Molecular regulation of steroidogenesis in endocrine Leydig cells

Synergistic endocrine disruption and cellular toxicity of polyethylene microplastics and bisphenol A in MLTC-1 cells and zebrafish

The study investigates the synergistic endocrine disruption and cellular toxicity resulting from co-exposure to polyethylene microplastics (PE-MPs) and bisphenol A (BPA) in zebrafish and MLTC-1 cells. Previous research has extensively examined the individual effects of PE-MPs and BPA on endocrine systems and cellular health. However, the specific interactions and combined toxicological impacts of these two common environmental pollutants remain underexplored, particularly in terms of their synergistic effects on endocrine pathways and cellular viability. To fill this knowledge gap, we characterized PE-MPs using scanning electron microscopy and Raman spectrometry and exposed MLTC-1 cells to PE-MPs, BPA, or combinations of both. The results showed that co-exposure to 100 µg/mL PE-MPs and 100-150 µmol/L BPA for 48 h significantly decreased cell viability, increased apoptosis rates, induced G2/M cell cycle arrest, reduced mitochondrial membrane potential, and altered the transcriptional expression of genes related to steroidogenesis. Specifically, co-exposure upregulated the Ar while downregulating Lhr and 3β-Hsd, with these effects being more pronounced than those observed with single exposures. In a complementary in vivo study, adult zebrafish were exposed to environmentally relevant concentrations of PE-MPs (1 mg/L) and BPA (1.5 µg/L) for 28 days. This co-exposure resulted in significant increases in the GSI and alterations in the gene expression associated with the HPG axis. In male zebrafish brains, genes such as Gnrh2, Esr1, and Ar were downregulated, while in female brains, Gnrh3, Esr1, and Ar also exhibited downregulation. In male testes, Star, Cyp11a1, and Hsd11b2 were upregulated, whereas Cyp19a1a, Hsd3b, Hsd20b, and Hsd17b3 were downregulated. In contrast, female ovaries showed upregulation of Cyp11a1, Cyp17, Cyp11b, Hsd3b, Hsd20b, and Hsd17b3, while Cyp19a1a was downregulated, indicating a sex-specific endocrine disruption. Overall, the findings reveal that co-exposure to PE-MPs and BPA induces synergistic toxic effects both in vitro and in vivo, which underscores the importance of studying the effects of combined pollutants to better assess environmental health risks.

Spermidine as a Potential Protective Agents Against Poly(I:C)-Induced Immune Response, Oxidative Stress, Apoptosis, and Testosterone Decrease in Yak Leydig Cells

Viral infections of the reproductive tract and testis in male yaks, often resulting from natural mating under grazing conditions, can lead to infertility due to Leydig cell (LC) apoptosis, immune activation, oxidative stress, and reduced testosterone production. Spermidine (SPD), a potential therapeutic agent with antioxidant and anti-aging properties, might alleviate oxidant stress, immune response, and virus infection caused by apoptosis. In this study, firstly testicular Leydig cells of yak were induced with Poly(I:C), the pathogen-associated molecular pattern of the dsRNA virus, as a pathogenic model at the cellular level. Secondly, immune response, apoptosis, oxidative stress, and testosterone synthesis were measured in LC with or without SPD culture medium. Finally, transcriptomic sequencing was utilized to investigate the molecular mechanisms underlying the protective effects of SPD. These results suggested Poly(I:C) damaged the function of Leydig cells, significantly decreased the concentration of testosterone, and induced immune response, oxidative stress, and cell apoptosis, while SPD significantly alleviated the immune response and oxidative stress, and then significantly inhibited cell apoptosis and restores testosterone production in LCs. Transcriptomic analysis revealed that SPD significantly alleviates inflammation and apoptosis induced by Poly(I:C), reducing immune response and cellular damage through the regulation of several key gene expressions. These findings suggest SPD has the potential ability to mitigate Poly(I:C)-induced immune response, oxidative stress, and apoptosis, and then restore testosterone production in Leydig cells, offering a promising strategy to protect and enhance male yak fertility after infection with dsRNA virus.

Down-regulation of TET2 inhibits testosterone synthesis in offspring mice exposed to DBP during pregnancy through LH/cAMP/PKA/StAR signaling mediated by LHR

Exposure to di-n-butyl phthalate (DBP) during embryo development or lactation has been linked to reproductive toxicity. The ten-eleven translocation (TET) protein family plays a role in various pathological processes; however, its involvement in reproductive dysfunction in offspring mice exposed to DBP during gestation remains sparsely reported. In this study, SPF C57BL/6 pregnant mice were intragastrically administered DBP at doses of 0.5, 5, and 75 mg/kg body weight, or corn oil as a control, from gestational days 5-19. Following weaning, the offspring mice were maintained on a standard diet for 5 weeks. Additionally, mono-n-butyl phthalate (MBP)-induced TM3 cells were utilized to explore the underlying mechanisms in vitro. The results showed that in utero exposure to DBP resulted in diminished sperm quality, testicular damage, decreased reproductive hormone levels, and reduced expression of testosterone synthesis proteins in male offspring mice. Moreover, DBP exposure influenced the expression of steroidogenic acute regulatory protein (StAR) via the cAMP/PKA signaling pathway, associated with luteinizing hormone receptor (LHR)-mediated suppression of testosterone synthesis. Notably, DBP exposure led to decreased expression of TET methylcytosine dioxygenase 2 (TET2) in the progeny, and overexpression or silencing of TET2 affected the levels of proteins involved in the LHR-mediated testosterone synthesis pathway. Further investigations revealed that TET2 downregulation inhibits testosterone synthesis through the LHR-mediated LH/cAMP/PKA/StAR signaling pathway, ultimately impairing reproductive function in DBP-exposed offspring mice during gestation. This study provides a novel perspective for identifying molecular markers that may be more sensitive indicators of male reproductive damage from an epigenetic standpoint.

Emerging per- and polyfluoroalkyl substance perfluoro-(3,5,7,9-tetraoxadecanoic) acid (PFO4DA) impairs steroidogenesis and spermatogenesis by suppressing StAR and CYP11A1 expression in mice

Perfluoroalkyl ether carboxylic acids (PFECA) represent an important group of emerging per- and polyfluoroalkyl substances (PFAS). PFECA have been found in a variety of environmental matrices. While legacy PFAS have been extensively documented for their reproductive toxicity, the health implications of emerging alternatives like PFECA remains unclear. The present study is aimed at investigating the potential reproductive toxicity of perfluoro-(3,5,7,9-tetraoxadecanoic) acid (PFO4DA), a type of PFECA, through combining in vivo and in vitro assays. Adult male BALB/c mice were exposed to 2 and 10 mg/kg body-weight/day of PFO4DA via oral gavage for four consecutive weeks. While no overt structural or morphological changes were observed in the testes following PFO4DA exposure, significant reductions in both sperm quantity and quality were evident, correlating with increased PFO4DA dosage. PFO4DA exposure compromised the integrity of the blood-testis barrier (BTB) and led to a moderate decrease in BTB-associated junction proteins, including Connexin-43 and Claudin-11. Notably, PFO4DA disrupted androgen production, resulting in a significant reduction in testosterone (T) levels (> 60 %) in both serum and testicular tissue. Mechanistic analysis revealed that PFO4DA significantly repressed the expression levels of steroidogenic genes StAR and CYP11A1 both in testes and in cultured Leydig cells (TM3). These findings suggest that PFO4DA primarily targets the steroidogenic pathway in Leydig cells by suppressing StAR and CYP11A1, thereby inhibiting T synthesis. The subsequent T deficiency impairs Sertoli cell function and BTB integrity, ultimately disrupting spermatogenesis and impacting male reproductive health.

Effect of bisphenol F on reproductive function in F1 generation male mice and its potential mechanisms

Bisphenol F (BPF) is an environmental endocrine disruptor capable of crossing the placental barrier and affecting the growth and development of offspring. Despite its potential impact, systematic research about effects of BPF on the reproductive function of male offspring remains limited. In this study, pregnant female mice were exposed to BPF at doses of 40, 400, and 4000 μg/kg during gestation and lactation, respectively, to evaluate its impact on testicular damage, testosterone levels, and spermatogenesis of male offspring (F1 generation), and further explore the mechanisms using transcriptomics. First, the study demonstrated that BPF induces testicular damage in F1 generation mice, leading to decreased testosterone levels and sperm quality. Second, transcriptomic analysis revealed that BPF affected spermatogenesis in F1 generation mice by disrupting retinol metabolism. Third, transcriptomic analysis revealed that BPF reduce the capacity for testosterone synthesis in F1 generation mice by diverting the testosterone precursor dehydroepiandrosterone (DHEA) towards the synthesis of 16α-hydroxydehydroepiandrosterone rather than testosterone. Finally, it was confirmed that BPF hinder cholesterol transport to mitochondria by inhibiting the cAMP signaling pathway, thereby impacting testosterone synthesis. In summary, the results of this study suggest that gestational exposure to BPF can lead to reproductive dysfunction in F1 generation male mice.

Polyphenols as a strategy for improving male reproductive system

Reproduction in males is one of the complicated processes that is mediated by many environmental factors, as well as by diet (e.g. supplements, nutritional value). The parameters of reproduction like sperm cells, hormones and testicular histology are highly prone to oxidative stress due to influence of factors on reproductive processes. Polyphenols are naturally present in feed of animals as shrubs, trees and agro-industrial by products. The exposures of these polyphenols through diet have strong antioxidants properties. However, the benefits of these substances on reproductive health are not always certain. The use of these polyphenols in the diet of animals and in the semen extender has been reported as remarkable benefits. These beneficial effects are manifested in the form of improvement of antioxidant potential via the reduction in the production of reactive oxygen species. Polyphenols are also used for cryopreservation of various species for the genetic improvement of various species. This review gathers all the findings related to dietary consumptions of polyphenols on reproductive performance of male of various species as well as use in semen extender in fresh and frozen semen.

