Zearalenone and alpha-zearalenol inhibit the synthesis and secretion of pig follicle stimulating hormone via the non-classical estrogen membrane receptor GPR30

Effects of Alginic Acid on the Porcine Granulosa Cells and Maturation of Porcine Oocytes

SCOPE

Alginic acid (AA) from brown algae is a marine organic compound. There is extensive use of AA in the food industry and healthcare, suggesting a high probability of AA exposure. The present study investigates the effects of AA on porcine ovarian granulosa cells (GCs) and oocytes to explore its mechanism in female reproduction because of its adverse effects on reproduction.

METHODS AND RESULTS

The study adds 20 µM AA to the porcine primary ovarian GCs medium and porcine oocyte in vitro maturation (IVM) medium. Estrogen and progesterone levels are downregulated in GCs. Reactive oxygen species are excessive, and the antioxidant capacity declines. Then mitochondria-mediated apoptosis pathway is involved in GCs apoptosis. In addition, scores of autophagosomes are found in the experimental cells. Furthermore, AA significantly inhibits the proliferation of GCs around cumulus-oocyte complexes (COCs) accompanied by abnormal spindle assembly, chromosome arrangement disorder, and aberrant cortical granules distribution in oocytes, leading to a decreased oocyte maturation rate.

CONCLUSION

These findings suggest that 20 µM AA is toxic to sow reproduction by interfering with estrogen production, oxidative stress, mitochondria-mediated apoptosis, autophagy in GCs of sows, and oocyte maturation.

Visfatin in the porcine pituitary gland: expression and regulation of secretion during the oestrous cycle and early pregnancy

Visfatin is a multifunctional protein which, besides the control of energy homeostasis, seems to be also involved in the regulation of female fertility through the influence on the endocrine hypothalamus-pituitary-gonadal axis, including the pituitary. The aim of this study was to investigate the expression of visfatin mRNA and protein in the anterior (AP) and posterior pituitary lobes of the pig during the oestrous cycle and early pregnancy. In AP, we also examined colocalisation of visfatin with pituitary tropic hormones. Moreover, we aimed to evaluate the in vitro effects of GnRH, FSH, LH, and insulin on visfatin protein concentration and secretion in AP cells during the cycle. The study showed that visfatin is present in all types of porcine pituitary endocrine cells and its expression is reliant on stage of the cycle or pregnancy. GnRH, FSH, LH and insulin stimulated visfatin secretion by AP cells on days 17 to 19 of the cycle, while on days 2 to 3 visfatin release was enhanced only by LH. Summarising, visfatin is locally produced in the pituitary in a way dependent on hormonal milieu typical for reproductive status of pigs. Further research is required to clarify the role of visfatin in the pituitary gland.

The Role of G Protein-Coupled Estrogen Receptor (GPER) in Vascular Pathology and Physiology

OBJECTIVE

Estrogen is indispensable in health and disease and mainly functions through its receptors. The protection of the cardiovascular system by estrogen and its receptors has been recognized for decades. Numerous studies with a focus on estrogen and its receptor system have been conducted to elucidate the underlying mechanism. Although nuclear estrogen receptors, including estrogen receptor-α and estrogen receptor-β, have been shown to be classical receptors that mediate genomic effects, studies now show that GPER mainly mediates rapid signaling events as well as transcriptional regulation via binding to estrogen as a membrane receptor. With the discovery of selective synthetic ligands for GPER and the utilization of GPER knockout mice, significant progress has been made in understanding the function of GPER. In this review, the tissue and cellular localizations, endogenous and exogenous ligands, and signaling pathways of GPER are systematically summarized in diverse physiological and diseased conditions. This article further emphasizes the role of GPER in vascular pathology and physiology, focusing on the latest research progress and evidence of GPER as a promising therapeutic target in hypertension, pulmonary hypertension, and atherosclerosis. Thus, selective regulation of GPER by its agonists and antagonists have the potential to be used in clinical practice for treating such diseases.

Adaptation of the Porcine Pituitary Transcriptome, Spliceosome and Editome during Early Pregnancy

The physiological mechanisms of the porcine reproduction are relatively well-known. However, transcriptomic changes and the mechanisms accompanying transcription and translation processes in various reproductive organs, as well as their dependence on hormonal status, are still poorly understood. The aim of this study was to gain a principal understanding of alterations within the transcriptome, spliceosome and editome occurring in the pituitary of the domestic pig (Sus scrofa domestica L.), which controls basic physiological processes in the reproductive system. In this investigation, we performed extensive analyses of data obtained by high-throughput sequencing of RNA from the gilts' pituitary anterior lobes during embryo implantation and the mid-luteal phase of the estrous cycle. During analyses, we obtained detailed information on expression changes of 147 genes and 43 long noncoding RNAs, observed 784 alternative splicing events and also found the occurrence of 8729 allele-specific expression sites and 122 RNA editing events. The expression profiles of the selected 16 phenomena were confirmed by PCR or qPCR techniques. As a final result of functional meta-analysis, we acquired knowledge regarding intracellular pathways that induce changes in the processes accompanying transcription and translation regulation, which may induce modifications in the secretory activity of the porcine adenohypophyseal cells.

G Protein-Coupled Estrogen Receptor GPER: Molecular Pharmacology and Therapeutic Applications

The actions of estrogens and related estrogenic molecules are complex and multifaceted in both sexes. A wide array of natural, synthetic, and therapeutic molecules target pathways that produce and respond to estrogens. Multiple receptors promulgate these responses, including the classical estrogen receptors of the nuclear hormone receptor family (estrogen receptors α and β), which function largely as ligand-activated transcription factors, and the 7-transmembrane G protein-coupled estrogen receptor, GPER, which activates a diverse array of signaling pathways. The pharmacology and functional roles of GPER in physiology and disease reveal important roles in responses to both natural and synthetic estrogenic compounds in numerous physiological systems. These functions have implications in the treatment of myriad disease states, including cancer, cardiovascular diseases, and metabolic disorders. This review focuses on the complex pharmacology of GPER and summarizes major physiological functions of GPER and the therapeutic implications and ongoing applications of GPER-targeted compounds.

