Maternal exposure to zearalenone in masculinization window affects the fetal Leydig cell development in rat male fetus

Highly Specific Aptamer-Antibody Birecognized Sandwich Module for Ultrasensitive Detection of a Low Molecular Weight Compound

Herein, the aptamer-antibody sandwich module was first introduced to accurately recognize a low molecular weight compound (mycotoxin). Impressively, compared with the large steric hindrance of a traditional dual-antibody module, the aptamer-antibody sandwich with low Gibbs free energy and a low dissociation constant has high recognition efficiency; thus, it could reduce false positives and false negatives caused by a dual-antibody module. As a proof of concept, a sensitive electrochemiluminescence (ECL) biosensor was constructed for detecting mycotoxin zearalenone (ZEN) based on an aptamer-antibody sandwich as a biological recognition element and porous ZnO nanosheets (Zn NSs) supported Cu nanoclusters (Cu NCs) as the signal transduction element, in which the antibody was modified on the vertex of a tetrahedral DNA nanostructure (TDN) with a rigid structure to increase the kinetics of target recognition for promoting the detection sensitivity. Moreover, the Cu NCs/Zn NSs exhibited an excellent ECL response that was attributed to the aggregation-induced ECL enhancement through electrostatic interactions. The sensing platform achieved trace detection of ZEN with a low detection limit of 0.31 fg/mL, far beyond that of the enzyme-linked immunosorbent assay (ELISA, the current rapid detection method) and high-performance liquid chromatography (HPLC, the national standard detection method). The strategy has great application potential in food analysis, environmental monitoring, and clinical diagnosis.

Fetal Leydig cells: What we know and what we don't

During male fetal development, testosterone plays an essential role in the differentiation and maturation of the male reproductive system. Deficient fetal testosterone production can result in variations of sex differentiation that may cause infertility and even increased tumor incidence later in life. Fetal Leydig cells in the fetal testis are the major androgen source in mammals. Although fetal and adult Leydig cells are similar in their functions, they are two distinct cell types, and therefore, the knowledge of adult Leydig cells cannot be directly applied to understanding fetal Leydig cells. This review summarizes our current knowledge of fetal Leydig cells regarding their cell biology, developmental biology, and androgen production regulation in rodents and human. Fetal Leydig cells are present in basement membrane-enclosed clusters in between testis cords. They originate from the mesonephros mesenchyme and the coelomic epithelium and start to differentiate upon receiving a Desert Hedgehog signal from Sertoli cells or being released from a NOTCH signal from endothelial cells. Mature fetal Leydig cells produce androgens. Human fetal Leydig cell steroidogenesis is LHCGR (Luteinizing Hormone Chronic Gonadotropin Receptor) dependent, while rodents are not, although other Gαs -protein coupled receptors might be involved in rodent steroidogenesis regulation. Fetal steroidogenesis ceases after sex differentiation is completed, and some fetal Leydig cells dedifferentiate to serve as stem cells for adult testicular cell types. Significant gaps are acknowledged: (1) Why are adult and fetal Leydig cells different? (2) What are bona fide progenitor and fetal Leydig cell markers? (3) Which signaling pathways and transcription factors regulate fetal Leydig cell steroidogenesis? It is critical to discover answers to these questions so that we can understand vulnerable targets in fetal Leydig cells and the mechanisms for androgen production that when disrupted, leads to variations in sex differentiation that range from subtle to complete sex reversal.

Ex vivo effects of bisphenol A or zearalenone on the prepubertal rat testis

Bisphenol A (BPA) and zearalenone (ZEA) are two widespread xenoestrogens involved in male reproductive disorders. Few studies investigated the effects of these compounds on the prepubertal testis, which is highly sensitive to endocrine disruptors such as xenoestrogens. An ex vivo approach was performed to evaluate the effects of BPA or ZEA (10^-11, 10^-9, 10^-6 M) on the testes of 20 and 25 dpp rats. To investigate the involvement of classical nuclear ER-mediated estrogen signaling in these effects, pre-incubation with an antagonist (ICI 182.780 10^-6M) was performed. BPA and ZEA have similar effects on spermatogenesis- and steroidogenesis-related endpoints in the immature testis, but our study highlights different age-dependent patterns of sensitivity to each compound during the prepubertal period. Moreover, our results indicate that the effects of BPA are likely to be induced by nuclear ER, whereas those of ZEA appear to involve other mechanisms.

