Androgen action via testicular peritubular myoid cells is essential for male fertility

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 testicular form of angiotensin converting enzyme as a marker for human sperm quality assessment

INTRODUCTION

Spermatozoa are rapidly changing cellular structures that are highly dependent on their interaction with the environment. These interactions cause fundamental changes in the spermatozoa's cells and membrane.

Pregabalin alters reproductive performance in male mice and causes congenital anomalies in offspring

CONTEXT

Pregabalin is an anticonvulsant drug with analgesic activity for the treatment of neuropathic pain.

AIMS

To valuate the toxicity of pregabalin in reproductive parameters, spermatogenesis, and teratogenicity in the offspring of mice.

METHODS

Twenty male mice were randomly distributed into two groups: PGB group and group C (n =10 per group). The animals in the PGB group received, via gavage, 200mg/kg of pregabalin diluted in distilled water daily, for a period of 45days. Group C received distilled water under the same experimental design.

KEY RESULTS

In the paternal parameters of the PGB group, there was a significant increase in the size of the testicles, morphological alterations in the spermatozoa, a decrease in the Johnsen score, an increase in the Leydig cells, and a decrease in the serum level of testosterone. In the intrauterine development parameters of females mated with males from the PGB group, a significant decrease in placental weight, weight and length of fetuses, and fetal viability rate was observed. There was a significant increase in the number of resorptions and post-implantation losses. The significant anomalies observed in the offspring were alteration in the size of the kidneys, absent metacarpals and phalanges, alteration in the sternum, and supernumerary thoracic vertebrae.

CONCLUSION

Results suggest that pregabalin had toxic effects on the reproductive function of male mice and teratogenic potential.

IMPLICATIONS

The findings of this study may provide new hypotheses, taking into account the risk-benefit ratio for male reproduction and offspring health.

Sertoli cell-enriched proteins in mouse and human testicular interstitial fluid

Sertoli cells support the development of sperm and the function of various somatic cells in the interstitium between the tubules. Sertoli cells regulate the function of the testicular vasculature and the development and function of the Leydig cells that produce testosterone for fertility and virility. However, the Sertoli cell-derived factors that regulate these cells are largely unknown. To define potential mechanisms by which Sertoli cells could support testicular somatic cell function, we aimed to identify Sertoli cell-enriched proteins in the testicular interstitial fluid (TIF) between the tubules. We previously resolved the proteome of TIF in mice and humans and have shown it to be a rich source of seminiferous tubule-derived proteins. In the current study, we designed bioinformatic strategies to interrogate relevant proteomic and genomic datasets to identify Sertoli cell-enriched proteins in mouse and human TIF. We analysed proteins in mouse TIF that were significantly reduced after one week of acute Sertoli cell ablation in vivo and validated which of these are likely to arise primarily from Sertoli cells based on relevant mouse testis RNASeq datasets. We used a different, but complementary, approach to identify Sertoli cell-enriched proteins in human TIF, taking advantage of high-quality human testis genomic, proteomic and immunohistochemical datasets. We identified a total of 47 and 40 Sertoli cell-enriched proteins in mouse and human TIF, respectively, including 15 proteins that are conserved in both species. Proteins with potential roles in angiogenesis, the regulation of Leydig cells or steroidogenesis, and immune cell regulation were identified. The data suggests that some of these proteins are secreted, but that Sertoli cells also deposit specific proteins into TIF via the release of extracellular vesicles. In conclusion, we have identified novel Sertoli cell-enriched proteins in TIF that are candidates for regulating somatic cell-cell communication and testis function.

Pancreatic lipase-related protein 2 is selectively expressed by peritubular myoid cells in the murine testis and sustains long-term spermatogenesis

Spermatogenesis is a complicated process of germ cell differentiation that occurs within the seminiferous tubule in the testis. Peritubular myoid cells (PTMCs) produce major components of the basement membrane that separates and ensures the structural integrity of seminiferous tubules. These cells secrete niche factors to promote spermatogonial stem cell (SSC) maintenance and mediate androgen signals to direct spermatid development. However, the regulatory mechanisms underlying the identity and function of PTMCs have not been fully elucidated. In the present study, we showed that the expression of pancreatic lipase-related protein 2 (Pnliprp2) was restricted in PTMCs in the testis and that its genetic ablation caused age-dependent defects in spermatogenesis. The fertility of Pnliprp2 knockout animals (Pnliprp2-/-) was normal at a young age but declined sharply beginning at 9 months. Pnliprp2 deletion impaired the homeostasis of undifferentiated spermatogonia and severely disrupted the development and function of spermatids. Integrated analyses of single-cell RNA-seq and metabolomics data revealed that glyceride metabolism was changed in PTMCs from Pnliprp2-/- mice. Further analysis found that 60 metabolites were altered in the sperm of the Pnliprp2-/- animals; notably, lipid metabolism was significantly dysregulated. Collectively, these results revealed that Pnliprp2 was exclusively expressed in PTMCs in the testis and played a novel role in supporting continual spermatogenesis in mice. The outcomes of these findings highlight the function of lipid metabolism in reproduction and provide new insights into the regulation of PTMCs in mammals.

Extra-Gonadal and Non-Canonical Effects of FSH in Males

Recombinant follicle-stimulating hormone (FSH) is commonly used for the treatment of female infertility and is increasingly being used in males as well, as recommended by notable guidelines. FSH is composed of an α subunit, shared with other hormones, and a β subunit, which confers specificity of biological action by interacting with its surface receptor (FSHR), predominantly located in granulosa and Sertoli cells. However, FSHRs also exist in extra-gonadal tissues, indicating potential effects beyond male fertility. Emerging evidence suggests that FSH may have extra-gonadal effects, including on bone metabolism, where it appears to stimulate bone resorption by binding to specific receptors on osteoclasts. Additionally, higher FSH levels have been associated with worse metabolic and cardiovascular outcomes, suggesting a possible impact on the cardiovascular system. FSH has also been implicated in immune response modulation, as FSHRs are expressed on immune cells and may influence inflammatory response. Furthermore, there is growing interest in the role of FSH in prostate cancer progression. This paper aims to provide a comprehensive analysis of the literature on the extra-gonadal effects of FSH in men, with a focus on the often-conflicting results reported in this field. Despite the contradictory findings, the potential for future development in this area is substantial, and further research is needed to elucidate the mechanisms underlying these effects and their clinical implications.

Inactivation of Cops5 in Smooth Muscle Cells Causes Abnormal Reproductive Hormone Homeostasis and Development in Mice

COP9 constitutive photomorphogenic homolog subunit 5 (COPS5), also known as Jab1 or CSN5, has been implicated in a wide variety of cellular and developmental processes. By analyzing male germ cell-specific COPS5-deficient mice, we have demonstrated previously that COPS5 is essential to maintain male germ survival and acrosome biogenesis. To further determine the role of Cops5 in peritubular myoid cells, a smooth muscle lineage surrounding seminiferous tubules, we herein derived mice conditionally deficient for the Cops5 gene in smooth muscle cells using transgenic Myh11-Cre mice. Although these conditional Cops5-deficient mice were born at the expected Mendelian ratio and appeared to be normal within the first week after birth, the homozygous mice started to show growth retardation after 1 week. These mice also exhibited a variety of developmental and reproductive disorders, including failure of development of reproductive organs in both males and females, spermatogenesis defects, and impaired skeletal development and immune functions. Furthermore, conditional Cops5-deficient mice revealed dramatic impairment of the endocrine system associated with testicular functions, including a marked reduction in serum levels of gonadotropins (follicle-stimulating hormone, luteinizing hormone), testosterone, insulin-like growth factor 1, and glucose, but not vasopressin. All homozygous mice died before age 67 days in the study. Collectively, our results provide novel evidence that Cops5 in smooth muscle lineage plays an essential role in postnatal development and reproductive functions.