Discovery of phloridzin as a new antagonist for Di(2-ethylhexyl) phthalate-induced male reproductive toxicity based on the adverse outcome pathway network and drug-target gene set enrichment analysis

Di(2-ethylhexyl) phthalate (DEHP) is a widespread ubiquitous phthalate environmental contaminant. The male reproductive toxicity (MRT) from exposure to DEHP and its main metabolite, mono(2-ethylhexyl) phthalate (MEHP), has been well documented. Fully elucidating its toxic mechanism and discovering effective antagonists are desirable means to reduce the health risks of DEHP. In this study, 552 genes related to MRT induced by DEHP/MEHP were screened out from the Comparative Toxicogenomics Database (CTD) and DisGeNET database. Next, we developed a global adverse outcome pathway (AOP) network based on the existed AOP-wiki. After functional enrichment analyses and mapping to the global AOP network, we found that the increased ROS level, cell cycle arrest, and increased apoptosis are key events (KEs) involved in DEHP-mediated MRT, which was validated in TM3 Leydig cell model. Among them, cellular apoptosis is the core KE in DEHP-induced MRT via network topological analysis. Eventually, we developed a novel in silico antagonist screening platform (http://43.136.69.224:3838/wlab/) based on drug-target gene set enrichment analysis (dtGSEA version 2.0). Several potential candidates that mitigate DEHP-mediated cellular apoptosis have been screened out, including quercetin, taurine, methionine, and phloridzin. Further experimental results demonstrated that phloridzin provided the most effective protection against MEHP-induced apoptosis in TM3 cells probably through the p53 and MAPK signaling pathways. Molecular docking and molecular dynamics simulations suggest that STAT3 and RUNX1 may be important targets for phloridzin to antagonize MEHP-induced MRT. Our study provides a new approach to discover the antagonists for the toxicity of environmental contaminants based on AOP network and dtGSEA methods.

The Role of Bone-Derived Osteocalcin in Testicular Steroidogenesis: Contributing Factor to Male Fertility

Osteocalcin (OCN), a protein predominantly produced by osteoblasts in bone, has emerged as a significant factor in bone metabolism and reproductive function. This article reviews the latest research on the role of OCN beyond its traditional functions in bone mineralisation, particularly its influence on testicular steroidogenesis and male fertility. The structure and modifications of OCN are elaborated upon, highlighting its uncarboxylated form (ucOCN), which is becoming increasingly recognised for its bioactive properties. The impact of OCN on bone quantity, quality and strength is summarised, emphasising its role as a regulator of bone metabolism. Furthermore, the influence of ucOCN on testicular steroidogenesis and the involvement of GPRC6A, a G protein-coupled receptor, in mediating these effects are also explored. Evidence suggests that ucOCN regulates testosterone synthesis and spermatogenesis, which indirectly have the potential to influence bone metabolism integrity. In conclusion, OCN, particularly in its uncarboxylated form, plays a crucial role in bone metabolism and male fertility by regulating testicular steroidogenesis, with GPRC6A mediating these effects, thereby linking bone health and reproductive functions.

Identification of crucial LncRNAs associated with testicular development and LOC108635509 as a potential regulator in black goat spermatogenesis

The establishment and maintenance of spermatogenesis is a complex process involving a vast of regulatory pathways. There is growing evidence revealing that long noncoding RNAs (lncRNA) play important roles in regulating testicular development and spermatogenesis in a stage-specific way. However, our understanding of how lncRNA regulates testicular development and spermatogenesis in black goats is quite limited. In the current study, we screened the transcriptomes (lncRNA and mRNA) of testicular from Guangxi black goats before puberty (3 days old, D3; 30 days old, D30), puberty (90 days old, D90) and postpuberty (180 days old, D180), in order to identify the lncRNA interaction with mRNAs contributes to goat spermatogenesis. The RNA-sequencing (RNA-seq) analysis showed that there were 1211, 12,180, 834 differential lncRNAs and 1196, 8838,269 differential mRNAs at the ages of D30 vs. D3, D90 vs. D30, and D180 vs. D90. The lncRNAs showed the most significantly changes from D30 to D90, which indicated that D90 was a key node of lncRNAs participated in the regulation of testicular development and spermatogenesis in black goat. According to functional enrichment analysis of GO and KEGG, we found that differentially expressed lncRNAs (DE lncRNAs) and their target genes regulated spermatogenesis through signal pathways including MAPK, Ras, and PI3K-Akt. Using cis- and trans-acting, 39 DE lncRNAs-targeted genes were found to be enriched for male reproduction. Of these, LOC108635509, which specific expressed in testis and upregulated the expression levels at D90, was found participated in the regulation of testicular development through promoting the proliferation of Sertoli cells (SCs). Overall, this study provides new insight into the regulatory mechanisms that support spermatogenesis and testicular development in black goats.

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).

Trajectory model to analyze the effect of multi-metal exposures on sperm parameters and sex hormones of the MARHCS cohort in China

BACKGROUND

At present, several cross-sectional studies have found that exposure to metal/metalloid elements is closely associated with male reproduction. However, the long-term effects of metal exposure on male reproduction have not been explored.

METHODS

In 2013, 796 volunteers were recruited, followed by first and second follow-ups in 2014 and 2015. Urine, semen, and blood samples were collected at each stage to examine urinary metal/metalloid levels, sperm parameters, and sex hormones. Initially, the latent class trajectory model (LCTM) was utilized to analyze the trajectories of urinary metals. Subsequently, the effects of urinary metal trajectories on semen parameters and sex hormones were examined using the linear mixed model. Finally, the impact of urinary metal trajectories on the classification of semen quality (normal or abnormal) was evaluated using the generalized linear mixed model.

RESULTS

Among the 18 metals/metalloids studied, trajectories were formed by 6 of them (Li, Al, Fe, Zn, As, Rb). Further analysis using the linear mixed model and the generalized linear mixed model revealed that Li was negatively correlated with semen volume, and sperm motility (P < 0.05). The maximum-decreasing trajectory group had a detrimental effect on semen quality (OR = 1.75, 95%CI: 1.22, 2.53) compared to the minimum-stable trajectory group. Al showed negative associations with sperm concentration, total sperm count, and normal morphology (P < 0.05). Rb was positively associated with progressive motility (P < 0.05). The high-stable trajectory group exhibited a protective effect on semen quality (OR = 0.66, 95%CI: 0.49, 0.90) compared to the low-stable trajectory group. Additionally, Fe was observed to have a negative relationship with follicle-stimulating hormone (FSH) (P < 0.05), and Rb exhibited a negative correlation with progesterone (P) (P < 0.05).

CONCLUSION

Our three-year cohort study provides new evidence that Li and Al have a negative impact on semen quality, whereas Rb is associated with beneficial effects. Additionally, Rb and Fe are endocrine disruptors of sex hormones.

New insights into the mechanisms underlying 5-hydroxymethylfurfural-induced suppression of testosterone biosynthesis in vivo and in vitro

5-hydroxymethylfurfural (HMF), produced by the Maillard reaction, can indicate thermal processes in food. Previous research has examined the cytotoxic, genotoxic, mutagenic, and carcinogenic characteristics of HMF and its derivatives in different organs. Nevertheless, there is currently no available evidence about the impact of HMF on male reproductive toxicity. In this study, the effects of HMF on testosterone biosynthesis in both mouse testis and TM3 Leydig cells were investigated. HMF was administered to mice at doses of 30 and 300 mg/kg/day for 21 days and to Leydig cells at concentrations of 0.1, 1, and 10 mM for 24 h. The mechanism of action of HMF on testosterone biosynthesis in both mouse testis and Leydig cells was revealed by measuring the amount of testosterone, 3',5'-cyclic adenosine monophosphate (cAMP) levels, and the expression level of some important genes in the steroidogenic pathway. In addition, its effects on general testis were examined through histopathological evaluations. Upon examination of the results, it was observed that HMF had a significant impact on reducing testosterone and cAMP levels. Furthermore, HMF inhibited the expression of steroidogenic genes, including steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, 3β-hydroxy dehydrogenase, and 17β-hydroxy dehydrogenase, as well as transcription factors, such as steroidogenic factor-1, GATA binding protein-4, and nerve growth factor IB. HMF-administrated groups had germinal epithelium degradation, vacuolization, and disorders in the interstitial area. Consequently, it has been proven for the first time that HMF can damage the male reproductive system by detrimentally impacting the production of testosterone.

The impact of furan exposure on steroidogenesis in Leydig cells: cellular and molecular observations

BACKGROUND

Furan is an organic compound that occurs as a result of heat treatment during the processing and cooking of many food products. Furthermore, the environment contains furan in tobacco smoke and vehicle exhaust gases, and it serves as an intermediate molecule in the synthesis of various pharmaceutical and chemical agents, pesticides, and stabilizers. Studies on the male reproductive system have not been able to elucidate the pathway through which furan exerts its negative effects.