Phytoestrogens and Health Effects

Phytoestrogens are literally estrogenic substances of plant origin. Although these substances are useful for plants in many aspects, their estrogenic properties are essentially relevant to their predators. As such, phytoestrogens can be considered to be substances potentially dedicated to plant-predator interaction. Therefore, it is not surprising to note that the word phytoestrogen comes from the early discovery of estrogenic effects in grazing animals and humans. Here, several compounds whose activities have been discovered at nutritional concentrations in animals and humans are examined. The substances analyzed belong to several chemical families, i.e., the flavanones, the coumestans, the resorcylic acid lactones, the isoflavones, and the enterolignans. Following their definition and the evocation of their role in plants, their metabolic transformations and bioavailabilities are discussed. A point is then made regarding their health effects, which can either be beneficial or adverse depending on the subject studied, the sex, the age, and the physiological status. Toxicological information is given based on official data. The effects are first presented in humans. Animal models are evoked when no data are available in humans. The effects are presented with a constant reference to doses and plausible exposure.

Exposure to Low Zearalenone Doses and Changes in the Homeostasis and Concentrations of Endogenous Hormones in Selected Steroid-Sensitive Tissues in Pre-Pubertal Gilts

This study was undertaken to analyze whether prolonged exposure to low-dose zearalenone (ZEN) mycotoxicosis affects the concentrations of ZEN, α-zearalenol (α-ZEL), and β-zearalenol (β-ZEL) in selected reproductive system tissues (ovaries, uterine horn-ovarian and uterine sections, and the middle part of the cervix), the hypothalamus, and pituitary gland, or the concentrations of selected steroid hormones in pre-pubertal gilts. For 42 days, gilts were administered per os different ZEN doses (MABEL dose [5 µg/kg BW], the highest NOAEL dose [10 µg/kg BW], and the lowest LOAEL dose [15 µg/kg BW]). Tissue samples were collected on days seven, twenty-one, and forty-two of exposure to ZEN (exposure days D1, D2, and D3, respectively). Blood for the analyses of estradiol and progesterone concentrations was collected in vivo on six dates at seven-day intervals (on analytical dates D1-D6). The analyses revealed that both ZEN and its metabolites were accumulated in the examined tissues. On successive analytical dates, the rate of mycotoxin accumulation in the studied tissues decreased gradually by 50% and proportionally to the administered ZEN dose. A hierarchical visualization revealed that values of the carry-over factor (CF) were highest on exposure day D2. In most groups and on most exposure days, the highest CF values were found in the middle part of the cervix, followed by the ovaries, both sections of the uterine horn, and the hypothalamus. These results suggest that ZEN, α-ZEL, and β-ZEL were deposited in all analyzed tissues despite exposure to very low ZEN doses. The presence of these undesirable compounds in the examined tissues can inhibit the somatic development of the reproductive system and compromise neuroendocrine coordination of reproductive competence in pre-pubertal gilts.

Determination of Zearalenone and Its Derivatives in Feed by Gas Chromatography-Mass Spectrometry with Immunoaffinity Column Cleanup and Isotope Dilution

In this study, a gas chromatography-mass spectrometry (GC-MS) method was established for the determination of zearalenone and its five derivatives in feed, including zearalanone, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol. An effective immunoaffinity column was prepared for sample purification, which was followed by the silane derivatization of the eluate after an immunoaffinity chromatography analysis for target compounds by GC-MS. Matrix effects were corrected by an isotope internal standard of zearalenone in this method. The six analytes had a good linear relationship in the range of 2-500 ng/mL, and the correlation coefficients were all greater than 0.99. The limits of detection (LODs) and limits of quantification (LOQs) were less than 1.5 μg/kg and 5.0 μg/kg, respectively. The average spike recoveries for the six feed matrices ranged from 89.6% to 112.3% with relative standard deviations (RSDs) less than 12.6%. Twenty actual feed samples were analyzed using the established method, and at least one target was detected. The established GC-MS method was proven to be reliable and suitable for the determination of zearalenone and its derivatives in feed.

Identification of molecular initiating events and key events leading to endocrine disrupting effects of PFOA: Integrated molecular dynamic, transcriptomic, and proteomic analyses

Perfluorooctanoic acid (PFOA) can rapidly activate signaling pathways independent of nuclear hormone receptors through membrane receptor regulation, which leads to endocrine disrupting effects. In the present work, the molecular initiating event (MIE) and the key events (KEs) which cause the endocrine disrupting effects of PFOA have been explored and determined based on molecular dynamics simulation (MD), fluorescence analysis, transcriptomics, and proteomics. MD modeling and fluorescence analysis proved that, on binding to the G protein-coupled estrogen receptor-1 (GPER), PFOA could induce a conformational change in the receptor, turning it into an active state. The results also indicated that the binding to GPER was the MIE that led to the adverse outcome (AO) of PFOA. In addition, the downstream signal transduction pathways of GPER, as regulated by PFOA, were further investigated through genomics and proteomics to identify the KEs leading to thr endocrine disrupting effects. Two pathways (Endocrine resistance, ERP and Estrogen signaling pathway, ESP) containing GPER were regulated by different concentration of PFOA and identified as the KEs. The knowledge of MIE, KEs, and AO of PFOA is necessary to understand the links between PFOA and the possible pathways that lead to its negative effects.

