencing revealed that UNA administration significantly upregulated the expression of genes associated with spermatogenesis, such as Tnp1, Tnp2, Prm1, among others. These proteins are crucial in the histone to protamine transition during sperm chromatin remodeling. Network pharmacology analysis reveals a close association between UNA and proteins related to the transformation of histones to protamine. Molecular docking studies reveal that UNA can interact with the ferroptosis-inhibiting gene SLC7A11, thereby modulating ferroptosis. Taken together, UNA alleviated BUS-induced oligozoospermia by regulating hormone secretion, mitigating oxidative stress and promoting recovery of spermatogenesis by inhibiting the ferroptosis.

Improvements in in vitro spermatogenesis: oxygen concentration, antioxidants, tissue-form design, and space control

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMα, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis. Moreover, based on our experience with microfluidic devices (MFD), we developed an alternative approach, the PDMS-ceiling method (PC method), which involves simply covering the tissue with a flat chip made of PDMS, a silicone resin material used in MFD. The PC method, while straightforward, integrates the advantages of MFD, enabling improved and uniform oxygen and nutrient supply via tissue flattening. Furthermore, our studies underscored the significance of lowering the oxygen concentration to 10-15%. Using an integrated cultivation method based on these findings, we successfully achieved in vitro spermatogenesis in rats, which has been a long-standing challenge. Further improvements in culture conditions would pave the way for spermatogenesis completion in diverse animal species.

Combined effects of organochlorine pesticides on type 2 diabetes mellitus: Insights from endocrine disrupting effects of hormones

Association between organochlorine pesticides (OCPs) exposure and type 2 diabetes mellitus (T2DM) remains contradictory, and the evidence is mostly focused on a single exposure. Here, we assessed the associations between individual and combined OCPs exposure and T2DM, and explored the underlying mechanism of sex hormones and the methylation levels of sex hormone receptors in above associations. A case-control study with 1812 participants was performed. Gas chromatography mass spectrometry, liquid chromatography-tandem mass spectrometry, and pyrosequencing were used to measure plasma OCPs, serum sex hormones, and whole blood methylation levels of sex hormone receptors, respectively. Generalized linear models were used to analyze the relationships between OCPs, sex hormones, the methylation levels of sex hormone receptors, and T2DM. Quantile based g-computation (QGC) and Bayesian Kernel Machine Regression (BKMR) were employed to assess the combined OCPs exposure. The roles of sex hormones and the methylation levels of their receptors were evaluated by moderating mediation models. After adjusting for covariates, each unit (2.718 ng/ml) increase in p,p'-DDE was associated with a higher risk of T2DM in males (odds ratio (OR) and 95% confidence interval (CI): 1.066 (1.023, 1.112)). QGC and BKMR showed a positive combined effect in the associations of OCPs mixtures on T2DM among premenopausal females, and positive effects but not statistically significant among males and postmenopausal females. p,p'-DDE was the largest contributor for the positive associations. Furthermore, testosterone mediated 21.149% of the associations of p,p'-DDE with T2DM moderated by the androgen receptor methylation (ARm) located in CpG island 1. Individual and mixtures of OCPs exposure were positively linked to elevated risk of T2DM. Testosterone and ARm may participate in the related processes of OCPs with T2DM, providing new insights into the adverse endocrine effects caused by OCPs and specific pathways for the etiology and control of diabetes.

Developmental and functional roles of androgen and interactive signals for external genitalia and erectile tissues

Background

Recent progress in molecular and signal analyses revealed essential functions of cellular signals including androgen and related growth factors such as Wnt regulators for external genitalia (ExG) development and its pathogenesis. Accumulated data showed their fundamental functions also for erectile tissue (corporal body) development and its abnormalities. The current review focuses on such signals from developmental and functional viewpoints.

Methods

Experimental strategies including histological and molecular signal analyses with conditional mutant mice for androgen and Wnt signals have been extensively utilized.

Main findings

Essential roles of androgen for the development of male-type ExG and urethral formation are shown. Wnt signals are associated with androgen for male-type ExG organogenesis. Androgen plays essential roles in the development of erectile tissue, the corporal body and it also regulates the duration time of erection. Wnt and other signals are essential for the regulation of mesenchymal cells of erectile tissue as shown by its conditional mutant mouse analyses. Stress signals, continuous erection, and the potential of lymphatic characteristics of the erectile vessels with sinusoids are also shown.

Conclusion

Reiterated involvement of androgen, Wnt, and other regulatory factors is stated for the development and pathogenesis of ExG and erectile tissues.

A Single-Step Genome-Wide Association Study for Semen Traits of Egyptian Buffalo Bulls

The present study aimed to contribute to the limited research on buffalo (Bubalus bubalis) semen traits by incorporating genomic data. A total of 8465 ejaculates were collected. The genotyping procedure was conducted using the Axiom® Buffalo Genotyping 90 K array designed by the Affymetrix Expert Design Program. After conducting a quality assessment, we utilized 67,282 SNPs genotyped in 192 animals. We identified several genomic loci explaining high genetic variance by employing single-step genomic evaluation. The aforementioned regions were located on buffalo chromosomes no. 3, 4, 6, 7, 14, 16, 20, 22, and the X-chromosome. The X-chromosome exhibited substantial influence, accounting for 4.18, 4.59, 5.16, 5.19, and 4.31% of the genomic variance for ejaculate volume, mass motility, livability, abnormality, and concentration, respectively. In the examined genomic regions, we identified five novel candidate genes linked to male fertility and spermatogenesis, four in the X-chromosome and one in chromosome no. 16. Additional extensive research with larger sample sizes and datasets is imperative to validate these findings and evaluate their applicability for genomic selection.

