Regulation of spermatogenesis in the microenvironment of the seminiferous epithelium: new insights and advances

Selenium Distribution and Speciation in Tissues from Rats Administered with Non-Native Selenotrisulfides

Selenotrisulfides (STS, R-S-Se-S-R) are metabolic intermediates in the bioconversion of inorganic Se species to organoselenium compounds. These Se species are reactive with a variety of endogenous molecules, particularly thiol-containing proteins, with this reactivity facilitating Se transport and subsequent utilization within the body. In this study, X-ray fluorescence microscopy (XFM) and high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) were applied to investigate Se distribution and speciation in vivo. Male rats administered with 1 mg Se/kg b.w. as selenious acid (SA), L-penicillamine selenotrisulfide (PenSSeSPen) or selenenyl penicillamine bound to rat serum albumin (RSA-SSeSPen) showed statistically significant elevations in Se concentrations in the kidney, liver, and blood after 48 h treatment; however, no change in Se concentration was observed in the testes. Notably, XFM revealed a strong colocalization of Se and Cu in the renal cortex, a phenomenon previously observed in cultured cells and in rats fed diets supplemented with 5 mg Se/kg as selenite. Linear combination and principal component analyses of Se Kα1 HERFD-XAS spectra revealed marked differences in Se speciation between the renal cortex and medulla and between red blood cells and plasma for all groups, including the control. STS were identified in linear combination fits of spectra from all tissues, except the testes. These results highlight the vital roles of STS in the intracellular reduction and transport of Se throughout the bloodstream and various tissues.

Genetic insights into non-obstructive azoospermia: Implications for diagnosis and TESE outcomes

BACKGROUND

Non-obstructive azoospermia (NOA) is considered one of the most severe forms of male infertility. Despite the limited range of testicular phenotypes, NOA exhibits considerable genetic heterogeneity. The aim of this study was to uncover the etiopathogenesis of NOA and provide insights into the outcomes of testicular sperm extraction (TESE).

MATERIAL METHOD

To elucidate the potential causes of testicular pathogenesis, a cohort of 61 patients was analyzed. The genetic etiology was assessed using our developed gene panel, based on genes with prior functional studies conducted specifically in the context of testicular characterization.

RESULTS

Our analytical approach, built upon these findings, enabled us to explore the potential genetic causes of NOA and assess their relevance to TESE outcomes. A potential causal defect was identified in 14 genes across a total of 26 individuals (42%). Of these, three genes-MEIOB, TERB1, and USP26-had been previously described in men, while eight genes-SPO11, RBBP7, STS, RBMXL3, ZCCHC13, HUWE1, ESR1, and ABCD1-had been reported in prior studies. Additionally, three genes-CEP85, NAP1L3, and CENPI-had been previously described only in knockout (KO) phenotype studies, and this study represents the first identification of these genes in men.

CONCLUSION

Interestingly, the histological findings of meiotic arrest were strongly linked to genes involved in meiosis, reinforcing the clinical diagnosis of patients in this cohort. Additionally, our study underscores the importance of refining diagnostic strategies that focus on genes associated with testicular phenotypes, which could enhance the accuracy of TESE success predictions.

Exposure to titanium dioxide nanoparticles disrupts the BTB by interfering with the assembly of stress granules in germ cells

Titanium dioxide nanoparticles (TiO2 NPs) are among the most prevalent nanomaterials utilized in industrial and medical fields. However, their impact on spermatogenesis and male fertility remains insufficiently characterized. This study addresses the reproductive toxicity of TiO2 NPs and elucidates the underlying molecular mechanisms involved. Our findings demonstrate that exposure to TiO2 NPs leads to a significant reduction in sperm count and motility. Specifically, TiO2 NPs disrupt the integrity of the blood-testis barrier (BTB) and compromise the cytoskeletal structure in both spermatogenic and Sertoli cells. Additionally, treatment with TiO2 NPs is associated with cell death and a decrease in the protein levels of BTB-related components, including N-cadherin, β-catenin, occludin, and ZO-1. Mechanistic investigations reveal that TiO2 NPs inhibit stress granule formation in germ cells subjected to heat stress and promote germ cell apoptosis via activation of the ATM/P53 signaling pathway. Collectively, our study highlights a potential connection between environmental health and reproductive health, revealing multiple detrimental effects of TiO2 NPs and uncovering previously unrecognized mechanisms by which nanomaterials may adversely impact the reproductive system.

Advances in human In vitro spermatogenesis: A review

Recent advances surrounding in vitro spermatogenesis (IVS) have shown potential in creating a new paradigm of regenerative medicine in the future of fertility treatments for males experiencing non-obstructive azoospermia (NOA). Male infertility is a common condition affecting approximately 15% of couples, with azoospermia being present in 15% of infertile males (Cocuzza et al., 2013; Esteves et al., 2011a). Treatment for patients with NOA has primarily been limited to surgical sperm retrieval combined with in vitro fertilization intracytoplasmic sperm injection (IVF-ICSI); however, sperm retrieval is successful in only half of these patients, and live birth rates typically range between 10 and 25% (Aljubran et al., 2022). Therefore, a significant need exists for regenerative therapies in this patient population. IVS has been considered as a model for further understanding the molecular and cellular processes of spermatogenesis and as a potential regenerative therapeutic approach. While 2D cell cultures using human testicular cells have been attempted in previous research, lack of proper spatial arrangement limits germ cell differentiation and maturation, posing challenges for clinical application. Recent research suggests that 3D technology may have advantages for IVS due to mimicry of the native cytoarchitecture of human testicular tissue along with cell-cell communication directly or indirectly. 3D organotypic cultures, scaffolds, organoids, microfluidics, testis-on-a-chip, and bioprinting techniques have all shown potential to contribute to the technology of regenerative treatment strategies, including in vitro fertilization (IVF). Although promising, further work is needed to develop technology for successful, replicable, and safe IVS for humans. The intersection between tissue engineering, molecular biology, and reproductive medicine in IVS development allows for multidisciplinary involvement, where challenges can be overcome to realize regenerative therapies as a viable option.

The Intricate Functional Networks of Pre-mRNA Alternative Splicing in Mammalian Spermatogenesis

Spermatogenesis is a highly coordinated process that requires the precise expression of specific subsets of genes in different types of germ cells, controlled both temporally and spatially. Among these genes, those that can exert an indispensable influence in spermatogenesis via participating in alternative splicing make up the overwhelming majority. mRNA alternative-splicing (AS) events can generate various isoforms with distinct functions from a single DNA sequence, based on specific AS codes. In addition to enhancing the finite diversity of the genome, AS can also regulate the transcription and translation of certain genes by directly binding to their cis-elements or by recruiting trans-elements that interact with consensus motifs. The testis, being one of the most complex tissue transcriptomes, undergoes unparalleled transcriptional and translational activity, supporting the dramatic and dynamic transitions that occur during spermatogenesis. Consequently, AS plays a vital role in producing an extensive array of transcripts and coordinating significant changes throughout this process. In this review, we summarize the intricate functional network of alternative splicing in spermatogenesis based on the integration of current research findings.

The key to 2,6-dichloro-1,4-benzoquinone reproductive toxicity and green tea detoxification: Covalent binding and competitive binding

Halobenzoquinones (HBQs) are ubiquitous disinfection by-products (DBPs) in chlorinated drinking water with various health risks including reproductive toxicity, while the potential mechanisms are still unclear. Although green tea exhibits common detoxifying properties, its ability to mitigate the toxicity of HBQs still needs to be further deepened and explored. This study attempted to investigate the possible mechanism of the most common HBQ, 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ) induced reproductive toxicity and elucidate the protective effect of green tea using a series of liquid chromatography-tandem mass spectrometry (LC-MS) approaches. Firstly, in vivo experiments showed that 2,6-DCBQ could induce testicular damage in male rats via significantly decreasing sperm-associated Leydig cells and seminiferous tubules. Then, in vitro incubation of 2,6-DCBQ with amino acids suggested that 2,6-DCBQ could bind to proteins via residues of cysteine or lysine and provided five additional modification patterns. Following, proteomics analysis revealed that at least 42 proteins were modified by 2,6-DCBQ, which were mainly enriched in the reproductive system. These results highlighted the significance of covalent protein modification in 2,6-DCBQ reproductive toxicity. Fortunately, we found that catechins (a class of major components of green tea) could competitively bind to 2,6-DCBQ in vivo and in vitro, reducing the amount and type of 2,6-DCBQ-protein adducts, thereby attenuating the reproductive system damage caused by 2,6-DCBQ. This study provides new insights into 2,6-DCBQ-induced reproductive system damage and reveals a new mechanism of green tea detoxification. Moreover, these findings offer potential strategies for alleviating the harmful impacts of environmental toxicants on human health.