METHODS AND RESULTS

In this study, the TM3 Leydig cell line was exposed to various furan concentrations (0.03, 0.3, and 3 mM) for 24 h. In order to assess the cytotoxic effects of furan on Leydig cells, we examined cell viability, cell proliferation, and lactate dehydrogenase enzyme levels. To investigate the detrimental effects of furan on testosterone biosynthesis, quantitative analyses were conducted on cAMP and testosterone levels, as well as the expression levels of key genes and transcription factors implicated in the steroidogenic pathway. The results indicate that furan inhibited the viability and proliferation of Leydig cells and enhanced the activity of lactate dehydrogenase. Leydig cells administered to furan exhibited notable reductions in cAMP and testosterone levels. Additionally, while the expression levels of steroidogenic genes were downregulated, significant changes were detected in the expression levels of the transcription factors responsible for the regulation of these genes.

CONCLUSIONS

Consequently, our findings suggest that furan exerts inhibitory effects on steroidogenesis in Leydig cells through multiple mechanisms, ultimately leading to infertility by inducing dysfunction in Leydig cells.

Association of Atrazine-Induced Overexpression of Aldo-Keto-Reductase 1C2 (AKR1C2) with Hypoandrogenism and Infertility: An Experimental Study in Male Wistar Rat

Atrazine (ATZ, C8H14ClN5) is a widely used synthetic herbicide that contaminates drinking water. It is a known endocrine disruptor that disrupts various molecular pathways involved in hormone signaling, and DNA damage, and can cause reproductive disorders, including decreased fertility, and abnormal development of reproductive organs, as revealed in animal model studies. However, the effect of ATZ on steroidogenesis in the male reproductive system, especially reduction of ketosteroids to hydroxysteroids, remains unclear. This study investigated the toxicity of ATZ on the male reproductive system in the Wistar rat model, with an emphasis on its adverse effect on aldo-ketoreductase family 1 member C2 (AKR1C2). Male Wistar rats were administered ATZ for 56 days (duration of one spermatogenic cycle) through oral route, at 20, 40 and 60 mg/kg body weight (bw) doses. The results indicate that ATZ exposure affects the body weight, impairs sperm production, and decrease FSH, LH, and testosterone levels. Additionally, the down-regulation of key steroidogenic enzymes by ATZ disrupted the synthesis of testosterone, leading to decreased levels of this essential male hormone. On the other hand, the expression of AKR1C2 (mRNA and protein) in the testis was upregulated. The findings suggest that AKR1C2 plays a role in androgen metabolism. Furthermore, its overexpression may lead to alteration in the expression of genes in the connected pathway, causing an increase in the breakdown or inactivation of androgens, which would result in lower androgen levels and, thereby, lead to hypoandrogenism, as the combined effects of down-regulation of steroidogenic genes and up-regulation of AKR1C2. These findings reveal direct implication of disrupted AKR1C2 in male reproductive health and highlight the need for further research on the impact of environmental toxins on human fertility, ultimately providing for better patient care.

Potential role of mitochondria and endoplasmic reticulum in the response elicited by D-aspartate in TM4 Sertoli cells

D-Aspartic Acid (D-Asp) affects spermatogenesis by enhancing the biosynthesis of the sex steroid hormones acting either through the hypothalamus-pituitary-testis axis or directly on Leydig cells. Recently, in vitro studies have also demonstrated the direct effects of D-Asp on the proliferation and/or activity of germ cells. However, although D-Asp is present in Sertoli cells (SC), the specific role of the amino acid in these cells remains unknown. This study investigated the effects of D-Asp on the proliferation and activity of TM4 SC, focusing on the mitochondrial compartment and its association with the endoplasmic reticulum (ER). We found that D-Asp enhanced the proliferation and activity of TM4 cells as evidenced by the activation of ERK/Akt/PCNA pathway and the increase in the protein levels of the androgen receptor. Furthermore, D-Asp reduced both the oxidative stress and apoptotic process. An increase in mitochondrial functionality and dynamics, as well as a reduction in ER stress, were also found in D-Asp-treated TM4 cells. It is known that mitochondria are closely associated with ER to form the Mitochondrial-Associated Endoplasmic Reticulum Membranes (MAM), the site of calcium ions and lipid transfer from ER to the mitochondria, and vice versa. The data demonstrated that D-Asp induced stabilization of MAM in TM4 cells. In conclusion, this study is the first to demonstrate a direct effect of D-Asp on SC activity and to clarify the cellular/molecular mechanism underlying these effects, suggesting that D-Asp could stimulate spermatogenesis by improving the efficiency of SC.

Multi-omics reveals the testosterone promotion effect mechanism of Cordyceps Sobolifera on Leydig cells

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps sobolifera (CS) has been traditionally utilized as an ethnic remedy for various health conditions, including chronic kidney diseases, anti-fatigue interventions, and management of chronic inflammation. Notably, CS is recognized for its substantial content of bioactive compounds, among which nucleosides prominently feature as constituents with diverse therapeutic advantages.

AIM OF THE STUDY

This study aims to investigate the effects of CS on testosterone secretion in Leydig cells and explore the underlying mechanism.

MATERIALS AND METHODS

Leydig cells were isolated from rat testes to establish a primary rat Leydig cells model. Cell proliferation and testosterone secretion were assessed via the methyl-piperidino-pyrazole (MTT) assay and enzyme-linked immunosorbent assay (ELISA), respectively. Samples earmarked for RNA sequencing (RNA-Seq) analysis facilitated the identification of significantly differentially expressed genes (DEGs), and we conducted Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) functional annotation and enrichment analyses. The veracity of our findings was validated through quantitative real time polymerase chain reaction (qRT-PCR) and western blotting.

RESULTS

The results showed that CS and guanosine could promote Leydig cell proliferation and bolster testosterone secretion. Our integrative analysis of metabolomics and transcriptomics has unveiled the potential mechanisms governing testosterone synthesis. Specifically, metabolomics has illuminated striking correlations within cholesterol metabolism, and bile secretion. Concurrently, transcriptomics has underscored the pivotal roles played by the cyclic adenosine monophosphate (cAMP) signaling pathway and steroid hormone biosynthesis. Furthermore, our investigation has demonstrated CS's aptitude in elevating the expression of proteins and genes. Notably, our findings have elucidated that these effects can be mitigated by protein kinase A (PKA) and adenylate cyclase (AC) specific inhibitors.

CONCLUSION

This study delineates the cAMP-PKA pathways as plausible mechanisms underpinning the testosterone-enhancing properties of CS, with guanosine emerging as a fundamental bioactive constituent.

A critical review on male-female reproductive and developmental toxicity induced by micro-plastics and nano-plastics through different signaling pathways

It is widely accepted that humans are constantly exposed to micro-plastics and nano-plastics through various routes, including inhalation of airborne particles, exposure to dust, and consumption of food and water. It is estimated that humans may consume thousand to millions of micro-plastic particles, equating to several milligrams per day. Prolonged exposure to micro-plastics and nano-plastics has been linked to negative effects on different living organisms, including neurotoxicity, gastrointestinal toxicity, nephrotoxicity, and hepatotoxicity, and developmental toxicities. The main purpose of this review is to explore the effect of micro-plastics and nano-plastics on the male and female reproductive system, as well as their offspring, and the associated mechanism implicated in the reproductive and developmental toxicities. Micro-plastics and nano-plastics have been shown to exert negative effects on the reproductive system of both male and female mammals and aquatic animals, including developmental impacts on gonads, gametes, embryo, and their subsequent generation. In addition, micro-plastics and nano-plastics impact the hypothalamic-pituitary axes, leading to oxidative stress, reproductive toxicity, neurotoxicity, cytotoxicity, developmental abnormalities, poor sperm quality, diminishes ovarian ovulation and immune toxicity. This study discusses the so many different signaling pathways associated in the male and female reproductive and developmental toxicity induced by micro-plastics and nano-plastics.

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

Effect of Curcuma longa extract on reproduction function in mice and testosterone production in Leydig cells

Curcuma longa, best known for its culinary application as the main constituent of curry powder, has shown potential impact on the reproductive system. This study aimed to investigate the efficacy of Curcuma longa extract (CLE) on Kidney-Yang deficiency mice induced by hydrocortisone and the possible roles in testosterone secretion in Leydig cells. We evaluated male sexual behaviour, reproductive organ weight, testosterone levels, and histological tissue changes in hydrocortisone-induced mice. CLE effectively reversed hydrocortisone-induced Kidney-Yang deficiency syndrome by improving sexual behaviour, testis and epididymis weight, testosterone levels and reducing pathological damage. Our in vitro study further indicated that CLE stimulated testosterone production via upregulating the mRNA and protein expression of steroidogenic enzymes in Leydig cells. It significantly improved H89-inhibited protein expression of StAR and cAMP-response element-binding (CREB), as well as melatonin-suppressed StAR protein expression. The data obtained from this study suggest that CLE could alleviate Kidney-Yang deficiency symptoms and stimulate testosterone production by upregulating the steroidogenic pathway. This research identifies CLE as a potential nutraceutical option for addressing testosterone deficiency diseases.