A single-nucleus transcriptomic atlas of primate testicular aging reveals exhaustion of the spermatogonial stem cell reservoir and loss of Sertoli cell homeostasis

The testis is pivotal for male reproduction, and its progressive functional decline in aging is associated with infertility. However, the regulatory mechanism underlying primate testicular aging remains largely elusive. Here, we resolve the aging-related cellular and molecular alterations of primate testicular aging by establishing a single-nucleus transcriptomic atlas. Gene-expression patterns along the spermatogenesis trajectory revealed molecular programs associated with attrition of spermatogonial stem cell reservoir, disturbed meiosis and impaired spermiogenesis along the sequential continuum. Remarkably, Sertoli cell was identified as the cell type most susceptible to aging, given its deeply perturbed age-associated transcriptional profiles. Concomitantly, downregulation of the transcription factor Wilms' Tumor 1 (WT1), essential for Sertoli cell homeostasis, was associated with accelerated cellular senescence, disrupted tight junctions, and a compromised cell identity signature, which altogether may help create a hostile microenvironment for spermatogenesis. Collectively, our study depicts in-depth transcriptomic traits of non-human primate (NHP) testicular aging at single-cell resolution, providing potential diagnostic biomarkers and targets for therapeutic interventions against testicular aging and age-related male reproductive diseases.

Polystyrene nanoplastics aggravate reproductive system damage in obese male mice by perturbation of the testis redox homeostasis

The potential impact of the combination of a high-fat diet (HFD) and polystyrene nanoplastics (PS-NPs) on fertility cannot be ignored, especially when the fertility rate is declining. However, it has not attracted considerable attention. In this study, an obese mouse model was established using an HFD, and the reproductive function of male mice was evaluated after intragastric administration of 100 μL of a 10 mg/mL PS-NP suspension for 4 weeks. By determining the morphology and vitality of sperm and related indicators of testosterone production, it was found that PS-NPs aggravated the destruction of sperm mitochondrial structure, decrease sperm activity, and testosterone production in HFD-fed mice. To comprehensively analyze the injury mechanism, the integrity of the blood testicular barrier (BTB) and the function of Leydig and Sertoli cells were further analyzed. It was found that PS-NPs could destroy BTB, promote the degeneration of Leydig cells, reduce the number of Sertoli cells, and decrease lactate secretion in HFD-fed mice. PS-NPs further interfered with redox homeostasis in the testicular tissues of HFD-fed mice. This study found that PS-NPs could aggravate the damage to the reproductive system of obese male mice by further perturbing its redox homeostasis and revealed the potential health risk of PS-NPs exposure under an HFD.

Geographic Variation in Testicular Morphometrics, Androgen Receptor Expression and Anti-Müllerian Hormone Levels in the Intermediate Roundleaf Bats across Distinct Regions in Thailand

The hipposideros larvatus (intermediate roundleaf bat) is one of the insectivorous bats which has an agro-ecological role as a controller of the insect population. The reproductive patterns of H. larvatus are intricately linked to its ecological role and survival. An understanding of the testicular morphology can contribute to conservation for this species particularly in areas where its populations might be declining or under threat. However, these bats may also be associated with zoonotic diseases which can have significant public health implications. The aims of the study were to examine the morphological data as well as the expression of the androgen receptor (AR) and anti-Müllerian hormone (AMH) in the male reproductive organs of H. larvatus from different areas of Thailand and at different sampling periods. Their testes were processed for histological investigation and immunohistochemistry for AR and AMH. The results showed differences among the various sampling areas and different sampling periods, which suggested seasonal breeding characteristics. The higher testicular morphometric data were observed in H. larvatus from the Dong Phayayen (DY) and Chiang Dao (CD) areas during June, while the size of seminiferous tubules decreased thereafter. High AR immunostaining was noticed when the testicular morphometric data were higher in DY bats during June. On the other hand, low AR was observed in bats during August and September, which was concomitant with the decreases in seminiferous tubule size and germinal epithelial height. The results suggest a potential correlation between AR immunostaining and the active phase of testicular functions in H. larvatus during June which may imply the involvement of AR with the enhancement of testicular activity. Conversely, the low expression of AR may contribute to the upregulation of AMH in the testes and may indicate lower testicular activity in H. larvatus in Thailand.

The long noncoding RNA CIRBIL is a regulator of steroidogenesis in mice

Infertility affects roughly 8-12 % of couples worldwide, and in above 50 % of couples, male factors are the primary or contributing cause. Many long noncoding RNAs (lncRNAs) are detected in the testis, but their functions are not well understood. CIRBIL was 862 nucleotides in length and was found to be localized mostly in the cytosol of Leydig cell, a small portion was positioned inside the seminiferous tubules. Loss of CIRBIL in mice resulted in male subfertility, characterized by smaller testis and increased germ cell apoptosis. Deletion of CIRBIL significant decreased the number of sperm and impaired the integrity of sperm head and tail. In CIRBIL KO mice, testosterone levels in serum and expression of testosterone biosynthesis genes (STAR and 3β-HSD) were both reduced. Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were primarily enriched in steroid synthesis process in CIRBIL-binding proteins. Protein-protein (PPI) interaction networks revealed that both cis- and trans-regulated target genes of CIRBIL were associated with testosterone synthesis. Collectively, our results strongly suggest that CIRBIL is a regulator of steroid hormone synthesis.

