The regulation of spermatogenesis by androgens

MicroRNA-150 regulates steroidogenesis of mouse testicular Leydig cells by targeting STAR

Leydig cells are essential for male reproductive development throughout life. Production of androgens as well as intermediate steroids is tightly regulated. Although microRNAs (miRNAs) are suggested to play important roles in spermatogenesis, little is currently known regarding the regulation of steroidogenesis by miRNAs in Leydig cells. Here, we found that miR-150 was predominantly expressed in Leydig cells within mouse testis. Therefore, we determined steroidogenesis of the Leydig cells in which miR-150 was knocked down or overexpressed using miR-150 antagomir and agomir, respectively. Compared with negative control group, a significant increase of STAR expression was observed in miR-150 antagomir-treated Leydig cells. Conversely, STAR expression was significantly reduced in miR-150 agomir-transfected Leydig cells. Production of sex-steroid precursors and testosterone of Leydig cells was also negatively controlled by miR-150. We further identified Star as a target of miR-150 using luciferase reporter assay. Finally, we confirmed that miR-150 was necessary for steroidogenesis and spermatogenesis in vivo via intratesticular injection of miR-150 antagomir or agomir. Taken together, our studies suggest that miR-150 negatively regulates the expression of STAR and steroidogenesis of Leydig cells in mice.

Leydig cell stem cells: Identification, proliferation and differentiation

Adult Leydig cells develop from undifferentiated mesenchymal-like stem cells (stem Leydig cells, SLCs) present in the interstitial compartment of the early postnatal testis. Putative SLCs also have been identified in peritubular and perivascular locations of the adult testis. The latter cells, which normally are quiescent, are capable of regenerating new Leydig cells upon the loss of the adult cells. Recent studies have identified several protein markers to identify these cells, including nestin, PDGFRα, COUP-TFII, CD51 and CD90. We have shown that the proliferation of the SLCs is stimulated by DHH, FGF2, PDGFBB, activin and PDGFAA. Suppression of proliferation occurred with TGFβ, androgen and PKA signaling. The differentiation of the SLCs into testosterone-producing Leydig cells was found to be regulated positively by DHH (Desert hedgehog), lithium-induced signaling and activin; and negatively by TGFβ, PDGFBB, FGF2, Notch and Wnt signaling. DHH, by itself, was found to induce SLC differentiation into LH-responsive steroidogenic cells, suggesting that DHH plays a critical role in the commitment of SLC into the Leydig lineage. These studies, taken together, address the function and regulation of low turnover stem cells in a complex, adult organ, and also have potential application to the treatment of androgen deficiency.

The Androgen Receptor and VEGF: Mechanisms of Androgen-Regulated Angiogenesis in Prostate Cancer

Prostate cancer progression is controlled by the androgen receptor and new blood vessel formation, or angiogenesis, which promotes metastatic prostate cancer growth. Angiogenesis is induced by elevated expression of vascular endothelial growth factor (VEGF). VEGF is regulated by many factors in the tumor microenvironment including lowered oxygen levels and elevated androgens. Here we review evidence delineating hormone mediated mechanisms of VEGF regulation, including novel interactions between the androgen receptor (AR), epigenetic and zinc-finger transcription factors, AR variants and the hypoxia factor, HIF-1. The relevance of describing the impact of both hormones and hypoxia on VEGF expression and angiogenesis is revealed in recent reports of clinical therapies targeting both VEGF and AR signaling pathways. A better understanding of the complexities of VEGF expression could lead to improved targeting and increased survival time for a subset of patients with metastatic castration-resistant prostate cancer.

Maternal exposure to butyl paraben impairs testicular structure and sperm quality on male rats

Parabens are hormonally active chemicals widely used as preservatives in foods and are frequently detected in human fluids and tissues. Therefore, the objective of this study was to determine the effects of maternal butyl paraben (BP) exposure on male sexual development. Pregnant Wistar rats received corn oil (control group), or BP at doses of 10, 100, or 200 mg/kg, subcutaneously, from gestational day 12 until postnatal day 21. Our results demonstrated that developmental BP exposure significantly increased the number of adult Leydig cells and the circulating concentrations of testosterone and attenuated FSH and LH concentrations at 200 mg/kg. BP exposure adversely affected spermatogenesis kinetics at doses of 10 and 200 mg/kg and provoked a decrease in the immunostaining of EsR1 and AR at 200 mg/kg. The sperm motility was impaired at the 10 mg/kg dose, and sperm head abnormalities were increased in all BP dose groups. We suggest that BP impairs testicular structure and function in the rat, affecting sperm quality. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1273-1289, 2017.

Semen quality and insulin-like factor 3: Associations with urinary and seminal levels of phthalate metabolites in adult males

Certain phthalates have adverse effects on male reproductive functions in animals, and potentially affect human testicular function and spermatogenesis, but little is known about the active mechanisms. We measured the urinary and seminal phthalate metabolites and explored their associations on insulin-like factor 3 (INSL3) and semen quality. Urine, blood, and semen samples were collected from the male partners of subfertile (n = 253) and fertile (n = 37) couples in a reproductive center in southern Taiwan. INSL3, reproductive hormones, semen-quality, and 11 phthalate metabolites in urine and semen were measured. There were significant correlations in the distribution pattern of metabolites, such as the relative contribution of low or high molecular weight phthalate metabolites. The significantly monotonic trends in semen volume, sperm concentration and motility were associated with increasing quartiles of INSL3 (all p-trend < 0.001). In adjusted regression models, increases in urinary phthalate metabolites levels were adversely associated with sperm concentration (monobenzyl phthalate [MBzP], mono-2-ethylhexyl phthalate [MEHP] and MEHP%), motility (MBzP and MEHP) and INSL3 (MBzP, MEHP and MEHP%) (all p < 0.01). Higher seminal phthalate metabolite levels were associated with decreases in sperm concentration (MEHP and mono-2-ethyl-5-hydroxyhexyl phthalate), motility (mono-ethyl phthalate [MEP] and di-(2-ethylhexyl) phthalate [DEHP] metabolites), normal morphology (MEP), and INSL3 (monomethyl phthalate and MEP) (all p < 0.05). Our data suggest that INSL3 secretion, reproductive hormone balance, and sperm production and quality might be simultaneously adversely affected for individuals excreting increasing levels of phthalates metabolites (especially di-ethyl phthalate, butylbenzyl phthalate, and DEHP) in urine and semen samples.

Disturbed testicular expression of the estrogen-metabolizing enzymes CYP1A1 and COMT in infertile men with primary spermatogenic failure: possible negative implications on Sertoli cells

Estradiol (E₂ ) is normally metabolized to hydroxyestradiols and methoxyestradiols by CYP1A1, CYP1B1 and COMT. However, an altered production of these metabolites by a disturbed expression of these enzymes is associated with reproductive and non-reproductive pathologies. In vitro studies suggest that increased hydroxyestradiols and methoxyestradiols intratesticular generation is related to male infertility, but no studies have explored whether infertile men have a disturbed testicular expression of the enzymes that generate these E₂ metabolites. The aim of this study was to assess CYP1A1, CYP1B1 and COMT testicular expression at mRNA and protein level in men with spermatogenic impairment. Seventeen men with primary spermatogenic failure (13 with Sertoli cell-only syndrome and four with maturation arrest) and nine controls with normal spermatogenesis were subjected to testicular biopsy. mRNA was quantified using real-time RT-PCR and protein expression was evaluated using western blot and immunohistochemistry followed by integrated optic density analysis. Besides, the effects of hydroxyestradiols and methoxyestradiols on testosterone-induced transcriptional activity were evaluated in TM4 cells using a luciferase reporter assay system. Our results show that patients with Sertoli cell-only syndrome had significantly elevated COMT expression at the mRNA level, higher COMT immunoreactivity in their seminiferous tubules and increased protein expression of the soluble COMT isoform (S-COMT), whereas patients with maturation arrest had significantly elevated CYP1A1 mRNA levels and higher CYP1A1 immunoreactivity in interstitial space. Finally, 2-hydroxyestradiol decreased testosterone-induced transcriptional activity in Sertoli cells in vitro. In conclusion, male infertility is related to disturbed testicular expression of the enzymes responsible for producing hydroxyestradiols and/or methoxyestradiols. If these changes are related with increased intratesticular hydroxyestradiols and methoxyestradiols concentrations, they could elicit an impaired Sertoli cell function. Our results suggest CYP1A1 and COMT as new potential targets in treating male infertility.