Neonatal undernutrition induced by litter size expansion alters testicular parameters in adult Wistar rats

Several models of maternal undernutrition reveal impairment of testicular development and compromise spermatogenesis in male offspring. The expansion of the litter size model, valuable for studying the impact of undernutrition on early development, has not yet been used to evaluate the consequences of early undernutrition in the adult male reproductive system. For this purpose, pups were raised in either normal litter (ten pups/dam) or large litter (LL; sixteen pups/dam). On postnatal day 90, sexual behaviour was evaluated or blood, adipose and reproductive tissues were collected for biochemical, histological and morphological analysis. Adult LL animals were lighter and thinner than controls. They showed increased food intake, but decrease of retroperitoneal white adipose tissue weight, glycaemia after oral glucose overload and plasma concentration of cholesterol. Reproductive organ weights were not altered by undernutrition, but histopathological analysis revealed an increased number of abnormal seminiferous tubules and number of immature spermatids in the tubular lumen of LL animals. These animals also showed reduction in total spermatic reserve and daily sperm production in the testes. Undernutrition decreased the number of Sertoli cells, and testosterone production was increased in the LL group. Mitochondrial activity of spermatozoa remained unchanged between experimental groups, suggesting no significant impact on the energy-related processes associated with sperm function. All animals from both experimental groups were considered sexually competent, with no significant difference in the parameters of sexual behaviour. We conclude that neonatal undernutrition induces histological and physiological testicular changes, without altering sperm quality and sexual behaviour of animals.

Combined exposure of PS-MPs with NaF induces Sertoli cell death and dysfunction via ferroptosis and apoptosis

The individual toxicity of sodium fluoride (NaF) and microplastics (MPs) has been extensively documented. Owing to their high specific surface area, widespread presence and durability, MPs can adsorb a broad spectrum of environmental contaminants into the organism. However, the combined toxicity of NaF and MPs has not been investigated. This study aimed to assess the effects of combined exposure to NaF and MPs on the function of testicular Sertoli cells (SCs) in male mice, and to investigate the underlying molecular mechanisms. The study revealed that combined exposure to NaF and MPs resulted in a decrease in the negative surface charge of MPs, along with an increase in the number of MPs entering the SCs. Through in vivo observation of the testicular pathological structure, spermatogenesis, and cell apoptosis in 180-day-old male mice, we discovered that combined exposure to NaF (80 mg/L) and MPs (10 mg/L) heightened reproductive toxicity compared to the individual exposure groups. This was evidenced by testicular structural defects, impaired spermatogenesis, and increased testicular cell apoptosis. Our in vitro studies showed that NaF (21 μg/mL) and MPs (100 μg/mL) synergistically induced SCs apoptosis and ferroptosis, leading to a reduction in SCs number and dysfunction. This ultimately resulted in structural and functional damage to the testes. Our findings demonstrate, for the first time, the synergistic effects of NaF and MPs on reproductive toxicity in mammals. These insights may provide valuable contributions to co-toxicity studies involving MPs and other environmental pollutants.

Seminoperitoneum in a Dog with a History of a Vasectomy: Case Report

An 8 yr old male German shorthaired pointer was presented on July 4, 2022, for acute abdominal and testicular pain. The dog was vasectomized at an unknown age under the care of his previous owners. The dog had an enlarged, painful left testis, scrotal edema, and an enlarged, nonpainful prostate. Abdominal ultrasound revealed mild peritoneal and retroperitoneal effusion, orchiepididymitis, enlarged ductus deferentes and testicles, and suspected benign prostatic hyperplasia versus prostatitis. Peritoneal effusion cytology revealed seminoperitoneum with marked neutrophilic inflammation. Peritoneal effusion aerobic culture and Brucella canis rapid slide agglutination test were negative. The dog was hospitalized overnight with IV antibiotic therapy and analgesics. The following day, the dog's abdominal pain, testicular pain, and scrotal edema were resolved. The dog was discharged and castrated after completion of antibiotic therapy and complete resolution of clinical signs. Testicular histopathology results were not available. Seminoperitoneum is uncommon in dogs and is a rare diagnosis for dogs with acute abdominal pain. This is the second known reported case of a seminoperitoneum in a vasectomized dog.

Alternative splicing and related RNA binding proteins in human health and disease

Alternative splicing (AS) serves as a pivotal mechanism in transcriptional regulation, engendering transcript diversity, and modifications in protein structure and functionality. Across varying tissues, developmental stages, or under specific conditions, AS gives rise to distinct splice isoforms. This implies that these isoforms possess unique temporal and spatial roles, thereby associating AS with standard biological activities and diseases. Among these, AS-related RNA-binding proteins (RBPs) play an instrumental role in regulating alternative splicing events. Under physiological conditions, the diversity of proteins mediated by AS influences the structure, function, interaction, and localization of proteins, thereby participating in the differentiation and development of an array of tissues and organs. Under pathological conditions, alterations in AS are linked with various diseases, particularly cancer. These changes can lead to modifications in gene splicing patterns, culminating in changes or loss of protein functionality. For instance, in cancer, abnormalities in AS and RBPs may result in aberrant expression of cancer-associated genes, thereby promoting the onset and progression of tumors. AS and RBPs are also associated with numerous neurodegenerative diseases and autoimmune diseases. Consequently, the study of AS across different tissues holds significant value. This review provides a detailed account of the recent advancements in the study of alternative splicing and AS-related RNA-binding proteins in tissue development and diseases, which aids in deepening the understanding of gene expression complexity and offers new insights and methodologies for precision medicine.

Tissue engineering studies in male infertility disorder

Infertility is an important issue among couples worldwide which is caused by a variety of complex diseases. Male infertility is a problem in 7% of all men. In vitro spermatogenesis (IVS) is the experimental approach that has been developed for mimicking seminiferous tubules-like functional structures in vitro. Currently, various researchers are interested in finding and developing a microenvironmental condition or a bioartificial testis applied for fertility restoration via gamete production in vitro. The tissue engineering (TE) has developed new approaches to treat male fertility preservation through development of functional male germ cells. This makes TE a possible future strategy for restoration of male fertility. Although 3D culture systems supply the perception of the effect of cellular interactions in the process of spermatogenesis, formation of a native gradient of autocrine/paracrine factors in 3D culture systems have not been considered. These results collectively suggest that maintaining the microenvironment of testicular cells even in the form of a 3D-culture system is crucial in achieving spermatogenesis ex vivo. It is also possible to engineer the testicular structures using biomaterials to provide a supporting scaffold for somatic and stem cells. The insemination of these cells with GFs is possible for temporally and spatially adjusted release to mimic the microenvironment of the in situ seminiferous epithelium. This review focuses on recent studies and advances in the application of TE strategies to cell-tissue culture on synthetic or natural scaffolds supplemented with growth factors.

The Decellularized Calf Testis: Introducing Suitable Scaffolds for Spermatogenesis Studies

BACKGROUND

Men's infertility and lack of production of healthy and active sperm are concerns of recent years in most countries. Studies on the preparation of extracellular matrix (ECM) from decellularization of testis tissue and spermatogenesis could provide proper results to solve some of the men's infertility problems. This study aims to decellularize calf testis by different methods to reach a suitable scaffold and introduce it in spermatogenesis studies.

