The roles and mechanisms of Leydig cells and myoid cells in regulating spermatogenesis

CircRNA profiling reveals the regulatory role of circPAN3 in Hezuo boars Sertoli cell growth

BACKGROUND

The Hezuo (HZ) pig, a famous indigenous breed in China, is characterized by precocious puberty compared with foreign-introduced pig breeds. Sexual maturation is a complex physiological process, and in recent years, circular RNAs (circRNAs), a new class of noncoding RNAs with endogenous regulatory functions, have been shown to play important roles in regulating sexual maturation. However, the dynamic expression and regulatory mechanism of circRNAs during sexual maturation in HZ pigs remain unclear. In this study, we performed RNA sequencing and bioinformatics analysis to reveal circRNA expression patterns in the testes of HZ boars at 30 days (sexual immaturity; Ha) and 120 days (sexual maturity; Hb), with Landrace (LC) boars of the same age (La and Lb) as controls. Subsequently, an abundant circ_005678 (circPAN3) transcribed from the PAN3 gene, was functionally investigated by RT-qPCR, Western Blot, CCK-8, and flow cytometry.

RESULTS

We identified 31,134 circRNAs in 12 samples, and 2,562, 2,401, 749, and 831 differentially expressed (DE) circRNAs were identified in the Ha-vs-Hb, La-vs-Lb, Ha-vs-La, and Hb-vs-Lb groups, respectively. The results of functional enrichment analyses indicated that these source genes of the DE circRNAs were involved mainly in testicular development and spermatogenesis. Furthermore, we constructed a circRNA-miRNA-mRNA interaction network and functionally analyzed the target genes. GO functional annotation of the target genes suggested that they were mainly involved in biological processes such as gland development, cell proliferation, and reproduction. KEGG pathway analysis further revealed that these genes were enriched mainly in signaling pathways involved in testicular development and spermatogenesis, including the PI3K-Akt and MAPK signaling pathways. Cellular assays revealed that circPAN3 promoted proliferation and inhibited apoptosis in immature Sertoli cells, whereas opposite changes were observed by circPAN3 knockdown.

CONCLUSIONS

This study revealed the dynamic expression profiles and regulatory mechanisms of circRNAs during sexual maturation in HZ pigs. Further functional studies demonstrated that circPAN3 promoted the proliferation and inhibited the apoptosis of immature Sertoli cells, suggesting that circPAN3 may be closely related to the characteristics of precocious puberty in HZ boars. These findings provide a new perspective for exploring the regulatory mechanism of circRNAs in precocious puberty in HZ pigs.

Prenatal Exposure to Dibutyl Phthalate and Its Negative Health Effects on Offspring: In Vivo and Epidemiological Studies

Dibutyl phthalate (DBP) is a low-molecular-weight phthalate commonly found in personal care products, such as perfumes, aftershaves, and nail care items, as well as in children's toys, pharmaceuticals, and food products. It is used to improve flexibility, make polymer products soft and malleable, and as solvents and stabilizers in personal care products. Pregnancy represents a critical period during which both the mother and the developing embryo can be significantly impacted by exposure to endocrine disruptors. This article aims to elucidate the effects of prenatal exposure to DBP on the health and development of offspring, particularly on the reproductive, neurological, metabolic, renal, and digestive systems. Extensive research has examined the effects of DBP on the male reproductive system, where exposure is linked to decreased testosterone levels, reduced anogenital distance, and male infertility. In terms of the female reproductive system, DBP has been shown to elevate serum estradiol and progesterone levels, potentially compromising egg quality. Furthermore, exposure to this phthalate adversely affects neurodevelopment and is associated with obesity, metabolic disorders, and conditions such as hypospadias. These findings highlight how urgently stronger laws prohibiting the use of phthalates during pregnancy are needed to lower the risks to the fetus's health and the child's development.

3-Acetyldeoxynivalenol induces pyroptosis in leydig cells via METTL3-mediated N6-methyladenosine modification of NLRP3

3-acetyldeoxynivalenol (3-ADON), an acetylated derivative of deoxynivalenol, is a prevalent contaminant found in food products contaminated with mycotoxins. While the toxicological effects of 3-ADON on human and animal health are well-documented, its specific impact on the reproductive system remains underexplored. In this study, we comprehensively examined the toxicological effects of 3-ADON on TM3 Leydig cells through both in vivo and in vitro experimental models. Our results demonstrate that 3-ADON exposure leads to substantial testicular damage in vivo and significantly reduces cell viability while increasing mortality in TM3 cells in vitro (P = 0.012). Mechanistic investigations further revealed that 3-ADON exposure triggers pyroptosis in TM3 cells, as evidenced by upregulation of NLRP3, activation of caspase-1, ASC, and GSDMD. Moreover, 3-ADON treatment resulted in a significant upregulation of METTL3 expression and increased global mRNA m6A modification levels. m6A sequencing and functional assays established that METTL3-mediated m6A modification of NLRP3 mRNA enhances its stability and expression. RNA immunoprecipitation (RIP) assays further demonstrated that IGF2BP1 selectively recognizes m6A-modified NLRP3 mRNA, contributing to its stabilization. Notably, IGF2BP1 was found to inhibit the recruitment of the BTG2/CCR4-NOT complex by competitively binding to PABPC1, thereby preventing the deadenylation of NLRP3 mRNA and maintaining its expression. Additionally, we identified that METTL3 also methylates and stabilizes c-MyB mRNA, which subsequently binds to the promoter region of NLRP3, thereby enhancing its transcription. Collectively, our findings reveal a novel mechanism by which 3-ADON exerts its reproductive toxicity, underscoring the pivotal role of METTL3-mediated m6A modifications in regulating Leydig cell dysfunction.

Leydig cells pyroptosis in testis mediates deoxynivalenol-induced male reproductive toxicity in mice

Deoxynivalenol (DON) is a toxic secondary metabolite produced by Fusarium spp. It is widely distributed among various cereals and has attracted much attention as a potential health threat to humans and domestic animals. However, the effects of DON on the reproductive systems of mammals are still ambiguous. In this study, the toxic effects of DON in the male reproduction of mice were investigated. The results showed that DON caused the shedding of sperm cells at all testis levels and the presence of inflammatory cells in the testicular interstitium. The rate of living sperm was significantly reduced, and the rate of sperm deformity was increased after DON exposure. The DON exposure resulted in decreased levels of testosterone (T) and increased levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the serum. Measurements of oxidative stress markers showed that DON induced oxidative stress in mice testis. Meanwhile, DON triggered the assembly of NLRP3-ASC-Caspase-1 inflammatory complex and pyroptosis in both mice testis and TM3 cells, further causing the activation of GSDMD, promoting the leakage of inflammatory cytokines, including IL-1β and IL-18. Notably, the inhibition of oxidative stress was found to protect pyroptosis in TM3 cells exposed to DON. We identified a novel mechanism of reproductive damage induced by DON, demonstrating the activation of the canonical Caspase-1-dependent pyroptosis pathway and clarifying the protection of antioxidation against pyroptosis damage. Our discovery provided support for the risk assessment of DON and target exploration for clinical treatment related to pyroptosis.

Supplementing ageing male laying breeders with lycopene alleviates oxidative stress in testis and improves testosterone secretion

BACKGROUND

Reproductive performance is a crucial aspect of poultry production and is carefully controlled by endocrine, paracrine, and autocrine factors. This study aimed to investigate the effect of lycopene on testosterone synthesis in Leydig cells of laying breeder roosters, clarify the mechanism of lycopene improving Leydig cells function and promoting testosterone production, and explore the role of related signal transduction pathways in testosterone synthesis.

RESULTS

A total of 96 healthy 55-week-old breeding roosters were randomly assigned to one of five dietary treatments. They were provided with a corn-soybean meal-based diet containing different levels of lycopene: 0 mg/kg (control), 50 mg/kg, 100 mg/kg, or 200 mg/kg. The experiment lasted for 6 weeks. With the increase in lycopene levels, the testosterone content in the plasma was significantly higher than in the control group. Testicular Leydig cells were isolated and cultured from fresh testicular tissue of 45-wk-old to 60-wk-old breeding roosters. Various doses of lycopene were administered to Leydig cells, and subsequently, cells were collected for the detection of cell viability and testosterone content. The optimal concentration of lycopene to be added was determined, and changes in mRNA expression and protein levels of key proteins involved in testosterone synthesis were investigated. The results showed that lycopene treatment significantly increased testosterone secretion, mRNA expression, and protein levels of steroid-producing enzymes. Cells were collected to measure the activity of antioxidant enzymes, the mRNA transcription level of apoptotic factors, and the protein expression of apoptotic factors after treatment with lycopene. The results showed that lycopene significantly increased the activities of antioxidant enzymes, and the ability to inhibit oxygen radicals, and decreased the content of malondialdehyde. Apoptosis was inhibited by regulating the expression of apoptosis-inducing and anti-apoptosis factors. After that, the MAPK signaling pathway and downstream SF-1, Nrf2 gene, and protein expression levels were detected. The results showed that lycopene treatment significantly increased the gene and protein expression of JNK, SF-1, and Nrf2, and significantly decreased the gene and protein expression of p38.

