Toxic effects of the mycotoxin zearalenone and its derivatives on in vitro maturation of bovine oocytes and 17 beta-estradiol levels in mural granulosa cell cultures

Real-life exposure to Fusarium toxins deoxynivalenol and zearalenone triggers apoptosis and activates NLRP3 inflammasome in bovine primary theca cells

Cattle are deemed less susceptible to mycotoxins due to the limited internal exposure resulting from rumen microbiota activity. However, the significant amounts of Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) frequently detected in bovine follicular fluid samples suggest that they could affect ovarian function. Both mycotoxins trigger several patterns of cell death and activate the NLRP3 inflammasome in the intestine. In vitro studies have reported a number of adverse effects on bovine oocytes. However, the biological relevance of such findings with regard to realistic concentrations of DON and ZEN in bovine follicular fluid is still not clear. Hence, it is important to better characterize the effects of dietary exposure to DON and ZEN on the bovine ovary. Using bovine primary theca cells, this study investigated the effects of real-life patterns for bovine ovary exposure to DON and ZEN, but also DON metabolite DOM-1, on cell death and NLRP3 inflammasome activation. Exposure to DON starting from 0.1 μM significantly decreased theca cell viability. The kinetics of phosphatidylserine translocation and loss of membrane integrity showed that ZEN and DON, but not DOM-1, induce an apoptotic phenotype. qPCR analysis of the expression of NLRP3, PYCARD, IL-1β, IL-18, and GSDMD in primary theca cells at concentrations of mycotoxin previously reported in cow follicular fluid clearly indicated that DON and DOM-1 individually and in mixture, but not ZEN, activate NLRP3 inflammasome. Altogether, these results suggest that real-life dietary exposure of cattle to DON may induce inflammatory disorders in the ovary.

Presence of the toxigenic fungi Aspergillus spp. and Fusarium spp. in Musca domestica L. (Diptera: Muscidae) collected from dairy farms

The objective of the study was to identify the presence of toxigenic fungi Aspergillus spp. and Fusarium spp. in domestic flies collected from dairy farms. We selected 10 dairy farms distributed in the central valley of the state of Aguascalientes, México. The flies were trapped using entomological traps with an olfactory attractant in 7 sites of the farm (silo-cutting surface, feed store, milking parlor, 3 feeders, and the rearing room). The fungi were cultivated in Sabouraud agar through direct sowing by serial dilutions to obtain the isolates, and a taxonomical identification was carried out under the microscope. The aflatoxins and zearalenone production capacity of the pure isolates were quantified using the ELISA test. The flies were present in all of the capture sites (45.3 flies, 567 mg, trap per day). We obtained 50 isolates of Aspergillus spp. genus, 12 of which produced aflatoxins (327 ± 143 µg/kg), whereas from 56 of the Fusarium spp. isolates, 10 produced large quantities of zearalenone (3,132 ± 665 µg/kg). These results suggest that the presence of domestic flies on dairy farms can constitute a source of dissemination for toxigenic fungi that can eventually contaminate grains and forage that are part of the daily cattle diet.

In vitro effect of zearalenone on sperm parameters, oocyte maturation and embryonic development in buffalo

The negative impact of zearalenone (ZEN; potent estrogenic mycotoxin) exposure on buffalo embryo production has not yet been determined. In the current study, buffalo sperm and oocytes were exposed to ZEN at different concentrations during maturation. Sperms (with and without ZEN exposure) were incubated for 2 h and evaluated for motility, viability, acrosome integrity, normality, and ultrastructure. Matured oocytes exposed to ZEN were stained to determine their nuclear maturation. Further, their developmental ability was evaluated after in vitro fertilization. Our results showed the toxic effects of ZEN at high concentrations (2000 ng/mL) on different buffalo sperm parameters. The number of acrosome-intact sperm was reduced at 0 h after exposure to a concentration of ≥ 100 ng/mL. Furthermore, the maturation rate of buffalo oocytes (telophase I + metaphase II) was significantly decreased in ZEN-treated oocytes with a higher degeneration rate. Oocytes matured in 1000 ng/mL ZEN and subsequently exhibited considerable reduction in cleavage rate and blastocyst formation compared with control oocytes (2.6% vs. 13.1%). Moreover, the morula rate was decreased (p < 0.001) in ZEN-treated oocytes at concentrations of ≥ 10 ng/mL. Overall, the adverse effects of in vitro ZEN exposure on buffalo sperm parameters and oocyte meiotic progression with a notable reduction in cleavage, morula, and blastocyst rates were defined by these results. Altogether, buffaloes should be considered sensitive to ZEN exposure with respect to their reproductive function.

Effects of Zearalenone on Apoptosis and Copper Accumulation of Goat Granulosa Cells In Vitro

Zearalenone (ZEA), also known as F-2 toxin, is a mycotoxin. Despite numerous reports of ZEA impairing livestock production performance and fertility, little information is available, including information about the mechanism underlying damage to cell metal ion transport. Copper, which is essential for cell survival as a metal ion, can consist of a variety of enzymes that facilitate abundant metabolic processes. However, the accumulation of copper in cells can have toxic effects. Here, we intended to determine whether ZEA could impair goat granulosa cells (GCs) and alter the cellular copper concentration. GCs were divided into a negative control (NC) group (cells cultured with 0.1% dimethyl sulfoxide (DMSO) for 8 h) and a ZEA group (cells cultured with 200 μmol/L ZEA diluted in DMSO for 8 h). The results showed that ZEA could inhibit GC proliferation and impair cell viability. GCs showed significant increases in the apoptosis rate and oxidative stress levels, while their ability to synthesize estrogen decreased. In addition, RNA-seq results showed dramatic changes in the expression of copper transport-related genes. The expression levels of ATPase copper transporting alpha (ATP7A) and ATPase copper transporting beta (ATP7B) were significantly downregulated (p < 0.01), while the expression of solute carrier family 31 member 1 (SLC31A1) was not modified in the ZEA group compared with the NC group. In accordance with these trends, the copper concentration increased significantly in the ZEA group (p < 0.01). In summary, our results show that ZEA can negatively affect GCs and cause copper accumulation. This finding may provide a prospective line of research on the relationship between ZEA and the transport of copper ions in GCs.