Altered transcriptomic and metabolomic profiles of testicular interstitial fluid during aging in mice

The testicular interstitial fluid (TIF) that bathes seminiferous tubules and testicular interstitial cells is the main microenvironment of the testis and involved in crosstalk between testicular cells. TIF also provides a new mean to investigate dysfunctional states of testis such as spermatogenic disorder and aging. In this study, we performed integrative omics analysis on the exosomal transcriptomics and liquid chromatography-tandem mass spectrometry (LC-MS/MS) based non-targeted metabolomics in TIF by comparison between 21-month-old and 3-month-old male mice. A total of 1627 genes were identified as aging-related differently expressed genes (DEGs) in mouse TIF exosomes, with 1139 downregulated and 488 upregulated. Functional and pathway analysis revealed that the DEGs were associated with oxidative stress, carbon metabolism, and systemic lupus erythematosus. By comparing the DEGs with the Aging Atlas Database, we screened out key aging-related genes functioning as oxidative stress regulators, and their expression pattern in human testis with age was confirmed by immunohistochemistry results in the Human Protein Atlas database. In addition, the metabolomic analysis identified mild differences between young and old groups with 28 downregulated differently expressed metabolites (DEMs) and 6 upregulated DEMs, in the negative ion mode, including decreased level of several antioxidant metabolites. The KEGG analysis demonstrated that 10 pathways were upregulated, while the pyrimidine metabolism pathway was downregulated in the aged mice TIF. Taken together, this study highlighted the prominent role of oxidative stress that contributed to the aging microenvironment in the TIF, and brought comprehensive transcriptomic and metabolomic perspectives for understanding the mechanism underlying the testicular aging.

Functions of Steroid Hormones in the Male Reproductive Tract as Revealed by Mouse Models

Steroid hormones are capable of diffusing through cell membranes to bind with intracellular receptors to regulate numerous physiological processes. Three classes of steroid hormones, namely androgens, estrogens and glucocorticoids, contribute to the development of the reproductive system and the maintenance of fertility. During the past 30 years, mouse models have been produced in which the expression of genes encoding steroid hormone receptors has been enhanced, partially compromised or eliminated. These mouse models have revealed many of the physiological processes regulated by androgens, estrogens and to a more limited extent glucocorticoids in the testis and male accessory organs. In this review, advances provided by mouse models that have facilitated a better understanding of the molecular regulation of testis and reproductive tract processes by steroid hormones are discussed.

Defining Gene Function in Spermatogonial Stem Cells Through Conditional Knockout Approaches

Mammalian male fertility is maintained throughout life by a population of self-renewing mitotic germ cells known as spermatogonial stem cells (SSCs). Much of our current understanding regarding the molecular mechanisms underlying SSC activity is derived from studies using conditional knockout mouse models. Here, we provide a guide for the selection and use of mouse strains to develop conditional knockout models for the study of SSCs, as well as their precursors and differentiation-committed progeny. We describe Cre recombinase-expressing strains, breeding strategies to generate experimental groups, and treatment regimens for inducible knockout models and provide advice for verifying and improving conditional knockout efficiency. This resource can be beneficial to those aiming to develop conditional knockout models for the study of SSC development and postnatal function.

Development of the human fetal testis: Morphology and expression of cellular differentiation markers

A comprehensive immunohistochemical ontogeny of the developing human fetal testis has remained incomplete in the literature to date. We collected human fetal testes from 8 to 21 weeks of fetal age, as well as postnatal human testes at minipuberty, pre-pubertal, and pubertal stages. Immunohistochemistry was performed with a comprehensive panel of antigens targeting gonadocytes, Sertoli cells, fetal Leydig cells, peritubular myoid cells, and other hormonal and developmental targets. Testicular cords, precursor structures to seminiferous tubules, developed from 8 to 14 weeks of fetal age, separating the testis into the interstitial and intracordal compartments. Fetal gonadocytes were localized within the testicular cords and evaluated for Testis-Specific Protein Y, Octamer-binding transcription factor 4, Sal-like protein 4, and placental alkaline phosphatase expression. Fetal Sertoli cells were also localized in the testicular cords and evaluated for SRY-box Transcription Factor 9, inhibin, and anti-Mullerian hormone expression. Fetal Leydig cells were present in the interstitium and stained for cytochrome p450c17 and calretinin, while interstitial peritubular myoid cells were examined using smooth muscle α-actin staining. Androgen receptor expression was localized close to the testicular medulla at 8 weeks and then around the testicular cords in the interstitium as they matured in structure. Postnatal staining showed that Testis-Specific Protein Y remained positive of male gonadocytes throughout adulthood. Anti-Mullerian hormone, SRY-box Transcription Factor 9, and Steroidogenic factor 1 are expressed by the postnatal Sertoli cells at all ages examined. Leydig cell markers cytochrome p450c17 and calretinin are expressed during mini-puberty and puberty, but not expressed during the pre-pubertal period. Smooth muscle α-actin and androgen receptor were not expressed during mini-puberty or pre-puberty, but again expressed during the pubertal period. The ontogenic map of the human fetal and postnatal testicular structure and expression patterns described here will serve as a reference for future investigations into normal and abnormal testicular development.

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.

Cyclic Adenosine Monophosphate: A Central Player in Gamete Development and Fertilization, and Possible Target for Infertility Therapies

Human infertility, of both male and female origin, is often caused by the deficient response of the testis and the ovary to hormonal stimuli that govern sperm and oocyte development and fertilization. The effects of hormones and other extracellular ligands involved in these events are often mediated by G-protein-coupled receptors that employ cyclic adenosine monophosphate (cAMP) as the principal second messenger transducing the receptor-generated signal to downstream elements. This opinion article summarizes the actions of cAMP in sperm and oocyte development and fertilization, leading to therapeutic actions targeting cAMP metabolism to alleviate human male and female infertility.

A Novel Model Using AAV9-Cre to Knockout Adult Leydig Cell Gene Expression Reveals a Physiological Role of Glucocorticoid Receptor Signalling in Leydig Cell Function

Glucocorticoids are steroids involved in key physiological processes such as development, metabolism, inflammatory and stress responses and are mostly used exogenously as medications to treat various inflammation-based conditions. They act via the glucocorticoid receptor (GR) expressed in most cells. Exogenous glucocorticoids can negatively impact the function of the Leydig cells in the testis, leading to decreased androgen production. However, endogenous glucocorticoids are produced by the adrenal and within the testis, but whether their action on GR in Leydig cells regulates steroidogenesis is unknown. This study aimed to define the role of endogenous GR signalling in adult Leydig cells. We developed and compared two models; an inducible Cre transgene driven by expression of the Cyp17a1 steroidogenic gene (Cyp17-iCre) that depletes GR during development and a viral vector-driven Cre (AAV9-Cre) to deplete GR in adulthood. The delivery of AAV9-Cre ablated GR in adult mouse Leydig cells depleted Leydig cell GR more efficiently than the Cyp17-iCre model. Importantly, adult depletion of GR in Leydig cells caused reduced expression of luteinising hormone receptor (Lhcgr) and of steroidogenic enzymes required for normal androgen production. These findings reveal that Leydig cell GR signalling plays a physiological role in the testis and highlight that a normal balance of glucocorticoid activity in the testis is important for steroidogenesis.