CONCLUSIONS

Lycopene treatment could promote testosterone synthesis of testicular Leydig cells by activating MAPK-SF-1 (increasing steroid-producing enzyme level) and MAPK-Nrf2 pathways (resisting oxidative damage).

Exploring the mechanism of carbamazepine decreasing testosterone levels based on cAMP/PKA/CREB pathway

The aim of this study was to explore the molecular mechanisms underlying carbamazepine (CBZ)-induced testicular toxicity and testosterone reduction in rats. For this purpose, Sprague-Dawley (SD) rats were intervened with 200 mg/kg CBZ for 12 weeks, and R2C cells were exposed to CBZ at concentrations of 0.5, 1 and 1.5 mM for 24 h. HE, Tunel, ELISA, immunofluorescence staining, RT-qPCR, and western blot were used to reveal the effects of CBZ on spermatozoa quality, testicular tissue structure, testosterone level and testosterone synthesis-related enzymes in rats. The results showed that CBZ significantly damaged the testicular tissue structure of rats, induced cell apoptosis, down-regulated the gene and protein expression levels of testosterone synthesis-related enzymes (STAR, TSPO, 17β-HSD and 3β-HSD), inhibited the expression of related proteins in the cAMP/PKA/CREB signalling pathway, and suppressed testosterone levels. In addition, the use of Db-cAMP (a PKA activator) significantly upregulated the protein expressions of PKA and p-CREB, evidently alleviated the CBZ-induced decrease in testosterone levels. In conclusion, CBZ induced testosterone resynthesis by inhibiting the cAMP/PKA/CREB pathway, affecting the expression of steroid synthesis-related enzymes and reducing testosterone levels.

Di-(2-ethylhexyl) phthalate induces prepubertal testicular injury through MAM-related mitochondrial calcium overload in Leydig and Sertoli cell apoptosis

As one of the most prevalent environmental endocrine disruptors, di-(2-ethylhexyl) phthalate (DEHP) is known for its significant developmental toxicity to the male reproductive system in humans and mice. Prepubertal exposure to DEHP has been shown to cause testicular damage, but the underlying mechanisms require further investigation. To investigate this effect, prepubertal mice were exposed to 100, 250 or 500 mg/kg body weight (bw) of DEHP for 14 days, which resulted in impaired histological structure and increased apoptosis of the testes. RNA sequencing (RNA-seq) of testicular tissue suggested that DEHP led to injury in Leydig and Sertoli cells. To further elucidate these mechanisms, we conducted experiments using immature mouse Leydig (TM3) and Sertoli (TM4) cells, and exposed them to 200 μM mono-(2-ethylhexyl) phthalate (MEHP), the primary metabolite of DEHP, for 24 h. We found that MEHP exposure induced oxidative stress injury and promoted cell apoptosis, and that cotreatment with N-acetylcysteine partially reversed these injuries. Given the close association between oxidative stress and mitochondrial calcium levels, we demonstrated that MEHP exposure disrupted mitochondria and increased mitochondrial calcium levels. In addition, MEHP exposure facilitated the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs), upregulated protein expression and enhanced the interactions of the IP3R3-Grp75-VDAC1 complex. Furthermore, inhibition of calcium transfer in the IP3R3-Grp75-VDAC1-MCU axis relieved MEHP-induced mitochondrial injury, oxidative stress and apoptosis in TM3 and TM4 cells. This study highlights the importance of MAM-mediated mitochondrial calcium overload and the subsequent apoptosis of Leydig and Sertoli cells as pivotal factors contributing to testicular injury induced by prepubertal exposure to DEHP.

BPA induces testicular damage in male rodents via apoptosis, autophagy, and ferroptosis

Bisphenol A (BPA), chemically known as 2,2-bis(4-hydroxyphenyl) propane, is one of the most common endocrine-disrupting chemicals in our environment. Long-term or high-dose exposure to BPA may lead to testicular damage and adversely affect male reproductive function. In vivo studies on rodents have demonstrated that BPA triggers apoptosis in testicular cells through both intrinsic and extrinsic pathways. Further in vitro studies on spermatogonia, Sertoli cells, and Leydig cells have all confirmed the pro-apoptotic effects of BPA. Given these findings, apoptosis is considered a primary mode of cell death induced by BPA in testicular tissue. In addition, BPA promotes autophagy by altering the activity of the Akt/mTOR pathway and upregulating the expression of autophagy-related genes and proteins. Recent studies have also identified ferroptosis as a significant contributing factor to BPA-induced testicular damage, further complicating the landscape of BPA's effects. This review summarizes natural substances that mitigate BPA-induced testicular damage by inhibiting these cell death pathways. These findings not only highlight potential therapeutic strategies but also underscore the need for further research into the underlying mechanisms of BPA-induced toxicity, particularly as it pertains to human health risk assessment and the development of more effective BPA management strategies.

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.

Dissecting the dynamic cellular transcriptional atlas of adult teleost testis development throughout the annual reproductive cycle

Teleost testis development during the annual cycle involves dramatic changes in cellular compositions and molecular events. In this study, the testicular cells derived from adult black rockfish at distinct stages - regressed, regenerating and differentiating - were meticulously dissected via single-cell transcriptome sequencing. A continuous developmental trajectory of spermatogenic cells, from spermatogonia to spermatids, was delineated, elucidating the molecular events involved in spermatogenesis. Subsequently, the dynamic regulation of gene expression associated with spermatogonia proliferation and differentiation was observed across spermatogonia subgroups and developmental stages. A bioenergetic transition from glycolysis to mitochondrial respiration of spermatogonia during the annual developmental cycle was demonstrated, and a deeper level of heterogeneity and molecular characteristics was revealed by re-clustering analysis. Additionally, the developmental trajectory of Sertoli cells was delineated, alongside the divergence of Leydig cells and macrophages. Moreover, the interaction network between testicular micro-environment somatic cells and spermatogenic cells was established. Overall, our study provides detailed information on both germ and somatic cells within teleost testes during the annual reproductive cycle, which lays the foundation for spermatogenesis regulation and germplasm preservation of endangered species.

Novel Insights into Ethanol-Soluble Oyster Peptide-Zinc-Chelating Agents: Structural Characterization, Chelation Mechanism, and Potential Protection on MEHP-Induced Leydig Cells

Numerous studies have reported that mono-(2-ethylhexyl) phthalate (MEHP) (bioactive metabolite of Di(2-ethylhexyl) phthalate) has inhibitory effects on Leydig cells. This study aims to prepare an oyster peptide-zinc complex (PEP-Zn) to alleviate MEHP-induced damage in Leydig cells. Zinc-binding peptides were obtained through the following processes: zinc-immobilized affinity chromatography (IMAC-Zn2+), liquid chromatography-mass spectrometry technology (LC-MS/MS) analysis, molecular docking, molecular dynamic simulation, and structural characterization. Then, the Zn-binding peptide (PEP) named Glu-His-Ala-Pro-Asn-His-Asp-Asn-Pro-Gly-Asp-Leu (EHAPNHDNPGDL) was identified. EHAPNHDNPGDL showed the highest zinc-chelating ability of 49.74 ± 1.44%, which was higher than that of the ethanol-soluble oyster peptides (27.50 ± 0.41%). In the EHAPNHDNPGDL-Zn complex, Asn-5, Asp-7, Asn-8, His-2, and Asp-11 played an important role in binding to the zinc ion. Additionally, EHAPNHDNPGDL-Zn was found to increase the cell viability, significantly increase the relative activity of antioxidant enzymes and testosterone content, and decrease malondialdehyde (MDA) content in MEHP-induced TM3 cells. The results also indicated that EHAPNHDNPGDL-Zn could alleviate MEHP-induced apoptosis by reducing the protein level of p53, p21, and Bax, and increasing the protein level of Bcl-2. These results indicate that the zinc-chelating peptides derived from oyster peptides could be used as a potential dietary zinc supplement.