MATERIALS AND METHODS

In this experimental study, calf testis were decellularized by a freeze-de freeze, 1% sodium deoxycholate (SD), 0.1% sodium dodecyl sulfate (SDS), 0.1% SDS-vacuum, 1% SDS, 1% SDS-vacuum, and Triton- X100 methods. The content of DNA, collagen, and glycosaminoglycan (GAG) was analyzed using the kit and staining with Hematoxylin-Eosin, Masson's trichrome, Alcian blue, and Orcein methods. The morphology of the scaffolds was analyzed with a scanning electron microscope (SEM).

RESULTS

Methods of 1% SDS, 1% SDS-vacuum, and 1% SD completely removed the cells. The preservation of collagen and GAG was confirmed using the staining kit and methods. The use of a vacuum showed greater porosity in the SEM images. Toxicity and hemolysis were not observed in the scaffolds.

CONCLUSION

Testis decellularization with 1% SDS and 1% SD, in addition to cell removal, could maintain the ECM structure to a large extent without having cytotoxic and hemolysis effects.

Polystyrene nanoplastics aggravated dibutyl phthalate-induced blood-testis barrier dysfunction via suppressing autophagy in male mice

Nanoplastics (NPs) frequently cause adverse health effects by transporting organic pollutants such as dibutyl phthalate (DBP) into organisms by utilizing their large specific surface area, large surface charge, and increased hydrophobicity. However, the effects of NPs combined with DBP on the reproductive systems of mammals are still unclear. The present investigation involved the administration of polystyrene NPs (PS-NPs) to BALB/c mice via gavage, with a size of 100 nm and at doses of 5 mg/kg/day or 50 mg/kg/day, along with DBP at a dose of 0.5 mg/kg/day, or a combination of PS-NPs and DBP, for 30 days, to assess their potential for reproductive toxicity. The co-exposure of mice to PS-NPs and DBP resulted in a significant increase in reproductive toxicities compared to exposure to PS-NPs or DBP alone. This was demonstrated by a marked decrease in sperm quality, significant impairment of spermatogenesis, and increased disruption of the blood-testis barrier (BTB). Furthermore, a combination of in vivo and in vitro investigations were conducted to determine that the co-exposure of DBP and PS-NPs resulted in a noteworthy reduction in the expressions of tight junction proteins (ZO-1 and occludin). Moreover, the in vitro findings revealed that monobutyl phthalate (MBP, the active metabolite of DBP, 0.5 μg/mL) and PS-NPs (30 μg/mL or 300 μg/mL) inhibited autophagy in Sertoli cells, thereby increasing the expression of matrix metalloproteinases (MMPs). The study found that PS-NPs and DBP co-exposure caused harmful effects in male reproductive organs by disrupting BTB, which may be alleviated by reactivating autophagy. The paper's conclusions provided innovative perspectives on the collective toxicities of PS-NPs and other emerging pollutants.

A review on immunological aspects in male reproduction: An immune cells and cytokines

The male reproductive system, particularly the male gamete, offers a unique barrier to the immune system. The growing germ cells in the testis need to be shielded from autoimmune damage. Hence the testis has to establish and sustain an immune-privileged milieu. Sertoli cells create this safe space, protected by the blood-testis barrier. Cytokines are a type of immune reaction that can positively and negatively affect male reproductive health. Inflammation, disease, and obesity are just a few physiological conditions for which cytokines mediate signals. They interact with steroidogenesis, shaping the adrenals and testes to produce the hormones needed for survival. In particular pathological condition, including autoimmune disorders, contains high levels of the same cytokines in semen that play an essential role in the immunomodulation of the male gonad. This review focuses on understanding the immunological role of cytokines in the control and development of male reproduction. Also, in maintaining male reproductive health and diseases linked with their aberrant function in the testis.

Review: The role of male reproductive tract secretions in ruminant fertility

Male fertility largely depends on the ability to produce sperm that can transmit the paternal information onto the next generation. However, the factors that are critical for sperm function and the subsequent development of healthy offspring are still not completely understood in ruminants. Importantly, sperm function is not completely encoded by germ cell DNA, but rather, depends on sequential acquisition, loss, and modification of elements through interaction with secretions from the testes, epididymides, and accessory glands (collectively termed seminal plasma). In addition, these secretions can play a role in the inheritance of paternal environmental effects by progeny. This is likely achieved directly, by the regulation of sperm epigenetic effectors, and indirectly, by altering the female environment in which the individual develops. This review will provide an overview of the different organs that contribute to seminal plasma in ruminants, and summarise how their secretions shape sperm function and modulate the female reproductive tract. Finally, some consideration will be given to the potential of paternal factors to affect embryo development and offspring health in ruminants.

Biomaterials for Testicular Bioengineering: How far have we come and where do we have to go?

Traditional therapeutic interventions aim to restore male fertile potential or preserve sperm viability in severe cases, such as semen cryopreservation, testicular tissue, germ cell transplantation and testicular graft. However, these techniques demonstrate several methodological, clinical, and biological limitations, that impact in their results. In this scenario, reproductive medicine has sought biotechnological alternatives applied for infertility treatment, or to improve gamete preservation and thus increase reproductive rates in vitro and in vivo. One of the main approaches employed is the biomimetic testicular tissue reconstruction, which uses tissue-engineering principles and methodologies. This strategy pursues to mimic the testicular microenvironment, simulating physiological conditions. Such approach allows male gametes maintenance in culture or produce viable grafts that can be transplanted and restore reproductive functions. In this context, the application of several biomaterials have been proposed to be used in artificial biological systems. From synthetic polymers to decellularized matrixes, each biomaterial has advantages and disadvantages regarding its application in cell culture and tissue reconstruction. Therefore, the present review aims to list the progress that has been made and the continued challenges facing testicular regenerative medicine and the preservation of male reproductive capacity, based on the development of tissue bioengineering approaches for testicular tissue microenvironment reconstruction.

Evaluation of hazards of electronic -cigarette's liquid refill on testes of mice, complemented by histopathological and chromatographic analysis

Electronic-cigarettes (e-cigarettes) are devices designed to become an alternative to classic cigarettes. Vaping of e-cigarettes and their recharge liquid have become extremely popular among the adolescents; however, its safety is not well established. Evaluation of the components of e-cigarette liquid and their potential effects on testis of adult male mice. This aim will be fulfilled by histological, ultrastructural, and immunohistochemical analysis of mice testis biopsies. Twenty mice were allocated into two groups of equal size. The control group was given regular saline, whereas the treated group was given e-liquid (contains 3 mg of nicotine/kg of body weight) both groups daily intraperitoneally injected for 3 weeks. Analysis of e-liquid by Gas Chromatography-Mass Spectrometric GC/MS demonstrated nicotine, phenol, vanillin, aldehydes, and pyrethroid insecticide. Evaluation of oxidative stress parameters revealed significant reduction of SOD and GPx. Histological results revealed a significant reduction in the height of seminiferous tubules, sloughing of spermatogenic cells, most cells being dark and pyknotic, and thickening of the interstitium with accumulation of PAS positive exudate. Most spermatogenic cells showed degenerative changes as rarefied cytoplasm, ill-defined electron-dense nuclei, and elongated spermatid showed deformity of ectoplasmic specialization. Immunohistochemical studies revealed a significant increase in caspase-3 positive cells and a significant reduction of area % of E-cadherin. The analysis of an available E-liquid demonstrated potentially harmful chemicals that are not shown in the labeling of the product. E-liquid appears to impair anti-oxidant defense and cause degenerative changes in the body and disruption of blood testes barrier BTB. So, e-cigarettes cannot be regarded as a non-harmful smoking replacement.

Embryonic 6:2 FTOH exposure causes reproductive toxicity by disrupting the formation of the blood-testis barrier in offspring mice

Previous studies have revealed nephrotoxicity, hepatotoxicity, subchronic developmental and reproductive toxicity in rats exposed to fluorotelomer alcohol (FTOH). However, the effects of embryonic 6:2 FTOH exposure on the reproductive system of offspring mice remain unclear. The purpose of this study is to explore the reproductive toxic effects of embryonic 6:2 FTOH exposure on offspring male mice and the related molecular mechanisms. Therefore, the pregnant mice were given corn oil or 6:2 FTOH by gavage from gestational days 12.5-21.5. The results demonstrated that embryonic 6:2 FTOH exposure resulted in disrupted testicular structure, low expression of tight junction protein between Sertoli cells (SCs), impaired blood-testis barrier (BTB) formation and maturation, reduced sperm viability and increased malformation, and induced testicular inflammation in the offspring of mice. Further in vitro studies showed that 6:2 FTOH treatment upregulated MMP-8 expression by activating AKT/NF-κB signaling pathway, which in turn enhanced occludin cleavage leading to the disruption of SCs barrier integrity. In summary, this study demonstrated that 6:2 FTOH exposure caused reproductive dysfunction in male offspring through disruption of BTB, which provided new insights into the effects of 6:2 FTOH exposure on the offspring.