Dimethylbisphenol A inhibits the differentiation of stem Leydig cells in adult male rats by androgen receptor (NR3C4) antagonism

Dimethylbisphenol A (DMBPA) is a novel alternative to bisphenol A. Whether short-term exposure to DMBPA affects Leydig cell regeneration remains unknown. The Leydig cell regeneration model was generated by intraperitoneal injection of 75 mg/kg ethane dimethane sulfonate (EDS) to adult male Sprague-Dawley rats. Leydig cell regeneration began on day 14 after EDS. Rats were gavaged with 0, 10, 50, or 200 mg/kg DMBPA from days 14-28 post-EDS, and Leydig cell regeneration was assessed on days 28 and 56 post-EDS. DMBPA significantly reduced serum testosterone levels on days 28 and 56 at 10 mg/kg and higher doses and sperm count in the caudal epididymis on day 56 at 200 mg/kg, without affecting estradiol, luteinizing hormone, and follicle-stimulating hormone. DMBPA had no effect on Leydig cell number but significantly down-regulated Scarb1 expression at ≥ 10 mg/kg on day 28, Cyp17a1 expression on day 28 at 200 mg/kg and on day 56 at ≥ 10 mg/kg. DMBPA markedly upregulated Srd5a1 expression at doses of 50 and 200 mg/kg on day 56 after EDS. DMBPA significantly down-regulated the expression of Sod1 and Nr3c4 at a dose of 200 mg/kg on day 28. Further semi-quantitative immunohistochemistry showed that DMBPA reduced NR3C4 levels in Leydig and Sertoli cells at 50 and 200 mg/kg. In vitro DMBPA treatment of immature Leydig cells for 24 h showed that it significantly reduced testosterone production at 10 and 50 μM, and further mechanistic studies showed that an NR3C4 agonist 7α-methyl-19-nortestosterone significantly reversed DMBPA-mediated suppression on testosterone output, but the estrogen receptor antagonist ICI 182,780 and G-coupled estrogen receptor 1 agonist G15 had no effect. In conclusion, DMBPA delays Leydig cell regeneration after short-term exposure during early Leydig cell regeneration via NR3C4 antagonism.

Bisphenol F blocks Leydig cell maturation and steroidogenesis in pubertal male rats through suppressing androgen receptor signaling and activating G-protein coupled estrogen receptor 1 (GPER1) signaling

Bisphenol F (BPF) is a new analog of bisphenol A (BPA). BPA has deleterious effects on the male reproductive system, but the effect of BPF has not been studied in detail. In this study we focus on the effect of BPF on Leydig cell maturation. Male Sprague-Dawley rats were gavaged with 0, 1, 10, or 100 mg/kg BPF from postnatal days 35-56. BPF significantly reduced serum testosterone levels and sperm count in cauda epididymis at dose ≥1 mg/kg. It significantly down-regulated the expression of steroidogenic enzymes, while increasing FSHR and SOX9 levels at 10 and 100 mg/kg. Further studies showed that BPF reduced NR3C4 expression in Leydig and Sertoli cells without affecting its levels in peritubular myoid cells. BPF markedly increased GPER1 in Leydig cells at 100 mg/kg, and it significantly reduced SIRT1 and PGC1α levels in the testes at 100 mg/kg. BPF significantly inhibited testosterone production by immature Leydig cells at 50 μM after 24 h of treatment, which was completely reversed by NR3C4 agonist 7α-methyl-19-nortestosterone and partially reversed by GPER1 antagonist G15 not by ESR1 antagonist ICI 182,780. In conclusion, BPF negatively affects Leydig cell maturation in pubertal male rats through NR3C4 antagonism and GPER1 agonism.

Functions of somatic cells for spermatogenesis in stallions

Spermatogenesis and testis development are highly structured physiological processes responsible for post-pubertal fertility in stallions. Spermatogenesis comprises spermatocytogenesis, meiosis, and spermiogenesis. Although germ cell degeneration is a continuous process, its effects are more pronounced during spermatocytogenesis and meiosis. The productivity and efficiency of spermatogenesis are directly linked to pubertal development, degenerated germ cell populations, aging, nutrition, and season of the year in stallions. The multiplex interplay of germ cells with somatic cells, endocrine and paracrine factors, growth factors, and signaling molecules contributes to the regulation of spermatogenesis. A cell-to-cell communication within the testes of these factors is a fundamental requirement of normal spermatogenesis. A noteworthy development has been made recently on discovering the effects of different somatic cells including Leydig, Sertoli, and peritubular myoid cells on manipulation the fate of spermatogonial stem cells. In this review, we discuss the self-renewal, differentiation, and apoptotic roles of somatic cells and the relationship between somatic and germ cells during normal spermatogenesis. We also summarize the roles of different growth factors, their paracrine/endocrine/autocrine pathways, and the different cytokines associated with spermatogenesis. Furthermore, we highlight important matters for further studies on the regulation of spermatogenesis. This review presents an insight into the mechanism of spermatogenesis, and helpful in developing better understanding of the functions of somatic cells, particularly in stallions and would offer new research goals for developing curative techniques to address infertility/subfertility in stallions.

Understanding the Underlying Molecular Mechanisms of Meiotic Arrest during In Vitro Spermatogenesis in Rat Prepubertal Testicular Tissue

In vitro spermatogenesis appears to be a promising approach to restore the fertility of childhood cancer survivors. The rat model has proven to be challenging, since germ cell maturation is arrested in organotypic cultures. Here, we report that, despite a meiotic entry, abnormal synaptonemal complexes were found in spermatocytes, and in vitro matured rat prepubertal testicular tissues displayed an immature phenotype. RNA-sequencing analyses highlighted up to 600 differentially expressed genes between in vitro and in vivo conditions, including genes involved in blood-testis barrier (BTB) formation and steroidogenesis. BTB integrity, the expression of two steroidogenic enzymes, and androgen receptors were indeed altered in vitro. Moreover, most of the top 10 predicted upstream regulators of deregulated genes were involved in inflammatory processes or immune cell recruitment. However, none of the three anti-inflammatory molecules tested in this study promoted meiotic progression. By analysing for the first time in vitro matured rat prepubertal testicular tissues at the molecular level, we uncovered the deregulation of several genes and revealed that defective BTB function, altered steroidogenic pathway, and probably inflammation, could be at the origin of meiotic arrest.

The Fate of Leydig Cells in Men with Spermatogenic Failure

The steroidogenic cells in the testicle, Leydig cells, located in the interstitial compartment, play a vital role in male reproductive tract development, maintenance of proper spermatogenesis, and overall male reproductive function. Therefore, their dysfunction can lead to all sorts of testicular pathologies. Spermatogenesis failure, manifested as azoospermia, is often associated with defective Leydig cell activity. Spermatogenic failure is the most severe form of male infertility, caused by disorders of the testicular parenchyma or testicular hormone imbalance. This review covers current progress in knowledge on Leydig cells origin, structure, and function, and focuses on recent advances in understanding how Leydig cells contribute to the impairment of spermatogenesis.