Ellagic acid mitigates heat-induced testicular detriment in a mouse model

Heat stress has been shown to have a detrimental impact on testicular activity and spermatogenesis. Ellagic acid is a plant-derived organic compound that has a variety of biological functions. Thus, it is believed that ellagic acid may improve heat-stressed testicular dysfunction. There has been no research on the impact of ellagic acid on heat-stressed testicular dysfunction. The mice were divided into 4 groups. The first group was the normal control group (CN), and the second received heat stress (HS) by submerging the lower body for 15 min in a water bath with a thermostatically controlled temperature kept at 43°C (HS), and the third and fourth groups were subjected to heat-stress similar to group two and given two different dosages of ellagic acid (5 mg/kg (EH5) and 50 mg/kg (EH50) for 14 days. Ellagic acid at a dose of 50 mg/kg improved the level of circulating testosterone (increased 3βHSD) and decreases the oxidative stress. The testicular and epididymal architecture along with sperm parameters also showed improvement. Ellagic acid treatment significantly increases the germ cell proliferation (GCNA, BrdU staining) and Bcl2 expression and decreases active caspase 3 expression. Heat stress downregulated the expression of AR, ER-α and ER-β, and treatment with ellagic acid increased the expression of ER-α and ER-β markers in the 50 mg/kg treatment group. Thus, our finding suggests that ellagic acid ameliorates heat-induced testicular impairment through modulating testosterone synthesis, germ cell proliferation, and oxidative stress. These effects could be manifested by regulating androgen and estrogen receptors. However, the two doses showed differential effects of some parameters, which require further investigation.

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

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

Selection and direct biomarkers of reproductive capacity of breeding boars

Efficient management of pig reproduction is paramount for the sustainability and productivity of the global pork industry. Modern artificial insemination (AI) breeding programs have greatly benefited from the integration of advanced selection methods and biomarkers to enhance the reproductive performance of boars. While traditional selection methods have relied soley on boar phenotype, such as growth rate and conformation, modern pig breeding has shifted more and more toward molecular and genetic tools, which are still complemented by phenotypic traits. These methods encompass genomics, transcriptomics, and proteomics. Biomarkers serve as critical indicators of boar reproductive capacity. They can help to identify individuals with superior fertility and aid in the early identification of potential fertility issues, allowing for proactive management strategies. This review summarizes current knowledge of various biomarkers associated with semen quality, sperm function, and overall reproductive fitness in boars. Furthermore, we explore advanced technologies and their potential applications in uncovering novel selection methods and biomarkers for predicting boar fertility. A comprehensive understanding of selection criteria and biomarkers governing boar reproductive capacity is essential for developing effective breeding programs to enhance swine reproductive performance.

Autophagy accompanying the developmental process of male germline stem cells

Germline stem cells are a crucial type of stem cell that can stably pass on genetic information to the next generation, providing the necessary foundation for the reproduction and survival of organisms. Male mammalian germline stem cells are unique cell types that include primordial germ cells and spermatogonial stem cells. They can differentiate into germ cells, such as sperm and eggs, thereby facilitating offspring reproduction. In addition, they continuously generate stem cells through self-renewal mechanisms to support the normal function of the reproductive system. Autophagy involves the use of lysosomes to degrade proteins and organelles that are regulated by relevant genes. This process plays an important role in maintaining the homeostasis of germline stem cells and the synthesis, degradation, and recycling of germline stem cell products. Recently, the developmental regulatory mechanism of germline stem cells has been further elucidated, and autophagy has been shown to be involved in the regulation of self-renewal and differentiation of germline stem cells. In this review, we introduce autophagy accompanying the development of germline stem cells, focusing on the autophagy process accompanying the development of male spermatogonial stem cells and the roles of related genes and proteins. We also briefly outline the effects of autophagy dysfunction on germline stem cells and reproduction.

Fluorene-9-bisphenol impaired male fertility through disrupting the testicular function and local microenvironment

Past studies have observed that BHPF induces multi-organ toxicity, however, whether it induces damage to male reproductive system and the specific mechanism remains unclear. In the present study, male mice were given 0, 2, 10 or 50 mg/kg/day of BHPF by gavage for 35 days to observe its effect on reproductive organ and sperm quality. The results indicated that BHPF decreased sperm count and sperm motility in a dose-dependent manner. Besides, our results demonstrated that BHPF triggered the proliferation inhibition and cell death of germ cells in vivo and in vitro. Also, BHPF reduced the expression of function markers for germ cells, Sertoli cells, and Leydig cells, indicating its damage to function of testis cells. Simultaneously, testicular microenvironment was found to be altered by BHPF, as presented with declined testosterone level and decreased expression of local microenvironment regulators. Overall, our findings indicated the detrimental effects of BHPF on male reproductive function in mice, suggesting testicular function and local microenvironment disturbance as mechanism underlying testicular damage.

A multi-omics approach reveals that lotus root polysaccharide iron ameliorates iron deficiency-induced testicular damage by activating PPARγ to promote steroid hormone synthesis

Iron deficiency is a common nutritional issue that seriously affects male reproductive health. Lotus root polysaccharide iron (LRPF), a novel nutritional supplement, may ameliorate the damage caused by iron deficiency, however, the mechanism is unclear. In this study, we comprehensively determined the benefits of LRPF on reproduction in iron-deficient mice by integrating transcriptomics, microbiomics and serum metabolomics. Microbiomics showed that LRPF could restore changes to the intestinal microbiota caused by iron deficiency. Metabolomics results showed that LRPF stabilised steroid hormone and fatty acid metabolism in iron-deficient mice, reduced the content of ethyl chrysanthemumate (EC) and ameliorated the reproductive impairment. The transcriptomic analysis showed that LRPF regulated steroid hormone synthesis and the peroxisome proliferator-activated receptor (PPAR) signalling pathway in iron-deficient mice. In vitro experiments showed that LRPF could promote steroid hormone synthesis in Leydig cells by activating PPARγ. In conclusion, this study highlights the advantage of LRPF to improve testicular development.

Microenvironment of spermatogonial stem cells: a key factor in the regulation of spermatogenesis

Spermatogonial stem cells (SSCs) play a crucial role in the male reproductive system, responsible for maintaining continuous spermatogenesis. The microenvironment or niche of SSCs is a key factor in regulating their self-renewal, differentiation and spermatogenesis. This microenvironment consists of multiple cell types, extracellular matrix, growth factors, hormones and other molecular signals that interact to form a complex regulatory network. This review aims to provide an overview of the main components of the SSCs microenvironment, explore how they regulate the fate decisions of SSCs, and discuss the potential impact of microenvironmental abnormalities on male reproductive health.

Single-Cell RNA Sequencing Reveals an Atlas of Hezuo Pig Testis Cells

Spermatogenesis is a complex biological process crucial for male reproduction and is characterized by intricate interactions between testicular somatic cells and germ cells. Due to the cellular heterogeneity of the testes, investigating different cell types across developmental stages has been challenging. Single-cell RNA sequencing (scRNA-seq) has emerged as a valuable approach for addressing this limitation. Here, we conducted an unbiased transcriptomic study of spermatogenesis in sexually mature 4-month-old Hezuo pigs using 10× Genomics-based scRNA-seq. A total of 16,082 cells were collected from Hezuo pig testes, including germ cells (spermatogonia (SPG), spermatocytes (SPCs), spermatids (SPTs), and sperm (SP)) and somatic cells (Sertoli cells (SCs), Leydig cells (LCs), myoid cells (MCs), endothelial cells (ECs), and natural killer (NK) cells/macrophages). Pseudo-time analysis revealed that LCs and MCs originated from common progenitors in the Hezuo pig. Functional enrichment analysis indicated that the differentially expressed genes (DEGs) in the different types of testicular germ cells were enriched in the PI3K-AKT, Wnt, HIF-1, and adherens junction signaling pathways, while the DEGs in testicular somatic cells were enriched in ECM-receptor interaction and antigen processing and presentation. Moreover, genes related to spermatogenesis, male gamete generation, sperm part, sperm flagellum, and peptide biosynthesis were expressed throughout spermatogenesis. Using immunohistochemistry, we verified several stage-specific marker genes (such as UCHL1, WT1, SOX9, and ACTA2) for SPG, SCs, and MCs. By exploring the changes in the transcription patterns of various cell types during spermatogenesis, our study provided novel insights into spermatogenesis and testicular cells in the Hezuo pig, thereby laying the foundation for the breeding and preservation of this breed.