Adverse Effects of Fusarium Toxins in Ruminants: A Review of In Vivo and In Vitro Studies

With an increased knowledge of the mechanism of action of Fusarium mycotoxins, the concept that these substances are deleterious only for monogastric species is obsolete. Indeed, most mycotoxins can be converted into less toxic compounds by the rumen microflora from healthy animals. However, mycotoxin absorption and its conversion to more toxic metabolites, as well as their impact on the immune response and subsequently animal welfare, reproductive function, and milk quality during chronic exposure should not be neglected. Among the Fusarium mycotoxins, the most studied are deoxynivalenol (DON), zearalenone (ZEN), and fumonisins from the B class (FBs). It is remarkable that there is a paucity of in vivo research, with a low number of studies on nutrient digestibility and rumen function. Most of the in vitro studies are related to the reproductive function or are restricted to rumen incubation. When evaluating the production performance, milk yield is used as an evaluated parameter, but its quality for cheese production is often overlooked. In the present review, we summarize the most recent findings regarding the adverse effects of these mycotoxins with special attention to dairy cattle.

Zearalenone interferes with the sperm-triggered inflammation in the bovine uterus in vitro: Negative impact on sperm motility and survival

Zearalenone (ZEN)-contaminated diets induce detrimental effects on the bovine reproduction. Recently, we reported that active sperm induce pro-inflammatory responses in bovine endometrial epithelial cells (BEECs) in vitro. This study aimed to investigate the impact of presence of ZEN on the sperm-uterine crosstalk in vitro. BEECs monolayers were stimulated by ZEN (10, 100, and 1000 ng/mL) for 0, 3, 6, 12, or 24 h and gene expressions were analyzed by real-time PCR. Moreover, BEECs were pre-exposed to ZEN (10, 100, and 1000 ng/mL) for 24 h then, co-incubated with sperm for 6 h. Conditioned media (CM) from a sperm-BEECs co-culture, after pre-exposure to ZEN, were harvested and exploited to challenge either polymorphonuclear cells (PMNs) or sperm. Both PMNs phagocytic activity toward sperm and sperm motility parameters were then assessed. Results showed that ZEN alone induced pro-inflammatory responses in BEECs through the induction of mRNA expressions of pro-inflammatory cytokines (TNFA and IL1B) and PGES1 at different time points. Pre-exposure of BEECs to ZEN, amplified the sperm-triggered upregulation of pro-inflammatory cytokines (TNFA and IL1B) and chemokine IL8 mRNA abundance in BEECs. Sperm-BEECs conditioned media, primed by ZEN, stimulated the PMNs phagocytosis for sperm whereas suppressed sperm motility parameters. Taken together, these findings indicate that the presence of ZEN augments the pro-inflammatory cascade triggered by sperm in BEECs, provokes PMNs phagocytosis for sperm, and reduces sperm motility parameters. Such immunological reactions may create a hostile environment for sperm competence and survival in the bovine uterus, thus impair fertility.

Chromatin Accessibility and Transcriptomic Alterations in Murine Ovarian Granulosa Cells upon Deoxynivalenol Exposure

Deoxynivalenol (DON) is a common environmental toxin that is secreted by fusarium fungi that frequently contaminates feedstuff and food. While the detrimental effects of DON on human and animal reproductive systems have been well recognized, the underlying mechanism remains poorly understood. Ovarian granulosa cells (GCs), which surround oocytes, are crucial for regulating oocyte development, mainly through the secretion of hormones such as estrogen and progesterone. Using an in vitro model of murine GCs, we characterized the cytotoxic effects of DON and profiled genome-wide chromatin accessibility and transcriptomic alterations after DON exposure. Our results suggest that DON can induce decreased viability and growth, increased apoptosis rate, and disrupted hormone secretion. In total, 2533 differentially accessible loci and 2675 differentially expressed genes were identified that were associated with Hippo, Wnt, steroid biosynthesis, sulfur metabolism, and inflammation-related pathways. DON-induced genes usually have a concurrently increased occupancy of active histone modifications H3K4me3 and H3K27ac in their promoters. Integrative analyses identified 35 putative directly affected genes including Adrb2 and Fshr, which are key regulators of follicular growth, and revealed that regions with increased chromatin accessibility are enriched with the binding motifs for NR5A1 and NR5A2, which are important for GCs. Moreover, DON-induced inflammatory response is due to the activation of the NF-κB and MAPK signaling pathways. Overall, our results provide novel insights into the regulatory elements, genes, and key pathways underlying the response of ovarian GCs to DON cytotoxicity.

Inflammatory cytokines as key players of apoptosis induced by environmental estrogens in the ovary

Natural and synthetic environmental estrogens (EEs), interfering with the physiological functions of the body's estrogens, are widespread and are rising much concern for their possible deleterious effects on human and animal health, in particular on reproduction. In fact, increasing evidence indicate that EEs can be responsible for a variety of disfunctions of the reproductive system especially in females such as premature ovarian insufficiency (POI). Because of their great structural diversity, the modes of action of EEs are controversial. One important way through which EEs exert their effects on reproduction is the induction of apoptosis in the ovary. In general, EEs can exert pro-and anti-apoptotic effects by agonizing or antagonizing numerous estrogen-dependent signaling pathways. In the present work, results concerning apoptotic pathways and diseases induced by representative EEs (such as zearalenone, bisphenol A and di-2-ethylhexyl phthalate), in ovaries throughout development are presented into an integrated network. By reviewing and elaborating these studies, we propose inflammatory factors, centered on the production of tumor necrosis factor (TNF), as a major cause of the induction of apoptosis by EEs in the mammalian ovary. As a consequence, potential strategies to prevent such EE effect are suggested.