Effects of Au@Ag core-shell nanostructure with alginate coating on male reproductive system in mice

Despite the widespread use of silver nanoparticles (NPs), these NPs can accumulate and have toxic effects on various organs. However, the effects of silver nanostructures (Ag-NS) with alginate coating on the male reproductive system have not been studied. Therefore, this study aimed to investigate the impacts of this NS on sperm function and testicular structure. After the synthesis and characterization of Ag-NS, the animals were divided into five groups (n = 8), including one control group, two sham groups (received 1.5 mg/kg/day alginate solution for 14 and 35 days), and two treatment groups (received Ag-NS at the same dose and time). Following injections, sperm parameters, apoptosis, and autophagy were analyzed by the TUNEL assay and measurement of the mRNA expression of Bax, Bcl-2, caspase-3, LC3, and Beclin-1. Fertilization rate was assessed by in vitro fertilization (IVF), and testicular structure was analyzed using the TUNEL assay and hematoxylin and eosin (H&E) staining. The results showed that the NS was rod-shaped, had a size of about 60 nm, and could reduce sperm function and fertility. Gene expression results demonstrated an increase in the apoptotic markers and a decrease in autophagy markers, indicating apoptotic cell death. Moreover, Ag-NS invaded testicular tissues, especially in the chronic phase (35 days), resulting in tissue alteration and epithelium disintegration. The results suggest that sperm parameters and fertility were affected. In addition, NS has negative influences on testicular tissues, causing infertility in men exposed to these NS.

Variation in immuno-reproductive milieu of testis in Clarias magur from pre-spawning to spawning phase: An indication towards non-canonical role of immune elements in testes

Immune mechanisms are major players in ensuring the normal functioning of testicular functions. However, apart from their role in active defence against pathogens, prior studies have also suggested a possibility for reproduction-related (non-immune) functions of certain immune elements. This study employs a comparative transcriptomics approach followed by network analysis for tracking the variation in the immuno-reproductive milieu of Clarias magur testis in spawning versus pre-spawning phase. The results show a significant modulation of both reproduction and immune-relevant genes in spawning versus pre-spawning phase. The functional enrichment of the upregulated reproduction-relevant gene network also shows immune-related biological processes which indicates a probability of involvement of these candidates in spermatogenesis-related events for switching from pre-spawning to spawning phase. The upregulated immune network is highly dense with 40 hubs, 10 cluster sub-networks and 142 functionally enriched pathways in comparison to its downregulated counterpart with only 5 hubs, 1 cluster and 1 enriched pathway. These findings indicate that the synchronisation in modulation of both reproductive and immune-related factors is critical for progression of testicular events guiding the switch from pre-spawning to spawning phase. The reproductive phase-dependent variation in plasma sex steroid levels and the selected genes for quantitative PCR also corroborated this hypothesis. The study also serves as a preliminary screening step for probable immune candidates that may be involved in reproductive functions of testis in addition to defence.

Perfluorooctanoic acid alternatives hexafluoropropylene oxides exert male reproductive toxicity by disrupting blood-testis barrier

As alternatives to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide (HFPO) homologues, including hexafluoropropylene oxide dimer acid (HFPO-DA), hexafluoropropylene oxide trimer acid (HFPO-TA), and hexafluoropropylene oxide tetramer acid (HFPO-TeA), have attracted widespread attention recently due to their environmental ubiquity and high potential for bioaccumulation and toxicity. In the present study, a set of in vivo mouse and in vitro mouse testicular Sertoli TM4 cell experiments were employed to explore the male reproductive toxicity and underlying mechanisms of HFPO homologues on blood-testis barrier. Tissue and permeability analyses of mice testes after 28-day treatment with 5 mg/kg/day HFPO-DA or PFOA, or 0.05 mg/kg/day HFPO-TA or HFPO-TeA indicated that there was an increase in the degradation of TJ protein occludin in mice with a disrupted blood-testis barrier (BTB). Following exposure to 100 μM HFPO-DA, HFPO-TA or 10 μM PFOA, HFPO-TeA, transepithelial electrical resistance measurements of TM4 cells also indicated BTB disruption. Additionally, as a result of the exposure, matrix metalloproteinase-9 expression was enhanced through activation of p38 MAPK, which promoted the degradation of occludin. On the whole, the results indicated HFPO homologues and PFOA induced BTB disruption through upregulation of p-p38/p38 MAPK/MMP-9 pathway, which promoted the degradation of TJ protein occludin and caused the disruption of TJ.

Involvement of testicular N-glycoproteome heterogeneity in seasonal spermatogenesis of the American mink (Neovison vison)

Spermatogenesis in the American mink is characterized by an annual cycle of transition involving completely inactive and fully activated stages. N-glycosylation of proteins has emerged as an important regulator as it affects protein folding, secretion, degradation, and activity. However, the function of protein N-glycosylation in seasonal spermatogenesis of the American mink remains unclear. In the present study, we established a proteome-wide stoichiometry of N-glycosylation in mink testes at various phases of spermatogenesis using N-linked glycosylated-peptide enrichment in combination with liquid chromatography-tandem mass spectrometry analysis. A total of 532 N-glycosylated sites matching the canonical Asn-X-Ser/Thr motif were identified in 357 testicular proteins. Both the number of glycoproteins and the sites of N-glycosylated proteins in mink testes were highly dynamic at different stages. Functional analyses showed that testicular proteins with different N-glycosylation might play a vital role in spermatogenesis by affecting their folding, distribution, stability, and activity. Overall, our data suggest that the dynamics of N-glycosylation of testicular proteins are involved in seasonal spermatogenesis in the American mink.

Molecular mechanisms regulating spermatogenesis in vertebrates: Environmental, metabolic, and epigenetic factor effects

The renewal of the natural resources is one of the most concerning aspects of modern farming. In animal production, there are many barriers breeders and researchers have to overcome to develop new practices to improve reproductive potential and hasten sexual maturation of the commercially viable species, while maintaining meat quality and sustainability. With the utilization of molecular biology techniques, there have been relevant advances in the knowledge of spermatogenesis, especially in mammals, resulting in new possibilities to control male fertility and the selection of desirable characteristics. Most of these discoveries have not been implemented in animal production. In this review, recent studies are highlighted on the molecular pathways involved in spermatogenesis in the context of animal production. There is also exploration of the interaction between environmental factors and spermatogenesis and how this knowledge may revolutionize animal production techniques. Furthermore, new insights are described about the inheritance of desired characteristics in mammals and there is a review of nefarious actions of pollutants, nutrition, and metabolism on reproductive potential in subsequent generations. Even though there are these advances in knowledge base, results from recent studies indicate there are previously unrecognized environmental effects on spermatogenesis. The molecular mechanisms underlying this interaction are not well understood. Research in spermatogenesis, therefore, remains pivotal as a pillar of animal production sustainability.

House feeding pattern increased male yak fertility by improving gut microbiota and serum metabolites

Yaks usually live in an extremely harsh natural environment resulting in low reproductive performance, so the production of yak cannot meet local demand in China. In order to solve this problem, the experiment aims to explore the effect of different feeding modes on the semen quality of male yaks, so as to provide a theoretical basis for improving the yield of yaks in Tibet. We used the combined analysis of metabolomics and microbial sequencing to explore the underlying mechanisms that affect the differences in semen quality between the house feeding (HF) system and the free range (FR). The results showed that the sperm motility (P < 0.001) and sperm concentration (P < 0.05) in the HF group were significantly higher than the FR group, and the abnormal sperm rate (P < 0.01) in HF was significantly lower compared to FR. House feeding modes increased some beneficial materials in blood and testis especially some antioxidants, unsaturated fatty acids, and amino acids. House feeding group increased some gut microbiota at genus level namely Rikenellaceae, Bacteroides, Prevotellaceae_UCG-004, Bacteroidales_RF16, and Alloprevotella, DgA-11. It was interesting that blood metabolites, testicular metabolites, and fecal microbiota were well-correlated with sperm parameters. Meanwhile, the blood metabolites and testicular metabolites were well-correlated with microbes. The result indicated that the HF model was beneficial for yak semen quality by improving the gut microbiota and blood metabolism to increase yak fertility.