Differential lactate and cholesterol synthetic activities in XY and XX Sertoli cells

SRY, a sex-determining gene, induces testis development in chromosomally female (XX) individuals. However, mouse XX Sertoli cells carrying Sry (XX/Sry Sertoli cells) are incapable of fully supporting germ cell development, even when the karyotype of the germ cells is XY. While it has therefore been assumed that XX/Sry Sertoli cells are not functionally equivalent to XY Sertoli cells, it has remained unclear which specific functions are affected. To elucidate the functional difference, we compared the gene expression of XY and XX/Sry Sertoli cells. Lactate and cholesterol metabolisms, essential for nursing the developing germ cells, were down-regulated in XX/Sry cells, which appears to be caused at least in part by the differential expression of histone modification enzymes SMCX/SMCY (H3K4me3 demethylase) and UTX/UTY (H3K27me3 demethylase) encoded by the sex chromosomes. We suggest that down-regulation of lactate and cholesterol metabolism that may be due to altered epigenetic modification affects the nursing functions of XX/Sry Sertoli cells.

Effect of standardized extract of Bacopa monnieri (CDRI-08) on testicular functions in adult male mice

ETHNOPHARMACOLOGICAL RELEVANCE

Bacopa monnieri (BM) has been used in India since the time of Rig-Veda for augmentation of learning, memory, brain health etc.

AIM OF THE STUDY

The memory augmenting effect of BM is well documented. CDRI-08 is a standardized extract of Bacopa monnieri, but its effect on the male reproductive health has not been investigated. Therefore, the aim of the present study was to examine the effect of CDRI-08 administration on the male reproductive organs with special emphasis on testis in adult mice.

MATERIALS AND METHODS

CDRI-08, containing at least 55% bacosides (the major constituent of BM), was investigated for its effect on testicular functions in adult Parkes (P) mice. A suspension of CDRI-08 was orally administered in doses of 40 and 80mgkg^-1 body weight day^-1 for 28 days and various male reproductive end points were evaluated.

RESULTS

Compared to control, CDRI-08 treatment caused a significant increase (p<0.05) in spermatogenic cell density (germinal epithelial height: control, 55.03±4.22 vs 40mg, 67.15±2.65 and 80mg, 69.93±3.76; and tubular diameter: control, 206.55±2.62 vs 80mg, 253.23±12.19), PCNA index (control, 59.85±2.09 vs 40mg, 82.17±1.56 and 80mg, 84.05±3.51) and in steroidogenic indices in the testis, and in sperm viability (control, 0.67±0.010 vs 80mg, 0.80±0.04) in cauda epididymidis of the treated mice. On the other hand, however, the same treatment caused a significant decrease (p<0.05) in abnormal sperm morphology (control, 21.72±1.06 vs 40mg, 10.63±1.50 and 80mg, 15.86±0.87) in cauda epididymidis, and in lipid peroxidation level in testis of the treated mice compared to controls.

CONCLUSION

The results suggest that treatment with CDRI-08 extract improves sperm quality, and spermatogenic cell density and steroidogenic indices in the testis of P mice.

Beneficial effects of quercetin on titanium dioxide nanoparticles induced spermatogenesis defects in mice

Many recent studies have demonstrated that most nanoparticles (NPs) have an adverse or toxic action on male germ cells. In present study, protective effect of quercetin (Que) on titanium dioxide nanoparticle (NTiO₂)-induced spermatogenesis defects in mice was investigated. Thirty-two Naval Medical Research Institute (NMRI) mice were randomly divided into four groups. Que group received 75 mg/kg of Que for 42 days. NTiO₂ group received 300 mg/kg NTiO₂ for 35 days. NTiO₂ + Que group initially received 75 mg/kg Que for 7 days and was followed by concomitant administration of 300 mg/kg NTiO₂ for 35 days. Control group received only normal saline for 42 days. Sperm parameters, testosterone concentration, histological criteria, and apoptotic index were assessed. Product of lipid peroxidation (MDA), superoxide dismutase (SOD), and catalase (CAT) activities were also evaluated for oxidative stress in testicular tissue. Administration of NTiO₂ significantly induced histological changes in testicular tissue; increased apoptotic index; and decreased testicular weight, testosterone concentration, and sperm quality (p < 0.01). In the testis, NTiO₂ increased oxidative stress through an increase in lipid peroxidation and a decrease in SOD and CAT activities (p < 0.05). Que pretreatment could significantly attenuate testicular weight; apoptotic index; and histological criteria including vacuolization, detachment, and sloughing of germ cells in seminiferous tubules. Serum and tissue testosterone levels were significantly increased in Que-pretreated mice (p < 0.01). Sperm parameters including sperm number, motility, and percentage of abnormality were also effectively improved by Que pretreatment (p < 0.01). Pretreatment of Que significantly ameliorated oxidative stress and increased the activities of SOD and CAT in testicular tissue. These results indicate that sperm production can be increased by Que pretreatment in NTiO₂-intoxicated mice. The improved sperm quality and reverse testis histology by Que pretreatment may be a consequence of elevation testosterone concentration, reduction in germ cell apoptosis, and suppression of oxidative stress in testicular tissue.

New insights for male infertility revealed by alterations in spermatic function and differential testicular expression of thyroid-related genes

The impact of thyroid hormone (TH) disorders on male reproductive biology has been a controversial issue for many years. Recently, we reported that hypothyroid male rats have a disruption of the seminiferous epithelium, which may compromise spermatogenesis. To improve the understanding of the reproductive pathogenesis of hypothyroidism and hyperthyroidism, male Wistar rats that developed these dysfunctions in adulthood were used as an experimental model. We evaluated the sperm production, reserves, transit time, morphology, and functionality (acrosome integrity, plasma membrane integrity, and mitochondrial activity), and the testicular expression of the TH receptors (Thra1 and Thra2, Thrb1, and Thrb2), deiodinases (Dio2 and Dio3), and the Mct8 transporter (Slc16a2) were assessed by reverse transcription followed by real-time quantitative PCR (RT-qPCR). The results were evaluated statistically by ANOVA and Tukey HSD test (P < 0.05). Hypothyroidism decreased the total and daily sperm productions and increased the sperm transit time through the epididymis, while the sperm functionality was reduced in both thyroid dysfunctions. Regarding the modulation of gene expression in the testis, hypothyroidism increased the expression of Thra1 and decreased the expression of Dio3, and hyperthyroidism increased the expression of Slc16a2. The observed alterations in spermatic production and function and in the expression of the TH receptor, deiodinase, and the TH transporter are suggestive of TH participation in spermatogenesis in adulthood.