Maslinic acid supplementation prevents di(2-ethylhexyl) phthalate-induced apoptosis via PRDX6 in peritubular myoid cells of Chinese forest musk deer

Chinese forest musk deer (FMD), an endangered species, have exhibited low reproductive rates even in captivity due to stress conditions. Investigation revealed the presence of di(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, in the serum and skin of captive FMDs. Feeding FMDs with maslinic acid (MA) has been observed to alleviate the stress response and improve reproductive rates, although the precise molecular mechanisms remain unclear. Therefore, this study aims to investigate the molecular mechanisms underlying the alleviation of DEHP-induced oxidative stress and cell apoptosis in primary peritubular myoid cells (PMCs) through MA intake. Primary PMCs were isolated and exposed to DEHP in vitro. The results demonstrated that DEHP significantly suppressed antioxidant levels and promoted cell apoptosis in primary PMCs. Moreover, interfering with the expression of PRDX6 was found to induce excessive reactive oxygen species (ROS) production and cell apoptosis in primary PMCs. Supplementation with MA significantly upregulated the expression of PRDX6, thereby attenuating DEHP-induced oxidative stress and cell apoptosis in primary PMCs. These findings provide a theoretical foundation for mitigating stress levels and enhancing reproductive capacity of in captive FMDs.

Co-administration of thymol and sulfoxaflor impedes the expression of reproductive toxicity in male rats

This study investigated the capability of a co-delivery system of thymol (THY) and sulfoxaflor that can serve to minimize the development of epididymal and testicular injury arise from SFX exposures alone. Forty-eight adult male rats were orally treated by gavage for 28 consecutive days. The rats were divided into six groups comprising control, THY alone (30 mg/kg), low SFX alone (79.4 mg/kg), high SFX alone (205 mg/kg) and co-exposure groups. After euthanasia, the rats epididymal and testicular damage and antioxidant status markers, myeloperoxidase (MPO) activity, levels of nitric oxide, total antioxidant capacity (TAC), total oxidative stress (TOS) and lipid peroxidation (LPO) were analyzed. Levels of tumor necrosis factor alpha (TNF-α), interleukin-1 b (IL-1β) and caspase-3 activity were assessed using ELISA kits. The results revealed that SFX exposure caused a significant (p < 0.05) decrease in the body weight, sperm functional parameters, serum testosterone level with widespread histological abnormalities in a dose-dependent manner. Increased relative organ weights, serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were observed in low SFX-treated rats. Similarly, the epididymal and testicular myeloperoxidase activity, malondialdehyde (MDA), reactive oxygen species (RONS), tumor necrosis-α, interleukin-1β levels and caspase-3 activity were significant (p < 0.05) increased and a significant (p < 0.05) reduction in antioxidant enzyme activities and reduced glutathione (GSH) were revealed in SFX-treated rats. However, co-treatment of THY with SFX prevented SFX-induced epididymal and testicular toxicities. Thus, thymol protected against potential epididymis and testes alterations elicited by oxido-inflammatory mediators and up regulated antioxidant status.

AZIN2 is associated with apoptosis of germ cells in undescended testis

Undescended testis (UDT), known as cryptorchidism (CRY), is a common congenital disorder in which one or both testicles do not descend normally into the scrotum. A unilateral UDT model was established by inducing UDT in mice through surgery. The results showed that the testis in the UDT model group was abnormal; the lumen of the seminiferous tubule was atrophic; apoptosis, necrosis and shedding were observed in many of the germ cells; the level of sex hormones was abnormal; and mature sperm was reduced. Subsequently, transcriptome sequencing was conducted on the testicular tissue of UDT model mice. Through analysis and verification of differential genes, AZIN2 was identified as playing a key role in the decline in male fertility caused by cryptorchidism. AZIN2 expression and spermine content was down-regulated in the testis of the UDT group. We then used a combination of hypoxanthine and xanthine to create a GC-1 cell damage model. In this model, AZIN2 expression and spermine content was down-regulated. When si-Azin2 transfected GC-1 cells, cell viability and proliferation were decreased. However, in the GC-1 cell damage model transfected with Azin2 over-expressed plasmid, AZIN2 expression and spermine content was up-regulated, reversing the cell damage caused by hypoxanthine and xanthine, and restoring the proliferation ability of GC-1 cells. These results indicate that in UDT, down-regulated AZIN2 expression is a factor in testicular damage. This discussion of the connection between AZIN2 and germ cells has important clinical significance as it provides an important reference for the diagnosis and treatment of cryptorchidism.

A Step Forward in Understanding the Expression of Classical Aquaporins in the Male Reproductive Tract: Study Findings in Cattle (Bos taurus)

Aquaporins (AQPs), also known as water channels, appear to be particularly promising in maintaining male reproductive potential. Therefore, this study aimed to determine the presence of classical AQPs in the bovine (Bos taurus) reproductive system and analyze changes in their expression with age using immunohistochemistry and Western blotting. Of the six classical AQPs, AQP0, AQP1, AQP4, AQP5 and AQP6 were detected, while AQP2 was absent. In the testis, AQP0 was visible in Leydig cells in selected animals, while AQP1 was found in myoid cells surrounding the seminiferous tubules of mature individuals. This characteristic expression patterns of AQP0, limited only to certain bulls, is difficult to explain unequivocally. It is possible that AQP0 expression in cattle is subject to individual variability or changes in response to specific physiological conditions. In the caput and corpus epididymis, AQP0 showed weak expression in epithelial cells of immature animals and stronger expression in basal and principal cells of reproductive bulls. In all animals, AQP1 was present on the apical surface of epithelial cells in the initial segment of the caput epididymis. AQP4, AQP5 and AQP6 were identified in principal and basal cells along the entire epididymis of reproductive bulls. The abundance of AQP4 and AQP6 increased from the caput to the cauda epididymis with the growth and development of the animals. In all males, AQP4, AQP5 and AQP6 were observed in epithelial cells of the vas deferens, and their expression in this section increased with age. In conclusion, the abundance and distribution of the classical AQPs in various cell types and parts of the male reproductive system indicate their crucial role in maintaining water homeostasis, which is essential for normal reproductive function in cattle.

Mechanism of LncRNA Gm2044 in germ cell development

Germ cell development in mammals is a complex physiological process that involves the proliferation of primordial germ cells, meiosis, and the formation of male and female gametes. Long non-coding RNA (lncRNA) is a type of RNA with more than 200 nucleotides that does not code for proteins. A small number of lncRNAs have been shown to participate in spermatogenesis in the testes and in follicular development in the ovaries, but the role of the vast majority of lncRNAs and their molecular mechanisms still need further study. LncRNA Gm2044 was identified as a differentially expressed lncRNA in mouse spermatogenesis by microarray technology. In mouse testis, lncRNA Gm2044 can act as competing endogenous RNA to regulate SYCP1 expression in GC-2 cells derived from mouse spermatocyte cells, and it can also act as a host gene for miR-202 to regulate RBFOX2 protein expression. In female mouse ovaries, lncRNA Gm2044 regulates 17β-estradiol synthesis through the miRNA-138-5p-Nr5a1 pathway or by interacting with EEF2. In addition, studies suggest that lncRNA Gm2044 is also involved in the progression of reproductive system diseases such as male nonobstructive azoospermia. Here, we summarize the roles and molecular mechanisms of lncRNA Gm2044 in male and female gametogenesis and its potential role in some infertility disorders.