Melatonin Ameliorates the Toxicity Induced by Deoxynivalenol in Murine Ovary Granulosa Cells by Antioxidative and Anti-Inflammatory Effects

Melatonin is an important endogenous hormone that shows antioxidant functions and pleiotropic effects, playing a crucial role in animal reproduction. Ovary granulosa cells (GCs) surround the oocyte, which play an important role in regulating oocytes development. Deoxynivalenol (DON) is a common fusarium mycotoxin contaminant of feedstuff and food, posing a serious threat to human and animal reproductive systems. Herein, murine ovary GCs were studied as a reproduction cell model, aimed to assess the protective effect of melatonin on DON-induced toxicity in murine ovary GCs. The results showed that DON adversely affected the viability and growth of murine ovary GCs and increased the apoptosis rate, while melatonin administration ameliorated these toxic effects. We further reveal that DON exposure increased the intracellular reactive oxygen species level, reduced the mitochondrial membrane potential and ATP, and upregulated Tnfα (tumor necrosis factor α), Il6 (interleukin 6), and Il1β (interleukin 1 β) gene expression. Moreover, DON exposure downregulated reproductive hormone gene expression and significantly increased nuclear factor kappa B (p65) activation and mitogen-activated protein kinase phosphorylation. Melatonin treatment attenuated all these effects, suggesting that melatonin protects GCs from the adverse effects of DON by ameliorating oxidative stress, mitochondrial dysfunction, and inflammation. Overall, these results reveal the mechanisms of DON and melatonin in GCs and provide a theoretical basis for melatonin as a drug to improve mycotoxin contamination.

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.

Effects of experimental exposure to zearalenone on reproductive system morphometry, plasma oestrogen levels, and oocyte quality of beef heifer

The aim of the present study was to evaluate the effects of zearalenone (ZEA) on the reproductive system morphometry, oestrogen (E2) levels and oocyte quality of beef heifers. Twenty non-pregnant purebred Nellore (Bos indicus) heifers [age, ≥18 months; initial body weight, 348 ± 30 kg (mean ± standard deviation)] were used. The animals were randomly divided into experimental group and a control group of 10 animals each. Group experimental was administered 300 ppb ZEA per os for 98 days, and the control group was administered placebo per os for 98 days. The administration of ZEA was carried out daily by adding mycotoxin to the diet. All heifers were evaluated weekly via rectal ultrasound examinations (12 weeks). Diameters of the right and left uterine horns, right and left ovaries, largest antral follicle and corpus luteum were measured. Vulva size was also measured. Blood samples were collected to estimate E2 levels. At the end of 12 weeks, the heifers were slaughtered, and the ovaries were sent to the laboratory for in vitro embryo production. A completely randomized design was adopted, and repeated measures analysis of variance (p < .05) was performed (except for oocyte quality). Vulva size (p = .0985); diameters of uterine horns (p = .0522), ovaries (p = .6955), antral follicles (p = .6355) and corpus luteum (p = .3808); and E2 levels (p = .3379) were not affected by the treatments. ZEA-contaminated diet significantly reduced (p = .05) the proportion of viable oocytes (49.4%, n = 207) compared with the control diet (59.9%, n = 222); however, the blastocyst rate did not differ between the groups (p = .9418). The results indicate that contamination of beef heifer's diet with 300 ppb ZEA affected neither morphometric parameters nor plasma oestrogen levels; however, ZEA contamination was detrimental to oocyte quality.

Chemical repertoire and biosynthetic machinery of the Aspergillus flavus secondary metabolome: A review

Filamentous fungi represent a rich source of extrolites, including secondary metabolites (SMs) comprising a great variety of astonishing structures and interesting bioactivities. State-of-the-art techniques in genome mining, genetic manipulation, and secondary metabolomics have enabled the scientific community to better elucidate and more deeply appreciate the genetic and biosynthetic chemical arsenal of these microorganisms. Aspergillus flavus is best known as a contaminant of food and feed commodities and a producer of the carcinogenic family of SMs, aflatoxins. This fungus produces many SMs including polyketides, ribosomal and nonribosomal peptides, terpenoids, and other hybrid molecules. This review will discuss the chemical diversity, biosynthetic pathways, and biological/ecological role of A. flavus SMs, as well as their significance concerning food safety and security.

Multi-mycotoxins analysis in liquid milk by UHPLC-Q-Exactive HRMS after magnetic solid-phase extraction based on PEGylated multi-walled carbon nanotubes

A simple and rapid magnetic solid-phase extraction (MSPE) method using PEGylated multi-walled carbon nanotubes magnetic nanoparticles (PEG-MWCNTs-MNP) as absorbents is proposed for isolation and enrichment of aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁), aflatoxin G₂ (AFG₂), aflatoxin M₁ (AFM₁), aflatoxin M₂ (AFM₂), ochratoxin A (OTA), zearalenone (ZEA), zearalanone (ZAN), α-zeralanol (α-ZAL), β-zeralanol (β-ZAL), α-zeralenol (α-ZOL), and β-zeralenol (β-ZOL) from liquid milk. Combined with ultra-high performance liquid chromatography Q-Exactive high resolution mass spectrometry, simultaneous qualification of these mycotoxins was achieved with sensitivity and specificity. The proposed method showed a good linearity (R² ≥ 0.995), high sensitivity (limit of detection in the range of 0.005-0.050 μg/kg and limit of quantification in the range of 0.015-0.150 μg/kg), adequate recovery (81.8-106.4%), and good repeatability (intra-day precision in the range of 2.1-8.5% and inter-day precision in the range of 3.9-11.7%). It has been successfully applied to the determination of 13 mycotoxins in real liquid milk samples.

Melatonin alleviates β-zearalenol and HT-2 toxin-induced apoptosis and oxidative stress in bovine ovarian granulosa cells

β-zearalenol (β-zol) and HT-2 are mycotoxins which cause apoptosis and oxidative stress in mammalian reproductive cells. Melatonin is an endogenous antioxidant involved in apoptosis and oxidative stress-related activities. This study investigated the effects of β-zol and HT-2 on bovine ovarian granulosa cells (BGCs), and how melatonin may counteract these effects. β-zol and HT-2 inhibited cell proliferation in a dose-dependent manner, and induced apoptosis of BGCs. They also yielded upregulation of the apoptosis-related genes Bax/Bcl-2 and Caspase3 and phosphorylation of p38MAPK. Increases in intracellular ROS were observed along with higher levels of mRNA anti-oxidation markers SOD1, SOD2, and CAT. SOD1, SOD2, malonaldehyde (MDA), and glutathione peroxidase (GSH-px) activities increased, as did the levels of SOD1 and SOD2 proteins. All of these effects were reduced or entirely attenuated in BGCs pre-treated with melatonin. Our results demonstrate that melatonin has protective effects against mycotoxin-induced apoptosis and oxidative stress in BGCs.