Alginate oligosaccharides increase boar semen quality by affecting gut microbiota and metabolites in blood and sperm

Alginate oligosaccharides (AOS), natural polymers from brown seaweeds (such as Laminaria japonica, Undaria pinnatifida, and Sargassum fusiforme), have been reported to possess many beneficial advantages for health. In the current study, after 9 weeks of dietary supplementation, AOS 10 mg/kg group (AOS 10) group increased boar sperm motility from 87.8% to 93.5%, p < 0.05. Moreover, AOS10 increased the relative abundances of Bifidobacterium, Coprococcus, Butyricicoccus (1.3–2.3-fold; p < 0.05) to increase the beneficial blood and sperm metabolites (1.2–1.6-fold; p < 0.05), and important sperm proteins such as gelsolin, Zn-alpha2 glycoprotein, Cation Channel Sperm-Associated Protein, outer dense fiber of sperm tails, etc. (1.5–2.2-fold; p < 0.05). AOS had a long-term beneficial advantage on boar semen quality by the increase in semen volume (175 vs. 160 ml/ejaculation, p < 0.05). AOS may be used as dietary additives for improving semen quality.

Multiple Targets of Toxicity in Environmental Exposure to Low-Dose Cadmium

Dietary assessment reports and population surveillance programs show that chronic exposure to low levels of environmental cadmium (Cd) is inevitable for most people, and adversely impacts the health of children and adults. Based on a risk assessment model that considers an increase in the excretion of β₂-microglobulin (β₂M) above 300 μg/g creatinine to be the "critical" toxicity endpoint, the tolerable intake level of Cd was set at 0.83 µg/kg body weight/day, and a urinary Cd excretion rate of 5.24 µg/g creatinine was considered to be the toxicity threshold level. The aim of this review is to draw attention to the many other toxicity endpoints that are both clinically relevant and more appropriate to derive Cd exposure limits than a β₂M endpoint. In the present review, we focus on a reduction in the glomerular filtration rate and diminished fecundity because chronic exposure to low-dose Cd, reflected by its excretion levels as low as 0.5 µg/g creatinine, have been associated with dose-dependent increases in risk of these pathological symptoms. Some protective effects of the nutritionally essential elements selenium and zinc are highlighted. Cd-induced mitochondrial dysfunction is discussed as a potential mechanism underlying gonadal toxicities and infertility.

Studying the nature of ascending-descending-floating-sinking of Chinese medicines based on gonadotropin-releasing hormone

OBJECTIVE

to explore the nature of ascending-descending-floating-sinking of Traditional Chinese Medicine on normal rats using gonadotropin-releasing hormone (GnRh).

METHODS

Normal male Sprague-Dawley rats were orally administered six floating Chinese medicines and seven sinking Chinese medicines for 14 d. then, GnRh and relevant indicators were detected. Initially, the different effects of floating and sinking drugs on the body were explored. To verify the effects of floating and sinking drugs on the body, normal rats were orally administered Mahuang (Herba Ephedra Sinica) and Tinglizi (Semen Lepidii Apetali) for 14 d. Then, GnRh antagonists were administered. We observed the changes of relevant indicators and clarified the correlation between GnRh and the laws of floating and sinking.

RESULTS

Floating Chinese medicines significantly increased the testicular coefficients; GnRh level in the serum; the protein level of GnRh receptor (GnRhR) in the testis; and the mRNA levels of androgen receptor (AR), small C-terminal domain phosphatase (SCP) 3, SCP2, SYCE1, SMC1B, SMC3, and Rec8 (P < 0.01 or < 0.05). Sinking Chinese medicines did not react similarly, while GnRh antagonists blocked the regulatory effect of Mahuang (Herba Ephedra Sinica) but did not affect Tinglizi (Semen Lepidii Apetali).

CONCLUSIONS

GnRh may be closely related to the nature of ascending-descending-floating-sinking of Chinese medicine. Floating Chinese medicines may promote their medicinal properties by regulating GnRH level; however, sinking Chinese medicines did not affect GnRh level.

Effect of low energy shock wave on testicular microenvironment homeostasis in rats

OBJECTIVE

To further investigate whether two sets of low-energy extracorporeal shock waves (LESWs) impulse parameters, i.e., 0.02 mJ/mm² for 500 impulses and 0.04 mJ/mm² for 500 impulses, which have been shown to directly affect the testes, can promote testicular spermatogenesis or positively regulate homeostasis of the testicular microenvironment.

METHODS

(1) Twenty-four experimental rats were randomly divided into a 0.02 mJ/mm² 500 impulses group (L1 group), a 0.04 mJ/mm² 500 impulses group (M1 group), a sham intervention group (S group) and a blank control group (N group). The experiment period was 8 weeks. (2) Apoptosis of the spermatogenic cells in the left testicle was detected by the TUNEL method, VEGF and eNOs protein expression was detected by immunohistochemistry, and histomorphological changes were observed in PAS-stained sections. Moreover, the morphologies of the spermatogenic tubules and testicular stroma were quantitatively analyzed by stereological analysis. The right testicle was used for Western blot detection of the protein expression levels of Bax, Cytochrome C, Caspase-3, Bcl-2, VEGF and eNOs.

RESULTS

Compared with the other three groups, the rate of M1 testicular germ cell apoptosis induced by shock treatment was higher, the expression levels of proapoptotic proteins increased significantly while that of the antiapoptotic protein was lower, and the suppression of cell proliferation correlated with the protein expression levels. Additionally, with respect to the absolute volume of the seminiferous tubules, the absolute interstitial testicular volume notably increased, producing a series of biological effects working against testicular sperm production and function. However, there was no significant difference between the L1 group and the N and S groups.

CONCLUSIONS

LESWs treatment with impulse parameters of 0.02 mJ/mm² for 500 impulses showed a better protective effect on testicular spermatic function in rats and has a positive regulatory biological effect.

BPA disrupted the testis testosterone levels by interfering ER enrichments within StAR 5' flanking region in rare minnow Gobiocypris rarus

Bisphenol A (BPA) is a widely used endocrine disruptor, which has attracted much attention due to its harmful effects on male reproduction. To investigate the interference of BPA on steroid synthesis in males, male rare minnows (Gobiocypris rarus) were exposed to 15 μg L^-1 BPA for 7, 14 and 21 d. Meanwhile, a positive control group was performed with 25 ng L^-1 17α-ethynyl estradiol (EE2). Results showed that BPA exposure induced lower testosterone (T) levels, while affecting the transcripts of steroidogenic gene StAR. Moreover, BPA induced abnormal germ cells proliferation in the testis in rare minnow. Transcriptome analysis showed that 354 transcripts significantly differentially expressed after BPA exposure for 14 d, several of them were enriched in the signaling pathways of cell cycle process, PPAR signaling pathway, the steroid synthesis pathway and estrogen signaling pathway. BPA significantly increased estrogen receptor (ER) levels and induced abnormal protein levels of PPARγ. BPA disrupted the StAR expression by interfering ER enrichments within StAR 5' flanking region. Additionally, our study also revealed that BPA and EE2 might have different mechanisms for interfering with steroid hormone levels and germ cells proliferation in the testis.