Genome-Wide microRNA Binding Site Variation between Extinct Wild Aurochs and Modern Cattle Identifies Candidate microRNA-Regulated Domestication Genes

The domestication of cattle from the now-extinct wild aurochs (Bos primigenius) involved selection for physiological and behavioral traits, with underlying genetic factors that remain largely unknown. Non-coding microRNAs have emerged as key regulators of the spatio-temporal expression of target genes controlling mammalian growth and development, including in livestock species. During the domestication process, selection of mutational changes in miRNAs and/or miRNA binding sites could have provided a mechanism to generate some of the traits that differentiate domesticated cattle from wild aurochs. To investigate this, we analyzed the open reading frame DNA sequence of 19,994 orthologous protein-coding gene pairs from extant Bos taurus genomes and a single extinct B. primigenius genome. We identified miRNA binding site polymorphisms in the 3′ UTRs of 1,620 of these orthologous genes. These 1,620 genes with altered miRNA binding sites between the B. taurus and B. primigenius lineages represent candidate domestication genes. Using a novel Score Site ratio metric we have ranked these miRNA-regulated genes according to the extent of divergence between miRNA binding site presence, frequency and copy number between the orthologous genes from B. taurus and B. primigenius. This provides an unbiased approach to identify cattle genes that have undergone the most changes in miRNA binding (i.e., regulation) between the wild aurochs and modern-day cattle breeds. In addition, we demonstrate that these 1,620 candidate domestication genes are enriched for roles in pigmentation, fertility, neurobiology, metabolism, immunity and production traits (including milk quality and feed efficiency). Our findings suggest that directional selection of miRNA regulatory variants was important in the domestication and subsequent artificial selection that gave rise to modern taurine cattle.

Identification of Stem Leydig Cells Derived from Pig Testicular Interstitium

Stem Leydig cells (SLCs), located in the testicular interstitial compartment in the mammalian testes, are capable of differentiating to testosterone-synthesizing Leydig cells (LCs), thus providing a new strategy for treating testosterone deficiency. However, no previous reports have identified and cultured SLCs derived from the pig. The aim of the current study was to isolate, identify, and culture SLCs from pigs. Haematoxylin and eosin staining and immunochemical analysis showed that SLCs were present and that PDGFRα was mainly expressed in the pig testicular interstitium, indicating that PDGFRα was a marker for SLCs in the neonatal pig. In addition, reverse transcription-PCR results showed that SLC markers were expressed in primary isolated LCs, indicating that they were putative SLCs. The putative SLCs were subsequently cultured with a testicular fluid of piglets (pTF) medium. Clones formed after 7 days and the cells expressed PDGFRα. However, no clones grew in the absence of pTF, but the cells expressed CYP17A1, indicating that pTF could sustain the features of porcine SLCs. To summarize, we isolated porcine SLCs and identified their basic characteristics. Taken together, these results may help lay the foundation for research in the clinical application of porcine SLCs.

Role of the testis interstitial compartment in spermatogonial stem cell function

Intricate cellular and molecular interactions ensure that spermatogonial stem cells (SSCs) proceed in a step-wise differentiation process through spermatogenesis and spermiogenesis to produce sperm. SSCs lie within the seminiferous tubule compartment, which provides a nurturing environment for the development of sperm. Cells outside of the tubules, such as interstitial and peritubular cells, also help direct SSC activity. This review focuses on interstitial (interstitial macrophages, Leydig cells and vasculature) and peritubular (peritubular macrophages and peritubular myoid cells) cells and their role in regulating the SSC self-renewal and differentiation in mammals. Leydig cells, the major steroidogenic cells in the testis, influence SSCs through secreted factors, such as insulin growth factor 1 (IGF1) and colony-stimulating factor 1 (CSF1). Macrophages interact with SSCs through various potential mechanisms, such as CSF1 and retinoic acid (RA), to induce the proliferation or differentiation of SSCs respectively. Vasculature influences SSC dynamics through CSF1 and vascular endothelial growth factor (VEGF) and by regulating oxygen levels. Lastly, peritubular myoid cells produce one of the most well-known factors that is required for SSC self-renewal, glial cell line-derived neurotrophic factor (GDNF), as well as CSF1. Overall, SSC interactions with interstitial and peritubular cells are critical for SSC function and are an important underlying factor promoting male fertility.

Antifertility efficacy of Coccinia indica in male mice and its possible mechanisms of action on spermatogenesis

The purpose of the present study was to investigate the antifertility efficacy of Coccinia indica and its possible mechanisms of action on testicular functions in Parkes male mice. Mice were orally administered 50% ethanolic leaf extract of Coccinia indica (200 and 500mgkg^-1 body weight day^-1) or distilled water (controls) for 35days. To assess reversibility, additional mice were treated with 500mgkg^-1 body weight of Coccinia or distilled water for 35days and sacrificed 56days later. Several male reproductive parameters such as motility, viability, morphology and number of spermatozoa in the cauda epididymidis, histopathology, serum level of testosterone, and fertility indices were evaluated; further, activities of 3β- and 17β-hydroxysteroid dehydrogenases, western blot analyses of StAR protein, cytochrome P450scc enzyme and of caspase-3, germ cell apoptosis by TUNEL, and lipid peroxidation and antioxidant enzymes activities in the testis were assessed. Toxicological parameters were also examined. Histologically, testes in Coccinia-treated mice showed nonuniform diverse degenerative changes in the seminiferous tubules. Treatment had adverse effect on serum level of testosterone, steroidogenic markers in the testis and on sperm parameters in the cauda epididymidis. The treatment also affected oxidative status of the testis and induced germ cell apoptosis. Serum levels of alanine aminotransferase, aspartate aminotransferase and creatinine, and haematological parameters were, however, not affected in treated mice. Fertility of the extract-treated males was also suppressed, but their libido remained unaffected. By 56days of treatment withdrawal, the above parameters recovered to control levels, suggesting that the Coccinia treatment causes reversible suppression of spermatogenesis and fertility in P mice, without producing detectable signs of toxicity. Further, suppression of spermatogenesis may be caused by germ cell apoptosis resulting from deficiency of testosterone, which, in turn, may result from the adverse effect of C. indica treatment on steroidogenesis and oxidative status in the testis.

Androgen Receptor Localizes to Plasma Membrane by Binding to Caveolin-1 in Mouse Sertoli Cells

The nonclassical androgen signaling pathway translates signals into alterations in cellular function within minutes, and this action is proposed to be mediated by an androgen receptor (AR) localized to the plasma membrane. This study was designed to determine the mechanism underlying the membrane association of androgen receptor in TM4 cells, a mouse Sertoli cell line. Western blot analysis indicated testosterone-induced AR translocation to the cell membrane. Data from coimmunoprecipitation indicated that AR is associated with caveolin-1, and testosterone enhanced this association. Knockdown of caveolin-1 by shRNA decreased the amount of AR localized to membrane fraction and prevented AR membrane trafficking after being exposed to testosterone at physiological concentration. The palmitoylation inhibitor 2-bromopalmitate decreased AR membrane localization in basal condition and completely blocked testosterone-induced AR translocation to membrane fraction. These data suggested that AR localized to membrane fraction by binding with caveolin-1 through palmitoylation of the cysteine residue. This study provided a new evidence for AR membrane localization and its application for clarifying the nonclassical signaling pathway of androgens.

Long-Term Effects of the Periconception Period on Embryo Epigenetic Profile and Phenotype: The Role of Stress and How This Effect Is Mediated

Stress represents an unavoidable aspect of human life, and pathologies associated with dysregulation of stress mechanisms - particularly psychiatric disorders - represent a significant global health problem. While it has long been observed that levels of stress experienced in the periconception period may greatly affect the offspring's risk of psychiatric disorders, the mechanisms underlying these associations are not yet comprehensively understood. In order to address this question, this chapter will take a 'top-down' approach, by first defining stress and associated concepts, before exploring the mechanistic basis of the stress response in the form of the hypothalamic-pituitary-adrenal (HPA) axis, and how dysregulation of the HPA axis can impede our mental and physical health, primarily via imbalances in glucocorticoids (GCs) and their corresponding receptors (GRs) in the brain. The current extent of knowledge pertaining to the impact of stress on developmental programming and epigenetic inheritance is then extensively discussed, including the role of chromatin remodelling associated with specific HPA axis-related genes and the possible role of regulatory RNAs as messengers of environmental stress both in the intrauterine environment and across the germ line. Furthering our understanding of the role of stress on embryonic development is crucial if we are to increase our predictive power of disease risk and devise-effective treatments and intervention strategies.