Androgen plays an important role in regulating the synthesis of pheromone in the scent gland of muskrat

The scent (musk) gland is an organ unique to muskrats and other scent-secreting animals, and the pheromones (musk) synthesized and secreted by the scent gland play a role in chemical communication among scent-secreting animals. The musk gland is synchronized with testicular developmental changes; however, little is known regarding androgen secretion from the testis and how this regulates pheromone synthesis and the secretion of scent. To investigate the effect of androgens on the synthesis of pheromones in the musk gland, we established a muskrat castration model by surgical removal of the testis, and analyzed the histomorphology, hormone concentration, gene expression, and changes in the chemical composition of the musk gland in castration and control groups by histomorphological analysis, Enzyme-Linked ImmunoSorbent Assay (ELISA), RNA sequencing (RNA-seq), and gas chromatography-mass spectrometry (GCMS). Histomorphological analysis results showed that after castration, muskrat gland cells underwent significant atrophy (P < 0.05). Hormone measurement results showed that there was a significant decrease in serum testosterone and muskrat musk testosterone (P < 0.05) after muskrat castration. Transcriptome sequencing results showed that 510 differentially expressed transcripts (DETs) were mainly enriched in fatty acid metabolism, terpenoid backbone biosynthesis, fatty acid degradation, PPAR signaling pathway, and fatty acid biosynthesis. GCMS results showed that macrocyclic ketones, steroids, fatty acids, alcohols, and esters in musk were significantly changed (P < 0.05). In conclusion, androgens were found to play an important function in the chemical communication exchange between muskrats through regulating pheromone synthesis in musk cells. This study provides a basis for understanding the mechanism of animal communication influenced by androgens.

Nuclear and Membrane Receptors for Sex Steroids Are Involved in the Regulation of Delta/Serrate/LAG-2 Proteins in Rodent Sertoli Cells

Delta/Serrate/LAG-2 (DSL) proteins, which serve as ligands for Notch receptors, mediate direct cell–cell interactions involved in the determination of cell fate and functioning. The present study aimed to explore the role of androgens and estrogens, and their receptors in the regulation of DSL proteins in Sertoli cells. To this end, primary rat Sertoli cells and TM4 Sertoli cell line were treated with either testosterone or 17β-estradiol and antagonists of their receptors. To confirm the role of particular receptors, knockdown experiments were performed. mRNA and protein expressions of Jagged1 (JAG1), Delta-like1 (DLL1), and Delta-like4 (DLL4) were analyzed using RT-qPCR, Western blot, and immunofluorescence. Testosterone caused downregulation of JAG1 and DLL1 expression, acting through membrane androgen receptor ZRT- and Irt-like protein 9 (ZIP9) or nuclear androgen receptor (AR), respectively. DLL4 was stimulated by testosterone in the manner independent of AR and ZIP9 in Sertoli cells. The expression of all studied DSL proteins was upregulated by 17β-estradiol. Estrogen action on JAG1 and DLL1 was mediated chiefly via estrogen receptor α (ERα), while DLL4 was controlled via estrogen receptor β (ERβ) and membrane G-protein-coupled estrogen receptor (GPER). To summarize, the co-operation of nuclear and membrane receptors for sex steroids controls DSL proteins in Sertoli cells, contributing to balanced Notch signaling activity in seminiferous epithelium.

Purinergic Signaling in Spermatogenesis

Adenosine triphosphate (ATP) serves as the essential source of cellular energy. Over the last two decades, however, ATP has also attracted increasing interest as an extracellular signal that activates purinergic plasma membrane receptors of the P2 family. P2 receptors are divided into two types: ATP-gated nonselective cation channels (P2X) and G protein-coupled receptors (P2Y), the latter being activated by a broad range of purine and pyrimidine nucleotides (ATP, ADP, UTP, and UDP, among others). Purinergic signaling mechanisms are involved in numerous physiological events and pathophysiological conditions. Here, we address the growing body of evidence implicating purinergic signaling in male reproductive system functions. The life-long generation of fertile male germ cells is a highly complex, yet mechanistically poorly understood process. Given the relatively sparse innervation of the testis, spermatogenesis relies on both endocrine control and multi-directional paracrine communication. Therefore, a detailed understanding of such paracrine messengers, including ATP, is crucial to gain mechanistic insight into male reproduction.⁠.

The Roles of Luteinizing Hormone, Follicle-Stimulating Hormone and Testosterone in Spermatogenesis and Folliculogenesis Revisited

Spermatogenesis and folliculogenesis involve cell–cell interactions and gene expression orchestrated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). FSH regulates the proliferation and maturation of germ cells independently and in combination with LH. In humans, the requirement for high intratesticular testosterone (T) concentration in spermatogenesis remains both a dogma and an enigma, as it greatly exceeds the requirement for androgen receptor (AR) activation. Several data have challenged this dogma. Here we report our findings on a man with mutant LH beta subunit (LHβ) that markedly reduced T production to 1–2% of normal., but despite this minimal LH stimulation, T production by scarce mature Leydig cells was sufficient to initiate and maintain complete spermatogenesis. Also, in the LH receptor (LHR) knockout (LuRKO) mice, low-dose T supplementation was able to maintain spermatogenesis. In addition, in antiandrogen-treated LuRKO mice, devoid of T action, the transgenic expression of a constitutively activating follicle stimulating hormone receptor (FSHR) mutant was able to rescue spermatogenesis and fertility. Based on rodent models, it is believed that gonadotropin-dependent follicular growth begins at the antral stage, but models of FSHR inactivation in women contradict this claim. The complete loss of FSHR function results in the complete early blockage of folliculogenesis at the primary stage, with a high density of follicles of the prepubertal type. These results should prompt the reassessment of the role of gonadotropins in spermatogenesis, folliculogenesis and therapeutic applications in human hypogonadism and infertility.

Age-Related Changes in the Testicular Morphophysiology of the Cane Rat (Thryonomys swinderianus)

This study evaluated age-related changes in the testicular morphophysiology of the cane rat (Thryonomys swinderianus) using histological, histochemical, and sex hormonal profile approaches. Twenty (20) pathogen-free male cane rats were used for the investigation. Cane rats were divided into four groups: prepubertal (≤4 months), pubertal (>4 ≤12 months), adult (>12 ≤30 months), and aged (>30 months) of 5 rats each. Blood was collected from the different cane rat groups and processed for sex serum hormonal levels. Testes were also excised and processed routinely for variations in histology, histochemistry (using Masson's trichrome [MT] and Periodic acid-Schiff [PAS]), and histomorphometric evaluations using GIMP2 software. Testosterone concentrations were significantly elevated (P < 0.05) in the prepubertal to adult, while there were no significant differences (P > 0.05) in this hormone between adult and aged. The concentrations of follicle-stimulating hormone (FSH) decreased significantly (P < 0.05) for prepubertal, pubertal, and adult, respectively. There were no significant differences (P > 0.05) between adult and aged for FSH and luteinizing hormone. Histologically, there were scanty interstitial cells, lack of patent lumen, and incomplete spermatogenetic cell series in prepubertal compared to other age groups. Testicular capsular (MT and PAS) staining intensity increased with age advancement, while in the parenchyma, remarkably high intensity was displayed by the pubertal compared to others. Seminiferous tubular and luminal diameters (LD) significantly (P < 0.05) increased with advancing age whereas epithelial height (EH) was markedly increased in pubertal relative to other groups. In conclusion, these sets of data have shown that reproductive activity is directly related to age and is at maximum in adult cane rat.

Sertoli cells as key drivers of testis function

Sertoli cells are the orchestrators of spermatogenesis; they support fetal germ cell commitment to the male pathway and are essential for germ cell development, from maintenance of the spermatogonial stem cell niche and spermatogonial populations, through meiosis and spermiogeneis and to the final release of mature spermatids during spermiation. However, Sertoli cells are also emerging as key regulators of other testis somatic cells, including supporting peritubular myoid cell development in the pre-pubertal testis and supporting the function of the testicular vasculature and in contributing to testicular immune privilege. Sertoli cells also have a major role in regulating androgen production within the testis, by specifying interstitial cells to a steroidogenic fate, contributing to androgen production in the fetal testis, and supporting fetal and adult Leydig cell development and function. Here, we provide an overview of the specific roles for Sertoli cells in the testis and highlight how these cells are key drivers of testicular sperm output, and of adult testis size and optimal function of other testicular somatic cells, including the steroidogenic Leydig cells.