In vitro and in vivo studies on the effect of a mitochondrial fusion promoter on Leydig cell integrity and function

Background: The interstitial testicular Leydig cells are responsible for the production of testosterone, which functionally deteriorate with normal aging. Decreased expression of mitochondrial steroidogenic interactome proteins and diminished mitochondrial function in aging Leydig cells suggest that mitochondrial dynamics play a role in maintaining adequate levels of testosterone. Optic atrophy 1 (OPA1) protein regulates mitochondrial dynamics and cristae formation in many cell types. Previous studies showed that increasing OPA1 expression in dysfunctional Leydig cells restored mitochondrial function and recovered androgen production to levels found in healthy Leydig cells. These findings suggested that mitochondrial dynamics may be a promising target to ameliorate diminished testosterone levels in aging males. Methods: We used twelve-month-old rats to explore the relationship between mitochondrial dynamics and Leydig cell function. Isolated Leydig cells from aged rats were treated ex vivo with the cell-permeable mitochondrial fusion promoter 4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl)hydrazono)ethyl) phenol (mitochondrial fusion promoter M1), which enhances mitochondrial tubular network formation. In parallel, rats were treated with 2 mg/kg/day M1 for 6 weeks before Leydig cells were isolated. Results: Ex vivo M1-treated cells showed enhanced mitochondrial tubular network formation by transmission electron microscopy, enhanced Leydig cell mitochondrial integrity, improved mitochondrial function, and higher testosterone biosynthesis compared to controls. However, in vivo treatment of aged rats with M1 not only failed to re-establish testosterone levels to that of young rats, it also led to further reduction of testosterone levels and increased apoptosis, suggesting M1 toxicity in the testis. The in vivo M1 toxicity seemed to be tissue-specific, however. Conclusion: Promoting mitochondrial fusion may be one approach to enhancing cell health and wellbeing with aging, but more investigations are warranted. Our findings suggest that fusion promoters could potentially enhance the productivity of aged Leydig cells when carefully regulated.

Temporal Changes in the Local Expression of Central Hormone-Regulating Factors in Rat Testis

Present study aimed to investigate the temporal changes in expression of some reproductive hormones in testis, originally found in hypothalamus and pituitary. Rats were sacrificed on postnatal day 23 (PND23; immature), pubertal (PND53) and PND 81 (young adult). The testicular RNAs were extracted, and semi-quantitative PCRs for gonadotropin-releasing hormone (GnRH), kisspeptin 1 (KiSS1), pituitary adenylate cyclase-activating polypeptide (PACAP), LH subunits and LH receptor were performed. Transcript levels of GnRH and KiSS1 at PND23 were significantly higher than levels of PND53 and PND81 (p <0.001). PACAP mRNA level at PND23 was significantly lower than those of PND53 and PND81 (p <0.001). The mRNA levels of both testis type and pituitary type luteinizing hormone β subunit (tLHβ and pLHβ, respectively) at PND23 were significantly lower than levels of PND53 and PND81 (p <0.001). The mRNA level of glycoprotein hormone common alpha subunit (Cgα) at PND23 was significantly lower than those of PND53 and PND81 (p <0.001). Present study revealed the intratesticular expression of KiSS1 and GnRH showed a very similar trend while the expression of PACAP in the testis showed reversed pattern. The expressions of LHβ subunits (tLHβ and pLHβ) were very low during immature stage then increased significantly during puberty and early adulthood. Our attempt to study the local role(s) of intratesticular factors will be helpful to achieve precise understanding on the testis physiology and pathology.

Unraveling the threat: Microplastics and nano-plastics' impact on reproductive viability across ecosystems

Plastic pollution pervades both marine and terrestrial ecosystems, fragmenting over time into microplastics (MPs) and nano-plastics (NPs). These particles infiltrate organisms via ingestion, inhalation, and dermal absorption, predominantly through the trophic interactions. This review elucidated the impacts of MPs/NPs on the reproductive viability of various species. MPs/NPs lead to reduced reproduction rates, abnormal larval development and increased mortality in aquatic invertebrates. Microplastics cause hormone secretion disorders and gonadal tissue damage in fish. In addition, the fertilization rate of eggs is reduced, and the larval deformity rate and mortality rate are increased. Male mammals exposed to MPs/NPs exhibit testicular anomalies, compromised sperm health, endocrine disturbances, oxidative stress, inflammation, and granulocyte apoptosis. In female mammals, including humans, exposure culminates in ovarian and uterine deformities, endocrine imbalances, oxidative stress, inflammation, granulosa cell apoptosis, and tissue fibrogenesis. Rodent offspring exposed to MPs experience increased mortality rates, while survivors display metabolic perturbations, reproductive anomalies, and weakened immunity. These challenges are intrinsically linked to the transgenerational conveyance of MPs. The ubiquity of MPs/NPs threatens biodiversity and, crucially, jeopardizes human reproductive health. The current findings underscore the exigency for comprehensive research and proactive interventions to ameliorate the implications of these pollutants.

Melatonin alleviates oxidative stress damage in mouse testes induced by bisphenol A

We investigated the effect of melatonin on bisphenol A (BPA)-induced oxidative stress damage in testicular tissue and Leydig cells. Mice were gavaged with 50 mg/kg BPA for 30 days, and concurrently, were injected with melatonin (10 mg/kg and 20 mg/kg). Leydig cells were treated with 10 μmol/L of BPA and melatonin. The morphology and organ index of the testis and epididymis were observed and calculated. The sperm viability and density were determined. The expressions of melatonin receptor 1A and luteinizing hormone receptor, and the levels of malonaldehyde, antioxidant enzymes, glutathione, steroid hormone synthases, aromatase, luteinizing hormone, testosterone, and estradiol were measured. TUNEL assay was utilized to detect testicular cell apoptosis. The administration of melatonin at 20 mg/kg significantly improved the testicular index and epididymis index in mice treated with BPA. Additionally, melatonin promoted the development of seminiferous tubules in the testes. Furthermore, the treatment with 20 mg/kg melatonin significantly increased sperm viability and sperm density in mice, while also promoting the expressions of melatonin receptor 1A and luteinizing hormone receptor in Leydig cells of BPA-treated mice. Significantly, melatonin reduced the level of malonaldehyde in testicular tissue and increased the expression of antioxidant enzymes (superoxide dismutase 1, superoxide dismutase 2, and catalase) as well as the content of glutathione. Moreover, melatonin also reduced the number of apoptotic Leydig cells and spermatogonia, aromatase expression, and estradiol level, while increasing the expression of steroid hormone synthases (steroidogenic acute regulatory protein, cytochrome P450 family 17a1, cytochrome P450 17α-hydroxylase/20-lyase, and, 17β-hydroxysteroid dehydrogenase) and the level of testosterone. Melatonin exhibited significant potential in alleviating testicular oxidative stress damage caused by BPA. These beneficial effects may be attributed to melatonin's ability to enhance the antioxidant capacity of testicular tissue, promote testosterone synthesis, and reduce testicular cell apoptosis.

Ethylene dimethanesulfonate effects on gene promoter activities related to the endocrine function of immortalized Leydig cell lines R2C and MA-10

Ethylene dimethanesulfonate (EDS) is a molecule with known selective cytotoxicity on adult Leydig cells. A single intraperitoneal injection in rats but not mice, leads to male androgen deprivation and infertility. In vitro studies using rat and mouse immortalized Leydig cell lines, showed similar effects of cell death promoted by EDS in rat cells as seen in vivo, and suggest that EDS affects gene transcription, which could firstly compromise steroidogenesis before the apoptosis process. Using gene reporter assay, this study aimed to investigate EDS effects on the promoter activity of genes important for endocrine function (Star, Insl3) and response to toxic agents (Gsta3) in immortalized Leydig cell lines (rat R2C and mouse MA-10 cells), as well as identify possible EDS-responsive elements in the Star gene promoter. EDS exposure of R2C and MA-10 Leydig cells increased Gsta3 promoter activity after 4 h of treatment and decreased Insl3 promoter activity only in R2C cells after 24 h of treatment. EDS also decreased Star promoter activity in both Leydig cell lines. Using R2C cells, the EDS-responsive region in the Star promoter was located between -400 and -195 bp. This suggests that this region and the associated transcription factors, which include MEF2, might be targeted by EDS. Additional somatic gonadal cell lines expressing Star were used and EDS did not affect Star promoter activity in DC3 granulosa cells while Star promoter activity was increased in MSC-1 Sertoli cells after 24 h of treatment. This study contributes to the knowledge regarding the mechanism of EDS action in Leydig cells, and in other gonadal cell lineages, and brings new light regarding the rats and mice differential susceptibility to EDS effects, in addition to providing new avenues for experimental approaches to better understand Leydig cell function and dynamics in different rodent species.

Antioxidant, anti-inflammatory, and anti-apoptotic effects of genkwanin against aflatoxin B1-induced testicular toxicity

Aflatoxin B1 (AFB1) is the most hazardous aflatoxin that causes significant damage to the male reproductive system. Genkwanin (GNK) is a bioactive flavonoid that shows antioxidant and anti-inflammatory potential. Therefore, the current study was planned to evaluate the effects of GNK against AFB1-induced testicular toxicity. Forty-eight male rats were distributed into four groups (n = 12 rats). AFB1 (50 μg/kg) and GNK (20 mg/kg) were administered to the rats for eight weeks. Results of the current study revealed that AFB1 exposure induced adverse effects on the Nrf2/Keap1 pathway and reduced the expressions and activities of antioxidant enzymes. Additionally, it increased the levels of oxidative stress markers. Furthermore, expressions of steroidogenic enzymes were down-regulated by AFB1 intoxication. Besides, AFB1 exposure reduced the levels of gonadotropins and plasma testosterone, which subsequently reduced the epididymal sperm count, motility, and hypo-osmotic swelled (HOS) sperms, while increasing the number of dead sperms and causing morphological anomalies of the head, midpiece, and tail of the sperms. In addition, AFB1 decreased the activities of testicular function marker enzymes and the levels of inflammatory markers. Moreover, it severely affected the apoptotic profile by up-regulating the expressions of Bax and Casp3, while down-regulating the Bcl2 expression. Besides, AFB1 significantly damaged the histoarchitecture of testicular tissues. However, GNK treatment reversed all the AFB1-induced damages in the rats. Taken together, the current study reports the potential use of GNK as a therapeutic agent to prevent AFB1-induced testicular toxicity due to its antioxidant, anti-inflammatory, and anti-apoptotic properties.