Zearalenone Promotes Uterine Development of Weaned Gilts by Interfering with Serum Hormones and Up-Regulating Expression of Estrogen and Progesterone Receptors

In this study, we aimed to assess the effect of diet ZEA on serum hormones, the location and expression of estrogen receptor ERα/β and progesterone receptor (PR) of the uterus in weaned piglets and to reveal the mechanism underneath. A total of 40 healthy weaned gilts were randomly allocated to basal diet supplemented with 0 (Control), 0.5 (ZEA0.5), 1.0 (ZEA1.0) and 1.5 (ZEA1.5) mg ZEA/kg and fed individually for 35 days. Meanwhile, the porcine endometrial epithelial cells (PECs) were incubated for 24 h with ZEA at 0 (Control), 5 (ZEA5), 20 (ZEA20) and 80 (ZEA80) μmol/L, respectively. The results showed that nutrient apparent digestibility (CP and GE), nutrient apparent availability (ME/GE, BV and NPU), the uterine immunoreactive integrated optic density (IOD), relative mRNA and protein expression of ER-α, ER-β and PR and the relative mRNA and protein expression of ER-α and ER-β in PECs all increased linearly (p < 0.05) with ZEA. Collectively, ZEA can interfere with the secretion of some reproductive hormones in the serum and promote the expression of estrogen/progesterone receptors in the uterus and PECs. All these indicate that ZEA may promote the development of the uterus in weaned gilts through estrogen receptor pathway.

Quantitative Proteomic Analysis of Zearalenone Exposure on Uterine Development in Weaned Gilts

The aim of this study was to explore the effect of zearalenone (ZEA) exposure on uterine development in weaned gilts by quantitative proteome analysis with tandem mass spectrometry tags (TMT). A total of 16 healthy weaned gilts were randomly divided into control (basal diet) and ZEA3.0 treatments groups (basal diet supplemented with 3.0 mg/kg ZEA). Results showed that vulva size and uterine development index were increased (p < 0.05), whereas serum follicle stimulation hormone, luteinizing hormone and gonadotropin-releasing hormone were decreased in gilts fed the ZEA diet (p < 0.05). ZEA, α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) were detected in the uteri of gilts fed a 3.0 mg/kg ZEA diet (p < 0.05). The relative protein expression levels of creatine kinase M-type (CKM), atriopeptidase (MME) and myeloperoxidase (MPO) were up-regulated (p < 0.05), whereas aldehyde dehydrogenase 1 family member (ALDH1A2), secretogranin-1 (CHGB) and SURP and G-patch domain containing 1 (SUGP1) were down-regulated (p < 0.05) in the ZEA3.0 group by western blot, which indicated that the proteomics data were dependable. In addition, the functions of differentially expressed proteins (DEPs) mainly involved the cellular process, biological regulation and metabolic process in the biological process category. Some important signaling pathways were changed in the ZEA3.0 group, such as extracellular matrix (ECM)-receptor interaction, focal adhesion and the phosphoinositide 3-kinase−protein kinase B (PI3K-AKT) signaling pathway (p < 0.01). This study sheds new light on the molecular mechanism of ZEA in the uterine development of gilts.

Protective and detoxifying effects conferred by selenium against mycotoxins and livestock viruses: A review

Animal feed can easily be infected with molds during production and storage processes, and this can lead to the production of secondary metabolites, such as mycotoxins, which eventually threaten human and animal health. Furthermore, livestock production is also not free from viral infections. Under these conditions, the essential trace element, selenium (Se), can confer various biological benefits to humans and animals, especially due to its anticancer, antiviral, and antioxidant properties, as well as its ability to regulate immune responses. This article reviews the latest literature on the antagonistic effects of Se on mycotoxin toxicity and viral infections in animals. We outlined the systemic toxicity of mycotoxins and the primary mechanisms of mycotoxin-induced toxicity in this analysis. In addition, we pay close attention to how mycotoxins and viral infections in livestock interact. The use of Se supplementation against mycotoxin-induced toxicity and cattle viral infection was the topic of our final discussion. The coronavirus disease 2019 (COVID-19) pandemic, which is currently causing a health catastrophe, has altered our perspective on health concerns to one that is more holistic and increasingly embraces the One Health Concept, which acknowledges the interdependence of humans, animals, and the environment. In light of this, we have made an effort to present a thorough and wide-ranging background on the protective functions of selenium in successfully reducing mycotoxin toxicity and livestock viral infection. It concluded that mycotoxins could be systemically harmful and pose a severe risk to human and animal health. On the contrary, animal mycotoxins and viral illnesses have a close connection. Last but not least, these findings show that the interaction between Se status and host response to mycotoxins and cattle virus infection is crucial.

Structure-toxicity relationships, toxicity mechanisms and health risk assessment of food-borne modified deoxynivalenol and zearalenone: A comprehensive review

Mycotoxin, as one of the most common pollutants in foodstuffs, poses great threat to food security and human health. Specifically, deoxynivalenol (DON) and zearalenone (ZEN)-two mycotoxin contaminants with considerable toxicity widely existing in food products-have aroused broad public concerns. Adding to this picture, modified forms of DON and ZEN, have emerged as another potential environmental and health threat, owing to their higher re-transformation rate into parent mycotoxins inducing accumulation of mycotoxin in humans and animals. Given this, a better understanding of the toxicity of modified mycotoxins is urgently needed. Moreover, the lack of toxicity data means a proper risk assessment of modified mycotoxins remains challenging. To better evaluate the toxicity of modified DON and ZEN, we have reviewed the relationship between their structures and toxicities. The toxicity mechanisms behind modified DON and ZEN have also been discussed; briefly, these involve acute, subacute, chronic, and combined toxicities. In addition, this review also addresses the global occurrence of modified DON and ZEN, and summarizes novel methods-including in silico analysis and implementation of relative potency factors-for risk assessment of modified DON and ZEN. Finally, the health risk assessment of modified DON and ZEN has also been discussed comprehensively.

