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

NRF2 inhibitors: Recent progress, future design and therapeutic potential

Nuclear factor erythroid 2-related factor 2 (NRF2) is a crucial transcription factor involved in oxidative stress response, which controls the expression of various cytoprotective genes. Recent research has indicated that constitutively activated NRF2 can enhance patients' resistance to chemotherapy drugs, resulting in unfavorable prognosis. Therefore, the development of NRF2 inhibitors has emerged as a promising approach for overcoming drug resistance in cancer treatment. However, there are limited reports and reviews focusing on NRF2 inhibitors. This review aims to provide a comprehensive analysis of the structure and regulation of the NRF2 signaling pathway, followed by a comprehensive review of reported NRF2 inhibitors. Moreover, the current design strategies and future prospects of NRF2 inhibitors will be discussed, aiming to establish a foundation for the development of more effective NRF2 inhibitors.

The influences of extraction methods on the chemical constituents of Lyonia ovalifolia (wall.) Drude and intracellular protective effects based on metabolomics analysis

Lyonia ovalifolia (Wall.) Drude (LO) is mainly distributed in China with health benefits. In this study, LO buds (LOB) were extracted by ultrasonic extraction (UE) with or without ultra-high-pressure (UHP-UE), microwave (MW-UE), subcritical (SC-UE) techniques. The metabolomic result showed that a total of 960 chemical compounds and 117 differential compounds were identified from LOB extracts. The UHP-UE extract was rich in total polyphenol and flavonoid contents, followed by MW-UE, UE and SC-UE extracts, respectively. All LOB extracts increased superoxide dismutase (SOD) and catalase (CAT) activities, and glutathione (GSH) content, decreased reactive oxygen species (ROS) accumulation, levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor -α (TNF-α), and nitric oxide (NO), and alleviated apoptosis in cells. The cellular protective effect was UHP-UE > MW-UE > UE > SC-UE. This study revealed that higher pressure and lower temperature may be key factors for increasing bioactivities of LOB extracts.

Procyanidine alleviates bisphenol A-induced apoptosis in TM3 cells via the Nrf2 signaling pathway

Contaminated foods are a major source of bisphenol A (BPA) and are widely used in food packaging. Prolonged exposure to BPA can cause reproductive dysfunction in humans. Procyanidine (PC) is a potent natural antioxidant; however, the exact mechanism by which PC mitigates Leydig cell damage caused by BPA is unknown. In this study, the protective effect of PC against BPA-induced TM3 cell damage was investigated, and the underlying mechanism was assessed. PC treatment attenuates BPA-induced TM3 cell damage by suppressing oxidative stress and inhibiting TM3 apoptosis. In addition, PC upregulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant target genes. Treatment with the NRF2 inhibitor ML385 reversed the PC-induced upregulation of the mRNA expression of these genes. Overall, PC may mitigate BPA-induced cell damage by activating the Nrf2 signaling pathway, suggesting that PC supplementation may alleviate BPA toxicity in TM3 cells.

Vigor King mitigates spermatogenic disorders caused by environmental estrogen zearalenone exposure

Zearalenone (ZEN) has been shown to cause reproductive damage by inducing oxidative stress. Astaxanthin and L-carnitine are widely used to alleviate oxidative stress and promote sperm maturation. However, it remains uncertain whether they are effective in mitigating spermatogenesis disorders induced by ZEN. This study aimed to investigate the therapeutic efficacy and potential mechanisms of Vigor King (Vig), a compound preparation primarily consisting of astaxanthin and L-carnitine, in alleviating ZEN-induced spermatogenesis disorders. In the experiment, mice received continuous oral gavage of ZEN (80 μg/kg) for 35 days, accompanied by a rescue strategy with Vig (200 mg/kg). The results showed that Vig effectively reduced the negative impact on semen quality and improved the structural and functional abnormalities of the seminiferous epithelium caused by ZEN. Additionally, the accumulation of reactive oxygen species (ROS), DNA double-strand breaks, apoptosis, and autophagy abnormalities were all significantly ameliorated. Intriguingly, the GSK3β-dependent BTRC-NRF2 signaling pathway was found to play an important role in this process. Furthermore, testing of offspring indicated that Vig could extend its protective effects to the next generation, effectively combating the transgenerational toxic effects of ZEN. In summary, our research suggests that Vig supplementation holds considerable promise in alleviating spermatogenesis disorders induced by zearalenone.

Fusarium mycotoxins: The major food contaminants

Mycotoxins, which are secondary metabolites produced by toxicogenic fungi, are natural food toxins that cause acute and chronic adverse reactions in humans and animals. The genus Fusarium is one of three major genera of mycotoxin-producing fungi. Trichothecenes, fumonisins, and zearalenone are the major Fusarium mycotoxins that occur worldwide. Fusarium mycotoxins have the potential to infiltrate the human food chain via contamination during crop production and food processing, eventually threatening human health. The occurrence and development of Fusarium mycotoxin contamination will change with climate change, especially with variations in temperature, precipitation, and carbon dioxide concentration. To address these challenges, researchers have built a series of effective models to forecast the occurrence of Fusarium mycotoxins and provide guidance for crop production. Fusarium mycotoxins frequently exist in food products at extremely low levels, thus necessitating the development of highly sensitive and reliable detection techniques. Numerous successful detection methods have been developed to meet the requirements of various situations, and an increasing number of methods are moving toward high-throughput features. Although Fusarium mycotoxins cannot be completely eliminated, numerous agronomic, chemical, physical, and biological methods can lower Fusarium mycotoxin contamination to safe levels during the preharvest and postharvest stages. These theoretical innovations and technological advances have the potential to facilitate the development of comprehensive strategies for effectively managing Fusarium mycotoxin contamination in the future.