Exploring the Molecular Characteristics and Role of PDGFB in Testis and Epididymis Development of Tibetan Sheep

Platelet-derived growth factor B (PDGFB), as an important cellular growth factor, is widely involved in the regulation of cellular events such as cell growth, proliferation, and differentiation. Although important, the expression characteristics and biological functions in the mammalian reproductive system remain poorly understood. In this study, the PDGFB gene of Tibetan sheep was cloned by RT-PCR, and its molecular characteristics were analyzed. Subsequently, the expression of the PDGFB gene in the testes and epididymides (caput, corpus, and cauda) of Tibetan sheep at different developmental stages (3 months, 1 year, and 3 years) was examined by qRT-PCR and immunofluorescence staining. A bioinformatic analysis of the cloned sequences revealed that the CDS region of the Tibetan sheep PDGFB gene is 726 bp in length and encodes 241 amino acids with high homology to other mammals, particularly goats and antelopes. With the increase in age, PDGFB expression showed an overall trend of first decreasing and then increasing in the testis and epididymis tissues of Tibetan sheep, and the PDGFB mRNA expression at 3 months of age was extremely significantly higher than that at 1 and 3 years of age (p < 0.05). The PDGFB protein is mainly distributed in testicular red blood cells and Leydig cells in Tibetan sheep at all stages of development, as well as red blood cells in the blood vessel, principal cells, and the pseudostratified columnar ciliated epithelial cells of each epididymal duct epithelium. In addition, PDGFB protein expression was also detected in the spermatocytes of the 3-month-old group, spermatids of the 1-year-old group, spermatozoa and interstitial cells of the 3-year-old group, and loose connective tissue in the epididymal duct space in each developmental period. The above results suggest that the PDGFB gene, as an evolutionarily conserved gene, may play multiple roles in the development and functional maintenance of testicular cells (such as red blood cells, Leydig cells, and germ cells) and epididymal cells (such as red blood cells, principal cells, and ciliated epithelial cells) during testicular and epididymal development, which lays a foundation for the further exploration of the mechanisms by which the PDGFB gene influences spermatogenesis in Tibetan sheep.

Mutation of the Thap4 gene causes dwarfism and testicular anomalies in rats and mice

The petit (pet) locus is associated with dwarfism, testicular anomalies, severe thymic hypoplasia, and high postnatal lethality, which are inherited in autosomal recessive mode of inheritance in rats with a Wistar strain genetic background. Linkage analysis localized the pet locus between 98.7 Mb and 101.2 Mb on rat chromosome 9. Nucleotide sequence analysis identified 2 bp deletion in exon 2 of the Thap4 gene as the causative mutation for pet. This deletion causes a frameshift and premature termination codon, resulting in a truncated THAP4 protein lacking approximately two-thirds of the C-terminal side. Thap4 is expressed in various organs, including the testis and thymus in rats. To elucidate the biological function of THAP4 in other species, we generated Thap4 knockout mice lacking exon 2 of the Thap4 gene through genome editing. Thap4 knockout mice also exhibited dwarfism and small testis but did not show high postnatal lethality. Thymus weights of adult Thap4 knockout male mice were significantly higher compared to wild-type male mice. Although Thap4 knockout male mice were fertile, their testis contained seminiferous tubules with spermatogenesis and degenerative seminiferous tubules lacking germ cells. Additionally, we observed vacuoles in seminiferous tubules, and clusters of cells in the lumen in seminiferous tubules in Thap4 knockout male mice. These results demonstrate that spontaneous mutation of Thap4 gene in rats and knockout of Thap4 gene in mice both cause dwarfism and testicular anomalies. Thap4 gene in rats and mice is essential for normal testicular development, maintaining spermatogenesis throughout the entire region of seminiferous tubules.

Tris(2-ethylhexyl) phosphate induces cytotoxicity in TM3 Leydig cells by modulating autophagy and endoplasmic reticulum stress

Tris (2-ethylhexyl) phosphate (TEHP) is a frequently used organophosphorus flame retardant with significant ecotoxicity and widespread human exposure. Recent research indicates that TEHP has reproductive toxicity. However, the precise cell mechanism is not enough understood. Here, by using testicular mesenchymal stromal TM3 cells as a model, we reveal that TEHP induces apoptosis. Then RNA sequencing analysis, immunofluorescence, and western blotting results show that THEP inhibits autophagy flux and enhances endoplasmic reticulum (ER) stress. Moreover, the activation of the ER stress is critical for TEHP-induced cell injury. Interestingly, TEHP-induced ER stress is contributed to autophagic flux inhibition. Furthermore, pharmacological inhibition of autophagy aggravates, and activation of autophagy attenuates TEHP-induced apoptosis. In summary, these findings indicate that TEHP triggers apoptosis in mouse TM3 cells through ER stress activation and autophagy flux inhibition, offering a new perspective on the mechanisms underlying TEHP-induced interstitial cytotoxicity in the mouse testis.

Androgen synthesis cell-specific CREBZF deficiency alters adrenal cortex steroid secretion and develops behavioral abnormalities in adult male mice

The global challenge of male infertility is escalating, notably due to the decreased testosterone (T) synthesis in testicular Leydig cells under stress, underscoring the critical need for a more profound understanding of its regulatory mechanisms. CREBZF, a novel basic region-leucine zipper transcription factor, regulates testosterone synthesis in mouse Leydig cells in vitro; however, further validation through in vivo experiments is essential. Our study utilized Cyp17a1-Cre to knock out CREBZF in androgen-synthesis cells and explored the physiological roles of CREBZF in fertility, steroid hormone synthesis, and behaviors in adult male mice. Conditional knockout (cKO) CREBZF did not affect fertility and serum testosterone level in male mice. Primary Leydig cells isolated from CREBZF-cKO mice showed impaired testosterone secretion and decreased mRNA levels of Star, Cyp17a1, and Hsd3b1. Loss of CREBZF resulted in thickening of the adrenal cortex, especially X-zone, with elevated serum corticosterone and dehydroepiandrosterone levels and decreased serum dehydroepiandrosterone sulfate levels. Immunohistochemical staining revealed increased expression of StAR, Cyp11a1, and 17β-Hsd3 in the adrenal cortex of CREBZF-cKO mice, while the expression of AR was significantly reduced. Along with the histological changes and abnormal steroid levels in the adrenal gland, CREBZF-cKO mice showed higher anxiety-like behavior and impaired memory in the elevated plus maze and Barnes maze, respectively. In summary, CREBZF is dispensable for fertility, and CREBZF deficiency in Leydig cells promotes adrenal function in adult male mice. These results shed light on the requirement of CREBZF for fertility, adrenal steroid synthesis, and stress response in adult male mice, and contribute to understanding the crosstalk between testes and adrenal glands.

Reproductive toxicity of cadmium stress in male animals

Cadmium (Cd) is a common heavy metal pollutant in the environment, and the widespread use of products containing Cd compounds in industry has led to excessive levels in the environment, which enter the animal body through the food chain, thus seriously affecting the reproductive development of animals. Related studies have reported that Cd severely affects spermatogonia development and spermatogenesis in animals. In contrast, the reproductive toxicity of Cd in males and its mechanism of action have not been clarified. Therefore, this paper reviewed the toxic effects of Cd on germ cells, spermatogonia somatic cells and hypothalamic-pituitary-gonadal axis (HPG axis) of male animals and its toxic action mechanisms of oxidative stress, apoptosis and autophagy from the perspectives of cytology, genetics and neuroendocrinology. The effects of Cd stress on epigenetic modification of reproductive development in male animals were also analyzed. We hope to provide a reference for the in-depth study of the toxicity of Cd on male animal reproduction.

Bazi Bushen alleviates reproductive aging in aged male mice

Bazi Bushen (BZBS), a traditional Chinese medicine (TCM), has demonstrated therapeutic efficacy in testicular dysfunction within D-galactose and NaNO2 mouse models. This study aimed to ascertain if BZBS could also mitigate the decline in testicular function associated with natural aging. Therefore, male aged mice were employed to evaluate the preventive effects of BZBS on male reproductive aging. This was achieved by assessing sex hormone production, testicular histomorphology, and spermatogenesis. Relative to the untreated aged control group, BZBS administration elevated the levels of sex hormones and spermatocyte populations and preserved normal testicular structure in aged mice. Notably, spermatogenesis was maintained. Further analyses, including malondialdehyde (MDA) assays and real-time PCR, indicated that BZBS diminished testicular oxidative stress and the inflammatory burden. Corroborating these findings, mice treated with BZBS exhibited reductions in the populations of senescent and apoptotic cells within the seminiferous tubules, suggesting alleviated cellular damage. In contrast, we observed that rapamycin, a drug known for its longevity benefits, induced excessive testicular apoptosis and did not decrease lipid peroxidation. Collectively, our results highlight BZBS's promising clinical potential in counteracting male reproductive aging, underlining its mechanisms of action.