Mechanism and effects of Zearalenone on mouse T lymphocytes activation in vitro

Zearalenone (ZEA) is particularly toxic to the female reproductive system. Nevertheless, the effect of ZEA on the immune system is still not fully understood. The following study investigates the effects and mechanism of ZEA on mouse T cell activation in vitro. Briefly, T lymphocytes were extracted from primary splenic lymphocyte in mice, activated by concanavalin A, and then were exposed to different concentrations of ZEA for a certain period of time. Flow cytometry was used to detect the expression of activating and co-stimulatory molecules, and the secretion of cytokines in T cells at various stages. The expression of initiation regulatory protein in T cell activation, nuclear factor protein and co-stimulatory molecule related PI3K-Akt-mTOR signaling pathway proteins were detected by western blot. Our data showed that ZEA exposure inhibits the activity of T cell, and inhibits the expression of different activation signals in T cell. Additionally, ZEA exposure reduces the expression of initiative regulatory protein, i.e. LAT, Lck, Zap-70 during the activation of T cells. Thus, the results showed that ZEA exposure inhibits the formation and transmission of activated signal in T cells, interferes with signal pathway of T cell activation nuclear factor NFAT and NFκB, and decreases the secretion of cytokines after activation. Moreover, ZEA exposure interferes with co-stimulatory molecule CD28 during T cell activation, and with the activity of the PI3K-Akt-mTOR signaling pathway downstream of CD28. To conclude, our results indicated that ZEA toxin interferes with the activation of mouse T lymphocytes by affecting TCR signal and co-stimulatory signal, thus playing an essential role in immune toxicity.

HERP depletion inhibits zearalenone-induced apoptosis through autophagy activation in mouse ovarian granulosa cells

HERP is an endoplasmic reticulum (ER) membrane protein and is strongly induced by stress conditions. A recent study has indicated that HERP cooperates in apoptosis during zearalenone (ZEA) treatment. However, regulatory mechanisms and the role of HERP in ZEA-induced apoptosis remain elusive in ovarian granulosa cells. In this study, MTT and flow cytometry assays demonstrated that ZEA gradually decreased cell viability and increased apoptosis in granulosa cells in a dose-dependent manner. Western blot analysis showed that ZEA significantly activated autophagy by upregulating LC3-II. Chloroquine (CQ) significantly increased LC3-II and induced granulosa cell apoptosis. Moreover, Western blot analysis showed that ZEA inhibited the mTOR and ERK1/2 signaling pathways. Furthermore, we found that ZEA activated ER stress by upregulating the ER stress-related proteins GRP78, HERP and CHOP. 4-PBA significantly decreased GRP78, HERP, CHOP and LC3-II. In addition, knockdown of HERP (shHERP) significantly protected ovarian granulosa cells from apoptosis induced by ZEA. We found that HERP depletion activated autophagy and ERK1/2 signaling pathways, while it inhibited the mTOR and caspase-dependent mitochondrial signaling pathways. In summary, autophagy and ER stress cooperated in apoptosis induced by ZEA; HERP depletion inhibits ZEA-induced apoptosis of ovarian granulosa cells through autophagy activation and apoptotic pathway inhibition.

Comparison of the toxic effects of different mycotoxins on porcine and mouse oocyte meiosis

Background

Aflatoxin B1 (AFB1), deoxynivalenol (DON), HT-2, ochratoxin A (OTA), zearalenone (ZEA) are the most common mycotoxins that are found in corn-based animal feed which have multiple toxic effects on animals and humans. Previous studies reported that these mycotoxins impaired mammalian oocyte quality. However, the effective concentrations of mycotoxins to animal oocytes were different.

Methods

In this study we aimed to compare the sensitivity of mouse and porcine oocytes to AFB1, DON, HT-2, OTA, and ZEA for mycotoxin research. We adopted the polar body extrusion rate of mouse and porcine oocyte as the standard for the effects of mycotoxins on oocyte maturation.

Results and Discussion

Our results showed that 10 μM AFB1 and 1 μM DON significantly affected porcine oocyte maturation compared with 50 μM AFB1 and 2 μM DON on mouse oocytes. However, 10 nM HT-2 significantly affected mouse oocyte maturation compared with 50 nM HT-2 on porcine oocytes. Moreover, 5 μM OTA and 10 μM ZEA significantly affected porcine oocyte maturation compared with 300 μM OTA and 50 μM ZEA on mouse oocytes. In summary, our results showed that porcine oocytes were more sensitive to AFB1, DON, OTA, and ZEA than mouse oocytes except HT-2 toxin.

Fusarium Molds and Mycotoxins: Potential Species-Specific Effects

This review summarizes the information on biochemical and biological activity of the main Fusarium mycotoxins, focusing on toxicological aspects in terms of species-specific effects. Both in vitro and in vivo studies have centered on the peculiarity of the responses to mycotoxins, demonstrating that toxicokinetics, bioavailability and the mechanisms of action of these substances vary depending on the species involved, but additional studies are needed to better understand the specific responses. The aim of this review is to summarize the toxicological responses of the main species affected by Fusarium mycotoxins.

A QuEChERS-Based Liquid Chromatography-Tandem Mass Spectrometry Method for the Simultaneous Determination of Nine Zearalenone-Like Mycotoxins in Pigs

The determination of zearalenone (ZEN) and its derivatives as biomarkers in animal tissues or organs plays an important role in mycotoxin monitoring and can promote effective exposure assessment. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of nine ZEN-like mycotoxins, including three glucuronides in different pig tissues (heart, liver, spleen and muscle) was developed and validated in this study. Tissue samples were extracted using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and clean-up procedure, and analyzed by LC-MS/MS in multiple reaction monitoring (MRM) mode. Dynamic linear ranges for each target analyte were determined with R² between 0.916 and 0.999. The LODs of the six ZENs were achieved in the range of 0.5-1 ng/g and the LOQs varied from 1 ng/g to 2 ng/g. The satisfying intra-day and inter-day reproducibility (both RSDr and RSDR < 20%) indicated a good stability of this method. The recoveries of the nine target analytes were in the range of 70-110%. The validation results showed that this LC-MS/MS method coupled with QuEChERS sample pretreatment is effective and suitable for the simultaneous quantitation of ZEN metabolites in pigs. It has been applied to analysis of the pig tissues in this research and can be also adapted for samples in the mycotoxin research field.