Co-exposure to polystyrene microplastics and microcystin-LR aggravated male reproductive toxicity in mice

Microplastics (MPs) are plastic pollutants with a diameter of less than 5 mm and microcystins (MCs) are natural toxins produced by cyanobacteria. In recent years, the pollution of MPs and MCs attracted widespread attention. However, our understanding about the toxic effects of co-exposure of MPs and MCs on male reproduction is limited. Mice were continuously exposed to 0.04mg/(kg*bw) microcystin-leucine-arginine (MC-LR) or 45 mg/(kg*bw) polystyrene microplastics (PS-MPs) or a mixed solution of 0.04mg/(kg*bw) MC-LR and 45 mg/(kg*bw) PS-MPs by gavage for 28 days in this study. The results showed that PS-MPs could absorb MC-LR in ddH2O and MC-LR content in testis was increased in the group with combined exposure when compared to the group only exposed to MC-LR. Exposure to PS-MPs or MC-LR individually could destroy testis structure, increase the level of tissue apoptosis and decrease the quality of sperm, while the co-exposure enhanced the toxic effects. Furthermore, PS-MPs could carry MC-LR into testis Leydig cells, reduce testosterone levels and mRNA expression levels of key molecules involved in testosterone synthesis (StAR, P450scc, P450c17,3β-HSD and 17β-HSD). Among them, the combined effect of PS-MPs-MC-LR was the most severe. In summary, this study provides new insights into the toxicity of MPs and MCs in mammals.

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.

Effect of Fetal Pituitary-Testes Suppression on Brain Sexual Differentiation and Reproductive Function in Male Sheep

We previously demonstrated that treating fetal lambs on gestational day 62 with the long-acting gonadotrophin-releasing hormone (GnRH) antagonist degarelix (DG) suppresses pituitary-testicular function during midgestation. The objective of this study was to investigate whether impaired gonadotrophic drive during this fetal period has enduring effects on sexual differentiation and reproductive function in adult male sheep. We assessed the effects of prenatal administration of DG, with or without testosterone (T) replacement, on various sexually dimorphic behavioral traits in adult rams, including sexual partner preferences, as well as neuroendocrine responsiveness and testicular function. Our findings revealed that DG treatment had no effect on genital differentiation or somatic growth. There were some indications that DG treatment suppressed juvenile play behavior and adult sexual motivation; however, male-typical sexual differentiation of reproductive behavior, sexual partner preference, and gonadotropin feedback remained unaffected and appeared to be fully masculinized and defeminized. DG-treated rams showed an increased LH response to GnRH stimulation and a decreased T response to human chorionic gonadotropin stimulation, suggesting impaired Leydig cell function and reduced T feedback. Both effects were reversed by cotreatment with T propionate. DG treatment also suppressed the expression of CYP17 messenger RNA, a key enzyme for T biosynthesis. Despite the mild hypogonadism induced by DG treatment, ejaculate volume, sperm motility, and sperm morphology were not affected. In summary, these results suggest that blocking GnRH during midgestation does not have enduring effects on brain sexual differentiation but does negatively affect the testes' capacity to synthesize T.

Anti-apoptotic effect of adrenomedullin gene delivery on Leydig cells by suppressing TGF-β1 via the Hippo signaling pathway

This study aims to establish whether adrenomedullin (ADM) is capable to restore the steroidogenic functions of Leydig cells by suppressing transforming growth factor-β1 (TGF-β1) through Hippo signaling. Primary Leydig cells were treated with lipopolysaccharide (LPS), an adeno-associated virus vector that expressed ADM (Ad-ADM) or sh-RNA of TGF-β1 (Ad-sh-TGF-β1). The cell viability and medium concentrations of testosterone were detected. Gene expression and protein levels were determined for steroidogenic enzymes, TGF-β1, RhoA, YAP, TAZ and TEAD1. The role of Ad-ADM in the regulation of TGF-β1 promoter was confirmed by ChIP and Co-IP. Similar to Ad-sh-TGF-β1, Ad-ADM mitigated the decline in the number of Leydig cells and plasma concentrations of testosterone by restoring the gene and protein levels of SF-1, LRH1, NUR77, StAR, P450scc, 3β-HSD, CYP17 and 17β-HSD. Similar to Ad-sh-TGF-β1, Ad-ADM not only inhibited the LPS-induced cytotoxicity and cell apoptosis but also restored the gene and protein levels of SF-1, LRH1, NUR77, StAR, P450scc, 3β-HSD, CYP17 and 17β-HSD, along with the medium concentrations of testosterone in LPS-induced Leydig cells. Like Ad-sh-TGF-β1, Ad-ADM improved LPS-induced TGF-β1 expression. In addition, Ad-ADM suppressed RhoA activation, enhanced the phosphorylation of YAP and TAZ, reduced the expression of TEAD1 which interacted with HDAC5 and then bound to TGF-β1 gene promoter in LPS-exposed Leydig cells. It is thus suspected that ADM can exert anti-apoptotic effect to restore the steroidogenic functions of Leydig cells by suppressing TGF-β1 through Hippo signaling.

ERK5 Cooperates With MEF2C to Regulate Nr4a1 Transcription in MA-10 and MLTC-1 Leydig Cells

Leydig cells produce hormones required for the development and maintenance of sex characteristics and fertility in males. MEF2 transcription factors are important regulators of Leydig cell gene expression and steroidogenesis. ERK5 is an atypical member of the MAP kinase family that modulates transcription factor activity, either by direct phosphorylation or by acting as a transcriptional coactivator. While MEF2 and ERK5 are known to cooperate transcriptionally, the presence and role of ERK5 in Leydig cells remained unknown. Our goal was to determine whether ERK5 is present in Leydig cells and whether it cooperates with MEF2 to regulate gene expression. We found that ERK5 is present in Leydig cells in testicular tissue and immortalized cell lines. ERK5 knockdown in human chorionic gonadotrophin-treated MA-10 Leydig cells reduced steroidogenesis and decreased Star and Nr4a1 expression. Luciferase assays using a synthetic reporter plasmid containing 3 MEF2 elements revealed that ERK5 enhances MEF2-dependent promoter activation. Although ERK5 did not cooperate with MEF2 on the Star promoter in Leydig cell lines, we found that ERK5 and MEF2C do cooperate on the Nr4a1 promoter, which contains 2 adjacent MEF2 elements. Mutation of each MEF2 element in a short version of the Nr4a1 promoter significantly decreased the ERK5/MEF2C cooperation, indicating that both MEF2 elements need to be intact. The ERK5/MEF2C cooperation did not require phosphorylation of MEF2C on Ser387. Taken together, our data identify ERK5 as a new regulator of MEF2 activity in Leydig cells and provide potential new insights into mechanisms that regulate Leydig cell gene expression and function.

Combined levothyroxine and testosterone treatment for restoring erectile dysfunction in propylthiouracil-induced hypothyroid rats

BACKGROUND

Sexual dysfunction may indicate severe endocrine diseases. Recent research has suggested a link between hypothyroidism, low testosterone (T) levels, and erectile dysfunction (ED); however, the exact cause is unknown.

AIM

We sought to investigate possible beneficial effects of levothyroxine and T alone or in combination on ED in propylthiouracil (PTU)-induced hypothyroid rats.

METHODS

Adult Wistar rats (n = 35) were divided into 5 groups: control, PTU-induced hypothyroidism, PTU + levothyroxine, PTU + Sustanon (a mixture of 4 types of T: propionate, phenylpropionate, isocaproate, and decanoate) and PTU + levothyroxine + Sustanon. PTU was given in drinking water for 6 weeks. Four weeks after PTU administration, levothyroxine (20 μg microgram kg/day, oral) and Sustanon (10 mg/kg/week, intramuscular) were given for 2 weeks. Serum levels of total T, triiodothyronine (T3), and thyroxine (T4) were determined. In vivo erectile response and in vitro relaxant responses were measured. Localization of neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS), and phosphodiesterase type 5 (PDE5) were determined using immunohistochemical analysis. The relative area of smooth muscle to collagen was measured using Masson trichrome staining.

OUTCOMES

Outcome variables included in vivo erectile function, in vitro relaxant and contractile responses of corpus cavernosum (CC) strips; protein localization of eNOS, nNOS, and PDE5; and smooth muscle content in penile tissue.

RESULTS

The rat model of hypothyroidism showed a significant decline in serum levels of total T, T3, and T4. Levothyroxine increased T3 and T4 levels, whereas Sustanon normalized only total T levels. Combined treatment enhanced all hormone levels. Rats with hypothyroidism displayed the lowest erectile response (P < 0.001 vs controls). Combined treatment returned reduced responses, while partial amelioration was observed after levothyroxine and Sustanon treatment alone. Acetylcholine (P < 0.01 vs controls), electrical field stimulation (P < 0.001 vs controls), and sildenafil-induced relaxant responses (P < 0.05 vs controls) were decreased in the CC strips from hypothyroid rats. The combined treatment increased the reduction in relaxation responses. Levothyroxine and Sustanon restored decreases in eNOS and nNOS expression in the hypothyroid group. There was no significant difference in PDE5 expression among groups. Monotreatment partially enhanced reduced smooth muscle mass, while combined therapy completely recovered.