A Testis-Specific Long Non-Coding RNA, lncRNA-Tcam1, Regulates Immune-Related Genes in Mouse Male Germ Cells

Spermatogenesis is precisely controlled by hormones from the hypothalamus-pituitary-gonadal axis and testis-specific genes, but the regulatory mechanism is not fully understood. Recently, a large number of long non-coding RNAs (lncRNAs) are found to be transcribed at each stage of meiosis of male germ cells, and their functions in spermatogenesis have yet to be fully investigated. lncRNA-testicular cell adhesion molecule 1 (lncRNA-Tcam1) is a nuclear lncRNA which is specifically expressed in mouse male germ cells and presumed to play a role in gene regulation during meiosis. Here, we present the identification of potential target genes of lncRNA-Tcam1 using spermatocyte-derived GC-2spd(ts) cells. Initially, 55 target gene candidates were detected by RNA-sequencing of two GC-2spd(ts) cell clones that were stably transfected with transgenes to express lncRNA-Tcam1 at different levels. Expression of 21 genes of the candidates was found to be correlated with lncRNA-Tcam1 at 7-14 postnatal days, when lncRNA-Tcam1 expression was elevated. Subsequently, we examined expression levels of the 21 genes in other two GC-2spd(ts) clones, and 11 genes exhibited the correlation with lncRNA-Tcam1. Induction of lncRNA-Tcam1 transcription using the Tet-off system verified that six genes, Trim30a, Ifit3, Tgtp2, Ifi47, Oas1g, and Gbp3, were upregulated in GC-2spd(ts) cells, indicating that lncRNA-Tcam1 is responsible for the regulation of gene expression of the six genes. In addition, five of the six genes, namely, Ifit3, Tgtp2, Ifi47, Oas1g, and Gbp3, are immune response genes, and Trim30a is a negative regulator of immune response. Altogether, the present study suggests that lncRNA-Tcam1 is responsible for gene regulation for the immune response during spermatogenesis.

Alanine and arginine rich domain containing protein, Aard, is directly regulated by androgen receptor in mouse Sertoli cells

Alanine and arginine rich domain containing protein (Aard) is specifically expressed in Sertoli cells (SCs) of mouse testis and the expression increases in an age‑dependent manner. A number of previous studies have indicated that androgen and androgen receptor (AR) signaling pathways are particularly important for spermatogenesis in mouse SCs, however, the association between Aard and AR remain to be elucidated. The present study identified Aard as a gene that is directly regulated by AR in mouse SCs, which is important in spermatogenesis. The expression of AARD was significantly downregulated in the testes of Sertoli cell‑selective AR knockout mice compared with wild‑type mice as analyzed by western blotting and immunofluorescence analyses. Quantitative polymerase chain reaction and western blotting indicated that AARD was predominantly expressed in adult mouse testis and its expression was increased in an age-dependent manner. In addition, AARD expression was upregulated by testosterone in primary SCs in vitro, which was confirmed by bioinformatics analysis and a dual‑luciferase reporter assay. Finally, chromatin immunoprecipitation and electrophoretic mobility shift assays indicated that the ligand‑bound AR activated Aard transcription via directly binding to the androgen‑responsive element of the Aard promoter. To the best of our knowledge, the present study is the first to document that Aard is directly regulated by AR in mouse Sertoli cells.

Effect of polybrominated diphenyl ether (BDE-209) on testicular steroidogenesis and spermatogenesis through altered thyroid status in adult mice

Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants (BFRs), have been widely used in many products to minimize the risk of fire, mainly by mixing in polymer products. BDE-209, a congener of PBDEs having structural similarity with thyroid hormones, acts as an endocrine disruptor by interfering with thyroid homeostasis. However, little is known about the effect of BDE-209 exposure on testicular steroidogenesis and spermatogenesis. This study was therefore conducted in adult mice to examine the effect of BDE-209 on testicular steroidogenesis and spermatogenesis in relation to thyroid status, and to explore possible mechanism(s) of its action. Adult Parkes strain male mice were orally gavaged with 750 and 950mg/kg BW of BDE-209 in corn oil for 35days. Significant reductions were noted in the levels of serum total T_3, T₄ and testosterone in mice treated with 950mg/kg BW of BDE-209 compared to controls; histologically, testes showed nonuniform degenerative changes in the seminiferous tubules as both affected and normal tubules were observed in the same section; further, number and viability of spermatozoa were also adversely affected in cauda epididymidis of these mice. Semiquantitative RT-PCR and western blot analyses also showed significant reductions in both testicular mRNA and protein levels of steroidogenic factor 1 (SF-1), steroidogenic acute regulatory (StAR) protein, cytochrome P450scc (CYP11A1), 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD) in 950mg dose treated-mice compared to controls. Immunohistochemical and immunoblot analyses further revealed a marked decrease in proliferating cell nuclear antigen (PCNA) positive cells in testes of 950mg dose of BDE-209-treated mice. However, 750mg dose of BDE-209 had no effect on the above parameters. In conclusion, our results suggest that exposure of BDE-209 to adult mice causes reduction in serum levels of thyroid hormones and altered thyroid status may partly result into impairment of testicular steroidogenesis because of down-regulated expression of SF-1, thereby causing suppression of spermatogenesis.

Spatial Localization and Quantitation of Androgens in Mouse Testis by Mass Spectrometry Imaging

Androgens are essential for male development and reproductive function. They are transported to their site of action as blood-borne endocrine hormones but can also be produced within tissues to act in intracrine and paracrine fashions. Because of this, circulating concentrations may not accurately reflect the androgenic influence within specific tissue microenvironments. Mass spectrometry imaging permits regional analysis of small molecular species directly from tissue surfaces. However, due to poor ionization and localized ion suppression, steroid hormones are difficult to detect. Here, derivatization with Girard T reagent was used to charge-tag testosterone and 5α-dihydrotestosterone allowing direct detection of these steroids in mouse testes, in both basal and maximally stimulated states, and in rat prostate. Limits of detection were ∼0.1 pg for testosterone. Exemplary detection of endogenous steroids was achieved by matrix-assisted laser desorption ionization and either Fourier transform ion cyclotron resonance detection (at 150 μm spatial resolution) or quadrupole-time-of-flight detection (at 50 μm spatial resolution). Structural confirmation was achieved by collision induced fragmentation following liquid extraction surface analysis and electrospray ionization. This application broadens the scope for derivatization strategies on tissue surfaces to elucidate local endocrine signaling in health and disease.

Development, function and fate of fetal Leydig cells

During fetal testis development, fetal Leydig cells (FLCs) are found to be originated from multiple progenitor cells. FLC specification and function are under tight regulation of specific genes and signaling proteins. Furthermore, Sertoli cells play a crucial role to regulate FLC differentiation during fetal testis development. FLC progenitor- and FLC-produced biomolecules are also involved in the differentiation and activity of rodent FLCs. The main function of FLCs is to produce androgens to masculinize XY embryos. However, FLCs are capable of producing androstenedione but not testosterone due to the lack of 17β-HSD (17β-hydroxysteroid dehydrogenase), but fetal Sertoli cells express 17β-HSD which thus transforms androstenedione to testosterone in the fetal testis. On the other hand, FLCs produce activin A to regulate Sertoli cell proliferation, and Sertoli cells in turn modulate testis cord expansion. It is now generally accepted that adult Leydig cells (ALCs) gradually replace FLCs during postnatal development to produce testosterone to support spermatogenesis as FLCs undergo degeneration in neonatal and pre-pubertal testes. However, based on studies using genetic tracing mouse models, FLCs are found to persist in adult testes, making up ∼20% of total Leydig cells. In this review, we evaluate the latest findings regarding the development, function and fate of FLCs during fetal and adult testis development.