Role of miR-300-3p in Leydig cell function and differentiation: A therapeutic target for obesity-related testosterone deficiency

MicroRNAs (miRNAs) regulate various cellular functions, but their specific roles in the regulation of Leydig cells (LCs) have yet to be fully understood. Here, we found that the expression of miR-300-3p varied significantly during the differentiation from progenitor LCs (PLCs) to adult LCs (ALCs). High expression of miR-300-3p in PLCs inhibited testosterone production and promoted PLC proliferation by targeting the steroidogenic factor-1 (Sf-1) and transcription factor forkhead box O1 (FoxO1) genes, respectively. As PLCs differentiated into ALCs, the miR-300-3p expression level significantly decreased, which promoted testosterone biosynthesis and suppressed proliferation of ALCs by upregulating SF-1 and FoxO1 expression. The LH/METTL3/SMURF2/SMAD2 cascade pathway controlled miR-300-3p expression, in which luteinizing hormone (LH) upregulated SMAD-specific E3 ubiquitin protein ligase 2 (SMURF2) expression through methyltransferase like 3 (METTL3)-mediated Smurf2 N6-methyladenosine modification. The Smurf2 then suppressed miR-300 transcription by inhibiting SMAD family member 2 (SMAD2) binding to the promoter of miR-300. Notably, miR-300-3p was associated with an obesity-related testosterone deficiency in men and the inhibition of miR-300-3p effectively rescued testosterone deficiency in obese mice. These findings suggested that miR-300-3p plays a pivotal role in LC differentiation and function, and could be a promising diagnostic or therapeutic target for obesity-related testosterone deficiency.

Dual effects of zearalenone on aflatoxin B1-induced liver and mammary gland toxicity in pregnant and lactating rats

Food and feed are frequently co-contaminated with aflatoxin B1 (AFB1) and zearalenone (ZEN). This study investigated the effects of ZEN on the AFB1-induced liver and mammary gland toxicity in pregnant and lactating rats. AFB1 and ZEN co-exposure inhibited the growth of rats and caused oxidative stress and inflammatory responses in the liver and mammary gland. Compared with the AFB1-only group, damage was aggravated in the AFB1 + 10 mg/kg ZEN group, and the AFB1 + 1 mg/kg ZEN group showed a reduction in some metrics. The metabolomic results of the mammary gland showed that metabolite changes were mainly in lipid, amino acid, and glucose metabolism. Compared with the AFB1 + 0 mg/kg ZEN group, the AFB1 + 1 mg/kg ZEN group had the most metabolite changes. Moreover, AFB1 and ZEN co-exposure reduced the levels of sex hormones and RNA m⁶A methylation in the mammary gland. We speculate that ZEN affects the toxicity of AFB1 to the liver and mammary gland by interfering with the function of sex hormones, regulating cell proliferation and metabolic processes.

Procyanidins inhibit zearalenone-induced apoptosis and oxidative stress of porcine testis cells through activation of Nrf2 signaling pathway