Testosterone upregulates progesterone production in mouse testicular interstitial macrophages, whose niche likely provides properties of progesterone production to tissue-resident macrophages

The niche of the macrophages (Mø) residence concept is now accepted; Mø colonize tissue/organ-specific microenvironments (niches) that shape Mø to perform tissue/organ-specific functions. Recently, we developed a simple propagation method for tissue-resident Mø by mixed culture with the respective tissue/organ-residing cells acting as the niche and demonstrated that testicular interstitial Mø propagated by mixed culture with testicular interstitial cells showing properties of Leydig cells in culture (we termed them "testicular Mø niche cells") produce progesterone (P4) de novo. Based on previous evidence of testosterone production downregulation in Leydig cells by P4 and androgen receptor expression in testicular Mø, we proposed a local feedback loop of testosterone production between Leydig cells and testicular interstitial Mø. To verify this hypothesis, we further examined P4 de novo production in propagated testicular interstitial Mø treated with testosterone using ELISA and found that exogenous testosterone upregulates P4 production in testicular interstitial Mø. Thus, testosterone production, which is controlled by the local feedback loop, likely becomes more reliable. Moreover, we examined whether tissue-resident Mø other than testicular interstitial Mø can be transformed into P4-producing cells by mixed culture with testicular Mø niche cells: using RT-PCR and ELISA we found that splenic Mø newly acquired P4 production properties by mixed-culturing with testicular Mø niche cells for 7 days. This likely indicates the substantiative in vitro evidence on the niche concept and possibly opens the door to using P4-secreting Mø as a transplantation tool for clinical application due to the migratory property of Mø into inflammatory sites.

Interrupting the blood-testis barrier with a flutamide-loaded nanostructured lipid carrier: A novel nonsurgical contraceptive approach for male animals

Flutamide is an antagonist of testosterone, an essential hormone in male reproduction. However, the use of flutamide as a contraceptive agent for nonsurgical castration in veterinary practice remains challenging due to its poor bioavailability. Here, the flutamide-loaded nanostructure lipid carrier (FLT-NLC) was synthesized, and its biological effects were demonstrated by an in vitro blood-testis barrier model. The flutamide was incorporated into the nanostructure lipid carrier by a homogenization method resulting in a high encapsulation efficiency (99.7 ± 0.04%). The FLT-NLC was negatively charged (-27.90 ± 0.10 mV), with a nano size (182.13 ± 0.47 nm) and narrow dispersity index (0.17 ± 0.01). An in vitro release study demonstrated a slower release profile of FLT-NLC when compared with flutamide solution (FLT). The FLT-NLC at doses up to 50 μM showed no significant cytotoxic effects against mouse Sertoli cells (TM4) or mouse fibroblast cells (NIH/3T3) (p > 0.05). An in vitro blood-testis barrier with FLT-NLC demonstrated remarkable lower transepithelial electrical resistance when compared with those lacking FLT-NLC (p < 0.01). Moreover, FLT-NLC significantly decreased the mRNA expression of blood-testis barrier proteins, CLDN11 and OCLN. In conclusion, we successfully synthesized FLT-NLC and confirmed its potential antifertility effects on in vitro blood-testis barrier, thus indicating its possible application as nonsurgical contraception for male animals.

Steroid receptors in the testis: implications in the physiology of prenatal and postnatal development and translation to clinical application

The testes are the main source of sex steroids in the male, especially androgens and to a lesser extent estrogens. In target cells, steroid hormones typically signal after binding to intracellular receptors, which act as transcription factors. Androgens and estrogens have ubiquitous functions in peripheral organs, but also have paracrine actions within the gonads where they are far more concentrated. The levels of steroid production by the testes vary throughout fetal and postnatal development: they are high in intrauterine life and in the first months after birth, then they decline and are almost undetectable in childhood and increase again during puberty to attain adult levels. The expression of the androgen and estrogen receptors also depict specific ontogenies in the various testicular cell types. The combination of intratesticular steroid concentration with the pattern of expression of the steroid hormone receptors defines androgen and estrogen action on Sertoli, germ and Leydig cells. Here, we review the ontogeny of expression of the androgen and estrogen receptors in the testis, its impact on testicular physiology during prenatal and postnatal development, as well as its implication on the pathophysiology of different disorders affecting gonadal function throughout life.

Protective effects of melatonin against physical injuries to testicular tissue: A systematic review and meta-analysis of animal models

Background

Modern societies face infertility as a global challenge. There are certain environmental conditions and disorders that damage testicular tissue and may cause male infertility. Melatonin, as a potential antioxidant, may protect testicular tissue. Therefore, we conducted this systematic review and meta-analysis to evaluate the effects of melatonin in animal models against physical, heat, and ischemic damage to the testicular tissue.