Enniatin B1 induces damage to Leydig cells via inhibition of the Nrf2/HO-1 and JAK/STAT3 signaling pathways

Enniatin B1 (ENN B1) is a mycotoxin that can be found in various foods. However, whether ENN B1 is hazardous to the reproductive system is still elusive. Leydig cells are testosterone-generating cells that reside in the interstitial compartment between seminiferous tubules. Dysfunction of Leydig cells could result in male infertility. This study aimed to examine the toxicological effects of ENN B1 against TM3 Leydig cells. ENN B1 significantly inhibited cell viability in a dose-dependent manner. ENN B1 treatment also decreased the expression of functional genes in Leydig cells. Moreover, ENN B1 induced Leydig cells apoptosis and oxidative stress. Mechanistically, ENN B1 leads to the upregulation of Bax and downregulation of Bcl-2 in Leydig cells. In addition, ENN B1 inhibited the Nrf2/HO-1 pathway, which is critical for the induction of oxidative stress. Additionally, ENN B1 treatment repressed the JAK/STAT3 signaling pathway in Leydig cells. Rescue experiments showed that activation of STAT3 resulted in alleviation of ENN B1-induced damage in Leydig cells. Collectively, our study demonstrated that ENN B1 induced Leydig cell dysfunction via multiple mechanisms.

Can exposure to lisdexamfetamine dimesylate from juvenile period to peripubertal compromise male reproductive parameters in adult rats?

Lisdexamfetamine (LDX) is a d-amphetamine prodrug used to treat attention deficit and hyperactivity disorder, a common neurodevelopmental disorder in children and adolescents. Due to its action mediated by elevated levels of catecholamines, mainly dopamine and noradrenaline, which influence hormonal regulation and directly affect the gonads, this drug may potentially disrupt reproductive performance. This study evaluated the effects of exposure to LDX from the juvenile to peripubertal period (critical stages of development) on systemic and reproductive toxicity parameters in male rats. Male Wistar rats (23 days old) were treated with 0; 5.2; 8.6 or 12.1 mg/kg/day of LDX from post-natal day (PND) 23 to 53, by gavage. LDX treatment led to reduced daily food and water consumption, as well as a decrease in social behaviors. The day of preputial separation remained unaltered, although the treated animals exhibited reduced weight. At PND 54, the treated animals presented signs of systemic toxicity, evidenced by a reduction in body weight gain, increase in the relative weight of the liver, spleen, and seminal gland, reduction in erythrocyte and leukocyte counts, reduced total protein levels, and disruptions in oxidative parameters. In adulthood, there was an increase in immobile sperm, reduced sperm count, morphometric changes in the testis, and altered oxidative parameters, without compromising male sexual behavior and fertility. These findings showed that LDX-treatment during the juvenile and peripubertal periods induced immediate systemic toxicity and adversely influenced reproductive function in adult life, indicating that caution is necessary when prescribing this drug during the peripubertal phase.

Cresyl Diphenyl Phosphate exposure induces reproductive functional defects in men and male mice

Cresyl Diphenyl Phosphate (CDP), as a novel organophosphate esters (OPEs), achieves widely used and exposed in multiple industries. However, its male reproductive toxicity and underlying mechanism remains unclear. In vivo, male mice were gavaged with CDP (0, 4, 20, or 100 mg/kg/d) for 8 weeks. And we treated TM3, TM4 and GC-2 cells with 0, 10, 25, and 50 μM CDP for 24 h to detect its reproductive toxicity effect in vitro. In our study, we revealed that CDP inhibited proliferation and induced apoptosis in mice testis and GC-2 cells, thereby leading to the decreased sperm quality. In mechanism, CDP trigger the oxidative stress and ROS production, thus partially causing DNA damage and cell apoptosis. Moreover, CDP exposure causes injury to Ledyig cells and Sertoli cells, thus disturbing the testicular microenvironment and inhibiting spermatogonia proliferation. In conclusion, this research reveals multiple adverse impacts of CDP on the male reproductive system and calls for further study of the toxicological effects of CDP on human health.

Omega-3 polyunsaturated fatty acids and its metabolite 12-HEPE rescue busulfan disrupted spermatogenesis via target to GPR120

Busulfan is an antineoplastic, which is always accompanied with the abnormal of spermatogonia self-renewal and differentiation. It has been demonstrated that the omega-3 polyunsaturated fatty acids (PUFAs) benefits mature spermatozoa. However, whether omega-3 can protect endogenous spermatogonia and the detailed mechanisms are still unclear. Evaluate of spermatogenesis function (in vivo) were examined by histopathological analysis, immunofluorescence staining, and western blotting. The levels of lipid metabolites in testicular tissue were determined via liquid chromatography. We investigated the effect of lipid metabolites on Sertoli cells provided paracrine factors to regulate spermatogonia proliferation and differentiation using co-culture system. In our study, we showed that omega-3 PUFAs significantly improved the process of sperm production and elevated the quantity of both undifferentiated Lin28+ spermatogonia and differentiated c-kit+ spermatogonia in a mouse model where spermatogenic function was disrupted by busulfan. Mass spectrometry revealed an increase in the levels of several omega-3 metabolites in the testes of mice fed with omega-3 PUFAs. The eicosapentaenoic acid metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) up-regulated bone morphogenic protein 4 (BMP4) expression through GPR120-ERK1/2 pathway activation in Sertoli cells and restored spermatogonia proliferation and differentiation. Our study provides evidence that omega-3 PUFAs metabolite 12-HEPE effectively protects spermatogonia and reveals that GPR120 might be a tractable pharmacological target for fertility in men received chemotherapy or severe spermatogenesis dysfunction.

Protective effects of melatonin on DEHP-induced apoptosis and oxidative stress in prepubertal testes via the PI3K/AKT pathway

Di(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, is one of the most common plasticizers and is widely used in various plastic products. DEHP induces apoptosis and oxidative stress and has been shown to have androgenic toxicity. However, the methods to combat DEHP-induced testicular damage and the mechanisms involved remain to be elucidated. In the present study, we used melatonin, which has strong antioxidant properties, to intervene in prepubertal mice and mouse Leydig cells (TM3) treated with DEHP or its metabolite mono(2-ethylhexyl) phthalate (MEHP). The results showed that melatonin protected against DEHP-induced testicular damage in prepubertal mice, mainly by protecting against DEHP-induced structural destruction of the germinal tubules and by attenuating the DEHP-induced decrease in testicular organ coefficients and testosterone levels. Transcriptomic analysis found that melatonin may attenuate DEHP-induced oxidative stress and apoptosis in prepubertal testes. In vitro studies further revealed that MEHP induces oxidative stress injury and increases apoptosis in TM3 cells, while melatonin reversed this damage. In vitro studies also found that MEHP exposure inhibited the expression levels of molecules related to the PI3K/AKT signaling pathway, and melatonin reversed this change. In conclusion, these findings suggest that melatonin protects against DEHP-induced prepubertal testicular injury via the PI3K/AKT signaling pathway, and provide a theoretical basis and experimental rationale for combating male reproductive dysfunction.

The multifaceted role of extracellular ATP in sperm function: From spermatogenesis to fertilization

Extracellular adenosine 5'-triphosphate (ATP) is a vital signaling molecule involved in various physiological processes within the body. In recent years, studies have revealed its significant role in male reproduction, particularly in sperm function. This review explores the multifaceted role of extracellular ATP in sperm function, from spermatogenesis to fertilization. We discuss the impact of extracellular ATP on spermatogenesis, sperm maturation and sperm-egg fusion, highlighting the complex regulatory mechanisms and potential clinical applications in the context of male infertility. By examining the latest research, we emphasize the crucial role of extracellular ATP in sperm function and propose future research directions to further.

ARTS is essential for di-2-ethylhexyl phthalate (DEHP)-induced apoptosis of mouse Leydig cells

As an extensively employed plasticizer in industrial applications, di-2-ethylhexyl phthalate (DEHP) can induce apoptosis of mouse Leydig cells, yet the precise mechanism remains elusive. In the current study, we identified that DEHP could specially induced apoptosis in the Leydig cells of the testis tissue, accompanied with the upregulation of apoptosis-related protein in the TGF-β signaling pathway (ARTS) in the cells. Overexpression of ARTS significantly induced apoptosis of TM3 cells, while knockdown of ARTS inhibited apoptosis. Furthermore, DEHP-induced apoptosis of TM3 cells could be alleviated by knockdown of ARTS, which indicated that ARTS was involved in DEHP-induced apoptosis of mouse Leydig cells. Bioinformation assay predicts that there are four potential p53-responsive elements (p53-REs) located at - 6060, - 5726, - 5631 and - 5554 before the transcription start site of ARTS gene, implying that gene transcription of ARTS could be regulated by p53. Interestingly, DEHP was shown to specifically upregulate the expression of p53 in the Leydig cells of the testis tissue and TM3 cells. Consistently, p53 was proved to bind to the RE4 site of the ARTS gene promoter and transcriptionally activated the promoter-driven expression of the luciferase reporter gene. Overexpression of p53 could induce apoptosis of TM3 cells; while knockdown of p53 could not only rescue DEHP-induced apoptosis of the cells, but also inhibit DEHP-caused upregulation of ARTS. Meanwhile, we showed that oxidative stress could induce apoptosis of TM3 cells, accompanied with the increased protein levels of p53 and ARTS; while inhibition of oxidative stress dramatically alleviated DEHP-induced apoptosis and the up-regulation of p53 and ARTS. Taken together, these results indicated that DEHP-induced oxidative stress activates the p53-ARTS cascade to promote apoptosis of mouse Leydig cells.