Proteomic analysis of zearalenone toxicity on mouse thymic epithelial cells

Zearalenone (ZEA) is one of the most major food contaminants in cereal crops worldwide, risking health of both livestock and humans. This study aimed to assess the cytotoxicity and the underlying mechanism of ZEA on thymic epithelial cells. By using proteomics analysis, we identified 596 differentially expressed proteins in MTEC1 cells upon zearalenone exposure, of which 245 were upregulated and 351 were downregulated. Gene ontology (GO) analysis suggested that differentially expressed proteins were participated in protein synthesis, oxidative phosphorylation, and ATP binding. KEGG pathway enrichment analysis showed that differentially expressed proteins were mainly related to mitochndrial metabolism, such as citrate cycle (TCA cycle) and oxidative phosphorylation. We demonstrated that ZEA treatment was able to increase the intracellular reactive oxygen species (ROS) level, to decrease ΔΨm, ATP level, and the copy number of mtDNA, leading to necrotic cell death. Moreover, we showed that ZEA treatment inhibited cell proliferation and induced G2/M phase arrest by downregulation of proliferation-associated proteins ERK, p-ERK, CDK1, and p-CHK1. Taken together, we found that the toxicity of ZEA on thymic epithelial cells is mainly caused by the inhibition of mitochondrial dysfunction and cell proliferation. Our study might open new avenues for treatment strategies.

Occurrence of Zearalenone and Its Metabolites in the Blood of High-Yielding Dairy Cows at Selected Collection Sites in Various Disease States

Zearalenone (ZEN) and its metabolites, alpha-zearalenol (α-ZEL) and beta-zearalenol (β-ZEL), are ubiquitous in plant materials used as feed components in dairy cattle diets. The aim of this study was to confirm the occurrence of ZEN and its selected metabolites in blood samples collected from different sites in the hepatic portal system (posthepatic-external jugular vein EJV; prehepatic-abdominal subcutaneous vein ASV and median caudal vein MCV) of dairy cows diagnosed with mastitis, ovarian cysts and pyometra. The presence of mycotoxins in the blood plasma was determined with the use of combined separation methods involving immunoaffinity columns, a liquid chromatography system and a mass spectrometry system. The parent compound was detected in all samples collected from diseased cows, whereas α-ZEL and β-ZEL were not identified in any samples, or their concentrations were below the limit of detection (LOD). Zearalenone levels were highest in cows with pyometra, where the percentage share of average ZEN concentrations reached 44%. Blood sampling sites were arranged in the following ascending order based on ZEN concentrations: EJV (10.53 pg/mL, 44.07% of the samples collected from this site), ASV (14.20 pg/mL, 49.59% of the samples) and MCV (26.67 pg/mL, 67.35% of the samples). The results of the study indicate that blood samples for toxicological analyses should be collected from the MCV (prehepatic vessel) of clinically healthy cows and/or cows with subclinical ZEN mycotoxicosis. This sampling site increases the probability of correct diagnosis of subclinical ZEN mycotoxicosis.

Correlations between Low Doses of Zearalenone, Its Carryover Factor and Estrogen Receptor Expression in Different Segments of the Intestines in Pre-Pubertal Gilts-A Study Protocol

Plant materials can be contaminated with Fusarium mycotoxins and their derivatives, whose toxic effects on humans and animals may remain subclinical. Zearalenone (ZEN), a low-molecular-weight compound, is produced by molds in crop plants as a secondary metabolite. The objective of this study will be to analyze the in vivo correlations between very low monotonic doses of ZEN (5, 10, and 15 μg ZEN/kg body weight—BW for 42 days) and the carryover of this mycotoxin and its selected metabolites from the intestinal contents to the intestinal walls, the mRNA expression of estrogen receptor alfa (ERα) and estrogen receptor beta (ERβ) genes, and the mRNA expression of genes modulating selected colon enzymes (CYP1A1 and GSTP1) in the intestinal mucosa of pre-pubertal gilts. An in vivo experiment will be performed on 60 clinically healthy animals with initial BW of 14.5 ± 2 kg. The gilts will be randomly divided into a control group (group C, n = 15) and three experimental groups (group ZEN5, group ZEN10, and group ZEN15; n = 15). Group ZEN5 will be administered per os 5 μg ZEN/kg BW (MABEL), group ZEN10—10 μg ZEN/kg BW (NOAEL), and group ZEN15—15 µg ZEN/kg BW (low LOAEL). In each group, five animals will be euthanized on analytical dates 1 (exposure day 7), 2 (exposure day 21), and 3 (exposure day 42). Samples for in vitro analyses will be collected from an intestinal segment resected from the following regions: the third (horizontal) part of the duodenum, jejunum, ileum, cecum, ascending colon, transverse colon, and descending colon. The experimental material will be collected under special conditions, and it will be transported to specialist laboratories where samples will be obtained for further analyses.

Impact of Fusarium-Derived Mycoestrogens on Female Reproduction: A Systematic Review

Contamination of the world’s food supply and animal feed with mycotoxins is a growing concern as global temperatures rise and promote the growth of fungus. Zearalenone (ZEN), an estrogenic mycotoxin produced by Fusarium fungi, is a common contaminant of cereal grains and has also been detected at lower levels in meat, milk, and spices. ZEN’s synthetic derivative, zeranol, is used as a growth promoter in United States (US) and Canadian beef production. Experimental research suggests that ZEN and zeranol disrupt the endocrine and reproductive systems, leading to infertility, polycystic ovarian syndrome-like phenotypes, pregnancy loss, and low birth weight. With widespread human dietary exposure and growing experimental evidence of endocrine-disrupting properties, a comprehensive review of the impact of ZEN, zeranol, and their metabolites on the female reproductive system is warranted. The objective of this systematic review was to summarize the in vitro, in vivo, and epidemiological literature and evaluate the potential impact of ZEN, zeranol, and their metabolites (commonly referred to as mycoestrogens) on female reproductive outcomes. We conducted a systematic review (PROSPERO registration CRD42020166469) of the literature (2000–2020) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The data sources were primary literature published in English obtained from searching PubMed, Web of Science, and Scopus. The ToxR tool was applied to assess risk of bias. In vitro and in vivo studies (n = 104) were identified and, overall, evidence consistently supported adverse effects of mycoestrogens on physiological processes, organs, and tissues associated with female reproduction. In non-pregnant animals, mycoestrogens alter follicular profiles in the ovary, disrupt estrus cycling, and increase myometrium thickness. Furthermore, during pregnancy, mycoestrogen exposure contributes to placental hemorrhage, stillbirth, and impaired fetal growth. No epidemiological studies fitting the inclusion criteria were identified.