The mycotoxin zearalenone (ZEA) in food and feed seriously harms human and animal health. How to reduce its toxicity is an important direction of current research on food safety. This study aim to assess the effects of procyanidins (PC) on cell apoptosis caused by ZEA and to clarify the role of Nrf2 in the process. Swine testicle (ST) cells were treated with ZEA (57.5 μmol/L) and/or PC (10 mg/L) for 24 h. Cell viability was detected by CCK-8 assay. Cell apoptosis and the level of ROS were detected by flow cytometry. The expression levels of mRNA and protein was detected by qRT-PCR and western blotting. Our results showed that ZEA reduced the antioxidant capacity of the ST cells, induced the cell apoptosis and inhibited the gene and protein expression of Nrf2 and its downstream genes (ho-1,nqo1), while PC improved the cell antioxidant capacity, reduced the degree of ZEA-induced cell apoptosis and promoted the gene and protein expression of Nrf2 and its downstream genes. However, when the Nrf2 small molecule inhibitor ML385 was added, the ability of PC to inhibit ZEA-induced cell apoptosis and promote the expression of Nrf2 and its downstream genes were decreased. Our results demonstrated that ZEA induced oxidative stress and apoptosis of ST cells, which were alleviated by PC intervention via activating Nrf2 signaling pathway. This finding of this study provided a molecular basis for the clinical application of PC to prevent ZEN-caused reproductive toxicity.

Gestational diabetes mellitus suppresses fetal testis development in mice

The prevalence of Gestational diabetes mellitus (GDM) is increasing rapidly. In addition to the metabolic disease risks, GDM might increase the risks of cryptorchidism in children. However, its mechanism involved in abnormalities of the male reproductive system is still unclear. The purpose of this study was to study the effects of GDM on the development of mouse fetal Leydig and Sertoli cells. Pregnant mice were treated on gestational day (GD) 6.5 and 12.5 with streptozotocin (STZ, 100 mg/kg) or vehicle (sodium citrate buffer). Leydig and Sertoli cell development and functions were evaluated by investigating serum testosterone levels, cell number and distribution, genes, and protein expression. GDM decreased serum testosterone levels, the anogenital distance, and the level of DHH in Sertoli cells of testes of male offspring. Fetal Leydig cell number was also decreased in testes of GDM offspring by delaying the commitment of stem Leydig cells into the Leydig cell lineage. RNA-seq showed that FOXL2, RSPO1/β-Catenin signaling was activated and Gsk3β signaling was inhibited in GDM offspring testis. In conclusion, GDM disrupted reproductive tract and testis development in mouse male offspring via altering genes related to development.

Insights into the Regulation on Proliferation and Differentiation of Stem Leydig Cells

Male hypogonadism is a clinical syndrome caused by testosterone deficiency. Hypogonadism can be caused by testicular disease (primary hypogonadism) or hypothalamic-pituitary dysfunction (secondary hypogonadism). The present strategy for treating hypogonadism is the administration of exogenous testosterone. But exogenous testosterone is reported to have negative side effects including adverse cardiovascular events and disruption of physiological spermatogenesis probably due to its inability to mimic the physiological circadian rhythm of testosterone secretion in vivo. In recent years, a growing number of articles demonstrated that stem Leydig cells (SLCs) can not only differentiate into functional Leydig cells (LCs) in vivo to replace chemically disrupted LCs, but also secrete testosterone in a physiological pattern. The proliferation and differentiation of SLCs are regulated by various factors. However, the mechanisms involved in regulating the development of SLCs remain to be summarized. Factors involved in the regulation of SLCs can be divided into environmental pollutants, growth factors, cytokine and hormones. Environmental pollutants such as Perfluorooctanoic acid (PFOA) and Triphenyltin (TPT) could suppress SLCs proliferation or differentiation. Growth factors including FGF1, FGF16, NGF and activin A are essential for the maintenance of SLCs self-renewal and differentiation. Interleukin 6 family could inhibit differentiation of SLCs. Among hormones, dexamethasone suppresses SLCs differentiation, while aldosterone suppresses their proliferation. The present review focuses on new progress about factors regulating SLC's proliferation and differentiation which will undoubtedly deepen our insights into SLCs and help make better clinical use of them. Different factors affect on the proliferation and differentiation of stem Leydig cells. Firstly, each rat was intraperitoneally injected EDS so as to deplete Leydig cells from the adult testis. Secondly, the CD51+ or CD90+ cells from the testis of rats are SLCs, and the p75+ cells from human adult testes are human SLCs. These SLCs in the testis start to proliferate and some of them differentiate into LCs. Thirdly, during the SLCs regeneration period, researchers could explore different function of those factors (pollutants, growth factors, cytokines and hormones) towards SLCs.