CLINICAL IMPLICATIONS

The combination of thyroid hormones and T is likely to be a therapeutic approach for treatment of hypothyroidism-induced ED in men.

STRENGTHS AND LIMITATIONS

Beneficial effects of levothyroxine and Sustanon treatment were shown in vitro and in vivo in PTU-induced hypothyroid rats. The main limitation of the study was the lack of measurement of androgen-sensitive organ weights and luteinizing hormone, follicle-stimulating hormone, and prolactin levels.

CONCLUSION

These findings demonstrate that neurogenic and endothelium-dependent relaxation responses are reduced by hypothyroidism, which is detrimental to T levels and erectile responses. Levothyroxine and Sustanon combination medication was able to counteract this effect.

Therapeutic effect of gossypetin against paraquat-induced testicular damage in male rats: a histological and biochemical study

Paraquat (PQ) is an organic compound, which is commonly used as a herbicide in the agriculture sector, and it is also known to stimulate critical damages in the male reproductive system. Gossypetin (GPTN) is one of important members of the flavonoid family, which is an essential compound in flowers and calyx of Hibiscus sabdariffa with potential pharmacological properties. The current investigation was aimed to examine the ameliorative potential of GPTN against PQ-instigated testicular damages. Adult male Sprague-Dawley rats (n = 48) were distributed into four groups: control, PQ (5 mg/kg), PQ + GPTN (5 mg/kg + 30 mg/kg respectively), and GPTN (30 mg/kg). After 56 days of treatment, biochemical, spermatogenic indices, hormonal, steroidogenic, pro-or-anti-apoptotic, and histopathological parameters were estimated. PQ exposure disturbed the biochemical profile by reducing the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GSR), while it increased the concentration of reactive oxygen species (ROS) and malondialdehyde (MDA) level. Furthermore, PQ exposure decreased the sperm motility, viability, number of hypo-osmotic tail swelled spermatozoa, and epididymal sperm count; additionally, it increased sperm morphological (head mid-piece and tail) abnormalities. Moreover, PQ lessened the follicle-stimulating hormone (FSH), luteinizing hormone (LH), and plasma testosterone levels. Besides, PQ-intoxication downregulated the gene expression of steroidogenic enzymes (StAR, 3β-HSD, and 17β-HSD) and anti-apoptotic marker (Bcl-2), whereas upregulated the gene expression of apoptotic markers (Bax and Caspase-3). PQ exposure led to histopathological damages in testicular tissues as well. Nonetheless, GPTN inverted all the illustrated impairments in testes. Taken together, GPTN could potently ameliorate PQ-induced reproductive dysfunctions due to its antioxidant, androgenic, and anti-apoptotic potential.

Mitochondrial Dynamics as Potential Modulators of Hormonal Therapy Effectiveness in Males

Worldwide the incidence of andrological diseases is rising every year and, together with it, also the interest in them is increasing due to their strict association with disorders of the reproductive system, including impairment of male fertility, alterations of male hormones production, and/or sexual function. Prevention and early diagnosis of andrological dysfunctions have long been neglected, with the consequent increase in the incidence and prevalence of diseases otherwise easy to prevent and treat if diagnosed early. In this review, we report the latest evidence of the effect of andrological alterations on fertility potential in both young and adult patients, with a focus on the link between gonadotropins' mechanism of action and mitochondria. Indeed, mitochondria are highly dynamic cellular organelles that undergo rapid morphological adaptations, conditioning a multitude of aspects, including their size, shape, number, transport, cellular distribution, and, consequently, their function. Since the first step of steroidogenesis takes place in these organelles, we consider that mitochondria dynamics might have a possible role in a plethora of signaling cascades, including testosterone production. In addition, we also hypothesize a central role of mitochondria fission boost on the decreased response to the commonly administrated hormonal therapy used to treat urological disease in pediatric and adolescent patients as well as infertile adults.

Oxytocin modulates steroidogenesis-associated genes and estradiol levels in the placenta

Oxytocin (OXT) plays a significant role during pregnancy, especially toward the end of pregnancy. Some studies have reported that OXT is involved in the stimulation of steroidogenesis in several organs. However, the effects of OXT on placental steroidogenesis have not yet been established. In this study, we investigated the regulation of steroid hormones and steroidogenic enzymes by OXT-associated signaling in vitro and in vivo. OXT increased the gene expression of steroidogenic enzymes, which convert pregnenolone to progesterone and dehydroepiandrosterone (DHEA) in vitro. In OXT-administered pregnant rats, pregnenolone and DHEA levels were significantly enhanced in the plasma and the expression of the enzymes synthesizing DHEA, testosterone, and estradiol (E2) was increased in placental tissues. Furthermore, OXT was found to affect placental cell differentiation, which is closely related to steroid hormone synthesis. After treatment of the pregnant rats with atosiban, an antagonist of the OXT receptor, the concentration of E2 in the plasma and the expression of E2-synthesizing enzyme were reduced. This regulation may be due to OXT-mediated differentiation, because OXT increases the expression of corticotropin-releasing hormone, which is a biomarker of placental cell differentiation. Our findings suggest that OXT contributes to maintaining pregnancy by regulating the differentiation of placental cells and steroidogenesis during pregnancy.

Review of electrochemical and optical biosensors for testosterone measurement

Testosterone is an anabolic steroid and a major sex hormone in males. It plays vital roles, including developing the testis, penis, and prostate, increasing muscle and bone, and sperm production. In both men and women, testosterone levels should be in normal ranges. Besides, testosterone and its analogs are major global contributors to doping in sport. Due to the importance of testosterone testing, novel, accurate biosensors have been developed. This review summarizes the various methods for testosterone measurement. Also, recent optical and electrochemical approaches for the detection of testosterone and its analogs have been discussed.

Silk sericin alleviates aberrant photoperiod-induced alterations in testicular and adrenal steroidogenesis in adult mice

BACKGROUND

Steroidogenesis is a complex process of sequential enzymatic reactions affected by climate change. Animals respond to altered day length, the so-called photoperiod, with changes in physiology. The study aimed to an evaluation of sericin effect in alleviating steroidogenesis disorders induced by disturbed photoperiod in mice.

METHODS

The animals were randomly divided into three groups according to the lighting cycle: a control group with a standard 12_Light:12_Dark cycle, a short-term photoperiod group with a 6_Light:18_Dark cycle, and a long-term photoperiod group with an 18_Light:6_Dark cycle. Both short and long-term groups were subdivided into two equal subgroups: The placebo and the sericin-treated subgroups received, for five weeks from prepubertal throughout adulthood, one intraperitoneal injection per week of the solvent and 1 g sericin/kg body weight, respectively.

RESULTS

Selected oxidative stress parameters and testicular and adrenal steroidogenic capacities of adult mice were measured. After five weeks, the placebo group with impaired photoperiod showed a decrease in the quality and quantity of sperm and a reduction in testosterone, corticosterone, aldosterone, total antioxidant capacity, xanthine oxidase, and melatonin. At the same time, in these groups, there was an increase in the level of aromatase, malondialdehyde, cholesterol, and steroidogenic factor-1 (SF-1) expression in the adrenal cortex and an enhancement in histological lesions. Mice receiving sericin had parameters similar to the control group.

CONCLUSION

Our findings reveal that silk sericin can reduce the stress caused by photoperiod disorders regarding testicular function, sex hormone levels, and sperm quantity and quality. Thus, sericin is a biocompatible protein with a promising potential for its use in the case of organisms living under an abnormal photoperiod.

Differential Response of Transcription Factors to Activated Kinases in Steroidogenic and Non-Steroidogenic Cells

Hormone-induced Leydig cell steroidogenesis requires rapid changes in gene expression in response to various hormones, cytokines, and growth factors. These proteins act by binding to their receptors on the surface of Leydig cells leading to activation of multiple intracellular signaling cascades, downstream of which are several kinases, including protein kinase A (PKA), Ca2+/calmodulin-dependent protein kinase I (CAMKI), and extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). These kinases participate in hormone-induced steroidogenesis by phosphorylating numerous proteins including transcription factors leading to increased steroidogenic gene expression. How these various kinases and transcription factors come together to appropriately induce steroidogenic gene expression in response to specific stimuli remains poorly understood. In the present work, we compared the effect of PKA, CAMKI and ERK1/2 on the transactivation potential of 15 transcription factors belonging to 5 distinct families on the activity of the Star gene promoter. We not only validated known cooperation between kinases and transcription factors, but we also identified novel cooperations that have not yet been before reported. Some transcription factors were found to respond to all three kinases, whereas others were only activated by one specific kinase. Differential responses were also observed within a family of transcription factors. The diverse response to kinases provides flexibility to ensure proper genomic response of steroidogenic cells to different stimuli.

A Short Promoter Region Containing Conserved Regulatory Motifs Is Required for Steroidogenic Acute Regulatory Protein (Star) Gene Expression in the Mouse Testis

In the testis, Leydig cells produce steroid hormones that are needed to masculinize typical genetic males during fetal development and to initiate and maintain spermatogenesis at puberty and adulthood, respectively. Steroidogenesis is initiated by the transfer of cholesterol from the outer to the inner mitochondrial membrane through the action of steroidogenic acute regulatory protein (STAR). Given its importance for the steroidogenic process, the regulation of STAR gene expression has been the subject of numerous studies. These studies have involved the characterization of key promoter sequences through the identification of relevant transcription factors and the nucleotide motifs (regulatory elements) that they bind. This work has traditionally relied on in vitro studies carried out in cell cultures along with reconstructed promoter sequences. While this approach has been useful for developing models of how a gene might be transcriptionally regulated, one must ultimately validate that these modes of regulation occur in an endogenous context. We have used CRISPR/Cas9 genome editing to modify a short region of the mouse Star promoter (containing a subset of regulatory elements, including conserved CRE, C/EBP, AP1, and GATA motifs) that has been proposed to be critical for Star transcription. Analysis of the resultant mutant mice showed that this short promoter region is indeed required for maximal STAR mRNA and protein levels in the testis. Analysis also showed that both basal and hormone-activated testosterone production in mature mice was unaffected despite significant changes in Star expression. Our results therefore provide the first in vivo validation of regulatory sequences required for Star gene expression.