Relative levels of the proprotein and cleavage-activated form of circulating human anti-Müllerian hormone are sexually dimorphic and variable during the life cycle

Anti‐Müllerian hormone (AMH) is a gonadal hormone, which induces aspects of the male phenotype, and influences ovarian follicular recruitment. AMH is synthesized as a proprotein (proAMH), which is incompletely cleaved to the receptor‐competent AMH_N,C. AMH ELISAs have not distinguished between proAMH and AMH_N,C; consequently, the physiological ranges of circulating proAMH and AMH_N,C are unknown. A novel proAMH ELISA has been used to assay serum proAMH in humans. Total AMH was also measured, enabling the AMH_N,C concentration to be calculated. Stored serum from 131 boys, 80 younger, and 106 older men were examined, with serum from 14 girls and 18 women included for comparison. The mean levels of proAMH and AMH_N,C in pM were respectively: boys (253, 526), men (7.7, 36), elderly men (5.7, 19), girls (3.3, 15), and women (5.2, 27) (boys vs. men, P < 0.001; girls vs. women, P = 0.032). The proportion of proAMH as a percentage of total AMH (API) was approximately twofold higher in boys than men (P < 0.001) with little overlap between the ranges, with girls also exhibiting lesser cleavage of their AMH than women (P < 0.001). The API varied within each population group. In young men, the API did not correlate with circulating levels of the other testicular hormones (testosterone, InhB, and INSL3). In conclusion, the cleavage of circulating AMH varies extensively within the human population, with most individuals having significant levels of proAMH. The physiological and clinical relevance of circulating proAMH needs to be established.

Identification of androgen receptor antagonists: In vitro investigation and classification methodology for flavonoid

A tremendous gap exists between the number of potential endocrine disrupting chemicals (EDCs) possibly in the environment and the limitation of traditional regulatory testing. In this study, the anti-androgenic potencies of 21 flavonoids were analyzed in vitro, and another 32 flavonoids from the literature were selected as additional chemicals. Molecular dynamic simulations were employed to obtain four different separation approaches based on the different behaviors of ligands and receptors during the process of interaction. Specifically, ligand-receptor complex which highlighted the discriminating features of ligand escape or retention via "mousetrap" mechanism, hydrogen bonds formed during simulation times, ligand stability and the stability of the helix-12 of the receptor were investigated. Together, a methodology was generated that 87.5% of flavonoids could be discriminated as active versus inactive antagonists, and over 90% inactive antagonists could be filtered out before QSAR study. This methodology could be used as a "proof of concept" to identify inactive anti-androgenic flavonoids, as well could be beneficial for rapid risk assessment and regulation of multiple new chemicals for androgenicity.

A novel variant of androgen receptor is associated with idiopathic azoospermia

A variety of genetic variants can lead to abnormal human spermatogenesis. The androgen receptor (AR) is an important steroid hormone receptor that is critical for male sexual differentiation and the maintenance of normal spermatogenesis. In the present study, each exon of AR in 776 patients diagnosed with idiopathic azoospermia (IA) and 709 proven fertile men were sequenced using use panel re‑sequencing methods to examine whether AR is involved in the pathogenesis of IA. Two synonymous variants and seven missense variants were detected. Of the missense variants, a luciferase assay demonstrated that the R630W variant reduced the transcriptional regulatory function of AR. This novel variant (p. R630W) of AR is the first to be identified in association with IA, thereby highlighting the importance of AR during spermatogenesis.

Elevated expression of the Sertoli cell androgen receptor disrupts male fertility

Recently, we created a unique gain-of-function mouse model with Sertoli cell-specific transgenic androgen receptor expression (TgSCAR) showing that SCAR activity controls the synchronized postnatal development of somatic Sertoli and Leydig cells and meiotic-postmeiotic germ cells. Moderate TgSCAR (TgSCAR(m)) expression reduced testis size but had no effect on male fertility. Here, we reveal that higher TgSCAR expression (TgSCAR(H)) causes male infertility. Higher SCAR activity, shown by upregulated AR-dependent transcripts (Rhox5, Spinw1), resulted in smaller adult TgSCAR(H) testes (50% of normal) despite normal or elevated circulating and intratesticular testosterone levels. Unlike fertile TgSCAR(m) males, testes of adult TgSCAR(H) males exhibited focal regions of interstitial hypertrophy featuring immature adult Leydig cells and higher intratesticular dihydrotestosterone and 5α-androstane 3α,17β-diol levels that are normally associated with pubertal development. Mature TgSCAR(H) testes also exhibited markedly reduced Sertoli cell numbers (70%), although meiotic and postmeiotic germ cell/Sertoli cell ratios were twofold higher than normal, suggesting that elevated TgSCAR activity supports excessive spermatogenic development. Concurrent with the higher germ cell load of TgSCAR(H) Sertoli cells were increased levels of apoptotic germ cells in TgSCAR(H) relative to TgSCAR(m) testes. In addition, TgSCAR(H) testes displayed unique morphological degeneration that featured accumulated cellular and spermatozoa clusters in dilated channels of rete testes, consistent with reduced epididymal sperm numbers. Our findings reveal for the first time that excessive Sertoli cell AR activity in mature testes can reach a level that disturbs Sertoli/germ cell homeostasis, impacts focal Leydig cell function, reduces sperm output, and disrupts male fertility.

Molecular Mechanisms Elicited by d-Aspartate in Leydig Cells and Spermatogonia

A bulk of evidence suggests that d-aspartate (d-Asp) regulates steroidogenesis and spermatogenesis in vertebrate testes. This review article focuses on intracellular signaling mechanisms elicited by d-Asp possibly via binding to the N-methyl-d-aspartate receptor (NMDAR) in both Leydig cells, and spermatogonia. In Leydig cells, the amino acid upregulates androgen production by eliciting the adenylate cyclase-cAMP and/or mitogen-activated protein kinase (MAPK) pathways. d-Asp treatment enhances gene and protein expression of enzymes involved in the steroidogenic cascade. d-Asp also directly affects spermatogonial mitotic activity. In spermatogonial GC-1 cells, d-Asp induces phosphorylation of MAPK and AKT serine-threonine kinase proteins, and stimulates expression of proliferating cell nuclear antigen (PCNA) and aurora kinase B (AURKB). Further stimulation of spermatogonial GC-1 cell proliferation might come from estradiol/estrogen receptor β (ESR2) interaction. d-Asp modulates androgen and estrogen levels as well as the expression of their receptors in the rat epididymis by acting on mRNA levels of Srd5a1 and Cyp19a1 enzymes, hence suggesting involvement in spermatozoa maturation.

The protective effects of zinc in lead-induced testicular and epididymal toxicity in Wistar rats

The aim of this study was to investigate the beneficial effects of zinc (Zn) in preventing lead (Pb)-induced reproductive toxicity in Wistar rats. The rats were divided into four groups, namely, control group, Pb group, Zn group, and Pb + Zn group. Animals were exposed to Pb (819 mg of Pb/L) or Zn (71 mg of Zn/L) or both through drinking water for 65 days. Rats exposed to Pb showed decreased weights of testes and accessory sex organs. Significant decrease in the testicular daily sperm production, epididymal sperm count, motility, viability, and number of hypoosmotic tail coiled sperm was observed in Pb-exposed rats. Testicular 3β- and 17β-hydroxysteroid dehydrogenase activity levels and circulatory testosterone levels were also decreased significantly in Pb-exposed rats. A significant increase in the lipid peroxidation products with a significant decrease in the activities of catalase and superoxide dismutase were observed in the testes and epididymis of Pb-exposed rats. Moreover, the testicular architecture showed lumens devoid of sperm in Pb-exposed rats. Supplementation of Zn mitigated Pb-induced oxidative stress and restored the spermatogenesis and steroidogenesis in Pb-exposed rats. In conclusion, cotreatment of Zn is effective for recovering suppressed spermatogenesis, steroidogenesis, elevated oxidative status, and histological damage in the testis of rats treated with Pb.