Obesity alters the ovarian proteomic response to zearalenone exposure†

Zearalenone (ZEN), a nonsteroidal estrogenic mycotoxin, is detrimental to female reproduction. Altered chemical biotransformation, depleted primordial follicles and a blunted genotoxicant response have been discovered in obese female ovaries, thus, this study investigated the hypothesis that obesity would enhance ovarian sensitivity to ZEN exposure. Seven-week-old female wild-type nonagouti KK.Cg-a/a mice (lean) and agouti lethal yellow KK.Cg-Ay/J mice (obese) received food and water ad libitum, and either saline or ZEN (40 μg/kg) per os for 15 days. Body and organ weights, and estrous cyclicity were recorded, and ovaries collected posteuthanasia for protein analysis. Body and liver weights were increased (P < 0.05) in the obese mice, but obesity did not affect (P > 0.05) heart, kidney, spleen, uterus, or ovary weight and there was no impact (P > 0.05) of ZEN exposure on body or organ weight in lean or obese mice. Obese mice had shorter proestrus (P < 0.05) and a tendency (P = 0.055) for longer metestrus/diestrus. ZEN exposure in obese mice increased estrus but shortened metestrus/diestrus length. Neither obesity nor ZEN exposure impacted (P > 0.05) circulating progesterone, or ovarian abundance of EPHX1, GSTP1, CYP2E1, ATM, BRCA1, DNMT1, HDAC1, H4K16ac, or H3K9me3. Lean mice exposed to ZEN had a minor increase in γH2AX abundance (P < 0.05). In lean and obese mice, LC–MS/MS identified alterations to proteins involved in chemical metabolism, DNA repair and reproduction. These data identify ZEN-induced adverse ovarian modes of action and suggest that obesity is additive to ZEN-induced ovotoxicity.

Zearalenone Induces Endothelial Cell Apoptosis through Activation of a Cytosolic Ca2+/ERK1/2/p53/Caspase 3 Signaling Pathway

Zearalenone (ZEN) is a mycotoxin that has been reported to damage various types of cells/tissues, yet its effects on endothelial cells (ECs) have never been investigated. Therefore, this study investigates the potential effects of ZEN using bovine aortic ECs (BAECs). In this study, we found that ZEN induced apoptosis of BAECs through increased cleavage of caspase 3 and poly ADP-ribose polymerase (PARP). ZEN also increased phosphorylation of ERK1/2 and p53, and treatment with the ERK1/2 or p53 inhibitor reversed ZEN-induced EC apoptosis. Transfection of BAECs with small interfering RNA against ERK1/2 or p53 revealed ERK1/2 as an upstream target of p53 in ZEN-stimulated apoptosis. ZEN increased the production of reactive oxygen species (ROS), yet treatment with the antioxidant did not prevent EC apoptosis. Similarly, blocking of estrogen receptors by specific inhibitors also did not prevent ZEN-induced apoptosis. Finally, chelation of cytosolic calcium (Ca²⁺) using BAPTA-AM or inhibition of endoplasmic reticulum (ER) Ca²⁺ channel using 2-APB reversed ZEN-induced EC apoptosis, but not by inhibiting ER stress using 4-PBA. Together, our findings demonstrate that ZEN induces EC apoptosis through an ERK1/2/p53/caspase 3 signaling pathway activated by Ca²⁺ release from the ER, and this pathway is independent of ROS production and estrogen receptor activation.

Resveratrol alleviates zea-induced decidualization disturbance in human endometrial stromal cells

Decidualization, which endows the endometrium competency to adopt developing embryo and maintain appropriate milieu for following growth, is a pivotal process for human pregnancy. The delicate collaboration between ovarian steroid hormones estrogen and progesterone governs the process of decidualization and subsequent establishment of embryo implantation. Mycotoxin zearalenone (ZEA) is well known as endocrine disruptor due to its potent estrogenic activity. In this study, we investigated effects of ZEA on decidualization of human endometrial stromal cells. Results indicated that ZEA exhibited its inhibitory action through nuclear translocation of ERα. ZEA exposure led to dampened progress of decidualization, which could be attenuated by estrogen receptor antagonist. Notably, resveratrol (RSV) administration restored impaired decidualization process by induction of anti-oxidative gene glutathione peroxidase 3 (GPX3). This study provides novel insights into the mechanism underlying adverse effects of ZEA in human decidual stromal cells and suggests RSV a potential therapeutic candidate to alleviate ZEA-induced cytotoxicity during decidualization.

Effects of zearalenone on genital organ development, serum immunoglobulin, antioxidant capacity, sex hormones and liver function of prepubertal gilts