Exposure to the bromodomain inhibitor N-methyl pyrrolidone blocks spermatogenesis in a hormonal and non-hormonal fashion

N-methyl pyrrolidone (NMP) is an FDA approved molecule used as an excipient in pharmaceutical industry. Besides having a central role in formulation of drugs, the most important function of any excipient is to guarantee the safety of the medicine during and after its administration. Several studies have shown that exposure to NMP and especially in rats produce a gonadotoxic effect leading to infertility. However, the mechanisms underlying the effect of NMP on male reproduction are unknown. The aim of this study was to assess the reproductive toxicity of NMP in male rats and to elucidate the underlying mechanism. Male Sprague Dawley rats were injected intraperitoneally, twice/ week, at a dose of 108 mg/ 100 g of body weight with NMP. Analysis of reproductive parameters revealed testicular atrophy in NMP treated animals compared to control animals. Germ cell composition within the seminiferous tubules was disturbed and manifested in an increase in number of cells with fragmented DNA. A subsequent decrease in number of spermatocytes and spermatids was observed. Alpha screen assay shows that NMP acts at the concentrations we applied in vivo as a low affinity inhibitor for BRDT (testis specific bromodomain protein). BRDT inhibition is mirrored by a significant decrease in the expression of early stage spermatocyte markers (lmna, aurkc and ccna1), during which BRDT expression predominates. A significant decrease in testosterone levels was also observed. Since NMP interferes with spermatogenesis on various levels, its use in humans must be carefully monitored.

Differentiation of seminiferous tubule-associated stem cells into leydig cell and myoid cell lineages

Peritubular stem Leydig cells (SLCs) have been identified from rat testicular seminiferous tubules. However, no stem cells for peritubular myoid cells have been reported in the adult testis so far. In the present study, we tested the hypothesis that the peritubular SLCs are multipotent and able to form either Leydig or myoid cells. Using cultured tubules, we show that in the presence of PDGFAA and luteinizing hormone, SLCs became testosterone-producing Leydig cells, while in the presence of PDGFBB and TGFB, the cells formed α-smooth muscle actin-expressing myoid cells. This multipotency was also confirmed by culture of isolated CD90+ SLCs. These results suggest that these stem cells outside the myoid layer are multipotent and give rise to either Leydig or myoid cells, depending on the inducing factors. These cells may serve as a common precursor population for maintaining homeostasis of both Leydig and myoid cell populations in the adult testis.

Regulation of Cell Types Within Testicular Organoids

Organoids are 3-dimensional (3D) structures grown in vitro that emulate the cytoarchitecture and functions of true organs. Therefore, testicular organoids arise as an important model for research on male reproductive biology. These organoids can be generated from different sources of testicular cells, but most studies to date have used immature primary cells for this purpose. The complexity of the mammalian testicular cytoarchitecture and regulation poses a challenge for working with testicular organoids, because, ideally, these 3D models should mimic the organization observed in vivo. In this review, we explore the characteristics of the most important cell types present in the testicular organoid models reported to date and discuss how different factors influence the regulation of these cells inside the organoids and their outcomes. Factors such as the developmental or maturational stage of the Sertoli cells, for example, influence organoid generation and structure, which affect the use of these 3D models for research. Spermatogonial stem cells have been a focus recently, especially in regard to male fertility preservation. The regulation of the spermatogonial stem cell niche inside testicular organoids is discussed in the present review, as this research area may be positively affected by recent progress in organoid generation and tissue engineering. Therefore, the testicular organoid approach is a very promising model for male reproductive biology research, but more studies and improvements are necessary to achieve its full potential.

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

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

INSL-3 protein expression in normal and cryptorchid testes of Ziwuling black goats

Ziwuling black goats are typically found in loess plateaus regions and the Ziwuling Nature Reserve. Cryptorchidism is a common disease in this inbred goat, and its pathogenesis has been linked with the expression of insulin-like factor 3 (INSL-3). Therefore, this study aimed to investigate anatomical alterations caused by cryptorchism and the expression and distribution of INSL-3 in normal and cryptorchid testicular tissues. The testicular tissues of 6-month-old Ziwuling black goats were collected for microscopic analyses using histochemical, immunohistochemical, immunofluorescence and biometrical methods, as well as Western blotting to compare the expression and distribution of INSL-3. A lower expression of INSL-3 was observed in cryptorchid compared with normal testicular tissues (p < .01). Cryptorchidism caused a significant reduction in layers of spermatogenic epithelium and tubule areas in Ziwuling black goat (p < .01). The interstitial to seminiferous tubule area ratio was larger in cryptorchid than in normal group. Periodic Acid-Schiff (PAS) staining revealed pronounced positive bands in the interstitial tissue, while positive Alcian blue (AB) staining was not clear, and AB-PAS staining revealed a positive red band in the basement membrane of cryptorchid group. Immunofluorescence revealed a strong signal of INSL-3 expression in Sertoli and peritubular myoid cells, and moderate signal in Leydig and spermatogenic cells in the normal group. However, in cryptorchid testicular tissues, the signal of INSL-3 expression was strong in primary spermatocytes, occasional in Sertoli cells, limited in Leydig cells and absent in peritubular myoid cells. Furthermore, immunohistochemistry showed that INSL-3 expression was higher in normal testes compared with cryptorchid testicular tissues (p < .05), especially in primary spermatocytes and Sertoli cells. Collectively, our results indicate that cryptorchidism is closely related to the disorder of acid glycoprotein metabolism and the reduction in release of INSL-3 from Leydig cells. Moreover, Sertoli and peritubular myoid cells are crucial for INSL signalling and could underpin further research on the mechanism of cryptorchidism in animal.

ATP activation of peritubular cells drives testicular sperm transport

Spermatogenesis, the complex process of male germ cell proliferation, differentiation, and maturation, is the basis of male fertility. In the seminiferous tubules of the testes, spermatozoa are constantly generated from spermatogonial stem cells through a stereotyped sequence of mitotic and meiotic divisions. The basic physiological principles, however, that control both maturation and luminal transport of the still immotile spermatozoa within the seminiferous tubules remain poorly, if at all, defined. Here, we show that coordinated contractions of smooth muscle-like testicular peritubular cells provide the propulsive force for luminal sperm transport toward the rete testis. Using a mouse model for in vivo imaging, we describe and quantify spontaneous tubular contractions and show a causal relationship between peritubular Ca2+ waves and peristaltic transport. Moreover, we identify P2 receptor-dependent purinergic signaling pathways as physiological triggers of tubular contractions both in vitro and in vivo. When challenged with extracellular ATP, transport of luminal content inside the seminiferous tubules displays stage-dependent directionality. We thus suggest that paracrine purinergic signaling coordinates peristaltic recurrent contractions of the mouse seminiferous tubules to propel immotile spermatozoa to the rete testis.

Androgen Receptor Is Dispensable for X-Zone Regression in the Female Adrenal but Regulates Post-Partum Corticosterone Levels and Protects Cortex Integrity

Adrenal androgens are fundamental mediators of ovarian folliculogenesis, embryonic implantation, and breast development. Although adrenal androgen function in target tissues are well characterized, there is little research covering the role of androgen-signaling within the adrenal itself. Adrenal glands express AR which is essential for the regression of the X-zone in male mice. Female mice also undergo X-zone regression during their first pregnancy, however whether this is also controlled by AR signaling is unknown. To understand the role of the androgen receptor (AR) in the female adrenal, we utilized a Cyp11a1-Cre to specifically ablate AR from the mouse adrenal cortex. Results show that AR-signaling is dispensable for adrenal gland development in females, and for X-zone regression during pregnancy, but is required to suppress elevation of corticosterone levels post-partum. Additionally, following disruption to adrenal AR, aberrant spindle cell development is observed in young adult females. These results demonstrate sexually dimorphic regulation of the adrenal X-zone by AR and point to dysfunctional adrenal androgen signaling as a possible mechanism in the early development of adrenal spindle cell hyperplasia.