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

Zearalenone (ZEA) is one of the most popular endocrine-disrupting chemicals and is mainly produced by fungi of the genus Fusarium. The excessive intake of ZEA severely disrupts human and animal fertility by affecting the reproductive axis. However, most studies on the effects of ZEA and its metabolite α-zearalenol (α-ZOL) on reproductive systems have focused on gonads. Few studies have investigated the endocrine-disrupting effects of ZEA and α-ZOL on pituitary gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The present study was designed to investigate the effects of ZEA and α-ZOL on the synthesis and secretion of FSH and LH and related mechanisms in female pig pituitary. Our in vivo and in vitro results demonstrated that ZEA significantly inhibited the synthesis and secretion of FSH in the pig pituitary gland, but ZEA and α-ZOL had no effects on LH. Our study also showed that ZEA and α-ZOL decreased FSH synthesis and secretion through non-classical estrogen membrane receptor GPR30, which subsequently induced protein kinase cascades and the phosphorylation of PKC, ERK and p38MAPK signaling pathways in pig pituitary cells. Furthermore, our study showed that the LIM homeodomain transcription factor LHX3 was involved in the mechanisms of ZEA and α-ZOL actions on gonadotropes in the female pig pituitary. These findings elucidate the mechanisms behind the physiological alterations resulting from endocrine-disrupting chemicals and further show that the proposed key molecules of the α-ZOL signaling pathway could be potential pharmacological targets.

Simultaneous determination of six mycotoxins in peanut by high-performance liquid chromatography with a fluorescence detector

BACKGROUND

Mycotoxins, which may contaminate peanut and peanut products, are responsible for many diseases to humans. Aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), aflatoxin B2 (AFB2), aflatoxin G2 (AFG2), ochratoxin A (OTA) and zearalenone (ZEN) are considered the most relevant groups of mycotoxins found in food. This work aimed to develop a high-performance liquid chromatography method with a fluorescence detector (HPLC-FLD) combined with dispersive liquid-liquid microextraction (DLLME) method for the simultaneous determination of the six mycotoxins in peanuts. The six mycotoxins were simultaneously determined under their best wavelength by means of changing wavelength.

RESULTS

Under the optimum conditions, the linear ranges were 1-100 ng mL^-1 for AFB1, AFG1 and OTA, 0.3-30 ng mL^-1 for AFB2 and AFG2, 5-1000 ng mL^-1 for ZEN, with the correlation coefficient (R² ) of 0.9969-0.9997. Limits of detection (LODs) were 0.10, 0.10, 0.30, 0.03, 0.03 and 1.0 µg kg^-1 , respectively, and the mean recoveries were in the range of 83.1% to 99.3% with RSD < 10% (n = 6, independent analysis). Thirteen (46%) of these tested samples were contaminated with at least one mycotoxin.

CONCLUSION

The proposed method was demonstrated to be simple, highly selective, accurate, reliable, and was successfully applied to simultaneously analyse the six mycotoxins in real peanut samples from China. © 2016 Society of Chemical Industry.

Zearalenone exposure impairs ovarian primordial follicle formation via down-regulation of Lhx8 expression in vitro

Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced as a secondary metabolite by numerous species of Fusarium. Previous work showed that ZEA had a negative impact on domestic animals with regard to reproduction. The adverse effects and the mechanisms of ZEA on mammalian ovarian folliculogenesis remain largely unknown, particularly its effect on primordial follicle formation. Thus, we investigated the biological effects of ZEA exposure on murine ovarian germ cell cyst breakdown and primordial follicle assembly. Our results demonstrated that newborn mouse ovaries exposed to 10 or 30μM ZEA in vitro had significantly less germ cell numbers compared to the control group. Moreover, the presence of ZEA in vitro increased the numbers of TUNEL and γH2AX positive cells within mouse ovaries and the ratio of mRNA levels of the apoptotic genes Bax/Bcl-2. Furthermore, ZEA exposure reduced the mRNA of oocyte specific genes such as LIM homeobox 8 (Lhx8), newborn ovary homeobox (Nobox), spermatogenesis and oogenesis helix-loop-helix (Sohlh2), and factor in the germline alpha (Figlα) in a dose dependent manner. Exposure to ZEA led to remarkable changes in the Lhx8 3'-UTR DNA methylation dynamics in oocytes and severely impaired folliculogenesis in ovaries after transplantation under the kidney capsules of immunodeficient mice. In conclusion, ZEA exposure impairs mouse primordial follicle formation in vitro.

Efficacy of activated diatomaceous clay in reducing the toxicity of zearalenone in rats and piglets

Two experiments were conducted to evaluate the efficacy of an activated diatomaceous clay (ADC) in reducing the toxic effects of zearalenone (ZEA) in the diet of rats and piglets. In the rat experiment, 90 Sprague-Dawley female weanling rats with an initial BW of 45 ± 1.0 g were assigned to 1 of 6 dietary treatments for 28 d in a completely randomized design (CRD) with a 2 × 3 factorial arrangement (0 or 6 mg ZEA/kg feed and 0, 1, and 5 g ADC/kg feed). In the piglet experiment, 64 female piglets ([Large White × Landrace] × Pietrain with an initial BW of 14.9 ± 1.65 kg) were fed 1 of 8 experimental diets for 26 d in a CRD design with a 2 × 4 factorial arrangement (0 or 0.8 mg ZEA/kg feed and 0, 1, 2, and 5 g ADC/kg feed). The ADFI, ADG, and G:F were determined at the end of each experiment. At the conclusion of studies, serum samples were collected and rats and piglets were euthanized to determine visceral organ weights. The diet contaminated with ZEA did not alter the growth of rats and the relative weight of liver and kidneys. However, ZEA increased ( < 0.05) the relative weight of uterus, ovaries, and spleen and decreased ( < 0.05) the serum activities of alkaline phosphatase and alanine aminotransferase compared to the control group. Supplementation of ADC in the rat diets counteracted ( < 0.05) the observed toxic effects of ZEA on the uterus and ovaries weight. The diet contaminated with ZEA (0.8 mg/kg feed) increased ( < 0.05) the weight of the uterus and ovaries in piglets but did not modify the serum biochemical variables or the relative weight of other visceral organs. The addition of 5 g ADC/kg to the contaminated feed reduced the toxic effects of ZEA on uterus and ovary weights to that of the control group. Zearalenone (10.5 μg/kg bile) and α-zearalenol (5.6 μg/kg bile) residues were detected in the bile of piglets fed the ZEA treatment. Supplementation of ADC to diets contaminated with ZEA reduced ( = 0.001) ZEA content in bile compared to the ZEA treatments. The results of these experiments indicate that a long-term consumption of ZEA-contaminated diets stimulated growth of the reproductive tract in rats and piglets and the presence of ZEA residue in bile in piglets. These effects may be counteracted by the addition of ADC to the diet.