Loss of Mafb and Maf distorts myeloid cell ratios and disrupts fetal mouse testis vascularization and organogenesis†

Testis differentiation is initiated when Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. Sertoli cells are essential for testis development, but cell types within the interstitial compartment, such as immune and endothelial cells, are also critical for organ formation. Our previous work implicated macrophages in fetal testis morphogenesis, but little is known about genes underlying immune cell development during organogenesis. Here we examine the role of the immune-associated genes Mafb and Maf in mouse fetal gonad development, and we demonstrate that deletion of these genes leads to aberrant hematopoiesis manifested by supernumerary gonadal monocytes. Mafb; Maf double knockout embryos underwent initial gonadal sex determination normally, but exhibited testicular hypervascularization, testis cord formation defects, Leydig cell deficit, and a reduced number of germ cells. In general, Mafb and Maf alone were dispensable for gonad development; however, when both genes were deleted, we observed significant defects in testicular morphogenesis, indicating that Mafb and Maf work redundantly during testis differentiation. These results demonstrate previously unappreciated roles for Mafb and Maf in immune and vascular development and highlight the importance of interstitial cells in gonadal differentiation.

Zearalenone and the Immune Response

Zearalenone (ZEA) is an estrogenic fusariotoxin, being classified as a phytoestrogen, or as a mycoestrogen. ZEA and its metabolites are able to bind to estrogen receptors, 17β-estradiol specific receptors, leading to reproductive disorders which include low fertility, abnormal fetal development, reduced litter size and modification at the level of reproductive hormones especially in female pigs. ZEA has also significant effects on immune response with immunostimulatory or immunosuppressive results. This review presents the effects of ZEA and its derivatives on all levels of the immune response such as innate immunity with its principal component inflammatory response as well as the acquired immunity with two components, humoral and cellular immune response. The mechanisms involved by ZEA in triggering its effects are addressed. The review cited more than 150 publications and discuss the results obtained from in vitro and in vivo experiments exploring the immunotoxicity produced by ZEA on different type of immune cells (phagocytes related to innate immunity and lymphocytes related to acquired immunity) as well as on immune organs. The review indicates that despite the increasing number of studies analyzing the mechanisms used by ZEA to modulate the immune response the available data are unsubstantial and needs further works.

Zearalenone disrupts the placental function of rats: A possible mechanism causing intrauterine growth restriction

Zearalenone is an estrogenic mycotoxin produced by a variety of Fusarium fungi. There is evidence that exposure to zearalenone can cause intrauterine growth restriction, but little is known about the mechanism in the rat placenta caused by zearalenone. From gestational day 14-21, female Sprague Dawley rats (60 days old) were gavaged with zearalenone (0, 2.5, 5, 10, and 20 mg/kg/day body weight). Zearalenone dose-dependently reduced serum LH and FSH levels of dams at ≥ 5 mg/kg. RNA-seq and qPCR showed that zearalenone significantly down-regulated Slc38a1 expression at 2.5 mg/kg, Echs1 and Pc at 10 mg/kg, as well as Slc1a5, Cd36, Ldlr, Hadhb, and Cyp17a1 expression at a dose of 20 mg/kg, while it up-regulated the expression of Notch signal (Dvl1 and Jag 1). After zearalenone treatment, their proteins showed a similar trend. Zearalenone reduced the phosphorylation of AKT1, ERK1/2, and mTOR at 5 mg/kg or higher and 4EBP1 at 5 mg/kg. Zearalenone also increased BECLIN1, LC3B, and p62 levels and elevated BAX/BCL2 and CASP3/PROCASP3 ratios. In conclusion, zearalenone disrupts placental function such as reduction of nutrient transport and lipid metabolism possibly via AKT1/ERK1/2/mTOR-mediated autophagy and apoptosis.