The study aimed to examine the effects of zearalenone on genital organ development, serum immunoglobulin, antioxidant capacity, sex hormones and liver function of prepubertal gilts. Forty-eight prepubertal gilts (Landrace × Yorkshire) were randomly divided into three treatment (T1, T2 and T3) groups and a control group (12 replicates per group, 1 gilt per replicate). Prepubertal gilts in the control group were fed with basal diet, and those in T1, T2 and T3 groups were fed with basal diets supplemented with 200 μg/kg, 800 μg/kg and 1600 μg/kg zearalenone during the experiment period, which lasted for 14 d. Feed intake was counted and vulvar area was measured. The blood samples were collected from the anterior vena cava of 6 prepubertal gilts in each group, and immunoglobulins, antioxidant indexes, inflammatory cytokines, genital hormones, and biochemical indexes were analyzed by enzyme-linked immunosorbent assay. The results showed that the average daily feed intake of prepubertal gilts in each group had no significant change (p > 0.05). On 14 d, compared with the control group, the vulva area of prepubertal gilts in each treatment group was significantly increased (p < 0.05). Compared with the control group, the serum immunoglobulin G content in the T3 group was significantly reduced (p < 0.05). The activities of total antioxidant capacity and the superoxide dismutase of serum in the T3 group were significantly reduced (p < 0.05). Compared with the control group, the serum interleukin-4 content in each test group were extremely significantly increased (p < 0.01). The serum contents of luteinizing hormone in the T2 and T3 groups and estradiol in the T3 group were significantly reduced (p < 0.05) than that of control group. Compared with the control group, the activity of aspartate aminotransferase in T3 group was significantly increased (p < 0.05). In conclusion, zearalenone has no significantly effect on the feed intake of prepubertal gilts, but it can reduce its serum immunoglobulin contents and antioxidant properties, disrupt the secretion of sex hormones, increase the vulva area, produce reproductive toxicity and cause liver damage. Therefore, in pig production, the use of antimould reagent together with products of immunity-boosting, antioxidant, anti-inflammatory and hepatoprotective may enhance protection.

Effects of endocrine disrupting chemicals in pigs

Endocrine-disrupting chemicals (EDCs) are compounds that interfere with the expression, synthesis, and activity of hormones in organisms. They are released into the environment from flame retardants and products containing plasticizers. Persistent pesticides, such as dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene, also disrupt the endocrine system through interaction with hormone receptors. Endogenous hormones, such as 17β-estradiol (E2), are released in the urine and feces of farm animals and seep into terrestrial and aquatic ecosystems through sewage. Pigs are widely used as animal models to determine the effects of EDCs because they are physiologically, biochemically, and histologically similar to humans. EDCs primarily disrupt the reproductive and nervous systems of pigs. Moreover, embryonic development during the prenatal and early postnatal periods is particularly sensitive to EDCs. Mycotoxins, such as zearalenone, are food contaminants that alter hormonal activities in pigs. Mycotoxins also alter the innate immune system in pigs, making them vulnerable to diseases. It has been reported that farm animals are exposed to various types of EDCs, which accumulate in tissues, such as those of gonads, livers, and intestines. There is a lack of an integrated understanding of the impact of EDCs on porcine reproduction and development. Thus, this article aims to provide a comprehensive review of literature regarding the effects of EDCs in pigs.

Zearalenone-Induced Interaction between PXR and Sp1 Increases Binding of Sp1 to a Promoter Site of the eNOS, Decreasing Its Transcription and NO Production in BAECs

Zearalenone (ZEN) is a non-steroidal mycotoxin that has various toxicological impacts on mammalian health. Here, we found that ZEN significantly affected the production of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS) of bovine aortic endothelial cells (BAECs). A promoter analysis using 5′-serially deleted human eNOS promoter revealed that the proximal region (−135 to +22) was responsible for ZEN-mediated reduction of the human eNOS promoter activity. This effect was reversed by mutation of two specificity protein 1 (Sp1) binding elements in the human eNOS promoter. A chromatin immunoprecipitation assay revealed that ZEN increased Sp1 binding to the bovine eNOS promoter region (−113 to −12), which is homologous to −135 to +22 of the human eNOS promoter region. We also found that ZEN promoted the binding of the pregnane X receptor (PXR) to Sp1 of the bovine eNOS, consequently decreasing eNOS expression. This reduction of eNOS could have contributed to the decreased acetylcholine-induced vessel relaxation upon ZEN treatment in our ex vivo study using mouse aortas. In conclusion, our data demonstrate that ZEN decreases eNOS expression by enhancing the binding of PXR-Sp1 to the eNOS promoter, thereby decreasing NO production and potentially causing vessel dysfunction.

Chlorogenic acid rescues zearalenone induced injury to mouse ovarian granulosa cells

Zearalenone (ZEA), a toxic substance produced by Fusarium fungi, accumulated in cereals grain and animal feed, causes injury to humans and animals. ZEA can induce obvious reproductive toxicity with the ovarian granulosa cells (GCs) as the main target. However, the study on exploring the protective compounds against ZEA-induced mouse primary ovarian GCs damage remains less. In the current study, the protective effect of 20 compounds derived from traditional Chinese medicines (TCMs) on the injury of mouse GCs caused by ZEA were evaluated using MTT assay and the cell morphology. Our results showed that chlorogenic acid (250, 500, and 1000 μg/mL) significantly suppress ZEA-induced GCs death. Western blot analysis suggested chlorogenic acid could rescue the up-regulated apoptosis of GCs induced by ZEA via attenuating the protein expression of cleaved caspase-3, the ratio of Bax/Bcl-2 and cleaved-PARP. Our results provide strong evidence that chlorogenic acid warrants further optimization for more potent and safer compounds for against the ZEA lead toxicity to humans and animals.

ERβ and NFκB-Modulators of Zearalenone-Induced Oxidative Stress in Human Prostate Cancer Cells

Nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) is commonly expressed in prostate cancer (PCa) cells and is associated with increased proliferation, metastases and androgen independence. Zearalenone (ZEA) is one of the most common mycotoxins contaminating food, which might mimic estrogens and bind to estrogen receptors (ERs). The ratio of androgens to estrogens in men decreases physiologically with age, and is believed to participate in prostate carcinogenesis. In this study, we evaluated the role of NFκB and ERβ in the induction of oxidative stress in human PCa cells by ZEA. As observed, ZEA at a dose of 30 µM induces oxidative stress in PCa cells associated with DNA damage and G2/M cell cycle arrest. We also observed that the inhibition of ERβ and NFΚB via specific inhibitors (PHTPP and BAY 117082) significantly increased ZEA-induced oxidative stress, although the mechanism seems to be different for androgen-dependent and androgen-independent cells. Based on our findings, it is possible that the activation of ERβ and NFΚB in PCa might protect cancer cells from ZEA-induced oxidative stress. We therefore shed new light on the mechanism of ZEA toxicity in human cells.