Sertoli Cell Immune Regulation: A Double-Edged Sword

The testis must create and maintain an immune privileged environment to protect maturing germ cells from autoimmune destruction. The establishment of this protective environment is due, at least in part, to Sertoli cells. Sertoli cells line the seminiferous tubules and form the blood-testis barrier (BTB), a barrier between advanced germ cells and the immune system. The BTB compartmentalizes the germ cells and facilitates the appropriate microenvironment necessary for spermatogenesis. Further, Sertoli cells modulate innate and adaptive immune processes through production of immunoregulatory compounds. Sertoli cells, when transplanted ectopically (outside the testis), can also protect transplanted tissue from the recipient’s immune system and reduce immune complications in autoimmune diseases primarily by immune regulation. These properties make Sertoli cells an attractive candidate for inflammatory disease treatments and cell-based therapies. Conversely, the same properties that protect the germ cells also allow the testis to act as a reservoir site for infections. Interestingly, Sertoli cells also have the ability to mount an antimicrobial response, if necessary, as in the case of infections. This review aims to explore how Sertoli cells act as a double-edged sword to both protect germ cells from an autoimmune response and activate innate and adaptive immune responses to fight off infections.

Combined Analysis of Gut Microbiota and Plasma Metabolites Reveals the Effect of Red-Fleshed Apple Anthocyanin Extract on Dysfunction of Mice Reproductive System Induced by Busulfan

Busulfan is currently an indispensable anti-cancer drug, but the side effects on male reproductive system are so serious. Meanwhile, red-fleshed apples are natural products with high anthocyanin content. In this research, we analyzed the effect of red-fleshed apple anthocyanin extract (RAAE) on busulfan-treated mice. Compared with the busulfan group, main plasma biochemical indicators were significantly improved after RAAE treatment. Compared with BA0 (busulfan without RAAE) group, total antioxidant capacity(T-AOC) and the activity of superoxide dismutase (SOD) and glutathione catalase (GSH-Px) in RAAE treatment groups were obviously increased, while the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly decreased. Malondialdehyde (MDA) was significantly decreased in the RAAE groups. In addition, we found RAAE alleviated busulfan-disrupted spermatogenesis through improving genes expression which are important for spermatogenesis, such as DDX4, PGK2, and TP1. Furthermore, we found that RAAE increased beneficial bacteria Akkermansia and Lactobacillaceae, and significantly depleted harmful bacteria Erysipelotrichia. The correlation studies indicated that RAAE ameliorated busulfan-induced rise in LysoPC levels through regulating gut microbial community and their associated metabolites. In conclusion, this study extends our understanding of the alleviated effect of RAAE on busulfan-induced male reproductive dysfunction through regulating the relationships between gut microbiota and metabolites.

Role of endocrine disruptors in male infertility and impact of COVID-19 on male reproduction

Several epidemiological studies suggest strong association of endocrine disruptors (EDs) with impaired male reproduction. High levels of polychlorinated biphenyls in serum are associated with low sperm count and poor fertility. A high dichloro diphenyl trichloroethane (DDT) concentration results in low serum testosterone (T) and poor semen quality. DDT stimulates estrogen production by acting as estrogen receptor agonist and potent androgen receptor antagonist. Phthalates, another group of EDs, induce seminiferous tubule degeneration with impaired spermatogenesis via disruption of gene expression that regulates cholesterol and lipid homeostasis resulting in low T. Bisphenol A, a strong exogenous estrogen with antiandrogen effect, lowers serum follicle-stimulating hormone, luteinizing hormone, and T, resulting in impaired development of seminiferous tubules and spermatogenesis. Di(2-ethylhexyl) phthalates can exert their antiandrogenic action by directly inhibiting testosterone biosynthesis via cytochrome P-450 dysfunction. Since these EDs are commonly found in plastic bottles, cosmetics, pesticides, some metal food cans, etc., and accumulate in the environment, it is very important to observe caution and avoid their exposure. This updated chapter also reviews the impact of COVID-19-related infection on male reproduction.

Activated AMPK promoted the decrease of lactate production in rat Sertoli cells exposed to Zearalenone

Zearalenone, which is ubiquitous in grains and animal feed, is a mycotoxin that can cause serious damage to animals and humans. Sertoli cells (SCs) can be used to study ZEA male reproductive toxicity in vitro. SCs provide energy for germ cells, where AMPK regulates intracellular energy. In order to explore the regulatory effect of AMPK on ZEA-induced lactate decline, we activated AMPK by AICAR and then inhibited AMPK by Compound C with ZEA-treated SCs for 24 h to detect intracellular lactate production-related indicators. Cell viability in the presence of 20 μmol/L ZEA and either 50 μmol/L AICAR or 5 μmol/L Compound C, respectively, did not damage SCs, and could effectively either activate or inhibit AMPK. Inhibition of AMPK promoted the production of pyruvate and lactate via increased expression of the glycolysis-related genes Pgam1 and the lactate production-related proteins GLUT1, LDHA, and MCT4. Activating AMPK inhibited the production of lactate and pyruvate by suppressing the expression of glycolysis-related genes HK1, Pgam1, and Gpi1 and that of lactate production-related proteins LDHA and MCT4. Zearalenone destroys the energy balance in SCs, activates P-AMPK, which inhibit the production of lactate and pyruvate in SCs. This also leads to the decrease of energy supply of SCs to spermatogenic cells, damages to reproductive system.

Impacts of Immunometabolism on Male Reproduction

The physiological process of male reproduction relies on the orchestration of neuroendocrine, immune, and energy metabolism. Spermatogenesis is controlled by the hypothalamic-pituitary-testicular (HPT) axis, which modulates the production of gonadal steroid hormones in the testes. The immune cells and cytokines in testes provide a protective microenvironment for the development and maturation of germ cells. The metabolic cellular responses and processes in testes provide energy production and biosynthetic precursors to regulate germ cell development and control testicular immunity and inflammation. The metabolism of immune cells is crucial for both inflammatory and anti-inflammatory responses, which supposes to affect the spermatogenesis in testes. In this review, the role of immunometabolism in male reproduction will be highlighted. Obesity, metabolic dysfunction, such as type 2 diabetes mellitus, are well documented to impact male fertility; thus, their impacts on the immune cells distributed in testes will also be discussed. Finally, the potential significance of the medicine targeting the specific metabolic intermediates or immune metabolism checkpoints to improve male reproduction will also be reassessed.

Step by Step about Germ Cells Development in Canine

Simple Summary

The progression of germ cells is a remarkable event that allows biological discovery in the differ-entiation process during in vivo and in vitro development. This is crucial for understanding one toward making oogenesis and spermatogenesis. Companion animals, such as canine, could offer new animal models for experimental and clinical testing for translation to human models. In this review, we describe the latest and more relevant findings on germ cell development. In addition, we showed the methods available for obtaining germ cells in vitro and the characterization of pri-mordial germ cells and spermatogonial stem cells. However, it is necessary to further conduct basic research in canine to clarify the beginning of germ cell development.

Abstract

Primordial germ cells (PGCs) have been described as precursors of gametes and provide a connection within generations, passing on the genome to the next generation. Failures in the formation of gametes/germ cells can compromise the maintenance and conservation of species. Most of the studies with PGCs have been carried out in mice, but this species is not always the best study model when transposing this knowledge to humans. Domestic animals, such as canines (canine), have become a valuable translational research model for stem cells and therapy. Furthermore, the study of canine germ cells opens new avenues for veterinary reproduction. In this review, the objective is to provide a comprehensive overview of the current knowledge on canine germ cells. The aspects of canine development and germ cells have been discussed since the origin, specifications, and development of spermatogonial canine were first discussed. Additionally, we discussed and explored some in vitro aspects of canine reproduction with germ cells, such as embryonic germ cells and spermatogonial stem cells.

Current progress, challenges, and future prospects of testis organoids†

Spermatogenic failure is believed to be a major cause of male infertility. The establishment of a testis organoid model would facilitate the study of such pathological mechanisms and open the possibility of male fertility preservation. Because of the complex structures and cellular events occurring within the testis, the establishment of a compartmentalized testis organoid with a complete spermatogenic cycle remains a challenge in all species. Since the late 20th century, a great variety of scaffold-based and scaffold-free testis cell culture systems have been established to recapitulate de novo testis organogenesis and in vitro spermatogenesis. The utilization of the hydrogel scaffolds provides a 3D microenvironment for testis cell growth and development, facilitating the reconstruction of de novo testis tissue-like structures and spermatogenic differentiation. Using a combination of different strategies, including the use of various scaffolding biomaterials, the incorporation of the living cells with high self-assembling capacity, and the integration of the advanced fabrication techniques, a scaffold-based testis organoid with a compartmentalized structure that supports in vitro spermatogenesis may be achieved. This article briefly reviews the current progress in the development of scaffold-based testis organoids while focusing on the scaffolding biomaterials (hydrogels), cell sources, and scaffolding approaches. Key challenges in current organoid studies are also discussed along with recommendations for future research.