Androgen Actions in the Testis and the Regulation of Spermatogenesis

Testosterone is essential for spermatogenesis and male fertility. In this review, topics related to testosterone control of spermatogenesis are covered including testosterone production and levels in the testis, classical and nonclassical testosterone signaling pathways, cell- and temporal-specific expression of the androgen receptor in the testis and autocrine and paracrine signaling of testis cells in the testis. Also discussed are the contributions of testosterone to testis descent, the blood-testis barrier, control of gonocyte numbers and spermatogonia expansion, completion of meiosis and attachment and release of elongaed spermatids. Testosterone-regulated genes identified in various mouse models of idsrupted Androgen receptor expression are discussed. Finally, examples of synergism and antagonism between androgen and follicle-stimulating hormone signaling pathways are summarized.

Regulation of Human Spermatogenesis

Human spermatogenesis (HS) is an intricate network of sequential processes responsible for the production of the male gamete, the spermatozoon. These processes take place in the seminiferous tubules (ST) of the testis, which are small tubular structures considered the functional units of the testes. Each human testicle contains approximately 600-1200 STs [1], and are capable of producing up to 275 million spermatozoa per day [2].

In Vivo Efficacy of TXCB, a Vietnamese Herbal Medicine Prescription, on Seminal Quality, Serum Testosterone, and Malondialdehyde Concentration in Rabbits

The efficacy of Truong Xuan Cao Bang (TXCB), a Vietnamese herbal medicine prescription, on the quality of semen, serum testosterone (TES), and malondialdehyde (MDA) concentrations in rabbits whose reproductive ability were impaired by fluconazole was investigated. Mature male rabbits were randomly assigned into control (G1), fluconazole (G2), fluconazole and 180 mg/kg/day (G3), and 360 mg/kg/day TXCB (G4) groups. The reaction time (RT), ejaculate volume (EV), sperm concentration (SC), total sperm output (TSO), total sperm motility (TSM), progressive sperm motility (PSM), nonprogressive sperm motility (NPSM), sperm immobility (SIM), dead sperm (DS), and abnormal sperm (AS) levels were determined after TXCB administration. After 60 days, G3 showed a significant increase in serum TES and a significant decrease in the concentrations of serum MDA (SMDA) and seminal plasma MDA (SPMDA) compared with G1, in addition to increase in EV, SC, TSO, TSM, PSM, and serum TES, and decrease in RT, SIM, DS, AS, SMDA, and SPMDA compared with G2. G4 showed a steep rise in EV, SC, and serum TES and a downturn in DS, SMDA, and SPMDA compared with G1, and, compared with G2, a significant increase in EV, SC, TSO, TSM, PSM, and serum TES and a significant decrease in RT, SIM, DS, AS, SMDA, and SPMDA. Taken together, TXCB rehabilitates and simultaneously enhances spermatogenesis in rabbits whose reproductive ability was impaired by fluconazole.

AR regulates porcine immature Sertoli cell growth via binding to RNF4 and miR-124a

Sertoli cells are the only somatic cells in the seminiferous epithelium which directly contact with germ cells. Sertoli cells exhibit polarized alignment at the basal membrane of seminiferous tubules to maintain the microenvironment for growth and development of germ cells, and therefore play a crucial role in spermatogenesis. Androgens exert their action through androgen receptor (AR) and AR signalling in the testis is essential for maintenance of spermatogonial numbers, blood-testis barrier integrity, completion of meiosis, adhesion of spermatids and spermiation. In the present study, we demonstrated that AR gene could promote the proliferation of immature porcine Sertoli cells (ST cells) and the cell cycle procession, and accelerate the transition from G1 phase into S phase in ST cells. Meanwhile, miR-124a could affect the proliferation and cell cycle procession of ST cells by targeting 3'-UTR of AR gene. Furthermore, AR bound to the RNF4 via AR DNA-binding domain (DBD) and we verified that RNF4 was necessary for AR to regulate the growth of ST cells. Above all, this study suggests that AR regulates ST cell growth via binding to RNF4 and miR-124a, which may help us to further understand the function of AR in spermatogenesis.

Proteomic Insights into Senescence of Testicular Peritubular Cells from a Nonhuman Primate Model

Age-related changes in the human testis may include morphological alterations, disturbed steroidogenesis, and impaired spermatogenesis. However, the specific impact of cell age remains poorly understood and difficult to assess. Testicular peritubular cells fulfill essential functions, including sperm transport, contributions to the spermatogonial stem cell niche, and paracrine interactions within the testis. To study their role in age-associated decline of testicular functions, we performed comprehensive proteome and secretome analyses of repeatedly passaged peritubular cells from Callithrix jacchus. This nonhuman primate model better reflects the human testicular biology than rodents and further gives access to young donors unavailable from humans. Among 5095 identified proteins, 583 were differentially abundant between samples with low and high passage numbers. The alterations indicate a reduced ability of senescent peritubular cells to contract and secrete proteins, as well as disturbances in nuclear factor (NF)-κB signaling and a reduced capacity to handle reactive oxygen species. Since this in vitro model may not exactly mirror all molecular aspects of in vivo aging, we investigated the proteomes and secretomes of testicular peritubular cells from young and old donors. Even though the age-related alterations at the protein level were less pronounced, we found evidence for impaired protein secretion, altered NF-κB signaling, and reduced contractility of these in vivo aged peritubular cells.

Reversible Contraceptive Potential of FDA Approved Excipient N, N-Dimethylacetamide in Male Rats

Development of an effective male contraceptive agent remains a challenge. The present study evaluates the potential of N, N-Dimethylacetamide (DMA), a FDA approved excipient as a male contraceptive agent. Male Sprague Dawley rats injected with DMA for a period of 8 weeks (one injection per week) showed a significant alteration of reproductive parameters. Furthermore, DMA treated animals showed complete infertility in a dose dependent manner, as no pups were born despite proper mating between females and DMA treated males. However, stopping the DMA treatment for a period of 8 weeks (after the initial treatment) restored the reproductive parameters to normal. Moreover, the fertility was resumed to normal as pups were born in the groups where DMA treatment was halted after initial DMA treatment. All these changes had no effect on the level of reproductive hormones FSH, LH and testosterone. Taken together, our results indicate that DMA acts in a reversible and non-hormonal manner to achieve contraception in rats. Therefore, repurposing the use of DMA could lead in a short time to an inexpensive and safer male contraceptive option.

A comparison of in vivo viral targeting systems identifies adeno-associated virus serotype 9 (AAV9) as an effective vector for genetic manipulation of Leydig cells in adult mice

BACKGROUND

Despite the increasing popularity of deliverable transgenics, a robust and fully validated method for targeting Leydig cells, capable of delivering long-term transgene expression, is yet to be defined.

OBJECTIVES

We compared three viral vector systems in terms of their cell targeting specificity, longevity of gene expression and impact on targeted cell types when delivered to the interstitial compartment of the mouse testis.

MATERIALS & METHODS

We delivered lentiviral, adenoviral and adeno-associated (AAV) viral particles to the interstitial compartment of adult mouse testis. Immunolocalization and stereology were performed to characterize ability of vectors to target and deliver transgenes to Leydig cells.