Correlations between exposure to deoxynivalenol and zearalenone and the immunohistochemical expression of estrogen receptors in the intestinal epithelium and the mRNA expression of selected colonic enzymes in pre-pubertal gilts

Plant-based materials used in the production of pig feed are very often contaminated with deoxynivalenol and zearalenone. Daily intake of small amounts of these mycotoxins with feed induces various subclinical states in gilts and influences different biological processes. The aim of this preclinical study was to determine the correlation between monotonic doses of zearalenone and deoxynivalenol (40 μg/kg body weight and 12 μg/kg body weight, respectively, administered over a period of 42 days) and the immunohistochemical expression of estrogen receptors in the intestinal tract and the mRNA expression of selected colonic enzymes. The immunohistochemical expression of estrogen receptor alpha was observed in the colon, but its intensity varied in different weeks of exposure. A minor increase in estrogen receptor beta expression was noted only in the colon, whereas the expression of cytochrome P450 1A1 enzyme mRNA and mRNA isoform of the glutathione S-transferase π gene decreased. The observed correlations suggest that the risk of loss of control over the biotransformation and biological activity of the parent compounds in distal intestinal mucosa is delayed.

Imbalance in the Blood Concentrations of Selected Steroids in Pre-pubertal Gilts Depending on the Time of Exposure to Low Doses of Zearalenone

Zearalenone (ZEN) is a mycotoxin that not only binds to estrogen receptors, but also interacts with steroidogenic enzymes and acts as an endocrine disruptor. The aim of this study was to verify the hypothesis that low doses, minimal anticipated biological effect level (MABEL), no-observed-adverse-effect level (NOAEL) and lowest-adverse-effect level (LOAEL), of ZEN administered orally for 42 days can induce changes in the peripheral blood concentrations of selected steroid hormones (estradiol, progesterone and testosterone) in pre-pubertal gilts. The experiment was performed on 60 clinically healthy gilts with average BW of 14.5 ± 2 kg, divided into three experimental groups and a control group. Group ZEN5 animals were orally administered ZEN at 5 μg ZEN/kg BW, group ZEN10 - at 10 μg ZEN/kg BW, group ZEN15 - at 15 μg ZEN/kg BW, whereas group C received a placebo. Five gilts from every group were euthanized on analytical dates 1, 2 and 3 (days 7, 14 and 42 of the experiment). Qualitative and quantitative changes in the biotransformation of low ZEN doses were observed. These processes were least pronounced in group ZEN5 (MABEL dose) where ZEN metabolites were not detected on the first analytical date, and where β-ZEL was the predominant metabolite on successive dates. The above was accompanied by an increase in the concentration of estradiol (E2) which, together with "free ZEN", probably suppressed progesterone (P4) and testosterone (T) levels.

Biotransformation of the Mycotoxin Zearalenone to its Metabolites Hydrolyzed Zearalenone (HZEN) and Decarboxylated Hydrolyzed Zearalenone (DHZEN) Diminishes its Estrogenicity In Vitro and In Vivo

Zearalenone (ZEN)-degrading enzymes are a promising strategy to counteract the negative effects of this mycotoxin in livestock. The reaction products of such enzymes need to be thoroughly characterized before technological application as a feed additive can be envisaged. Here, we evaluated the estrogenic activity of the metabolites hydrolyzed zearalenone (HZEN) and decarboxylated hydrolyzed zearalenone (DHZEN) formed by hydrolysis of ZEN by the zearalenone-lactonase Zhd101p. ZEN, HZEN, and DHZEN were tested in two in vitro models, the MCF-7 cell proliferation assay (0.01–500 nM) and an estrogen-sensitive yeast bioassay (1–10,000 nM). In addition, we compared the impact of dietary ZEN (4.58 mg/kg) and equimolar dietary concentrations of HZEN and DHZEN on reproductive tract morphology as well as uterine mRNA and microRNA expression in female piglets (n = 6, four weeks exposure). While ZEN increased cell proliferation and reporter gene transcription, neither HZEN nor DHZEN elicited an estrogenic response, suggesting that these metabolites are at least 50–10,000 times less estrogenic than ZEN in vitro. In piglets, HZEN and DHZEN did not increase vulva size or uterus weight. Moreover, RNA transcripts altered upon ZEN treatment (EBAG9, miR-135a-5p, miR-187-3p and miR-204-5p) were unaffected by HZEN and DHZEN. Our study shows that both metabolites exhibit markedly reduced estrogenicity in vitro and in vivo, and thus provides an important basis for further evaluation of ZEN-degrading enzymes.

MicroRNAs in porcine uterus and serum are affected by zearalenone and represent a new target for mycotoxin biomarker discovery

The mycotoxin zearalenone (ZEN) poses a risk to animal health because of its estrogenic effects. Diagnosis of ZEN-induced disorders remains challenging due to the lack of appropriate biomarkers. In this regard, circulating microRNAs (small non-coding RNAs) have remarkable potential, as they can serve as indicators for pathological processes in tissue. Thus, we combined untargeted and targeted transcriptomics approaches to investigate the effects of ZEN on the microRNA expression in porcine uterus, jejunum and serum, respectively. To this end, twenty-four piglets received uncontaminated feed (Control) or feed containing 0.17 mg/kg ZEN (ZEN low), 1.46 mg/kg ZEN (ZEN medium) and 4.58 mg/kg ZEN (ZEN high). After 28 days, the microRNA expression in the jejunum remained unaffected, while significant changes in the uterine microRNA profile were observed. Importantly, 14 microRNAs were commonly and dose-dependently affected in both the ZEN medium and ZEN high group, including microRNAs from the miR-503 cluster (i.e. ssc-miR-424-5p, ssc-miR-450a, ssc-miR-450b-5p, ssc-miR-450c-5p, ssc-miR-503 and ssc-miR-542-3p). Predicted target genes for those microRNAs are associated with regulation of gene expression and signal transduction (e.g. cell cycle). Although the effects in serum were less pronounced, receiver operating characteristic analysis revealed that several microRNA ratios were able to discriminate properly between non-exposed and ZEN-exposed pigs (e.g. ssc-miR-135a-5p/ssc-miR-432-5p, ssc-miR-542-3p/ssc-miR-493-3p). This work sheds new light on the molecular mechanisms of ZEN, and fosters biomarker discovery.