Bioactive Compounds Protect Mammalian Reproductive Cells from Xenobiotics and Heat Stress-Induced Oxidative Distress via Nrf2 Signaling Activation: A Narrative Review

Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defenses. It poses a significant threat to the physiological function of reproductive cells. Factors such as xenobiotics and heat can worsen this stress, leading to cellular damage and apoptosis, ultimately decreasing reproductive efficiency. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays a crucial role in defending against oxidative stress and protecting reproductive cells via enhancing antioxidant responses. Dysregulation of Nrf2 signaling has been associated with infertility and suboptimal reproductive performance in mammals. Recent advancements in therapeutic interventions have underscored the critical role of Nrf2 in mitigating oxidative damage and restoring the functional integrity of reproductive cells. In this narrative review, we delineate the harmful effects of heat and xenobiotic-induced oxidative stress on reproductive cells and explain how Nrf2 signaling provides protection against these challenges. Recent studies have shown that activating the Nrf2 signaling pathway using various bioactive compounds can ameliorate heat stress and xenobiotic-induced oxidative distress and apoptosis in mammalian reproductive cells. By comprehensively analyzing the existing literature, we propose Nrf2 as a key therapeutic target for mitigating oxidative damage and apoptosis in reproductive cells caused by exposure to xenobiotic exposure and heat stress. Additionally, based on the synthesis of these findings, we discuss the potential of therapies focused on the Nrf2 signaling pathway to improve mammalian reproductive efficiency.

Toxicity, biodegradation, and nutritional intervention mechanism of zearalenone

Zearalenone (ZEA), a global mycotoxin commonly found in a variety of grain products and animal feed, causes damage to the gastrointestinal tract, immune organs, liver and reproductive system. Many treatments, including physical, chemical and biological methods, have been reported for the degradation of ZEA. Each degradation method has different degradation efficacies and distinct mechanisms. In this article, the global pollution status, hazard and toxicity of ZEA are summarized. We also review the biological detoxification methods and nutritional regulation strategies for alleviating the toxicity of ZEA. Moreover, we discuss the molecular detoxification mechanism of ZEA to help explore more efficient detoxification methods to better reduce the global pollution and hazard of ZEA.

Bacillus velezensis A2 Can Protect against Damage to IPEC-J2 Cells Induced by Zearalenone via the Wnt/FRZB/β-Catenin Signaling Pathway

Zearalenone (ZEA) has adverse effects on human and animal health, and finding effective strategies to combat its toxicity is essential. The probiotic Bacillus velezensis A2 shows various beneficial physiological functions, including the potential to combat fungal toxins. However, the detailed mechanism by which the Bacillus velezensis A2 strain achieves this protective effect is not yet fully revealed. This experiment was based on transcriptome data to study the protective mechanism of Bacillus velezensis A2 against ZEA-induced damage to IPEC-J2 cells. The experiment was divided into CON, A2, ZEA, and A2+ZEA groups. This research used an oxidation kit to measure oxidative damage indicators, the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) method to detect cell apoptosis, flow cytometry to determine the cell cycle, and transcriptome sequencing to screen and identify differentially expressed genes. In addition, gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were adopted to screen out relevant signaling pathways. Finally, to determine whether A2 can alleviate the damage caused by ZEA to cells, the genes and proteins involved in inflammation, cell apoptosis, cell cycles, and related pathways were validated using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot methods. Compared with the CON group, the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in the ZEA group increased significantly (p < 0.01), while the levels of antioxidant enzyme activity, total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), and catalase (CAT) decreased significantly (p < 0.01). Compared with the ZEA group, the A2+ZEA group showed a significant decrease in ROS and MDA levels (p < 0.01), while the levels of T-SOD, GSH-PX, T-AOC, and CAT increased significantly (p < 0.01). TUNEL and cell cycle results indicated that compared with the ZEA group, the A2+ZEA group demonstrated a significant decrease in the cell apoptosis rate (p < 0.01), and the cell cycle was restored. Combining transcriptome data, qRT-PCR, and Western blot, the results showed that compared with the CON group, the mRNA and protein expression levels of Wnt10 and β-catenin increased significantly (p < 0.01), while the expression level of FRZB decreased significantly (p < 0.01); compared with the ZEA group, the expression levels of these mRNA and proteins were reversed. Bacillus velezensis A2 can increase the antioxidant level, reduce inflammatory damage, decrease cell apoptosis, and correct the cell cycle when that damage is being caused by ZEA. The protective mechanism may be related to the regulation of the Wnt/FRZB cell/β-catenin signaling pathway.