Methods

PubMed, Scopus, and Web of Science were systematically searched to identify animal trials evaluating the protective effect of melatonin therapy on rodent testicular tissue when it is exposed to physical, thermal, ischemic, or hypobaric oxygen stress. Random-effect modeling was used to estimate the standardized mean difference and 95% confidence intervals based on the pooled data. Additionally, the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool was used to assess the risk of bias. The study protocol was prospectively registered in PROSPERO (CRD42022354599).

Results

A total of 41 studies were eligible for review out of 10039 records. Studies employed direct heat, cryptorchidism, varicocele, torsion-detorsion, testicular vascular occlusion, hypobaric hypoxia, ischemia-reperfusion, stress by excessive or restraint activity, spinal cord injury, and trauma to induce stress in the subjects. The histopathological characteristics of testicular tissue were generally improved in rodents by melatonin therapy. Based on the pooled data, sperm count, morphology, forward motility, viability, Johnsen's biopsy score, testicular tissue glutathione peroxidase, and superoxide dismutase levels were higher in the melatonin treatment rodent arms. In contrast, the malondialdehyde level in testicular tissue was lower in the treatment rodent arms. The included studies suffered from a high risk of bias in most of the SYRCLE domains.

Conclusion

This study concludes that melatonin therapy was associated with improved testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress in male rodents with physical, ischemic, and thermal testicular injuries. In this regard, melatonin deserves scientific investigations as a potential protective drug against rodent male infertility.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022354599.

Development of the human ovary: Fetal through pubertal ovarian morphology, folliculogenesis and expression of cellular differentiation markers

A definition of normal human fetal and early postnatal ovarian development is critical to the ability to accurately diagnose the presence or absence of functional ovarian tissue in clinical specimens. Through assembling an extensive histologic and immunohistochemical developmental ontogeny of human ovarian specimens from 8 weeks of gestation through 16 years of postnatal, we present a comprehensive immunohistochemical mapping of normal protein expression patterns in the early fetal through post-pubertal human ovary and detail a specific expression-based definition of the early stages of follicular development. Normal fetal and postnatal ovarian tissue is defined by the presence of follicular structures and characteristic immunohistochemical staining patterns, including granulosa cells expressing Forkhead Box Protein L2 (FOXL2). However, the current standard array of immunohistochemical markers poorly defines ovarian stromal tissue, and additional work is needed to identify new markers to advance our ability to accurately identify ovarian stromal components in gonadal specimens from patients with disorders of sexual differentiation.

Circular RNAs: Novel Biomarkers in Spermatogenesis Defects and Male Infertility

Circular RNAs (circRNAs) are a new class of endogenous non-coding RNAs involved in several cellular and biological processes, including gene expression regulation, microRNA function, transcription regulation, and translation modification. Therefore, these non-coding RNAs have important roles in the pathogenesis of various diseases. Male infertility is mainly due to abnormal sperm parameters such as motility, morphology, and concentration. Recent studies have confirmed the role of circRNAs in spermatogenesis, and the expression of several circRNAs is confirmed in seminal plasma, spermatozoa, and testicular tissue. It is suggested that deregulation of circRNAs is involved in different types of male infertility, including azoospermia, oligozoospermia, and asthenozoospermia. In the present review, we aimed to discuss the potential roles of circRNAs in spermatogenesis failure, sperm defects, and male infertility. Due to their conserved and special structure and tissue-specific expression pattern, circRNAs can be applied as reliable noninvasive molecular biomarkers, therapeutic and pharmaceutical targets in male infertility.

Revisiting the gonadotropic regulation of mammalian spermatogenesis: evolving lessons during the past decade

Spermatogenesis is a multi-step process of male germ cell (Gc) division and differentiation which occurs in the seminiferous tubules of the testes under the regulation of gonadotropins - Follicle Stimulating Hormone (FSH) and Luteinising hormone (LH). It is a highly coordinated event regulated by the surrounding somatic testicular cells such as the Sertoli cells (Sc), Leydig cells (Lc), and Peritubular myoid cells (PTc). FSH targets Sc and supports the expansion and differentiation of pre-meiotic Gc, whereas, LH operates via Lc to produce Testosterone (T), the testicular androgen. T acts on all somatic cells e.g.- Lc, PTc and Sc, and promotes the blood-testis barrier (BTB) formation, completion of Gc meiosis, and spermiation. Studies with hypophysectomised or chemically ablated animal models and hypogonadal (hpg) mice supplemented with gonadotropins to genetically manipulated mouse models have revealed the selective and synergistic role(s) of hormones in regulating male fertility. We here have briefly summarized the present concept of hormonal control of spermatogenesis in rodents and primates. We also have highlighted some of the key critical questions yet to be answered in the field of male reproductive health which might have potential implications for infertility and contraceptive research in the future.

Ontogeny of mouse Sertoli, Leydig and peritubular myoid cells from embryonic day 10 to adulthood

We present a comprehensive description of the differentiating somatic cell types (Sertoli, Leydig, and peritubular myoid cells) of the mouse testis from embryonic day 10.5 (E10.5) to adulthood, postnatal day 60 (P60). Immunohistochemistry was used to analyze expression of: Sox9 (a Sertoli cell marker), 3βHSD-1 (a fetal Leydig cell marker), 3βHSD-6 (an adult Leydig cell marker), α-actin (a peritubular myoid cell marker), and androgen receptor (a marker of all three somatic cell types). The temporal-spatial expression of these markers was used to interrogate findings of earlier experimental studies on the origin of Sertoli, Leydig and peritubular myoid cells, as well as extend previous descriptive studies across a broader developmental period (E10.5-P60). Such comparisons demonstrate inconsistencies that require further examination and raise questions regarding conservation of developmental mechanisms across higher vertebrate species.