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].

Testis and blood-testis barrier in Covid-19 infestation: role of angiotensin-converting enzyme 2 in male infertility

Severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) that causes COVID-19 infections penetrates body cells by binding to angiotensin-converting enzyme-2 (ACE2) receptors. Evidence shows that SARS-CoV-2 can also affect the urogenital tract. Hence, it should be given serious attention when treating COVID-19-infected male patients of reproductive age group. Other viruses like HIV, mumps, papilloma and Epstein-Barr can induce viral orchitis, germ cell apoptosis, inflammation and germ cell destruction with attending infertility and tumors. The blood-testis barrier (BTB) and blood-epididymis barrier (BEB) are essential physical barricades in the male reproductive tract located between the blood vessel and seminiferous tubules in the testes. Despite the significant role of these barriers in male reproductive function, studies have shown that a wide range of viruses can still penetrate the barriers and induce testicular dysfunctions. Therefore, this mini-review highlights the role of ACE2 receptors in promoting SARS-CoV-2-induced blood-testis/epididymal barrier infiltration and testicular dysfunction.

Novel targets identified by integrated proteomic and phosphoproteomic analysis in spermatogenesis of swamp buffalo (Bubalus bubalis)

To understand mechanisms of spermatogenesis, the proteome and the phosphoproteome in prepubertal and pubertal swamp buffalo (Bubalus bubalis) testes were analyzed using tandem mass tag (TMT) coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS). In prepubertal testes, 80 proteins were overexpressed, 148 proteins were underexpressed, and 139 and 142 protein sites had higher and lower phosphorylation, respectively, compared to the levels in pubertal testes. Several of these proteins were associated with reproductive processes such as sexual reproduction, spermatogenesis, fertilization, and spermatid development. In particular, outer dense fiber protein 1 (ODF1), protein maelstrom homolog (MAEL), actin-like protein 7B (ACTL7B), tyrosine-(Y)-phosphorylation regulated (CABYR), and tripartite motif containing 36 (TRIM36) were upregulated with age at both the proteome and phosphoproteome levels. Combining proteome and phosphoproteome analysis can be effectively applied to study the protein/phosphorylation patterns of buffalo testes. These data provide new regulatory candidates and evidence for a complex network in spermatogenesis in buffalo testes, and serve as an important resource for exploring the physiological mechanism of spermatogenesis in mammals.

Relationship between the G protein-coupled oestrogen receptor and spermatogenesis, and its correlation with male infertility

The aim of this study was to investigate the diagnostic value of serum G protein-coupled oestrogen receptor (GPER) levels and their correlation with semen parameters in men with infertility. The participants were divided into two groups as follows: 76 fertile control men (Group 1) and 77 infertile men (Group 2). Semen analysis, hormonal evaluation, serum GPER level and scrotal ultrasound of the participants were evaluated. Follicle-stimulating hormone and total testosterone levels were not significantly different between the groups (p = .413 and p = .535 respectively). The oestradiol level in Group 1 was significantly lower than that in Group 2 (p < .001). The serum GPER level was found to be significantly higher in Group 1 than that of Group 2 (p < .001). GPER levels were positively correlated with the total sperm count, sperm concentration, motility and morphology in Group 2 (r = 0.303, 0.345, 0.260 and 0.322, respectively, p < .001). In this study, GPER levels were positively correlated with sperm parameters, and it was hypothesised that the decrease in GPER expression might be associated with male infertility by adversely affecting spermatogenesis.

Maternal Exposure to Di-n-butyl Phthalate Promotes the Formation of Testicular Tight Junctions through Downregulation of NF-κB/COX-2/PGE2/MMP-2 in Mouse Offspring

Previous studies demonstrated that maternal exposure to di-n-butyl phthalate (DBP) resulted in developmental disorder of the male reproductive organ; however, the underlying mechanism has not been thoroughly elucidated to date. The present study was aimed to investigate the effects of maternal exposure to DBP on the formation of the Sertoli cell (SC)-based tight junctions (TJs) in the testes of male offspring mice and the underlying molecular mechanism. By observing the pathological structure and ultrastructure, permeability analysis of the testis of 22 day male offspring in vivo, and transepithelial electrical resistance measurement of inter-SCs in vitro, we found that the formation of TJs between SCs in offspring mice was accelerated, which was paralleled by the accumulation of TJ protein occludin at 50 mg/kg/day DBP exposure in utero and 0.1 mM monobutyl phthalate (MBP, the active metabolite of DBP) in vitro. Our in vitro results demonstrated that 0.1 mM MBP downregulated the expression of matrix metalloproteinase-2 (MMP-2) by inhibiting the activation of nuclear factor-κB (NF-κB)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE₂) cascades via attenuated binding of NF-κB to both the MMP-2 promoter and COX-2 promoter. Taken together, the data confirmed that maternal exposure to a relatively low dose of DBP promoted the formation of testicular TJs through downregulation of NF-κB/COX-2/PGE₂/MMP-2, which might promote the development of the testis during puberty. Our findings may provide new perspectives for prenatal DBP exposure, which is a potential environmental contributor, leading to earlier puberty in male offspring mice.

Flutamide Alters the Expression of Chemerin, Apelin, and Vaspin and Their Respective Receptors in the Testes of Adult Rats

Adipokines influence energy metabolism and have effects on male reproduction, including spermatogenesis and/or Sertoli cell maturation; however, the relationship between these active proteins and androgens in testicular cells is limited. Here, we studied the impact of short-term exposure to flutamide (an anti-androgen that blocks androgen receptors) on the expression of chemerin, apelin, vaspin and their receptors (CCRL2, CMKLR1, GPR1, APLNR, GRP78, respectively) in adult rat testes. Moreover, the levels of expression of lipid metabolism-modulating proteins (PLIN1, perilipin1; TSPO, translocator protein) and intercellular adherens junction proteins (nectin-2 and afadin) were determined in testicular cells. Plasma levels of adipokines, testosterone and cholesterol were also evaluated. Gene expression techniques used included the quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB) and immunohistochemistry (IHC). The androgen-mediated effects observed post-flutamide treatment were found at the gonadal level as chemerin, apelin, and vaspin gene expression alterations at mRNA and protein levels were detected, whereas the cellular targets for these adipokines were recognised by localisation of respective receptors in testicular cells. Plasma concentrations of all adipokines were unchanged, whereas plasma cholesterol content and testosterone level increased after flutamide exposure. Differential distribution of adipokine receptors indicates potential para- or autocrine action of the adipokines within the rat testes. Additionally, changes in the expression of PLIN1 and TSPO, involved in the initial step of testosterone synthesis in Leydig cells, suggest that testicular cells represent a target of flutamide action. Increase in the gene expression of PLIN1 and TSPO and higher total plasma cholesterol content indicates enhanced availability of cholesterol in Leydig cells as a result of androgen-mediated effects of flutamide. Alterations in adherens junction protein expression in the testis confirm the flutamide efficacy in disruption of androgen signalling and presumably lead to impaired para- and autocrine communication, important for proper functioning of adipokines.

Short- and long-term exposure to methamidophos impairs spermatogenesis in mice

Methamidophos (MET) is a pesticide that has toxic properties, including effects on fertility. This study aimed to assess the joint action of treatment time and exposure to methamidophos on the male reproductive system. MET was orally administered to adult male Swiss mice at a dose of 0.004 mg.kg⁻¹ for 15 and 50 consecutive days. The following parameters were evaluated: weight of reproductive organs, spermatogenesis, sperm and Sertoli cell count, daily sperm production and sperm transit time. Short-term exposure to methamidophos induced a decrease in epididymal weight. The frequency of stages V–VI of spermatogenesis increased and the frequency of stage IX decreased. In the epididymis, sperm transit time (caput/corpus) was reduced and the relative sperm number (cauda) increased. Long-term exposure induced an increase in the frequencies of stages I–IV and V-VI and decreased the stages VII-VIII and IX. The number of Sertoli cells with evident nucleoli was reduced in both exposures. These results confirm the reproductive toxicity of MET.