In vitro effects of deoxynivalenol and zearalenone major metabolites alone and combined, on cell proliferation, steroid production and gene expression in bovine small-follicle granulosa cells

The effects of deoxynivalenol (DON) and zearalenone (ZEA) on reproduction in ruminants are unclear. This study was performed to evaluate the impact of DON and ZEA hydroxylated metabolites, α-zearalenol (α-Zol) and β-zearalenone (β-Zol), on cell proliferation, steroidogenesis and gene expression using bovine granulosa cells (GC). Cell proliferation was negatively affected after exposure to β-Zol at 31 μM and after exposure to α-Zol (3.1 μM) alone and combined with DON (3.3 μM). DON and α-Zol decreased steroidogenesis, while β-Zol at high concentration had stimulatory effects. DON and β-Zol increased CYP19A1 mRNA abundance. CYP11A1 mRNA abundance was stimulated by DON, alone and combined with α-Zol and β-Zol, whereas was inhibited by β-Zol alone. Generally mycotoxins effects on cell proliferation, steroidogenesis and gene expression were influenced by the presence or absence of IGF1. In conclusion DON and ZEA metabolites may impair in vitro cell proliferation, steroid production and gene expression in cattle.

Individual and combined effects of deoxynivalenol and α-zearalenol on cell proliferation and steroidogenesis of granulosa cells in cattle

This study was conducted to evaluate the impact of deoxynivalenol (DON) and zearalenone (ZEA) metabolite, α-zearalenol (α-Zol), on cell proliferation and steroidogenesis of bovine large (LG) follicle granulosa cells (GC). LGGC were obtained from bovine ovarian follicles (8-22 mm) and were cultured for 2 days in medium containing 10% fetal bovine serum followed by 1 or 2 days in serum-free medium without (control) or with treatments. Three different experiments were performed using different dosages of DON and α-Zol and in different combinations and a fourth experiment evaluated estradiol effects on granulosa cell proliferation. DON inhibited progesterone (P4) and estradiol (E2) production at high dose. α-Zol alone and in combination with DON increased cell growth. Estradiol inhibited cell growth indicating α-Zol is not acting as an estrogen agonist. This study demonstrates that α-Zol and DON can impact in vitro GC function, however further studies will be required to better understand the mechanism of action and reproductive effects of Fusarium mycotoxins.

Mycotoxin mechanisms of action and health impact: ‘in vitro’ or ‘in vivo’ tests, that is the question

The aim of this paper is to present examples of in vitro and in vivo tests for mycotoxin mechanisms of action and evaluation of health effects, with a focus on the gut environment and toxicity testing. In vivo investigations may provide information on the net effects of mycotoxins in whole animals, whereas in vitro models represent effective tools to perform simplified experiments under uniform and well-controlled conditions and a suitable alternative to in vivo animal testing providing insights not achievable with animal studies. The main limits of in vitro models are the lack of interactions with other cells and extracellular factors, lack of hormonal or immunological influences, and lack or different levels of in vitro expression of genes involved in the overall response to mycotoxins. The translation of in vitro data into meaningful in vivo effects remains an unsolved problem. The main issues to be considered are the mycotoxin concentration range in accordance with levels encountered in realistic situations, the identification of reliable biomarkers of mycotoxin toxicity, the measurement of the chronic toxicity, the evaluation of single- or multi-toxin challenge. The gastrointestinal wall is the first barrier preventing the entry of undesirable substances. The intestinal epithelium can be exposed to high concentrations of mycotoxins upon ingestion of contaminated food and the amount of mycotoxin consumed via food does not always reflect the amount available to exert toxic actions in a target organ. In vitro digestion models in combination with intestinal epithelial cells are powerful tools to screen and predict the in vivo bioavailability and digestibility of mycotoxins in contaminated food and correctly estimate health effects. In conclusion, in vitro and in vivo tests are complementary approaches for providing a more accurate picture of the health impact of mycotoxins and improved understanding and evaluation of relevant dietary exposure and risk scenarios.

Zinc inhibits the reproductive toxicity of Zearalenone in immortalized murine ovarian granular KK-1 cells

Zearalenone (ZEA) mainly injures the reproductive system of mammals. In the present study, we aimed to explore the mechanism by which zinc inhibits ZEA-induced reproductive damage in KK-1 cells for the first time. The results shown that both zinc sulfate and zinc gluconate addition increased the intracellular zinc concentration and influenced the expression of zinc transporters (Slc30a1 and Slc39a1) in a time-dependent manner. Co-incubation of zinc with ZEA significantly reduced the ZEA-induced reactive oxygen species and malondialdehyde elevation by promoting the transcription of Mtf1 and Mt2. Meanwhile, two different zincs inhibited the ZEA-induced loss of mitochondrial membrane potential and elevation of late-stage apoptosis via activating the mitochondrial apoptotic pathway by recovering the mRNA and protein expression of pro-apoptotic genes (Bax, Casp3, Casp9). Zinc also recovered cells from S-phase cell cycle arrest. In addition, both of them promoted the ZEA-induced estrogen production but regulated the expression of steroidogenic enzymes (Star, Cyp11a1, Hsd3b1, Cyp17a1) in different way. All these results indicated that zinc could inhibit the reproductive toxicity of ZEA.