Low concentrations of benzophenone-type UV-filters impair testis development in the amphibian Xenopus laevis

Benzophenone-type UV filters (BPs) are ubiquitous contaminants in aquatic environments, possibly posing ecological risks to aquatic populations. So far, little is known about the potential adverse effects of BPs on amphibians. Given their potential estrogenic property, we investigated the detrimental effects of the commonly used BPs, BP-3, BP-2, and BP-1, on testis development in amphibians using Xenopus laevis as a model species. Following exposure to 10, 100, 1000 nM BP-3, BP-2, or BP-1 from stages 45/46 to 52, tadpoles presented morphological abnormal testes, characterized by reduced gonomere size and testis area, coupled with suppressed cell proliferation. Meanwhile, the downregulation of testis-biased gene expression and the upregulation of ovary-biased gene expression were observed in BPs-treated testes. Moreover, the estrogen receptor (ER) antagonist ICI 182780 significantly antagonized ovary-biased gene upregulation caused by BPs, suggesting that the effects of BPs on testis differentiation could be mediated by ER, at least partially. Of note, the effects of BPs were not concentration-dependent, but the lowest concentration generally exerted significant effects. Altogether, these observations indicate that the three BPs inhibited testis differentiation and exerted feminizing effects. Importantly, when BP-2 exposure was extended to two months post-metamorphosis, testes of froglets were generally less-developed, with relatively fewer spermatocytes, more spermatogonia, and poorly formed seminiferous tubules. Considering the fact that the lowest concentration (10 nM) of BPs in this study are detectable in aquatic environments, we conclude that BP-3, BP-2, and BP-1, even at environmentally relevant concentrations, can retard testis differentiation at pre-metamorphic stages and cause testis dysgenesis after metamorphosis in the amphibian X. laevis. Our findings suggest that ubiquitous BPs in aquatic environments could pose a potential risk to amphibians.

Melatonin alleviates heat stress-induced testicular damage in dairy goats by inhibiting the PI3K/AKT signaling pathway

Current measures mainly focus on how melatonin reduces physiological heat stress in animals, but its effects on reproductive damage to male dairy goats have been neglected. This study aimed to determine the protective effect of melatonin on male reproduction during heat stress in dairy goats and to further explore its mechanisms. A natural heat stress model of Saanen dairy goats was used to assess testicular tissue damage 7 days after heat stress and to examine semen quality changes during a spermatogenic cycle. RNA-seq, Western blot, RT-qPCR, and immunofluorescence staining were used to explore the mechanism by which melatonin protects against heat stress-induced reproductive damage and to validate the results. The data suggested that melatonin significantly alleviated the heat stress-induced decrease in sperm quality, protected varicose tubule structure, reduced the levels of heat shock proteins and apoptotic proteins and protected the spermatocytes and round spermatozoa, which are mainly affected by heat stress. RNA-seq results suggest that melatonin inhibits the PI3K/AKT signaling pathway, reduces the level of p-AKT, and promotes elevated BCL-2. In addition, melatonin treatment could upregulate the gene expression of MT2 which was downregulated by heat stress and improve the change in extracellular matrix components and restore serum testosterone levels. Our results suggest that melatonin can protect against testicular and spermatogenic cell damage and improve semen quality in male dairy goats under heat stress. This study provides an important reference for subsequent studies on the molecular mechanisms of melatonin in protecting male reproductive processes under heat stress and using exogenous melatonin to prevent heat stress.

Purinergic signaling in the male reproductive tract

Purinergic receptors are ubiquitously expressed throughout the body and they participate in the autocrine and paracrine regulation of cell function during normal physiological and pathophysiological conditions. Extracellular nucleotides activate several types of plasma membrane purinergic receptors that form three distinct families: P1 receptors are activated by adenosine, P2X receptors are activated by ATP, and P2Y receptors are activated by nucleotides including ATP, ADP, UTP, UDP, and UDP-glucose. These specific pharmacological fingerprints and the distinct intracellular signaling pathways they trigger govern a large variety of cellular responses in an organ-specific manner. As such, purinergic signaling regulates several physiological cell functions, including cell proliferation, differentiation and death, smooth muscle contraction, vasodilatation, and transepithelial transport of water, solute, and protons, as well as pathological pathways such as inflammation. While purinergic signaling was first discovered more than 90 years ago, we are just starting to understand how deleterious signals mediated through purinergic receptors may be involved in male infertility. A large fraction of male infertility remains unexplained illustrating our poor understanding of male reproductive health. Purinergic signaling plays a variety of physiological and pathophysiological roles in the male reproductive system, but our knowledge in this context remains limited. This review focuses on the distribution of purinergic receptors in the testis, epididymis, and vas deferens, and their role in the establishment and maintenance of male fertility.