Effects of zearalenone and its derivatives on the synthesis and secretion of mammalian sex steroid hormones: A review

Zearalenone (ZEA), a non-steroidal estrogen mycotoxin produced by several species of Fusarium fungi, can be metabolized into many other derivatives by microorganisms, plants, animals and humans. It can affect mammalian reproductive capability by impacting the synthesis and secretion of sex hormones, including testosterone, estradiol and progesterone. This review summarizes the mechanisms in which ZEA and its derivatives disturb the synthesis and secretion of sex steroid hormones. Because of its structural analogy to estrogen, ZEA and its derivatives can exert a variety of estrogen-like effects and engage in estrogen negative feedback regulation, which can result in mediating the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary gland. ZEA and its derivatives can ultimately reduce the number of Leydig cells and granulosa cells by inducing oxidative stress, endoplasmic reticulum (ER) stress, cell cycle arrest, cell apoptosis, and cell regeneration delay. Additionally, they can disrupt the mitochondrial structure and influence mitochondrial functions through overproduction of reactive oxygen species (ROS) and aberrant autophagy signaling ways. Finally, ZEA and its derivatives can disturb the expressions and activities of the related steroidogenic enzymes through cross talking between membrane and nuclear estrogen receptors.

Dietary exposure to mycotoxin zearalenone (ZEA) during post-implantation adversely affects placental development in mice

Zearalenone (ZEA) is a common food contaminant (ppb-ppm) derived from Fusarium fungi. With its estrogenicity and potential chronic exposure, ZEA poses a risk to pregnancy. Our previous studies implied post-implantational lethality by ZEA. Since a functional placenta is essential for fetal development and survival, it was hypothesized that ZEA may have adverse effects on placental development leading to post-implantational lethality. Exposure of young mice to 0, 0.8, 4, 10, and 40 ppm ZEA diets from gestation day 5.5 (D5.5) to D13.5 led to increased resorption of implantation sites, increased placental hemorrhage, decreased placental and fetal weights, proportionally reduced placental layers, and disorganized placental labyrinth vascular spaces in the 40 ppm ZEA group, as well as lipid accumulation in the labyrinth layer of all four ZEA treatment groups examined on D13.5. These data demonstrate adverse effects of ZEA on placental development.

MiR-7 Mediates the Zearalenone Signaling Pathway Regulating FSH Synthesis and Secretion by Targeting FOS in Female Pigs

Zearalenone (ZEA) acts as an environmental endocrine disruptor (EED) to cause health detriments. miRNAs were reported to influence the synthesis and secretion of pituitary hormones. However, the interactions between ZEA and miRNAs and related mechanisms remain unclear. The aims of this study were to determine whether and how miR-7 affects animal reproduction by its interactions with ZEA in the pig pituitary, which is sensitive to ZEA and has been used as an important animal model in medical research. Expressions of miRNA were detected by real-time PCR, in situ hybridization, and immunohistochemistry. The effects of ZEA, miR-7, and their interactions in the pituitary gland were identified by using an ovariectomized pig model, transfecting miR-7 mimics and inhibitor, radioimmunoassay, luciferase reporter assay, and Western blotting. The ZEA dosage was 7.5 mg/kg body weight in vivo and 1 μM in vitro. Our results demonstrate miR-7 acts to regulate gonadotropin synthesis and secretion. Furthermore, we found that ZEA leads to reproductive defects by enhancing miR-7 expression, which subsequently inhibits FSH synthesis and secretion. In vitro and in vivo experiments revealed that the effects of ZEA rely on G protein-coupled estrogen receptor 1, and miR-7 functions by mediating ZEA signaling pathway and targeting the Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog (FOS) gene. These findings show that miRNAs are key intrinsic factors regulating pituitary gonadotropins by mediating EED signaling in pituitary glands, and the actions of miRNAs and EEDs should be seriously considered in related studies about medical practice and animal production.

Mycotoxin zearalenone exposure impairs genomic stability of swine follicular granulosa cells in vitro

Zearalenone (ZEA), a metabolite of Fusarium fungi, is commonly found on moldy grains. Because it can competitively combine to estrogen receptor to disrupt estrogenic signaling, it has been reported to have serious adverse effects on animal reproduction systems. In order to explore the genotoxic effects of ZEA exposure on ovarian somatic cells, porcine granulosa cells were exposed to 10 μM and 30 μM ZEA for 24 or 72 h in vitro. The results showed that ZEA exposure for 24 h remarkably reduced the proliferation of porcine granulosa cells in a dose-dependent manner as determined by MTT analysis and flow cytometry. Furthermore, exposure to ZEA for 72 h induced apoptosis, and RNA sequence analysis also revealed that the expression of apoptosis related genes were altered. RT-qPCR, immunofluorescence and western blot analysis further confirmed the expression of DNA damage and repair related genes (γ-H2AX, BRCA1, RAD51 and PRKDC) were increased in ZEA exposed granulosa cells. When the estrogen antagonist, tamoxifen, was added with ZEA in the culture medium, the DNA damage and repairment by ZEA returned to normal level. Collectively, these results illustrate that ZEA disrupts genome stability and inhibits growth of porcine granulosa cells via the estrogen receptors which may promote granulosa cell apoptosis when the DNA repair system is not enough to rescue this serious damage.