Germline-dependent transmission of male reproductive traits induced by an endocrine disruptor, di-2-ethylhexyl phthalate, in future generations

In males, defective reproductive traits induced by an exposure to an endocrine disruptor are transmitted to future generations via epigenetic modification of the germ cells. Interestingly, the impacted future generations display a wide range of heterogeneity in their reproductive traits. In this study, the role that the Y chromosome plays in creating such heterogeneity is explored by testing the hypothesis that the Y chromosome serves as a carrier of the exposure impact to future generations. This hypothesis implies that a male who has a Y chromosome that is from a male that was exposed to an endocrine disruptor will display a more severe reproductive phenotype than a male whose Y chromosome is from an unexposed male. To test this hypothesis, we used a mouse model in which F1 generation animals were exposed prenatally to an endocrine disruptor, di-2-ethylhexyl phthalate (DEHP), and the severity of impacted reproductive traits was compared between the F3 generation males that were descendants of F1 males (paternal lineage) and those from F1 females (maternal lineage). Pregnant dams (F0 generation) were exposed to the vehicle or 20 or 200 μg/kg/day of DEHP from gestation day 11 until birth. Paternal lineage F3 DEHP males exhibited decreased fertility, testicular steroidogenic capacity, and spermatogenesis that were more severely impaired than those of maternal lineage males. Indeed, testicular transcriptome analysis found that a number of Y chromosomal genes had altered expression patterns in the paternal lineage males. This transgenerational difference in the DEHP impact can be attributed specifically to the Y chromosome.

Enrichment of imidacloprid and its metabolites in lizards and its toxic effects on gonads

Soil contaminants can cause direct harm to lizards due to their regular swallowing of soil particles. As the world's fastest growing insecticide with long half-life in soil, the endocrine disrupting effect of neonicotinoids on lizards deserves more attention. In this report, we assessed the endocrine disrupting effect of imidacloprid on Eremias argus during 28 days of continuous exposure. Among the imidacloprid and its metabolites, only the metabolite 6-chloropyridic acid had a significant accumulation in the gonads and was positively correlated with its blood concentration. Imidacloprid might cause endocrine disrupting effects on lizards in two ways. First, the desnitro metabolites of imidacloprid could accumulate in the brain, inhibited the secretion of gonadotropin-releasing hormone, and ultimately affected the feedback regulation of hypothalamic-pituitary-gonadal related hormones. Secondly, imidacloprid severely inhibited the gene expression of the corresponding enzymes in the gonadal anti-oxidative stress system, causing histological damage to the gonads and ultimately affecting gonadal function. Specifically, exposure to imidacloprid resulted in abnormal arrangement of spermatogenic epithelial epithelium, hyperplasia of epididymal wall, and oligospermia of male lizard. Meanwhile, gene expressions of cyp17, cyp19, and hsd17β were severely inhibited in the imidacloprid exposure group, consistent with decreased levels of testosterone and estradiol in plasma. Imidacloprid exposure could cause insufficient androgen secretion and less spermatogenesis in male lizards. The risk of imidacloprid exposure to female lizards was not as severe as that of male lizards, but it still inhibited the expression of cyp19 in the ovaries and led to a decrease in the synthesis of estradiol. This study firstly reported the endocrine disruption of imidacloprid to lizards, providing new data for limiting the use of neonicotinoids.

The Impact of Zinc Oxide Nanoparticles on Male (In)Fertility

Zinc oxide nanoparticles (ZnO NPs) are among nanoscale materials, attracting increasing attention owing to their exceptional set of characteristics, which makes these engineered nanoparticles a great option for improving the quality and effectiveness of diagnosis and treatment. The capacity of ZnO NPs to induce reactive oxygen species (ROS) production, DNA damage, and apoptosis represents a promise for their use in both cancer therapy and microbial treatment. However, their intrinsic toxicity together with their easy entrance and accumulation in organism have raised some concerns regarding the biomedical use of these NPs. Several studies have reported that ZnO NPs might induce cytotoxic effects on the male reproductive system, compromising male fertility. Despite some advances in this area, the knowledge of the effects of ZnO NPs on male fertility is still scarce. Overall, a brief outline of the major ZnO NPs biomedical applications and promises in terms of diagnostic and therapeutic use will also be explored. Further, this review intends to discuss the effect of ZnO NPs exposure on the male reproductive system and speculate their effects on male (in)fertility.

Alginate oligosaccharides improve germ cell development and testicular microenvironment to rescue busulfan disrupted spermatogenesis

Rationale: Busulfan is currently an indispensable anti-cancer drug, particularly for children, but the side effects on male reproduction are so serious that critical drug management is needed to minimize any negative impact. Meanwhile, alginate oligosaccharides (AOS) are natural products with many consequent advantages, that have attracted a great deal of pharmaceutical attention. In the current investigation, we performed single-cell RNA sequencing on murine testes treated with busulfan and/or AOS to define the mitigating effects of AOS on spermatogenesis at the single cell level.

Methods: Testicular cells (in vivo) were examined by single cell RNA sequencing analysis, histopathological analysis, immunofluorescence staining, and Western blotting. Testes samples (ex vivo) underwent RNA sequencing analysis. Blood and testicular metabolomes were determined by liquid chromatography-mass spectrometry (LC/MS).

Results: We found that AOS increased murine sperm concentration and motility, and rescued busulfan disrupted spermatogenesis through improving (i) the proportion of germ cells, (ii) gene expression important for spermatogenesis, and (iii) transcriptional factors in vivo. Furthermore, AOS promoted the ex vivo expression of genes important for spermatogenesis. Finally, our results showed that AOS improved blood and testis metabolomes as well as the gut microbiota to support the recovery of spermatogenesis.

Conclusions: AOS could be used to improve fertility in patients undergoing chemotherapy and to combat other factors that induce infertility in humans.

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.

Gonadal disruption after single dose exposure of prothioconazole and prothioconazole-desthio in male lizards (Eremias argus)

Prothioconazole (PTC) is a widely used triazole fungicide with low toxicity, and its desulfurization metabolite, prothioconazole-desthio (PTC-d), is reported to have higher reproductive toxicity to mammals. However, little is known about the reproductive toxicity, much less endocrine disrupting effect, of these two chemicals on reptiles. In this study, we investigated the effects of single dose of PTC/PTC-d (100 mg kg^-1 body weight) exposure on the pathomorphism of testes and epididymides, serum sex steroid hormones (testosterone and 17β-estradiol) and transcription of steroidogenic-related genes (STARD, cyp11A, cyp17, cyp19A, 17β-HSD, 3β-HSD, AR and ER-α) in gonads of male lizards (Eremias argus). Although structural disorder existed in PTC-d exposure group, severe gonadal disruption, especially suppression of spermatogenesis was only observed in testis after PTC treatment, which consequently led to the lack of spermatozoa in epididymal ducts. Consistent with this result, T/E₂ value in PTC exposure was elevated to a significant higher level compared with control and continually increased over time, while T/E₂ value in the PTC-d exposure group slightly increased only at 12 h. These results demonstrated a more serious disruption of PTC on male lizard gonads than PTC-d. In addition, the expression of cyp17 gene was inhibited at 6 h, however, was induced at 12 h, and exhibited negative correlations with STARD, cyp11A and 3β-HSD after PTC exposure at each timepoint. In PTC-d group, the expression of STARD and 3β-HSD were significantly down-regulated, in contrast, cyp11A and cyp17 were up-regulated, and each gene showed consistent changes over time. For 17β-HSD, no significance was observed in both treated groups. This study was the first to compare the gonadal disruption of PTC and PTC-d in male lizards and elucidated that these two chemicals influenced the physiological function of male gonads through differential transcriptional modulation.