Phthalate-induced testosterone/androgen receptor pathway disorder on spermatogenesis and antagonism of lycopene

Male infertility is an attracting growing concern owing to decline in sperm quality of men worldwide. Phthalates, in particular to di (2-ethylhexyl) phthalate (DEHP) or its main metabolite mono-2-ethylhexyl phthalate (MEHP), affect male reproductive development and function, which mainly accounts for reduction in male fertility. Lycopene (LYC) is a natural antioxidant agent that has been recognized as a possible therapeutic option for treating male infertility. Testosterone (T)/androgen receptor (AR) signaling pathway is involved in maintaining spermatogenesis and male fertility. How DEHP causes spermatogenesis disturbance and whether LYC could prevent DEHP-induced male reproductive toxicity have remained unclear. Using in vivo and vitro approaches, we demonstrated that DEHP caused T biosynthesis reduction in Leydig cell and secretory function disorder in Sertoli cell, and thereby resulted in spermatogenic impairment. Results also showed that MEHP caused mitochondrial damage and oxidative damage, which imposes a serious threat to the progress of spermatogenesis. However, LYC supplement reversed these changes. Mechanistically, DEHP contributed to male infertility via perturbing T/AR signaling pathway during spermatogenesis. Overall, our study reveals critical role for T/AR signal transduction in male fertility and provides promising insights into the protective role of LYC in phthalate-induced male reproductive disorders.

Protective effects of rivaroxaban against cisplatin-induced testicular damage in rats: Impact on oxidative stress, coagulation, and p-NF-κB/VCAM-1 signaling

Coagulation is a main pathway in various diseases pathogenesis including testicular damage. This study evaluated rivaroxaban (RVX) protective effects in testicular impairment by cisplatin (CP). Rats were randomly allocated into five groups: Control, RVX (7 mg/kg/day), CP (10 mg/kg), RVX 5 mg + CP and RVX 7 mg + CP. Serum testosterone and testicular ALT, AST, and ALP were assessed. Testicular oxidative stress and antioxidant parameters and inflammatory indicators including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were assessed. qRT-PCR was used to determine mRNA expression of 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), and steroidogenic acute regulatory protein (stAR). Protein expressions of p-Nuclear factor kappa B (p- NF-κB) and vascular cell adhesion protein-1 (VCAM-1) were analyzed by Western blot analysis. Tissue factor (TF) expression was immunohistochemically analyzed. Results revealed that RVX significantly increased serum testosterone and sperm count while significantly reduced IL-1β and TNF-α. It significantly decreased tissue MDA and NO contents while increased SOD and GPx. In addition, RVX attenuated CP-induced histopathological aberrations and normalized TF. It also decreased the VCAM-1 and p-NF-κB expression and showed strong expression of 3β-HSD, 17β-HSD, and stAR, indicating improvement of steroidogenesis. In conclusion, RVX counteracted testicular damage by CP via suppressing oxidative stress, inflammation, and coagulation and downregulating p-NF-κB/VCAM-1 signaling.

A Gly684Ala substitution in the androgen receptor is the cause for azoospermia in a Chinese family with mild androgen insensitivity syndrome and normal hormone levels

Androgen receptor gene (AR) is essential for male growth and fertility. Its mutations are responsible for androgen insensitivity syndrome (AIS) that usually shows the phenotype of azoospermia resulting in male infertility. This study reported the first case of mild AIS with complete normal serum hormones in a Chinese family. The proband referred for infertility because of azoospermia. His uncle and two cousins are both infertile and have azoospermia. Whole-exome sequencing in the genetic analyses showed that the proband carries a novel hemizygous AR missense mutation, NM_000044.6: c.2051G>C (p.Gly684Ala), in exon four within the ligand-binding domain. His mother and maternal aunt are heterozygous carriers, while his father and brother are wildtype, indicating that the mutation in the proband was inherited from his mother. This pattern is consistent with the genetic model of the X-linked recessive inheritance of AR in AIS pathogenesis. HOPE predicts that p.Gly684Ala increases the hydrophobicity of AR but does not change the AR conformation. PolyPhen-2 predicts that p.Gly684Ala is harmful. This study provides the new knowledge to understand the AR gene mutations in MAIS.

An Approach for Investigating Sexual Maturity in Wild Boar Males: Testosterone and 17β-Estradiol Analysis

Simple Summary

Wild boar numbers have increased constantly over the last three decades, as have their related conflicts with modern society. For this reason, wild boars have become a frequent topic of discussion. This article describes and explains the concentrations of the two main sexual steroids, testosterone and estradiol, as well as our effort to define threshold levels to recognize the sexual maturation of wild boar males and differentiate between immature and adult boars. With the help of additional analyses on spermatozoa and morphological data, it was shown that prepubertal boars at 8 months of age could be clearly differentiated from postpubertal boars, showing significantly lower concentrations of hormones. Wild boar males older than 11 months of age, in contrast, presented hormonal values like adults. Before the completion of their first year, wild boars are physiologically able to reproduce and may take part in reproduction. The high hormonal concentrations at the end of the breeding season suggest that the mating period could last longer than usually supposed, shifting farrowing into the summer.