RESULTS

Viral vectors utilized in this study were found to specifically target Leydig cells when delivered interstitially. Transgene expression in lentiviral-targeted Leydig cells was detected for 7 days post-injection before Leydig cells underwent apoptosis. Adenoviral-delivered transgene expression was detected for 10 days post-injection with no evidence of targeted cell apoptosis. We found serotype differences in AAV injected testis with AAV serotype 9 targeting a significant proportion of Leydig cells. Targeting efficiency increased to an average of 59.63% (and a maximum of 80%) of Leydig cells with the addition of neuraminidase during injection. In AAV injected testis sections, transgene expression was detectable for up to 50 days post-injection.

DISCUSSION & CONCLUSION

Lentivirus, Adenovirus and Adeno-Associated virus delivery to the testis resulted in key variances in targeting efficiency of Leydig cells and in longevity of transgene expression, but identified AAV9 + Neuraminidase as an efficient vector system for transgene delivery and long-term expression. Simple viral delivery procedures and the commercial availability of viral vectors suggests AAV9 + Neuraminidase will be of significant utility to researchers investigating the genetics underpinning Leydig cell function and holds promise to inform the development of novel therapeutics for the treatment of male reproductive disorders.

N, N-Dimethylacetamide, an FDA approved excipient, acts post-meiotically to impair spermatogenesis and cause infertility in rats

N, N-Dimethylacetamide is an FDA approved solvent widely used in pharmaceutical industry to facilitate the solubility of lipophilic, high molecular weight drugs with poor water solubility. However, the cytotoxic effects of DMA raises the concern about its use in clinical applications. In the present study, we address the effect of DMA on spermatogenesis. Male Sprague Dawley rats were injected intra-peritoneally for 8 weeks, once a week at a dose of 862 mg/kg. Analysis of reproductive parameters revealed that DMA treated animals exhibit spermatid formation defects within the testis describing the characteristics of oligozoospermia. A subsequent decrease in epididymal sperm concentration along with distortion of sperm morphology was observed. The mitochondrial and microtubule organization in the sperm is considerably modified by DMA. This disrupts the sperm kinetics thus decreasing the total and progressive sperm motility. Finally, DMA treatment resulted in loss of fertility. Our results indicate that exposure to DMA has a negative impact on spermatogenesis and leads to infertility in male rats by inhibiting the post meiotic stages of sperm development. Therefore, the use of DMA in humans must be closely monitored.

Histological Analysis, Bioinformatics Profile, and Expression of Methylenetetrahydrofolate Reductase (MTHFR) in Bovine Testes

Simple Summary

To date, several genes have been sequenced but their corresponding protein characteristics remain unknown. This study highlights the histological structure of bovine (yellow-cattle and yak) testes as a build-up to exploring the bioinformatics profile and expression characteristics of methylenetetrahydrofolate reductase (MTHFR) in bovine testes. Our findings suggest that yellow-cattle testis have similar anatomical characteristics with that of yak, except for the weight or size, for which that of yellow-cattle is significantly higher or greater than yak. We also found that the secondary and 3D protein structures of MTHFR were similar to that of humans, with differences in the number of nucleotides, amino acids, and some physico-chemical characteristics. Moreover, MTHFR mRNA expression was higher in adult yellow-cattle and yak compared to their juvenile ones, however, its protein expression was higher but not statistically significant in adult yellow-cattle and yak compared to the juvenile ones. This provides a basis for further investigations into the regulatory function of MTHFR in bovine testes.

Abstract

Methylenetetrahydrofolate reductase (MTHFR), an enzyme expressed in mammalian testes, exerts a direct effect on spermatogenesis; however, its protein characteristics in bovine testes remain unknown. Here, we analysed bovine testicular structure, MTHFR bioinformatics profile, mRNA, and protein expression characteristics in yellow-cattle (y-c) and yak testis using histological procedures, bioinformatics analysis, qRT-PCR, and western blot. Testes from 13 bovines, ≤2 years juvenile (y-c, n = 3; yak, n = 3) and ≥3 years adult (y-c, n = 3; yak, n = 4) were collected and analysed. Anatomical characteristics of testis in y-c and yak were similar except the weight or size for which that of y-c was significantly higher or greater than yak. In y-c, an open reading frame (ORF) for 2600 nucleotides sequence, encoding 655 amino acids showed high homology with zebu cattle (99.51%) and wild yak (98.68%). Secondary and 3D protein structures were similar to that of humans with differences in the number of nucleotides, amino acids, and some physico-chemical characteristics. MTHFR mRNA expression in y-c and yak were significantly higher in adult testes compared with juvenile ones. However, its protein expression was higher, but not statistically significant, in adult y-c and yak compared to the juvenile ones. The highlights and inferences of these and other findings are discussed.

Development and function of smooth muscle cells is modulated by Hic1 in mouse testis

In mammalian testis, contractile peritubular myoid cells (PMCs) regulate the transport of sperm and luminal fluid, while secreting growth factors and extracellular matrix proteins to support the spermatogonial stem cell niche. However, little is known about the role of testicular smooth muscle cells during postnatal testicular development. Here we report age-dependent expression of hypermethylated in cancer 1 (Hic1; also known as ZBTB29) in testicular smooth muscle cells, including PMCs and vascular smooth muscle cells, in the mouse. Postnatal deletion of Hic1 in smooth muscle cells led to their increased proliferation and resulted in dilatation of seminiferous tubules, with increased numbers of PMCs. These seminiferous tubules contained fewer Sertoli cells and more spermatogonia, and fibronectin was not detected in their basement membrane. The expression levels of genes encoding smooth muscle contractile proteins, Acta2 and Cnn1, were downregulated in the smooth muscle cells lacking Hic1, and the seminiferous tubules appeared to have reduced contractility. These data imply a role for Hic1 in determining the size of seminiferous tubules by regulating postnatal smooth muscle cell proliferation, subsequently affecting spermatogenesis in adulthood.

Dietary Exposure to Oxidized Frying Oil from Fetus to Adulthood Suppresses Male Reproductive Development by Altering Testicular Cholesterol and Testosterone Homeostasis in Sprague Dawley Rats

BACKGROUND

Dietary frying oil may have endocrine-disrupting effects, as a feminization effect was observed in cohorts of C57BL/6J male mice fetuses from dams consuming oxidized frying oil (OFO) during pregnancy.

OBJECTIVE

The aim of present study was to test the hypothesis that OFO is an anti-androgen.

METHODS

In experiment 1, male progeny of Sprague Dawley female rats fed fresh oil or an OFO diet (10 g fat/100 g, from fresh or 24-h-fried soybean oil; [control diet (C) and OFO groups, respectively] from midgestation through lactation were studied. Pups were weaned at 3 wk of age and then consumed their mothers' diet until 9 wk of age. In addition, a group of dams and pups that consumed a high-fat diet (HF; 10 g fried and 20 g fresh soybean oil/100 g) was included to counteract body-weight loss associated with OFO ingestion. Indices of male reproductive development and testosterone homeostasis were measured. In experiment 2, male rats were allocated to C and OFO groups (treated as above) and indices of male fertility compared at 9-10 wk of age.

RESULTS

In experiment 1, final body weights of the HF group were lower (17%) than the C group but higher (14%) than the OFO group (P < 0.0001 for each). In addition to abnormalities in seminiferous tubules, HF and OFO groups did not differ from one another, but, compared with the C group, had delayed preputial separation (4.9 d) and reductions in serum testosterone concentrations (17-74%), anogenital distance (8-20%), weights of androgen-dependent tissues (8-30%), testicular testosterone and cholesterol concentrations (30-40%), and mRNA levels of genes involved in steroidogenesis and cholesterol homeostasis (30-70%). In experiment 2, OFO-exposed males had 20% lower sperm motility (P < 0.05); however, when mated to normal females, pregnancy rates and litter sizes did not differ between OFO and C groups.