Zearalenone exposure affects mouse oocyte meiotic maturation and granulosa cell proliferation

Zearalenone (ZEN) is a metabolite of Fusarium and is a common contaminant of grains and foodstuffs. ZEN acts as a xenoestrogen and is considered to be cytotoxic, tissue toxic, and genotoxic, which causes abortions and stillbirths in humans and animals. Since estrogens affect oocyte maturation during meiosis, in this study we investigated the effects of ZEN on mouse oocyte meiotic maturation and granulosa cell proliferation. Our results showed that ZEN-treated oocyte maturation rates were decreased, which might be due to the disrupted cytoskeletons: (1) ZEN treatment resulted in significantly more oocytes with abnormal spindle morphologies; (2) actin filament expression and distribution were also disrupted after ZEN treatment, which was confirmed by the aberrant distribution of actin regulatory proteins. In addition, cortical granule-free domains (CGFDs) were disrupted after ZEN treatment, which indicated that ZEN may affect mouse oocyte fertilization capability. ZEN reduced mouse granulosa cell proliferation in a dose-dependent manner as determined by MTT assay and TUNEL apoptosis analysis, which may be another cause for the decreased oocyte maturation. Thus, our results demonstrated that exposure to zearalenone affected oocyte meiotic maturation and granulosa cell proliferation in mouse.

Effects of Panax ginseng, zearalenol, and estradiol on sperm function

BACKGROUND

Estrogen signaling pathways are modulated by exogenous factors. Panax ginseng exerts multiple activities in biological systems and is classified as an adaptogen. Zearalenol is a potent mycoestrogen that may be present in herbs and crops arising from contamination or endophytic association. The goal of this study was to investigate the impact of P. ginseng, zearalenol and estradiol in tests on spermatozoal function.

METHODS

The affinity of these compounds for estrogen receptor (ER)-alpha and beta (ERα and ERβ)-was assessed in receptor binding assays. Functional tests on boar spermatozoa motility, movement and kinematic parameters were conducted using a computer-assisted sperm analyzer. Tests for capacitation, acrosome reaction (AR), and chromatin decondensation in spermatozoa were performed using microscopic analysis.

RESULTS

Zearalenol-but not estradiol (E2)- or ginseng-treated spermatozoa-decreased the percentage of overall, progressive, and rapid motile cells. Zearalenol also decreased spontaneous AR and increased chromatin decondensation. Ginseng decreased chromatin decondensation in response to calcium ionophore and decreased AR in response to progesterone (P4) and ionophore.

CONCLUSION

Zearalenol has adverse effects on sperm motility and function by targeting multiple signaling cascades, including P4, E2, and calcium pathways. Ginseng protects against chromatin damage and thus may be beneficial to reproductive fitness.

Effects of the mycotoxin deoxynivalenol on steroidogenesis and apoptosis in granulosa cells

Mycotoxins can reduce fertility and development in livestock, notably in pigs and poultry, although the effect of most mycotoxins on reproductive function in cattle has not been established. One major mycotoxin, deoxynivalenol (DON), not only targets immune cells and activates the ribotoxic stress response (RSR) involving MAPK activation, but also inhibits oocyte maturation in pigs. In this study, we determined the effect of DON on bovine granulosa cell function using a serum-free culture system. Addition of DON inhibited estradiol and progesterone secretion, and reduced levels of mRNA encoding estrogenic (CYP19A1) but not progestogenic (CYP11A1 and STAR) proteins. Cell apoptosis was increased by DON, which also increased FASLG mRNA levels. The mechanism of action of DON was assessed by western blotting and PCR experiments. Addition of DON rapidly and transiently increased phosphorylation of MAPK3/1, and resulted in a more prolonged phosphorylation of MAPK14 (p38) and MAPK8 (JNK). Activation of these pathways by DON resulted in time- and dose-dependent increases in abundance of mRNA encoding the transcription factors FOS, FOSL1, EGR1, and EGR3. We conclude that DON is deleterious to granulosa cell function and acts through a RSR pathway.

Zearalenone Altered the Serum Hormones, Morphologic and Apoptotic Measurements of Genital Organs in Post-weaning Gilts

The present study was aimed at investigating the adverse effects of dietary zearalenone (ZEA) (1.1 to 3.2 mg/kg diet) on serum hormones, morphologic and apoptotic measurements of genital organs in post-weaning gilts. A total of twenty gilts (Landrace×Yorkshire×Duroc) weaned at 21 d with an average body weight of 10.36±1.21 kg were used in the study. Gilts were fed a basal diet with an addition of 0, 1.1, 2.0, or 3.2 mg/kg purified ZEA for 18 d ad libitum. Results showed that 3.2 mg/kg ZEA challenged gilts decreased (p<0.05) the serum levels of luteinizing hormone, however, serum levels of prolactin in gilts fed the diet containing 2.0 mg/kg ZEA or more were increased (p<0.05) compared to those in the control. Linear effects on all tested serum hormones except progesterone were observed as dietary ZEA levels increased (p<0.05). Gilts fed ZEA-contaminated diet showed increase (p<0.05) in genital organs size, hyperplasia of submucosal smooth muscles in the corpus uteri in a dose-dependent manner. However, the decreased numbers of follicles in the cortex and apoptotic cells in the ovarian were observed in gilts treated with ZEA in a dose-dependent manner. Degeneration and structural abnormalities of genital organs tissues were also observed in the gilts fed diet containing 1.1 mg/kg ZEA or more. Results suggested that dietary ZEA at 1.1 to 3.2 mg/kg can induce endocrine disturbance and damage genital organs in post-weaning gilts.

Assessment of a potential preventive ability of amygdalin in mycotoxin-induced ovarian toxicity

The possible effects of a natural substance amygdalin and its combination with the mycotoxin deoxynivalenol (DON) on the steroid hormone secretion (progesterone and 17-β-estradiol) by porcine ovarian granulosa cells (GCs) were examined in this in vitro study. Ovarian GCs were incubated without (control group) and with amygdalin (1, 10, 100, 1,000 and 10,000 μg mL(1)), or its combination with DON (1 μg mL(1)) for 24 h. The release of steroid hormones was determined by ELISA. The progesterone secretion by porcine ovarian GCs was not affected by amygdalin in comparison to the control. However, the highest amygdalin dose (10,000 μg mL(1)) caused a significant stimulation of the 17-β-estradiol release. A combination of amygdalin with DON significantly (P < 0.05) increased the progesterone release at all concentrations. Similarly, a stimulatory effect of amygdalin co-administered with DON was detected with respect to the 17-β-estradiol secretion at the highest dose (10,000 μg mL(1)) of amygdalin and 1 μg mL(1) of DON. Noticeable differences between the effects of amygdalin alone and its combination with DON on the progesterone release were detected. In contrast, no differences between the stimulatory effects of amygdalin and its combination with DON on the 17-β-estradiol synthesis by porcine GCs were observed. Findings from this in vitro study did not confirm the expected protective effect of amygdalin on mycotoxin induced reprotoxicity. Our results indicate that the stimulatory effect of amygdalin combined with DON on the progesterone release was clearly caused by the DON addition, not by the presence amygdalin per se. On the other hand, the stimulation of 17-β-estradiol production was solely caused by the presence of amygdalin addition. These findings suggest a possible involvement of both natural substances into the processes of steroidogenesis and appear to be endocrine modulators of porcine ovaries.