The cost of the circadian desynchrony on the Leydig cell function

The increased frequency of different lifestyles that disrupts circadian rhythms, together with a trend in the accretion of male idiopathic infertility, imposes the necessity to understand the contribution of circadian rhythms disruption to fertility regulation. In this study, the effects of circadian desynchrony (CD) on the steroidogenic capacity of adult Leydig cells were studied. Adult rats were housed under a disturbing light regime (2 days of constant light, 2 days of continual dark, and 3 days of 12:12 h light:dark schedule) designed to mimic shiftwork in humans. CD was characterized by changed and decreased rhythmic locomotor activity and reduced blood testosterone. In the Leydig cells changed transcription of the clock genes (Bmal1, Clock, Cry1 and Reverba/b increased while Per1/2 reversed phase) was detected. This was followed by reduced transcription of genes (Star, Cyp11a1, and Hsd3b1/2) primarily involved in mitosteroidogenesis. In parallel, mitochondrial membrane potential (Δψi) and ATP production declined losing their characteristic oscillatory pattern. Also, the main markers of mitochondrial biogenesis (Ppargc1a, Nrf1, Tfam, Cytc), fusion (Mfn2), and mitophagy (Pink1 and Tfeb) were disturbed. Collectively, CD targets mitochondria in Leydig cells by reducing mitosteroidogenesis, mitoenergetics, and disturbing mitochondrial dynamics. These changes contribute to testosterone decline compromising androgen-dependent functions, including reproduction.

Arsenic exposure during juvenile and puberty significantly affected reproductive system development of female SD rats

Infertility affects about 10-15% couples over the world, among which a large number of cases the underlying causes are still unclear. Recent studies suggest that environmental factors may play an important role in these idiopathic infertilities. Arsenic is a heavy metal found in drinking water over the world. Its effect on the development of female reproductive system at the environmental-relevant levels is still largely unknown. To test the hypothesis that arsenic exposure during juvenile and puberty may affect sex maturation and female reproductive system development, SD rats of 3 weeks of age were exposed to arsenic with environmental-relevant levels (0, 0.02, 0.2, or 2 mg/L, n = 16/group) through drinking water for about 44 days until the rats reached adulthood (65 days of age). Arsenic exposure significantly reduced the weights of both ovary and uterus without affecting the body weight. Also, arsenic exposure disturbed estrus cycles and reduced the numbers of primordial follicles and corpora lutea while increased atretic follicles. In addition, arsenic reduced serum levels of estradiol, progesterone and testosterone but increased LH and FSH levels in dose-dependent manners. QPCR and Western blot experiments indicated arsenic selectively down-regulated ovarian steroidogenic-related proteins FSHR, STAR, CYP17A1, HSD3B1 and CYP19A1 and signaling molecules PKA-ERK-JNK-cJUN, without affecting AKT and CREB. As about reproductive capacity, arsenic-exposed dams had smaller pups, reduced litter size and lower number of male pups without a change in female pups. In conclusion, juvenile and pubertal arsenic exposures at environmental-relevant levels significantly reduced reproductive functions and capacity by adult. Since the lowest effective dose is very close to the government safety standards, the relevancy of arsenic over exposure to reproductive defects in human deserves further study.

Developmental and reproductive toxic effects of exposure to microplastics: A review of associated signaling pathways

Microplastics (MPs), small pieces of plastic (∼5 mm), are released into the environment not only as a result of the decomposition of large-sized plastics but also from day-to-day use of plastic products. Chronic exposure to MPs has been attributed to harmful effects on aquatic organisms and rodents. Effects include gastrointestinal toxicity, hepatotoxicity, neurotoxicity, and reproductive and developmental toxicities. Exposure to MPs may also potentially affect human health. Herein, we reviewed the impact of MPs on male and female reproductive systems and the associated mechanisms involved in the reproductive and developmental toxicities of MPs. We performed a literature search in Google Scholar and PubMed using the following keywords: MPs and reproductive toxicity; MPs and developmental studies; MPs and infertility; MPs and aquatics; and MPs and rodents. Evidence of MPs accumulation has been reported in many organs of humans and experimental models. The harmful effects of MPs have been manifested in male and female reproductive systems of mammalian and aquatic animals, including developmental effects on gametes, embryos, and their offspring. This review describes various signaling pathways involved in MPs-associated male and female reproductive and developmental toxicities.

The aphrodisiac potential of β-cyclodextrin-curcumin via stimulating cAMP-PKA pathway in testicular Leydig cells

The water-soluble β-cyclodextrin–curcumin (CDC) is used in pharmaceutical applications and as a natural food colorant. The previous study revealed that curcumin potentially impacted the reproductive system. The present study investigated the possible roles of the CDC in testosterone secretion in Leydig cells and mice. Primary Leydig cells were treated with the CDC to determine their effect on cell proliferation, testosterone levels, the protein and mRNA expression of the transcription factor, and steroidogenic enzymes. Our data showed that CDC stimulated testosterone production via upregulating transcription factor steroidogenic factor-1 (NR5A1), cAMP-response element-binding protein (CREB), and steroidogenic enzymes steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (CYP11A1), 17-alpha-hydroxylase/17,20-lyase (CYP17A1), 3β-/17β-hydroxysteroid dehydrogenase type 1 (3β/17β-HSD, HSD3b1/HSD17b1). CDC could significantly stimulate H89-suppressed StAR and CREB expression but not reverse melatonin-suppressed StAR expression. We further detected the hormonal activity with transgenic yeast, and CDC showed potential androgenic antagonistic activity. Meanwhile, we investigated its aphrodisiac effect on hydrocortisone-induced mice. Exposure to hydrocortisone decreased the mating ability, reproductive organs, and testosterone level and disrupted testicular histology. However, all of these effects were significantly improved by CDC treatment. In conclusion, these results indicated that mechanisms of CDC in stimulating testosterone production involve upregulating the cAMP-PKA pathway.

Investigation of the effect of hesperidin on some reproductive parameters in testicular toxicity induced by Bisphenol A

Bisphenol A (BPA) is one of the chemicals that cause dysfunction and infertility in testicles. Therefore, it is crucial to develop effective treatments against this damage. In this study, the effects of Hesperidin (HESP), a flavonoid in testicular toxicity induced by BPA in rats, on oxidative stress, inflammation, apoptosis, histological damage, spermatogenesis, steroidogenic enzymes and reproductive hormones were investigated. Our study used 52 Sprague Dawley male rats weighing 250-300 g, and four experimental groups were formed. From the experimental groups, 1 ml of olive oil was administered to the control group, HESP at a dose of 50 mg/kg to the HESP group, BPA at a dose of 100 mg/kg to the BPA group, HESP at a dose of 50 mg/kg to the BPA + HESP group and 100 mg/kg BPA was administered intragastrically (ig) for 14 days. We determined that BPA administration causes apoptosis, histological damage, inflammation, oxidative stress and toxic effects on spermatogenesis and steroidogenic enzymes in testicles. We observed that the administration of HESP with BPA attenuated oxidative stress, inflammation and apoptosis resulting in therapeutic effects on both steroidogenic enzymes and spermatogenesis and reproductive hormones (FSH, LH and testosterone). Our findings from this study clearly showed that while HESP treatment alleviates oxidative damage, inflammation and apoptosis in testicles of rats treated with BPA, it has regulatory effects on steroidogenic enzymes, spermatogenesis and serum reproductive hormones.

Local adrenomedullin gene delivery inhibits Leydig cell dysfunction by rescuing steroidogenic enzymes in vivo

Adrenomedullin (ADM) has beneficial effects on Leydig cells under pathological conditions, including lipopolysaccharide (LPS)-induced orchitis. Our previous studies demonstrated that ADM exerts a restorative effect on steroidogenesis in LPS-treated primary rat Leydig cells by attenuating oxidative stress, inflammation and apoptosis. In this study, we aim to investigate whether ADM inhibits Leydig cell dysfunction by rescuing steroidogenic enzymes in vivo. Rats were administered with LPS and injected with Ad-ADM, an adeno-associated virus vector that expressed ADM. Then, rat testes were collected for 3β-hydroxysteroid dehydrogenase (3β-HSD) immunofluorescence staining. Steroidogenic enzymes or steroidogenic regulatory factors or protein, including steroidogenic factor-1 (SF-1), liver receptor homologue-1 (LRH1), Nur77, steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side chain cleavage enzyme (P450scc), 3β-HSD, cytochrome P450 17α-hydroxylase/17, 20 lyase (CYP17) and 17β-hydroxysteroid dehydrogenase (17β-HSD), were detected via gene expression profiling and western blot analysis. Plasma testosterone concentrations were measured. Results showed that ADM may inhibit Leydig cell dysfunction by rescuing steroidogenic enzymes and steroidogenic regulatory factors in vivo. The reduction in the number of Leydig cells after LPS exposure was reversed by ADM. ADM rescued the gene or protein levels of SF-1, LRH1, Nur77, StAR, P450scc, 3β-HSD, CYP17 and 17β-HSD and plasma testosterone concentrations. To summarize ADM could rescue some important steroidogenic enzymes, steroidogenic regulatory factors and testosterone production in Leydig cells in vivo.