Role of testosterone in regulating induction of TNF-α in rat spleen via ERK signaling pathway

Spleen is a pivotal organ for regulating immune homeostasis. It has been shown that testosterone diminishes secretion of various inflammatory molecules under multiple conditions. However, the mechanisms of action of endogenous testosterone affecting immune responses in the spleen remain unknown. The aim of the present study was to evaluate the immune functions of the spleen in response to testosterone withdrawal after orchidectomy, and the impact of splenocytes on the bacterial endotoxin lipopolysaccharide (LPS)-induced secretion of inflammatory molecules. Male rats were divided into 3 groups, i.e. intact, orchidectomized (Orch) and orchidectomized plus replacement of testosterone propionate (TP) (Orch+TP). The Orch and Orch+TP rats underwent bilateral orchidectomy one week before TP replacement (2mg/kg body weight) or sesame oil in intact rats as controls for seven days. Orch resulted in a significant increase of spleen weight and basal secretion of nitric oxide (NO) from splenocytes. Additionally, LPS up-regulated cell proliferation and the secretion of tumor necrosis factor-alpha (TNF-α) in splenocytes of Orch rats. Orch further up-regulated phosphorylation of extracellular signal-regulated kinases. Interestingly, the plasma corticosterone concentration in the Orch group was higher than that in the intact and Orch+TP groups. Deficiency of testosterone-elevated TNF-α and NO secretion in response to LPS were confirmed in the rat splenocytes. Testosterone also significantly attenuated LPS-elicited release of TNF-α and NO in a dose-dependent manner. However, testosterone did not suppress splenic blastogenesis at doses in the 10(-10)-10(-7)M concentration range. In this context, testosterone might have a protective role against inflammatory responses in the spleen. The present study provides evidence to indicate that testosterone might modulate the immune system.

The expression of several reproductive hormone receptors can be modified by perfluorooctane sulfonate (PFOS) in adult male rats

This study was undertaken to evaluate the possible role of several reproductive hormone receptors on the disruption of the hypothalamic-pituitary-testis (HPT) axis activity induced by perfluorooctane sulfonate (PFOS). The studied receptors are the gonadotropin-releasing hormone receptor (GnRHr), luteinizing hormone receptor (LHr), follicle-stimulating hormone receptor (FSHr), and the androgen receptor (Ar). Adult male rats were orally treated with 1.0; 3.0 and 6.0 mg of PFOS kg(-1) d(-1) for 28 days. In general terms, PFOS can modify the relative gene and protein expressions of these receptors in several tissues of the reproductive axis. At the testicular level, apart from the expected inhibition of both gene and protein expressions of FSHr and Ar, PFOS also stimulates the GnRHr protein and the LHr gene expression. The receptors of the main hormones involved in the HPT axis may have an important role in the disruption exerted by PFOS on this axis.

Regulation of the blood-testis barrier

The purpose of this review is to describe the endocrine and local testicular factors that contribute to the regulation of the blood-testis barrier (BTB), using information gained from in vivo and in vitro models of BTB formation during/after puberty, and from the maintenance of BTB function during adulthood. In vivo the BTB, in part comprised of tight junctions between adjacent somatic Sertoli cells, compartmentalizes meiotic spermatocytes and post-meiotic spermatids away from the vasculature, and therefore prevents autoantibody production by the immune system against these immunogenic germ cells. This adluminal compartment also features a unique biochemical milieu required for the completion of germ cell development. During the normal process of spermatogenesis, earlier germ cells continually cross into the adluminal compartment, but the regulatory mechanisms and changes in junctional proteins that allow this translocation step without causing a 'leak' remain poorly understood. Recent data describing the roles of FSH and androgen on the regulation of Sertoli cell tight junctions and tight junction proteins will be discussed, followed by an examination of the role of paracrine factors, including members of the TGFβ superfamily (TGFβ3, activin A) and retinoid signalling, as potential mediators of junction assembly and disassembly during the translocation process.

Cell polarity proteins and spermatogenesis

When the cross-section of a seminiferous tubule from an adult rat testes is examined microscopically, Sertoli cells and germ cells in the seminiferous epithelium are notably polarized cells. For instance, Sertoli cell nuclei are found near the basement membrane. On the other hand, tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific actin-rich anchoring junction), gap junction (GJ) and desmosome that constitute the blood-testis barrier (BTB) are also located near the basement membrane. The BTB, in turn, divides the epithelium into the basal and the adluminal (apical) compartments. Within the epithelium, undifferentiated spermatogonia and preleptotene spermatocytes restrictively reside in the basal compartment whereas spermatocytes and post-meiotic spermatids reside in the adluminal compartment. Furthermore, the heads of elongating/elongated spermatids point toward the basement membrane with their elongating tails toward the tubule lumen. However, the involvement of polarity proteins in this unique cellular organization, in particular the underlying molecular mechanism(s) by which polarity proteins confer cellular polarity in the seminiferous epithelium is virtually unknown until recent years. Herein, we discuss latest findings regarding the role of different polarity protein complexes or modules and how these protein complexes are working in concert to modulate Sertoli cell and spermatid polarity. These findings also illustrate polarity proteins exert their effects through the actin-based cytoskeleton mediated by actin binding and regulatory proteins, which in turn modulate adhesion protein complexes at the cell-cell interface since TJ, basal ES and GJ utilize F-actin for attachment. We also propose a hypothetical model which illustrates the antagonistic effects of these polarity proteins. This in turn provides a unique mechanism to modulate junction remodeling in the testis to support germ cell transport across the epithelium in particular the BTB during the epithelial cycle of spermatogenesis.

Protective Effect of Adrenomedullin on Rat Leydig Cells from Lipopolysaccharide-Induced Inflammation and Apoptosis via the PI3K/Akt Signaling Pathway ADM on Rat Leydig Cells from Inflammation and Apoptosis

This study was carried out to investigate whether ADM can modulate LPS-induced inflammation and apoptosis in rat Leydig cells. Leydig cells were treated with ADM before LPS-induced cytotoxicity. We determined the concentrations of ROS, MDA, GSH, LDH, and testosterone and the MMP. The mRNA levels of IL-1, IL-6, iNOS, and COX-2 were obtained, and the concentrations of IL-1, IL-6, NO, and PGE2 were determined. Apoptosis was assessed by TUNEL and detection of DNA fragmentation. The levels of mRNA and protein were determined for Bcl-2, Bax, caspase-3, and PARP. The protein contents for total and p-Akt were measured. ADM pretreatment significantly elevated the MMP and testosterone concentration and reduced the levels of ROS, MDA, GSH, and LDH. ADM pretreatment significantly decreased the mRNA levels of IL-1, IL-6, iNOS, and COX-2 and the concentrations of IL-1, IL-6, NO, and PGE2. LPS-induced TUNEL-positive Leydig cells were significantly decreased by ADM pretreatment, a result further confirmed by decreased DNA fragmentation. ADM pretreatment decreased apoptosis by significantly promoting Bcl-2 and inhibiting Bax, caspase-3, and PARP expressions. The LPS activity that reduced p-Akt level was significantly inhibited by ADM pretreatment. ADM protected rat Leydig cells from LPS-induced inflammation and apoptosis, which might be associated with PI3K/Akt mitochondrial signaling pathway.

Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes

Testicular Leydig cells are the primary source of testosterone in males. Adult Leydig cells have been shown to arise from stem cells present in the neonatal testis. Once established, adult Leydig cells turn over only slowly during adult life, but when these cells are eliminated experimentally from the adult testis, new Leydig cells rapidly reappear. As in the neonatal testis, stem cells in the adult testis are presumed to be the source of the new Leydig cells. As yet, the mechanisms involved in regulating the proliferation and differentiation of these stem cells remain unknown. We developed a unique in vitro system of cultured seminiferous tubules to assess the ability of factors from the seminiferous tubules to regulate the proliferation of the tubule-associated stem cells, and their subsequent entry into the Leydig cell lineage. The proliferation of the stem Leydig cells was stimulated by paracrine factors including Desert hedgehog (DHH), basic fibroblast growth factor (FGF2), platelet-derived growth factor (PDGF), and activin. Suppression of proliferation occurred with transforming growth factor β (TGF-β). The differentiation of the stem cells was regulated positively by DHH, lithium- induced signaling, and activin, and negatively by TGF-β, PDGFBB, and FGF2. DHH functioned as a commitment factor, inducing the transition of stem cells to the progenitor stage and thus into the Leydig cell lineage. Additionally, CD90 (Thy1) was found to be a unique stem cell surface marker that was used to obtain purified stem cells by flow cytometry.

Increased expression of dermatopontin and its implications for testicular dysfunction in mice

An array of specific and non-specific molecules, which are expressed in the testis, have been demonstrated to be responsible for testicular function. Our previous study revealed that dermatopontin (DPT) is expressed in Sertoli cells of the testis, however, its roles in testicular function remains somewhat elusive. In the present study, CdCl₂- and busulfan-induced testicular dysfunction models were used to investigate the implications of DPT expression for testicular function. The mRNA and protein expression levels of DPT were detected using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. A negative correlation was observed between testicular damage and the expression of DPT, which suggested that an increase in DPT expression may be a marker for testicular dysfunction. This result was corroborated by the finding that transgenic mice exhibiting Sertoli cell-specific overexpression of DPT exhibited damage to their testicular morphology. Additionally, DPT overexpression in the testis affected the expression levels of claudin-11 and zonula occludens-1, which indicated that DPT may affect testicular function by affecting the integrity of the blood-testis barrier (BTB). In conclusion, the present study provided evidence to suggest that DPT may be indicative of mouse testicular dysfunction, since increased expression may be associated with damage to the BTB.

The Sertoli cell: one hundred fifty years of beauty and plasticity

It has been one and a half centuries since Enrico Sertoli published the seminal discovery of the testicular 'nurse cell', not only a key cell in the testis, but indeed one of the most amazing cells in the vertebrate body. In this review, we begin by examining the three phases of morphological research that have occurred in the study of Sertoli cells, because microscopic anatomy was essentially the only scientific discipline available for about the first 75 years after the discovery. Biochemistry and molecular biology then changed all of biological sciences, including our understanding of the functions of Sertoli cells. Immunology and stem cell biology were not even topics of science in 1865, but they have now become major issues in our appreciation of Sertoli cell's role in spermatogenesis. We end with the universal importance and plasticity of function by comparing Sertoli cells in fish, amphibians, and mammals. In these various classes of vertebrates, Sertoli cells have quite different modes of proliferation and epithelial maintenance, cystic vs. tubular formation, yet accomplish essentially the same function but in strikingly different ways.

Varicocele and its effect on testosterone: implications for the adolescent

The treatment of varicoceles in adolescents is highly controversial. In contrast to adults with varicocele, fertility status is not yet known and it is not generally feasible to obtain a semen analysis in adolescents in order to guide treatment. Hence, the principal indication for surgery in teenagers is hypotrophy/atrophy of the left testis associated with a varicocele. Recent evidence in adults suggests that varicocele may be a cause of hypogonadism. If this is further documented in adults, it may be true in teens as well and indeed, might be an indication for early surgery. This is an important area for research in adolescents with a varicocele.

Is thyroid hormones evaluation of clinical value in the work-up of males of infertile couples?

STUDY QUESTION

Is thyroid hormones (TH) evaluation of clinical value in the work-up of males of infertile couples?

STUDY ANSWER

Our results suggest that TH evaluation is not mandatory in the work-up of male infertility.

WHAT IS KNOWN ALREADY

A few previous studies performed on a limited series of subjects reported a negative impact of hyper- and hypo-thyroidism on semen volume, sperm concentration, progressive motility and normal morphology. No previous study has systematically evaluated associations between TH variation, semen parameters and ultrasound characteristics of the male genital tract.

STUDY DESIGN, SIZE AND DURATION

Cross-sectional analysis of a consecutive series of 172 subjects seeking medical care for couple infertility from September 2010 to November 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Of the entire cohort, 163 men (age 38.9 ± 8.0 years) free of genetic abnormalities were studied. All subjects underwent a complete andrological and physical examination, biochemical and hormonal assessment, scrotal and transrectal colour-Doppler ultrasound (CDUS) and semen analysis (including seminal interleukin 8 levels, sIL-8) evaluation within the same day.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the patients studied, 145 (88.9%) showed euthyroidism, 6 (3.7%) subclinical hyper- and 12 (7.4%) subclinical hypo-thyroidism. No subjects showed overt hyper- or hypo-thyroidism. At univariate analysis, no associations among thyroid-stimulating hormone (TSH) or TH levels and sperm parameters were observed. Conversely, we observed positive associations among free triiodothyronine (fT3) and free thyroxine (fT4) levels, ejaculate volume and seminal fructose levels. In a multivariate model, after adjusting for confounders such as age, body mass index, smoking habit, sexual abstinence, calculated free testosterone, prolactin and sIL-8 levels, only the associations found for fT3 levels were confirmed. When CDUS features were investigated, using the same multivariate model, we found positive associations between fT3 levels and seminal vesicles (SV) volume, both before and after ejaculation (adj. r = 0.354 and adj. r = 0.318, both P < 0.0001), as well as with SV emptying (ΔSV volume; adj. r = 0.346, P < 0.0001) and echo-texture inhomogeneity. In addition, after adjusting for confounders, negative associations between fT4 levels and epididymal body and tail diameters were found. No significant associations between TSH or TH levels and CDUS features of other organs of the male genital tract, including testis and prostate, were found. Finally, when the features of subjects with euthyroidism, subclinical hypo- and hyper-thyroidism were compared, no significant differences in seminal or hormonal parameters were found. Conversely, evaluating CDUS parameters, subjects with subclinical hyperthyroidism showed a higher difference between the SV longitudinal diameters measured before and after ejaculation when compared with that of subclinical hypothyroid men, even after adjusting for confounders (P < 0.007). All the other male genital tract CDUS characteristics did not differ among groups.

LIMITATIONS, REASONS FOR CAUTION

First, the number of patients investigated is relatively small and those with (subclinical) thyroid dysfunctions are an even smaller number; hence, it is therefore difficult to draw firm conclusions. Moreover, the present results are derived from patients consulting an Italian Andrology Clinic for couple infertility, and could have different characteristics from the male general population or from those males consulting general practitioners for reasons other than couple infertility. Finally, due to the cross-sectional nature of the study, neither a causality hypothesis nor mechanistic models can be inferred.

WIDER IMPLICATIONS OF THE FINDINGS

Although no associations between TH and sperm parameters were observed, present data support a positive effect of TH on SV size and a permissive role on the ejaculatory machinery, likely through an action on SV and epididymal contractility. This is the first study reporting such evidence. However, in contrast with the view that TH assessment is important for female fertility, our results do not support a systematic evaluation of thyroid function in males of infertile couples. How TH abnormalities impact male fertility needs to be addressed by further studies.