Altered oxidative stress, apoptosis/autophagy, and epigenetic modifications in Zearalenone-treated porcine oocytes

ZEN affected porcine oocyte maturation and early embryonic development. Oxidative stress, autophagy and apoptosis occurred. Aberrant epigenetic modifications were also observed.

Usefulness of bovine and porcine IVM/IVF models for reproductive toxicology

Women presenting fertility problems are often helped by Assisted Reproductive Techniques (ART), such as in vitro fertilization (IVF) programs. However, in many cases the etiology of the in/subfertility remains unknown even after treatment. Although several aspects should be considered when assisting a woman with problems to conceive, a survey on the patients' exposure to contaminants would help to understand the cause of the fertility problem, as well as to follow the patient properly during IVF. Daily exposure to toxic compounds, mainly environmental and dietary ones, may result in reproductive impairment. For instance, because affects oocyte developmental competence. Many of these compounds, natural or synthetic, are endocrine disruptors or endocrine active substances that may impair reproduction. To understand the risks and the mechanism of action of such chemicals in human cells, the use of proper in vitro models is essential. The present review proposes the bovine and porcine models to evaluate toxic compounds on oocyte maturation, fertilization and embryo production in vitro. Moreover, we discuss here the species-specific differences when mice, bovine and porcine are used as models for human.

Zearalenone exposure affects epigenetic modifications of mouse eggs

Zearalenone (ZEA) is a mycotoxin produced by various Fusarium fungi, which has been shown to cause several cases of mycotoxicosis in farm animals and humans. However, there is no evidence regarding the effect of ZEA on mouse egg developmental competence. In this study, we found that the activation rate of maturated oocytes was affected in mice by ZEA treatment, indicating that ZEA affects egg developmental competence. And we explored possible mechanisms of low mouse maturated oocyte developmental competence after ZEA treatment from an epigenetic modification perspective. The fluorescence intensity analysis showed that 5-methyl cytosine level increased after ZEA treatment, indicating that the general DNA methylation level increased in the treated eggs. Moreover, histone methylations were also altered: H3K4me2 as well as H3K9me3 and H4K20me1, me2, me3 levels decreased in eggs that were cultured in high-dose ZEA medium. Thus, our results indicated that ZEA decreased egg developmental competence by affecting the epigenetic modifications.

Mycotoxins and female reproduction: in vitro approaches

Exposure to mycotoxins has been linked to adverse effects on female reproduction by interfering with the synthesis, metabolism or degradation of steroid hormones, interaction with steroid receptors or impairing oocyte maturation and competence. To assess such effects, many studies initially focussed on possible endocrine actions of mycotoxins using specific cell lines known to express key enzymes involved in the synthesis of steroid hormones. Using these models, zearalenone, deoxynivalenol, ochratoxin A, T-2 and HT-2 toxins, and aflatoxin B1 were claimed to be endocrine active substances. As yet, zearalenone is the only mycotoxin for which a direct interaction with oestrogen receptors could be demonstrated, classifying this mycotoxin as an endocrine disruptor. Mycotoxin exposure of complex cell systems like ovarian follicles at the earliest (primordial) to most advanced (pre-ovulatory) stages can serve not only as the first indication of the potential of a mycotoxin to affect female reproduction, but also provides insight in specific mechanisms involved in such an effect and identifies vulnerable phases in follicle development. Zearalenone is the most widely studied mycotoxin regarding female reproduction, but effects on oocyte maturation have also been demonstrated for deoxynivalenol. Exposure to zearalenone impairs the formation of primordial, while its metabolite ?-zearalenol is more harmful to fertilised oocytes than zearalenone itself. This short overview aims to provide an introduction into the different models, such as cell lines and oocytes, commonly used to assess the potential adverse effects of mycotoxins on female reproduction.

Postweaning exposure to dietary zearalenone, a mycotoxin, promotes premature onset of puberty and disrupts early pregnancy events in female mice

Zearalenone (ZEA) is a mycotoxin commonly found in contaminated livestock feed and human food with levels in the range of ppb and low ppm. It was hypothesized that ZEA, an endocrine disruptor, could affect puberty and early pregnancy. To test this hypothesis, newly weaned (3 weeks old) C57BL/6J female mice were exposed to 0, 0.002, 4, 10, and 40 ppm ZEA and 0.05 ppm diethylstilbestrol (positive control) in phytoestrogen-free AIN-93G diet. Females exposed to 10 and 40 ppm ZEA diets showed earlier onset of vaginal opening. Those treated with 40 ppm ZEA diet also had earlier first copulation plug and irregular estrous cyclicity. At 8 weeks old, all females were mated with untreated stud males on AIN-93G diet during mating. Treatment resumed upon identification of a vaginal plug on gestation day 0.5 (D0.5). Embryo implantation was assessed on D4.5. Exposure to 40 ppm ZEA diet resulted in reduced percentage of plugged mice with implantation sites, distended uterine appearance, and retained expression of progesterone receptor in D4.5 uterine epithelium. To determine the exposure timing and mechanisms of disrupted embryo implantation, four groups of females were fed with 0 or 40 ppm ZEA diets during premating (weaning to mating) and postmating (D0.5-D4.5), respectively. Premating exposure to 40 ppm ZEA diet reduced fertilization rate, whereas postmating exposure to 40 ppm ZEA diet delayed embryo transport and preimplantation embryo development, which subsequently affected embryo implantation. These data demonstrate that postweaning exposure to dietary ZEA can promote premature onset of puberty and disrupt early pregnancy events.