Trpv4-mediated apoptosis of Leydig cells induced by high temperature regulates sperm development and motility in zebrafish

Exposure of testes to high-temperature environment results in defective spermatogenesis. Zebrafish exposed to high temperature exhibited apoptosis not only in germ cells but also in Leydig cells, as expected from studies using mice or salmon. However, the role of testicular somatic cells in spermatogenesis defects remains unclear. We found that in Leydig cells the Trpv4 gene encoding the temperature sensitive ion channel was specifically upregulated in high temperature. High temperature also reduced hormone synthesis in Leydig cells and led to a prompt downregulation of sperm motility. In the Trpv4 null mutant, neither Leydig cell-specific apoptosis nor decreased sperm motility was observed under high temperature. These results indicate that Leydig cell specific-apoptosis is induced via Trpv4 by high temperature. Notably this Trpv4-dependent mechanism was specific to Leydig cells and did not operate in germ cells. Because sperm exposed to high temperature exhibited compromised genome stability, we propose that temperature sensing leading to apoptosis in Leydig cells evolved to actively suppress generation of offspring with unstable genome.

The Functions and Application Prospects of Hepatocyte Growth Factor in Reproduction

Hepatocyte growth factor (HGF) is expressed in multiple systems and mediates a variety of biological activities, such as mitosis, motility, and morphogenesis. A growing number of studies have revealed the expression patterns and functions of HGF in ovarian and testicular physiology from the prenatal to the adult stage. HGF regulates folliculogenesis and steroidogenesis by modulating the functions of theca cells and granulosa cells in the ovary. It also mediates somatic cell proliferation and steroidogenesis, thereby affecting spermatogenesis in males. In addition to its physiological effects on the reproductive system, HGF has shown advantages in preclinical studies over recent years for the treatment of male and female infertility, particularly in women with premature ovarian insufficiency. This review aims to summarize the pleiotropic functions of HGF in the reproductive system and to provide prospects for its clinical application.

Adverse effects of microplastics and nanoplastics on the reproductive system: A comprehensive review of fertility and potential harmful interactions

In recent years, microplastics (MPs) and nanoplastics (NPs) have caused ubiquitous environmental pollution and raised widespread concern about their potential toxicity to human health, especially in the reproductive system. Moreover, infertility affects >15 % of couples worldwide, and the birth rate is decreasing. Environmental factors are some of the most important causes of infertility. However, little is known about the effects of MPs and NPs on the testes and ovaries. These particles can enter the body primarily via ingestion, inhalation, and skin contact, target the reproductive system in a size-dependent manner and disturb germ cell and other somatic cell development. Our study systematically reviewed the adverse effects of plastic particles on reproductive function and offers valuable insights into the different stages of germ cells and the potential mechanisms. Moreover, the synergistic reproductive toxicity of these particles and carried contaminants was summarized. Given the limited research scale, a shift toward innovative technologies and the adoption of multiple omics are recommended for advancing related studies. Further study is needed to explore the reproductive toxicity of MPs and NPs based on their size, polymer type, shape, and carried toxins, establish effective protective measures, and develop precision medicine for targeted reproductive damage.

Trps1 acts as a regulator of Sf-1 transcription and testosterone synthesis in mouse Leydig cells

Infertility has attracted global concern, and disruption of testosterone is a common cause of male infertility. Exploring the critical factors in testosterone biosynthesis may provide new insights for disease research and clinical therapy. Research on trichorhinophalangeal syndrome-1 (Trps1) gene has recently been focus on cancers; it is yet unknown whether Trps1 produces a marked effect in the male reproductive system. In the current study, single-cell RNA sequencing analysis of trichorhinophalangeal syndrome-1 gene (Trps1) expression in mouse testes and cleavage under targets and tagmentation and RNA sequencing were utilized to investigate the functionality of Trps1 in mouse Leydig cells. Knockdown of Trps1 increased testosterone synthesis in vitro and vivo using adeno-associated viral delivery and conditional knockout models. The results showed that Trps1 was abundantly expressed in Leydig cells. The expression levels of both steroidogenic factor-1 (Sf-1) and steroidogenic enzymes (Cyp11a1, Hsd3b, Cyp17a1, and Hsd17b3) as well as testosterone secretion were increased after Trps1 deficiency in vivo and vitro. Furthermore, disruption of Trps1 reduced histone deacetylase 1/2 activity and increased histone H3 acetylation in the Sf-1 promoter, thereby promoting testosterone secretion. Interestingly, Sf-1 also regulated the transcription of Trps1 through activating transcription factor 2. These results indicate that Trps1 targets Sf-1 to affect steroidogenesis through histone acetylation and shed light on the critical role of Trps1 functioning in the mouse Leydig cells.

Cloning, expression analysis and localization of DAZL gene implicated in germ cell development of male Hezuo pig

Deleted in azoospermia-like (DAZL) is essential for mammalian testicular function and spermatogenesis. To explore the molecular characterization, expression patterns, and cellular localization of the DAZL in Hezuo pig testes, testicular tissue was isolated from Hezuo pig at five development stages including 30 days old (30 d), 90 days old (90 d), 120 days old (120 d), 180 days old (180 d), and 240 days old (240 d). DAZL cDNA was first cloned using the RT-PCR method, and its molecular characterization was analyzed using relevant bioinformatics software. Subsequently, the expression patterns and cellular localization of DAZL were evaluated using quantitative real-time PCR (qRT-PCR), Western blot, and immunohistochemistry. The cloning and sequence analysis showed that the Hezuo pig DAZL cDNA fragment contained 888 bp open reading frame (ORF) capable of encoding 295 amino acid residues and exhibited high identities with some other mammals. The qRT-PCR and Western blot results indicated that DAZL was specifically expressed in Hezuo pig testes, and DAZL levels of both mRNA and protein were expressed at all five reproductive stages of Hezuo pig testes, with extremely significant higher expression levels in 90 d, 120 d, 180 d, and 240 d than those in 30 d (p < 0.01). Additionally, immunohistochemistry results revealed that DAZL protein was mainly localized in gonocytes at 30 d testes, primary spermatocytes, and spermatozoon at other developmental stages, and Leydig cells throughout five development stages. Together, these results suggested that DAZL may play an important role by regulating the proliferation or differentiation of gonocytes, development of primary spermatocytes and spermatozoon, and functional maintenance of Leydig cells in testicular development and spermatogenesis of Hezuo pig. Nevertheless, the specific regulatory mechanisms underlying these phenomena still requires further investigated and verified.

Prenatal exposure to acetaminophen at different doses, courses and time causes testicular dysplasia in offspring mice and its mechanism

Epidemiological investigation suggested that the use of acetaminophen during pregnancy may cause offspring testicular dysplasia, but no systematic study has been conducted. In this study, Kunming mice were given acetaminophen at different doses (100/200/400 mg/kg.d), courses (single/multiple), time (second/third trimester) during pregnancy. Fetal blood and testes were collected on gestaional day 18 for detection. The results indicated abnormal testicular development in the PAcE (prenatal acetaminophen exposure) groups. The maximum diameter/cross-sectional area decreased, the interstitial space widened, and decreased proliferation/increased apoptosis were observed, especially in the high-dose, multi-course and second-trimester groups. Meanwhile, the serum testosterone level decreased in PAcE groups, and the steroid synthesis function in Leydig cells, Sertoli and spermatogenic cell function were inhibited, it was more significant in high-dose, multi-course and second-trimester groups. Furthermore, Wnt signal pathway was activated but Notch signal pathway was inhibited in the PAcE groups. Finally, in vitro experiment, acetaminophen could inhibit spermatogonial cell proliferation, enhance apoptosis, and change Wnt/Notch signal pathway. In conclusion, this study confirmed that PAcE can change fetal testicular development in a dose, course and time-dependent manner, and found that multicellular function impaired. This study provides theoretical and experimental basis for systematically elucidating the developmental toxicity of acetaminophen in testis.