Abstract

Analyses of sexual steroid hormones in wild boars are rarely described. Testosterone (T) and 17β-estradiol (E2) concentrations are useful to recognize sexual maturation. As threshold values for this species are unknown, additional parameters are required. A total of 127 blood samples from wild boar males were collected to measure T and E2. Age and weight were recorded. Thirty-one epididymides were sampled too. Males were sorted into pre-and postpubertal groups based on the absence/presence of spermatozoa in epididymides and on morphological data following previous results. Forty-four males were prepubertal: the mean age and weight were 10 months and 23 kg, respectively. They showed no spermatozoa. The mean concentrations of T and E2 were 1.2 ± 1.2 ng/mL and 39.7 ± 120.3 pg/mL, respectively. Sixty-six males were postpubertal, twenty-nine of which presented spermatozoa. Their mean concentration of T was 7.6 ± 6.3 ng/mL and E2 was 664.3 ± 250.4 pg/mL. Seventeen samples could not be defined; the hormone concentrations between the two groups suggested a transitional phase consistent with puberty. Wild boars before 12 months of age had high hormone levels like older boars, indicating that they could attempt to reproduce. Hormones at the end of the mating season (January) were high so that reproduction could occur thereafter, shifting farrowing from spring to summer.

Effect of Giving Traditional Drinks Kameko and Pongasih from Southeast Sulawesi on Sperm Quality of Mice (Mus musculus)

&lt;b&gt;Background and Objective:&lt;/b&gt; The traditional beverage of Southeast Sulawesi is Kameko and Pongasih, which is a traditional alcoholic beverage. One of the bad effects of alcohol on reproductive health is the occurrence of infertility. This research aimed to determine the effect of consuming traditional beverages of Kameko and Pongasih on the quality of sperm of mice (&lt;i&gt;Mus musculus&lt;/i&gt;). &lt;b&gt;Materials and Methods:&lt;/b&gt; This research used a true experiment. The samples were some healthy mice (&lt;i&gt;Mus musculus&lt;/i&gt;) aged 6-8 weeks as much 24 tails and divided into 4 groups. On the 36th day after the treatment was completed, the mice were terminated and prepared for microscopic sperm quality analysis. The quality of sperm includes motility, viability, concentration and morphology. The data test uses the Shapiro-Wilk Test, One-way ANOVA and &lt;i&gt;post hoc&lt;/i&gt; LSD Test. &lt;b&gt;Results:&lt;/b&gt; Kameko traditional beverage had a significant influence on sperm quality with motility, morphology, sperm concentration (p = 0.000) and viability (p = 0.001). Pongasih traditional beverage has a significant influence on sperm quality with motility parameter, morphology, sperm concentration (p = 0.000) and viability (p = 0.001). Kameko and Pongasih traditional beverages did not have a significant difference in sperm quality with motility parameter (p = 0.463), viability (p = 1.000), morphology (p = 0.553) and amount of concentration (p = 0.714). &lt;b&gt;Conclusion:&lt;/b&gt; South East Sulawesi traditional beverages Kameko and Pongasih have effects on mice's (&lt;i&gt;Mus musculus&lt;/i&gt;) sperm quality, but there was no difference in the group of mice which have been given Kameko and Pongasih.

Nano-Curcumin Prevents Copper Reproductive Toxicity by Attenuating Oxidative Stress and Inflammation and Improving Nrf2/HO-1 Signaling and Pituitary-Gonadal Axis in Male Rats

Copper is essential for several cellular processes and is an important catalytic factor for many proteins. However, excess copper can provoke oxidative stress and reproductive toxicity. This study evaluated the effect of liposomal nano-curcumin (N-CUR) and CUR on testicular oxidative injury, inflammation, and apoptosis, and altered steroidogenesis and Nrf2/HO-1 signaling induced by copper sulfate (CuSO4). Rats received CuSO4 and N-CUR or CUR via oral gavage for 7 days. CuSO4 induced histopathological changes and altered pituitary-gonadal axis manifested by decreased serum gonadotropins and testosterone. Testicular steroidogenesis genes (StAR, 3β-HSD, CYP17A1, and 17β-HSD) and androgen receptor (AR) were downregulated in rats that received CuSO4. N-CUR and CUR prevented testicular tissue injury, increased circulating FSH, LH, and testosterone, and upregulated testicular steroidogenesis genes and AR. Additionally, N-CUR and CUR decreased testicular MDA, NO, NF-κB, iNOS, TNF-α, Bax, and caspase-3 while enhanced Bcl-2, Nrf2, and the antioxidants GSH, HO-1, SOD, and catalase. In conclusion, N-CUR and CUR prevented CuSO4-induced reproductive toxicity in male rats by suppressing oxidative injury and inflammatory response and boosting steroidogenesis, sex hormones, and Nrf2/HO-1 signaling. N-CUR was more effective in ameliorating tissue injury, oxidative stress, inflammation, and apoptosis and enhancing steroidogenesis and Nrf2/HO-1 than the native form.