CONCLUSIONS

The anti-androgenic effect of OFO in Sprague Dawley rats was attributed to decreased testicular concentrations of cholesterol (testosterone precursor) and not body-weight loss.

Essential roles of interstitial cells in testicular development and function

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS AND DISCUSSION

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

CONCLUSION

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

A male germ cell assay and supporting somatic cells: its application for the detection of phase specificity of genotoxins in vitro

Male germ stem cells are responsible for transmission of genetic information to the next generation. Some chemicals exert a negative impact on male germ cells, either directly, or indirectly affecting them through their action on somatic cells. Ultimately, these effects might inhibit fertility, and may exhibit negative consequences on future offspring. Genotoxic anticancer agents may interact with DNA in germ cells potentially leading to a heritable germline mutation. Experimental information in support of this theory has not always been reproducible and suitable in vivo studies remain limited. Thus, alternative male germ cell tests, which are now able to detect phase specificity of such agents, might be used by regulatory agencies to help evaluate the potential risk of mutation. However, there is an urgent need for such approaches for identification of male reproductive genotoxins since this area has until recently been dependent on in vivo studies. Many factors drive alternative approaches, including the (1) commitment to the principles of the 3R's (Replacement, Reduction, and Refinement), (2) time-consuming nature and high cost of animal experiments, and (3) new opportunities presented by new molecular analytical assays. There is as yet currently no apparent appropriate model of full mammalian spermatogenesis in vitro, under the REACH initiative, where new tests introduced to assess genotoxicity and mutagenicity need to avoid unnecessary testing on animals. Accordingly, a battery of tests used in conjunction with the high throughput STAPUT gravity sedimentation was recently developed for purification of male germ cells to investigate genotoxicity for phase specificity in germ cells. This system might be valuable for the examination of phases previously only available in mammals with large-scale studies of germ cell genotoxicity in vivo. The aim of this review was to focus on this alternative approach and its applications as well as on chemicals of known in vivo phase specificities used during this test system development.

Analysis of the developmental expression of small VCP-interacting protein and its interaction with steroidogenic acute regulatory protein in Leydig cells

Small VCP-interacting protein (SVIP) is a 9-kDa protein that is composed of 76 amino acids, and it plays a role in the endoplasmic reticulum-associated protein degradation (ERAD) pathway. Recent studies have shown that SVIP is an androgen-responsive protein and its expression is regulated by androgens. Because no data are available regarding the cellular localization and expression of SVIP in the mouse testis, where androgens are highly expressed, immunohistochemistry and western blotting were performed. In the fetal testis, we found that moderate but consistent staining of SVIP is present in the cytoplasm of Leydig cells. In prepubertal and adult life, SVIP remains present in Leydig cells as well as in the cytoplasm of some peritubular and Sertoli cells. From postnatal day 15 onward, SVIP is strongly expressed in the cytoplasm of Leydig cells. Furthermore, TM3, MA-10 Leydig and Sertoli cell lines were also used to evaluate the expression of SVIP. To identify the interacting partners, such as steroidogenic acute regulatory (STAR) protein, colocalization studies were performed by fluorescence microscopy, showing that STAR colocalized with SVIP in the adult mouse testis. The expression changes of STAR were studied by using SVIP siRNAs in Leydig cell line cultures. Depletion of SVIP resulted in decreased expression of STAR. Additionally, the number and size of lipid droplets were significantly increased in SVIP-depleted Leydig cells. Taken together, our data identify SVIP as a marker of Leydig cell lineage and as a regulator of STAR protein expression and lipid droplet status in Leydig cells.

An exploration of the role of Sertoli cells on fetal testis development using cell ablation strategy

Sertoli cells (SCs) are presumed to be the center of testis differentiation because they provide both structural support and biological regulation for spermatogenesis. Previous studies suggest that SCs control germ cell (GC) count and Leydig cell (LC) development in mouse testes. However, the regulatory role of SCs on peritubular myoid (PTM) cell fate in fetal testis has not been clearly reported. Here, we employed Amh-Cre; diphtheria toxin fragment A (DTA) mouse model to selectively ablate SCs from embryonic day (E) 14.5. Results found that SC ablation in the fetal stage caused the disruption of testis cords and the massive loss of GCs. Furthermore, the number of α-smooth muscle actin-labeled PTM cells was gradually decreased from E14.5 and almost lost at E18.5 in SC ablation testis. Interestingly, some Ki67 and 3β-HSD double-positive fetal LCs could be observed in Amh-Cre; DTA testes at E16.5 and E18.5. Consistent with this phenomenon, the messenger RNA levels of Hsd3b1, Cyp11a1, Lhr, Star and the protein levels of 3β-HSD and P450Scc were significantly elevated by SC ablation. SC ablation appears to induce ectopic proliferation of fetal LCs although the total LC number appeared reduced. Together, these findings bring us a better understanding of SCs' central role in fetal testis development.

The Function of Pre-mRNA Alternative Splicing in Mammal Spermatogenesis

Alternative pre-mRNA splicing plays important roles in co-transcriptional and post-transcriptional regulation of gene expression functioned during many developmental processes, such as spermatogenesis. The studies focusing on alternative splicing on spermatogenesis supported the notion that the development of testis is regulated by a higher level of alternative splicing than other tissues. Here, we aim to review the mechanisms underlying alternative splicing, particularly the splicing variants functioned in the process of spermatogenesis and the male infertility. There are five points regarding the alternative splicing including ⅰ) a brief introduction of alternative pre-mRNA splicing; ⅱ) the alternative splicing events in spermatogenesis-associated genes enriched in different stages of spermatogenesis; ⅲ) the mechanisms of alternative splicing regulation, such as splicing factors and m⁶A demethylation; ⅳ) the splice site recognition and alternative splicing, including the production and degradation of abnormal transcripts caused by gene variations and nonsense-mediated mRNA decay, respectively; ⅴ) abnormal alternative splicing correlated with male infertility. Taking together, this review highlights the impacts of alternative splicing and splicing variants in mammal spermatogenesis and provides new insights of the potential application of the alternative splicing into the therapy of male infertility.

Androgen receptor signalling in the male adrenal facilitates X-zone regression, cell turnover and protects against adrenal degeneration during ageing

Androgens are known to be an essential regulator of male health. Androgen receptor (AR) is widely expressed throughout the adrenal cortex, yet the wider role for androgen signalling in the adrenal remains underexplored. To investigate AR-dependent and AR-independent androgen signalling in the adrenal, we used a novel mouse model with a specific ablation of androgen receptor in the adrenal cortex with or without reduction of circulating androgen levels by castration. Our results describe AR expression in the human and mouse adrenal and highlight that the mouse is a viable model to investigate androgen signalling in the adrenal cortex. We show androgen signalling via AR is required for X-zone regression during puberty. Furthermore, cortex measurements define differences in X-zone morphology depending on whether circulating androgens or AR have been removed. We show androgens promote both cortical cell differentiation and apoptosis but are dispensable for the formation of the definitive cortex. Additionally, investigation of aged mice with AR ablation reveals severe cortex disruption, spindle cell hyperplasia and X-zone expansion. The data described herein demonstrates AR-signalling is required to facilitate X-zone regression, cell clearance and to protect against adrenal degeneration during ageing.