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 construction of a testis transcriptional cell atlas from embryo to adult reveals various somatic cells and their molecular roles

BACKGROUND

The testis is a complex organ that undergoes extensive developmental changes from the embryonic stage to adulthood. The development of germ cells, which give rise to spermatozoa, is tightly regulated by the surrounding somatic cells.

METHODS

To better understand the dynamics of these changes, we constructed a transcriptional cell atlas of the testis, integrating single-cell RNA sequencing data from over 26,000 cells across five developmental stages: fetal germ cells, infants, childhood, peri-puberty, and adults. We employed various analytical techniques, including clustering, cell type assignments, identification of differentially expressed genes, pseudotime analysis, weighted gene co-expression network analysis, and evaluation of paracrine cell-cell communication, to comprehensively analyze this transcriptional cell atlas of the testis.

RESULTS

Our analysis revealed remarkable heterogeneity in both somatic and germ cell populations, with the highest diversity observed in Sertoli and Myoid somatic cells, as well as in spermatogonia, spermatocyte, and spermatid germ cells. We also identified key somatic cell genes, including RPL39, RPL10, RPL13A, FTH1, RPS2, and RPL18A, which were highly influential in the weighted gene co-expression network of the testis transcriptional cell atlas and have been previously implicated in male infertility. Additionally, our analysis of paracrine cell-cell communication supported specific ligand-receptor interactions involved in neuroactive, cAMP, and estrogen signaling pathways, which support the crucial role of somatic cells in regulating germ cell development.

CONCLUSIONS

Overall, our transcriptional atlas provides a comprehensive view of the cell-to-cell heterogeneity in the testis and identifies key somatic cell genes and pathways that play a central role in male fertility across developmental stages.

The male reproductive toxicity after nanoplastics and microplastics exposure: Sperm quality and changes of different cells in testis

Nanoplastics (NPs) and Microplastics (MPs) pollution has become a severe threat to the planet and is a growing concern. However, their effects on male reproductive toxicity remain poorly understood. In this study, a series of morphological analyses were completed to explore the influence of NPs and MPs exposure on the testis in mice. After 12-weeks exposure, although both NPs and MPs exposure can lead to reproductive toxicity, compared with NPs exposure, exposure to MPs leads to a more significant increase in reproductive toxicity dependent on some particle size. Moreover, increased reproductive toxicities, including increased spermatogenesis disorders, and sperm physiological abnormality, oxidative stress, testis inflammation was more associated with MPs group than NPs group. Ultra-pathological structure observed by transmission electron microscopy indicated that both NPs and MPs have different effects on spermatogonia, spermatocytes and Sertoli cells. Exposure to MPs resulted in decreased Sertoli cell numbers and reduced Leydig cell area, and showed no effects on differentiation of Leydig cells by the expression level of the Insulin-Like factor 3 (INSL3) in Leydig cells. Transcriptomic sequencing analysis provided valuable insights into the differential effects of NPs and MPs on cellular processes. Specifically, our findings demonstrated that NPs were predominantly involved in the regulation of steroid biosynthesis, whereas MPs primarily influenced amino acid metabolism. This study demonstrates the effect of adult-stage reproductive toxicity in mice after exposure to NPs and MPs, which will deep the understanding of the NPs and MPs induced toxicity.

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.

α-Linolenic acid-regulated testosterone biosynthesis via activation of the JNK-SF-1 signaling pathway in primary rooster Leydig cells

As a functional fatty acid, α-linolenic acid (ALA) is essential in promoting animal testosterone biosynthesis. This study investigated the effects of ALA on testosterone biosynthesis and the possible mechanism underlying the signaling pathway in primary Leydig cells of the rooster.

METHODS

Primary rooster Leydig cells were treated with ALA (0, 20, 40, or 80 μmol/L) or pretreated with a p38 inhibitor (50 μmol/L), a c-Jun NH2-terminal kinase (JNK) inhibitor (20 μmol/L), or an extracellular signal-regulated kinase (ERK) inhibitor (20 μmol/L) before ALA treatment. Testosterone content in the conditioned culture medium was detected using an enzyme-linked immunosorbent assay (ELISA). The expression of steroidogenic enzymes and JNK-SF-1 signaling pathway factors was detected using real-time fluorescence quantitative PCR (qRT-PCR).

RESULTS

Supplementation with ALA significantly increased testosterone secretion within culture media (P < 0.05), and the optimized dose was 40 μmol/L. Compared with the control group, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) mRNA expression significantly increased (P < 0.05) in the 40 μmol/L ALA group; 17-hydroxylase/c17-20 lyase (P450c17) and p38 mRNA expressions were not significantly different in the 40 μmol/L ALA group; ERK and JNK mRNA expressions were significantly upregulated (P < 0.05) in 40 μmol/L ALA group. In the inhibitor group, testosterone levels were significantly downregulated (P < 0.05). Compared with the 40 μmol/L ALA group, StAR, P450scc, and P450c17 mRNA expressions were significantly decreased (P < 0.05), and 3β-HSD mRNA expression in the p38 inhibitor group did not change; StAR, P450scc, and 3β-HSD mRNA expressions were significantly decreased (P < 0.05), and P450c17 mRNA expression in ERK inhibitor group did not change; StAR, P450scc, 3β-HSD, and P450c17 mRNA expressions were significantly decreased (P < 0.05) in JNK inhibitor group. Additionally, the increased steroidogenic factor 1 (SF-1) gene expression levels induced by ALA were reversed when the cells were pre-incubated with JNK and ERK inhibitors. The levels in the JNK inhibitor group were significantly lower than those in the control group (P < 0.05).

CONCLUSION

ALA may promote testosterone biosynthesis by activating the JNK-SF-1 signaling pathway to upregulate StAR, P450scc, 3β-HSD, and P450c17 expression in primary rooster Leydig cells.

Loss of gdnfa disrupts spermiogenesis and male courtship behavior in zebrafish

Spermatogenesis is essential for establishment and maintenance of reproduction in male vertebrates. Spermatogenesis, which is mainly regulated by the combined action of hormones, growth factors, and epigenetic factors, is highly conserved. Glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor-β superfamily. In this study, global gdnfa knockout and Tg (gdnfa: mcherry) transgenic zebrafish lines were generated. Loss of gdnfa resulted in disorganized testes, decreased gonadosomatic index, and low percentage of mature spermatozoa. In the Tg (gdnfa: mcherry) zebrafish line, we found that gdnfa was expressed in Leydig cells. The mutation in gdnfa significantly decreased Leydig cell marker gene expression and androgen secretion in Leydig cells. In addition, courtship behavior was disrupted in the male mutants. We present in vivo data showing that global knockout of gdnfa disrupts spermiogenesis and male courtship behavior in zebrafish. The first viable vertebrate model with a global gdnfa knockout may be valuable for studying the role of GDNF in animal reproduction.

Transcriptome Studies Reveal the N6-Methyladenosine Differences in Testis of Yaks at Juvenile and Sexual Maturity Stages

Studying the mechanism of spermatogenesis is key to exploring the reproductive characteristics of male yaks. Although N6-methyladenosine (m6A) RNA modification has been reported to regulate spermatogenesis and reproductive function in mammals, the molecular mechanism of m6A in yak testis development and spermatogenesis remains largely unknown. Therefore, we collected testicular tissue from juvenile and adult yaks and found that the m6A level significantly increased after sexual maturity in yaks. In MeRIP-seq, 1702 hypermethylated peaks and 724 hypomethylated peaks were identified. The hypermethylated differentially methylated RNAs (DMRs) (CIB2, AK1, FOXJ2, PKDREJ, SLC9A3, and TOPAZ1) mainly regulated spermatogenesis. Functional enrichment analysis showed that DMRs were significantly enriched in the adherens junction, gap junction, and Wnt, PI3K, and mTOR signaling pathways, regulating cell development, spermatogenesis, and testicular endocrine function. The functional analysis of differentially expressed genes showed that they were involved in the biological processes of mitosis, meiosis, and flagellated sperm motility during the sexual maturity of yak testis. We also screened the key regulatory factors of testis development and spermatogenesis by combined analysis, which included BRCA1, CREBBP, STAT3, and SMAD4. This study indexed the m6A characteristics of yak testicles at different developmental stages, providing basic data for further research of m6A modification regulating yak testicular development.