Understanding and managing the suppression of spermatogenesis caused by testosterone replacement therapy (TRT) and anabolic–androgenic steroids (AAS)

Use of testosterone replacement therapy (TRT) and anabolic–androgenic steroids (AAS) has increased over the last 20 years, coinciding with an increase in men presenting with infertility and hypogonadism. Both agents have a detrimental effect on spermatogenesis and pose a clinical challenge in the setting of hypogonadism and infertility. Adding to this challenge is the paucity of data describing recovery of spermatogenesis on stopping such agents. The unwanted systemic side effects of these agents have driven the development of novel agents such as selective androgen receptor modulators (SARMs). Data showing natural recovery of spermatogenesis following cessation of TRT are limited to observational studies. Largely, these have shown spontaneous recovery of spermatogenesis after cessation. Contemporary literature suggests the time frame for this recovery is highly variable and dependent on several factors including baseline testicular function, duration of drug use and age at cessation. In some men, drug cessation alone may not achieve spontaneous recovery, necessitating hormonal stimulation with selective oestrogen receptor modulators (SERMs)/gonadotropin therapy or even the need for assisted reproductive techniques. However, there are limited prospective randomized data on the role of hormonal stimulation in this clinical setting. The use of hormonal stimulation with agents such as gonadotropins, SERMs, aromatase inhibitors and assisted reproductive techniques should form part of the counselling process in this cohort of hypogonadal infertile men. Moreover, counselling men regarding the detrimental effects of TRT/AAS on fertility is very important, as is the need for robust randomized studies assessing the long-term effects of novel agents such as SARMs and the true efficacy of gonadotropins in promoting recovery of spermatogenesis.

Cypermethrin inhibits proliferation of Sertoli cells through AR involving DAB2IP/PI3K/AKT signaling pathway in vitro

Cypermethrin (CP) exhibits anti-androgenic effects through antagonism on androgen receptor (AR) activation. This study was to identify whether AR-mediated disabled 2 interacting protein (DAB2IP)/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway was involved in CP-induced mouse Sertoli cells (TM4) proliferation disorder. Real-Time Cell Analysis-iCELLigence system was to measure cell proliferation. Bioinformatic analyses were performed to identify AR-regulated genes. Quantitative Real-Time PCR and western blot were to detect the genes and proteins levels in AR-mediated DAB2IP/PI3K/AKT pathway. Results showed CP suppressed TM4 proliferation and the expression of AR. Activation of AR restored the inhibition efficacy of CP on TM4 proliferation. AR regulated DAB2IP expression and phosphorylation levels of PI3K and AKT in CP-exposed TM4 cells. In addition, knockdown of DAB2IP alleviated the inhibition efficacy of CP on cell proliferation and phosphorylation of PI3K and AKT. Taken together, AR was a modulator in CP-induced inhibition of Sertoli cells proliferation by negatively regulating DAB2IP/PI3K/AKT signaling pathway. The study may provide a new insight for the mechanisms of male reproductive toxicity induced by CP.

Zuogui Wan improves spermatogenesis of GC1-spg cells through modulating AR-related pathways

Zuogui Wan (ZGW) is a common prescription medication used in traditional Chinese medicine (TCM) to significantly improve the sperm quality and treat male infertility. This study evaluated the repair effect of ZGW and Levocarnitine (LEV) on GC1-spg cell injury induced by Glucosides of Tripterygium WilforDII Hook (GTW). The results showed that the ultrastructure and apoptosis rate of GC1- spg cells in LEV and ZGW group were considerably better than GTW. The transcriptional and translational level of CYP1A1, CYP17A1, androgen receptor (AR), SRD5A2 and proliferating cell nuclear antigen (PCNA) in GC-1spg cells of the LEV group were considerably elevated than GTW group (p < 0.05 or 0.01). Furthermore, the transcriptional and translational levels of CYP19A1, CYP17A1, AR, SRD5A2 and PCNA in GC-1spg cells in ZGW group were found to be considerably elevated than the LEV group (p < 0.05 or 0.01). The findings indicate that ZGW and LEV could increase the expression of PCNA, CYP17A1, CYP19A1, SRD5A2 and AR at transcriptional and translational levels, inhibit GC-1spg cell apoptosis and promoting cell proliferation, and the effect of ZGW was found to be significantly better than that of LEV.

COVID-19 Infection Induce miR-371a-3p Upregulation Resulting in Influence on Male Fertility

In December 2019, the first case of COVID-19 was reported and since then several groups have already published that the virus can be present in the testis. To study the influence of SARS-CoV-2 which cause a dysregulation of the androgen receptor (AR) level, thereby leading to fertility problems and inducing germ cell testicular changes in patients after the infection. Formalin-Fixed-Paraffin-Embedded (FFPE) testicular samples from patients who died with or as a result of COVID-19 (n = 32) with controls (n = 6), inflammatory changes (n = 9), seminoma with/without metastasis (n = 11) compared with healthy biopsy samples (n = 3) were analyzed and compared via qRT-PCR for the expression of miR-371a-3p. An immunohistochemical analysis (IHC) and ELISA were performed in order to highlight the miR-371a-3p targeting the AR. Serum samples of patients with mild or severe COVID-19 symptoms (n = 34) were analyzed for miR-371a-3p expression. In 70% of the analyzed postmortem testicular tissue samples, a significant upregulation of the miR-371a-3p was detected, and 75% of the samples showed a reduced spermatogenesis. In serum samples, the upregulation of the miR-371a-3p was also detectable. The upregulation of the miR-371a-3p is responsible for the downregulation of the AR in SARS-CoV-2-positive patients, resulting in decreased spermatogenesis. Since the dysregulation of the AR is associated with infertility, further studies have to confirm if the identified dysregulation is regressive after a declining infection.