The role of autophagy in paclitaxel and cremophor induced damage to rat testis

The anticancer drug, paclitaxel (PTX), is used to treat a variety of solid tumors, but its effects on normal tissues remain unclear. We investigated the effects of different doses of PTX and its vehicle, cremophor EL, on testis using histochemical, immunohistochemical and biochemical methods. We used 30 adult Wistar albino rats divided randomly into five groups: physiological saline was administered to the control group; the sham 8 group received 8 mg/kg cremophor EL; the sham 16 group received 16 mg/kg cremophor EL; 8 mg/kg PTX was administered to the PTX 8 group; and the PTX 16 group received 16 mg/kg PTX. The cremophore content in PTX groups was the same as in the sham group. All treatments were injected intraperitoneally (i.p.) once/week for 4 weeks. Tissue samples were excised 24 h after the last injection. Tissue sections were prepared and hematoxylin and eosin staining was performed to assess testicular morphology. Expression of Beclin-1, LC3A/B and P62 were assessed using immunohistochemistry. Serum and tissue testosterone levels were determined using ELISA. Light microscopy revealed seminiferous tubule damage, irregularities in germinal epithelium and decreased seminiferous tubule diameter in the PTX treated groups. The immunoreactivity of Beclin-1, LC3A/B, and P62 was increased significantly in the PTX groups compared to the control group. Cremophor EL alone damaged the testis, although not as much as PTX. PTX caused significant damage to testicular tissue and increased autophagy of spermatogenic cells; cremophore EL also may play a role in this effect.

The Urokinase-Type Plasminogen Activator Contributes to cAMP-Induced Steroidogenesis in MA-10 Leydig Cells

Leydig cells produce androgens which are essential for male sex differentiation and reproductive functions. Steroidogenesis, as well as expression of several genes in Leydig cells, are stimulated by LH/cAMP and repressed by AMP/AMPK. One of those genes is Plau, which codes for the urokinase-type plasminogen activator (uPA), a secreted serine protease. The role of uPA and the regulation of Plau expression in Leydig cells remain unknown. Using siRNA-mediated knockdown, uPA was required for maximal cAMP-induced STAR and steroid hormone production in MA-10 Leydig cells. Analysis of Plau mRNA levels and promoter activity revealed that its expression is strongly induced by cAMP; this induction is blunted by AMPK. The cAMP-responsive region was located, in part, in the proximal Plau promoter that contains a species-conserved GC box at −56 bp. The transcription factor Krüppel-like factor 6 (KLF6) activated the Plau promoter. Mutation of the GC box at −56 bp abolished KLF6-mediated activation and significantly reduced cAMP-induced Plau promoter activity. These data define a role for uPA in Leydig cell steroidogenesis and provide insights into the regulation of Plau gene expression in these cells.

Low-level and combined exposure to environmental metal elements affects male reproductive outcomes: Prospective MARHCS study in population of college students in Chongqing, China

BACKGROUND

Male fertility has shown a continuously declining tendency for decades. Over exposure to metal/metalloid elements has been proposed as associated with reproductive impairment. However, the hazard profile remained unclear in general public experiencing low-level and combined metal exposure.

METHODS

Based on the MARHCS cohort in Chongqing, China, 796 college students were recruited from June 2013 and 666 subjects were followed up next year. At each phase, semen and blood samples were collected for an assessment of semen quality and six sex hormones levels. Eighteen urinary metal/metalloid elements were quantified by ICP-MS as internal exposure biomarkers. Cluster analysis was conducted to characterize reproductive outcomes in the subgroups for different overall estimated exposure levels. Effects of each metal/metalloid element were analyzed using multiple statistical strategies: single-element mixed model, multiple-elements model and self before-after comparison design.

RESULTS

The urine concentration for 18 metal/metalloid elements was at a typically lower level (far away from the exposure limits) and positively associated with each other. After adjustment of the potential confounders, a decrease of 11.53% (95% CI: -18.61, -3.84%) and 10.84% (95% CI: -17.93, -3.14%) in spermatid morphology was observed in the highest quantile groups of vanadium (V) and nickel (Ni), respectively. Urinary silver (Ag) was dose-dependent associated with an increase in total sperm number (6.91%, 95% CI: 1.14, 13.00%), sperm concentration (16.38%, 95% CI: 5.15, 28.81%) and semen volume (23.73%, 95% CI: 10.46, 38.60%). Further, hormone testosterone presented a significant decrease in subgroup with higher overall estimated exposure and a stable negative association with lithium (Li). The above relationships remained significant across different statistical strategies (all p values <0.05).

CONCLUSION

Our study provided new evidences that exposure to metal/metalloid elements potentially exert bidirectional influences on semen quality at a relatively low level. And serum testosterone appears as a vulnerable index for metal exposure.

Insights Into the Roles of GATA Factors in Mammalian Testis Development and the Control of Fetal Testis Gene Expression

Defining how genes get turned on and off in a correct spatiotemporal manner is integral to our understanding of the development, differentiation, and function of different cell types in both health and disease. Testis development and subsequent male sex differentiation of the XY fetus are well-orchestrated processes that require an intricate network of cell-cell communication and hormonal signals that must be properly interpreted at the genomic level. Transcription factors are at the forefront for translating these signals into a coordinated genomic response. The GATA family of transcriptional regulators were first described as essential regulators of hematopoietic cell differentiation and heart morphogenesis but are now known to impact the development and function of a multitude of tissues and cell types. The mammalian testis is no exception where GATA factors play essential roles in directing the expression of genes crucial not only for testis differentiation but also testis function in the developing male fetus and later in adulthood. This minireview provides an overview of the current state of knowledge of GATA factors in the male gonad with a particular emphasis on their mechanisms of action in the control of testis development, gene expression in the fetal testis, testicular disease, and XY sex differentiation in humans.

Study on the SHP2-Mediated Mechanism of Promoting Spermatogenesis Induced by Active Compounds of Eucommiae Folium in Mice

Spermatogenesis directly determines the reproductive capacity of male animals. With the development of society, the increasing pressure on people’s lives and changes in the living environment, male fertility is declining. The leaf of Eucommia ulmoides Oliv. (Eucommiae Folium, EF) was recorded in the 2020 Chinese Pharmacopoeia and was used in traditional Chinese medicine as a tonic. In recent years, EF has been reported to improve spermatogenesis, but the mechanisms of EF remain was poorly characterized. In this study, the effect of EF ethanol extract (EFEE) on spermatogenesis was tested in mice. Chemical components related to spermatogenesis in EF were predicted by network pharmacology. The biological activity of the predicted chemical components was measured by the proliferation of C18-4 spermatogonial stem cells (SSCs) and the testosterone secretion of TM3 leydig cells. The biological activity of chlorogenic acid (CGA), the active compound in EF, was tested in vivo. The cell cycle was analysed by flow cytometry. Testosterone secretion was detected by ELISA. RNA interference (RNAi) was used to detect the effect of key genes on cell biological activity. Western blotting, qRT–PCR and immunofluorescence staining were used to analyse the molecular mechanism of related biological activities. The results showed that EFEE and CGA could improve spermatogenesis in mice. Furthermore, the main mechanism was that CGA promoted SSC proliferation, self-renewal and Leydig cell testosterone secretion by promoting the expression of SHP2 and activating the downstream signaling pathways involved in these biological processes. This study provided strong evidence for elucidating the mechanism by which EF promotes the spermatogenesis in mice and a new theoretical basis for dealing with the decrease in male reproductive capacity.

Mechanism of Action of an Environmentally Relevant Organochlorine Mixture in Repressing Steroid Hormone Biosynthesis in Leydig Cells

Within Leydig cells, steroidogenesis is induced by the pituitary luteinizing hormone (LH). The binding of LH to its receptor increases cAMP production, which then activates the expression of genes involved in testosterone biosynthesis. One of these genes codes for the steroidogenic acute regulatory (STAR) protein. STAR is part of a complex that shuttles cholesterol, the precursor of all steroid hormones, through the mitochondrial membrane where steroidogenesis is initiated. Organochlorine chemicals (OCs) are environmental persistent organic pollutants that are found at high concentrations in Arctic areas. OCs are known to affect male reproductive health by decreasing semen quality in different species, including humans. We previously showed that an environmentally relevant mixture of OCs found in Northern Quebec disrupts steroidogenesis by decreasing STAR protein levels without affecting the transcription of the gene. We hypothesized that OCs might affect STAR protein stability. To test this, MA-10 Leydig cell lines were incubated for 6 h with vehicle or the OCs mixture in the presence or absence of 8Br-cAMP with or without MG132, an inhibitor of protein degradation. We found that MG132 prevented the OC-mediated decrease in STAR protein levels following 8Br-cAMP stimulation. However, progesterone production was still decreased by the OC mixture, even in the presence of MG132. This suggested that proteins involved in steroid hormone production in addition to STAR are also affected by the OC mixture. To identify these proteins, a whole cell approach was used and total proteins from MA-10 Leydig cells exposed to the OC mixture with or without stimulation with 8Br-cAMP were analyzed by 2D SDS-PAGE and LC-MS/MS. Bioinformatics analyses revealed that several proteins involved in numerous biological processes are affected by the OC mixture, including proteins involved in mitochondrial transport, lipid metabolism, and steroidogenesis.