STUDY FUNDING/COMPETING INTERESTS

No funding was received for the study. None of the authors have any conflict of interest to declare.

Biology of the Sertoli Cell in the Fetal, Pubertal, and Adult Mammalian Testis

A healthy man typically produces between 50 × 10(6) and 200 × 10(6) spermatozoa per day by spermatogenesis; in the absence of Sertoli cells in the male gonad, this individual would be infertile. In the adult testis, Sertoli cells are sustentacular cells that support germ cell development by secreting proteins and other important biomolecules that are essential for germ cell survival and maturation, establishing the blood-testis barrier, and facilitating spermatozoa detachment at spermiation. In the fetal testis, on the other hand, pre-Sertoli cells form the testis cords, the future seminiferous tubules. However, the role of pre-Sertoli cells in this process is much less clear than the function of Sertoli cells in the adult testis. Within this framework, we provide an overview of the biology of the fetal, pubertal, and adult Sertoli cell, highlighting relevant cell biology studies that have expanded our understanding of mammalian spermatogenesis.

Non-coding RNA in Spermatogenesis and Epididymal Maturation

Testicular germ and somatic cells express many classes of small ncRNAs, including Dicer-independent PIWI-interacting RNAs, Dicer-dependent miRNAs, and endogenous small interfering RNA. Several studies have identified ncRNAs that are highly, exclusively, or preferentially expressed in the testis and epididymis in specific germ and somatic cell types. Temporal and spatial expression of proteins is a key requirement of successful spermatogenesis and large-scale gene transcription occurs in two key stages, just prior to transcriptional quiescence in meiosis and then during spermiogenesis just prior to nuclear silencing in elongating spermatids. More than 60 % of these transcripts are then stockpiled for subsequent translation. In this capacity ncRNAs may act to interpret and transduce cellular signals to either maintain the undifferentiated stem cell population and/or drive cell differentiation during spermatogenesis and epididymal maturation. The assignation of specific roles to the majority of ncRNA species implicated as having a role in spermatogenesis and epididymal function will underpin fundamental understanding of normal and disease states in humans such as infertility and the development of germ cell tumours.

Yangjing Capsule Ameliorates Spermatogenesis in Male Mice Exposed to Cyclophosphamide

Yangjing capsule (YC), a traditional Chinese compound herbal preparation, has been proven as an effective drug to improve spermatogenesis in clinical practice. However, its pharmacological mechanisms were not fully clarified. This study was designed to investigate the protective effects of YC on spermatogenesis in the mouse model of spermatogenesis dysfunction induced by cyclophosphamide (CP). The administration of YC significantly increased the epididymal index, sperm count, and sperm motility of model mice. Histopathological changes demonstrated that CP caused obvious structural damage to testis, which were reversed by the administration of YC. Results from TUNEL assay showed that treatment with YC dramatically decreased the apoptosis of spermatogenic cell induced by CP. Moreover, YC treatment could inhibit the mRNA and protein expression of Bax to Bcl-2 and also raised expression of AR at both mRNA and protein levels. These data suggest that YC might ameliorate spermatogenesis in male mice exposed to CP through inhibiting the apoptosis of spermatogenic cell and enhancing the actions of testosterone in spermatogenesis.

Androgen receptor binding to an androgen-responsive element in the promoter of the Srsf4 gene inhibits its expression in mouse Sertoli cells

The serine/arginine-rich splicing actor 4 (SRSF4) is essential for pre-mRNA splicing and can influence alternative-splice-site choice. Little is known about the specific function of this gene in the reproductive system, although a recent study identified a SRSF4 polymorphism significantly associated with a decreased risk of non-obstructive azoospermia in Chinese men. We previously found that the expression of Srsf4 was up-regulated in the testes of Sertoli-cell-selective androgen receptor knockout (S-Ar(-/y)) mice compared to wild-type mice using digital gene expression analysis. In this study, we confirmed and extended the selective gene expression data: SRSF4 was mainly located in the nucleus of Sertoli cells, and Srsf4 expression in the Sertoli-cell-derived cell line TM4 is down-regulation by testosterone. Moreover, androgen receptor directly binds the androgen-responsive element of the Srsf4 promoter. Taken together, these results demonstrate that Srsf4 is a direct downstream target of the androgen receptor in mouse Sertoli cells.

Sodium metabisulfite-induced changes on testes, spermatogenesis and epididymal morphometric values in adult rats

BACKGROUND

Sulphites are widely used as a preservative and antioxidant additives in the food and pharmaceutical industries. Many types of biological and toxicological effects of sulphites in multiple organs of mammals have been shown in previous studies.

OBJECTIVE

The aim of this study was to investigate the effects of sodium metabisulfite (SMB) on testicular function and morphometric values of epididymis in adult male Wistar rats.

MATERIALS AND METHODS

A total of 32 rats were randomly divided into four groups. The experimental groups received SMB at doses of 10 mg/kg (S10), 100mg/kg (S100), and 260 mg/kg (S260) while an equal volume of normal saline was administered to the control group via gavage. The rats were anaesthetized after 28 days and the left testis with the head of epididimis was excised following abdominal incision for histological observation using hematoxylin and eosin staining. Serum samples were collected for assay of testosterone level. The initial epididymis was analyzed for motility, morphology, and the number of sperms.

RESULT

The results of this study showed that normal morphology, count, and motility of sperms and testosterone level were decreased in the SMB treated groups. In comparison with the control group, SMB resulted in a lower total number of spermatogonia, primary spermatocyte, spermatids, and Leydig cells.

CONCLUSION

It is suggested that SMB decreases the sperm production and has the potential to affect the fertility adversely in male rats.

The Src non-receptor tyrosine kinase paradigm: New insights into mammalian Sertoli cell biology

Src kinases are non-receptor tyrosine kinases that phosphorylate diverse substrates, which control processes such as cell proliferation, differentiation and survival; cell adhesion; and cell motility. c-Src, the prototypical member of this protein family, is widely expressed by several organs that include the testis. In the seminiferous epithelium of the adult rat testis, c-Src is highest at the tubule lumen during the release of mature spermatids. Other studies show that testosterone regulates spermatid adhesion to Sertoli cells via c-Src, indicating Src phosphorylates key substrates that prompt the disassembly of Sertoli cell-spermatid junctions. A more recent in vitro study reveals that c-Src participates in the internalization of proteins that constitute the blood-testis barrier, which is present between Sertoli cells, suggesting a similar mechanism of junction disassembly is at play during spermiation. In this review, we discuss recent findings on c-Src, with an emphasis on its role in spermatogenesis in the mammalian testis.

Molecular regulation of steroidogenesis in endocrine Leydig cells

Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. Consequently, the process of steroid hormone biosynthesis is finely regulated. In the testis, the main steroidogenic cells are the Leydig cells. There are two distinct populations of Leydig cells that arise during development: fetal and adult Leydig cells. Fetal Leydig cells are responsible for masculinizing the male urogenital tract and inducing testis descent. These cells atrophy shortly after birth and do not contribute to the adult Leydig cell population. Adult Leydig cells derive from undifferentiated precursors present after birth and become fully steroidogenic at puberty. The differentiation of both Leydig cell populations is controlled by locally produced paracrine factors and by endocrine hormones. In fully differentially and steroidogenically active Leydig cells, androgen production and hormone-responsiveness involve various signaling pathways and downstream transcription factors. This review article focuses on recent developments regarding the origin and function of Leydig cells, the regulation of their differentiation by signaling molecules, hormones, and structural changes, the signaling pathways, kinases, and transcription factors involved in their differentiation and in mediating LH-responsiveness, as well as the fine-tuning mechanisms that ensure adequate production steroid hormones.