Zearalenone triggers programmed cell death and impairs milk fat synthesis via the AKT-mTOR-PPARγ-ACSL4 pathway in bovine mammary epithelial cells

Zearalenone (ZEN), a mycotoxin from Fusarium fungi, impairs fertility and milk production in female animals; however, the mechanisms remain poorly understood. Using the bovine mammary epithelial cells (MAC-T) as the model, this study investigated the impacts of ZEN on programmed cell death (PCD) and milk fat synthesis and explored the underlying mechanism. We found that 10 ng/mL prolactin (PRL) notably enhanced the differentiation of MAC-T cells, promoting the expression of genes related to the synthesis of milk fat, protein, and lactose. Next, the toxic effects of different doses of ZEN on the differentiated MAC-T with PRL treatment were determined. 10 and 20 μM ZEN significantly reduced cell viability, induced oxidative stress, and triggered PCD (e.g., apoptosis and necrosis). Notably, ZEN exposure downregulated the mRNA/protein levels of critical factors involved in milk fat synthesis by disrupting the AKT-mTOR-PPARγ-ACSL4 pathway. Interestingly, melatonin (MT), known for its antioxidant properties, protected against the above ZEN-induced effects by enhancing the binding of PPARγ to the promoter regions of ACSL4, which led to the upregulated expression of the ACSL4 gene. These results underscored the potential of MT to mitigate the adverse effects of ZEN on mammary cells, highlighting a way for potential therapeutic intervention.

Effect of zearalenone on the jejunum of weaned gilts through the Epac1/Rap1/JNK pathway

Zearalenone (ZEN) is a nonsteroidal estrogenic mycotoxin produced by Fusarium strains that is harmful to the intestinal health of animals and is widely present in contaminated crops. The objective of this study was to investigate the potential therapeutic target of ZEN-induced jejunal damage in weaned gilts. Sixteen weaned gilts either received a basal diet or a basal diet supplemented with 3.0 mg/kg ZEN in a 32-d experiment. The results showed that ZEN at the concentration of 3.0 mg/kg diet activated the inflammatory response and caused oxidative stress of gilts (P < 0.05). ZEN exposure resulted in the upregulation (P < 0.05) of the Exchange protein directly activated by the cAMP 1/Ras-related protein1/c-Jun N-terminal kinase (Epac1/Rap1/JNK) signaling pathway in the jejunum of gilts in vivo and in the intestinal porcine epithelial cells in vitro. The cell viability, EdU-positive cells, and the mRNA expression of B-cell lymphoma-2 (Bcl-2) were decreased, whereas the reactive oxygen species production and the mRNA expressions of Bcl-2-associated X (Bax) and Cysteine-aspartic acid protease 3 (Caspase3) were increased (P < 0.05) by ZEN. However, ZEN increased the mRNA expression of Bcl-2 and decreased the mRNA expressions of Bax and caspase3 (P < 0.05) after the Epac1 was blocked. These results collectively indicated that a 3.0 mg ZEN /kg diet induced jejunal damage via the Epac1/Rap1/JNK signaling pathway.

Dendrobium officinale polysaccharides improved reproductive oxidative stress injury in male mice treated with cyclophosphamide

Polysaccharides from Dendrobium officinale polysaccharides (DOPs) are the main bioactive components of Dendrobium officinale, which have the functions of antioxidation and immune regulation. However, it is not clear whether DOPs have any effect on the prevention of reproductive disorders induced by oxidative stress. The purpose of this study was to explore the protective effect of DOPs on reproductive oxidative stress injury in male mice and its possible mechanism. In this study, the mouse model of reproductive injury was established by intraperitoneal injection of cyclophosphamide (CTX). The reproductive function was evaluated by relative testicular mass, sperm parameters, and sex hormone levels. The oxidative stress level of male mice with reproductive injury treated with DOPs was analyzed by the levels of 8-hydroxydeoxyguanosine (8-OHdG), malondialdehyde (MDA), and nitric oxide (NO) in sperm. The expression of follicle-stimulating hormone receptor (FSHR) mRNA, androgen-binding (ABP) mRNA, and c-kit mRNA was detected by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) to explore its mechanism. After CTX administration, the sperm density, sperm motility, normal sperm morphology, and sex hormone levels in mice were significantly lower than those in the control group (P < 0.05). At the same time, the expression of p53 protein was upregulated, and the expression of Bcl-2 protein was downregulated (P < 0.05). In addition, the expression of FSHR and ABP mRNA on Sertoli cells was also significantly inhibited (P < 0.05). DOPs can effectively reduce the oxidative stress injury of testicular tissue. After DOP treatment, the sperm quality and sex-related hormone levels of mice were significantly improved and positively correlated with the dose of DOPs (P < 0.05). Administration of DOPs can reduce the damage caused by oxidative stress by reducing the level of oxidative stress, improving the hormone environment in testes, and regulating the expression of specific genes in Sertoli cells and spermatogenic cells.

Protective effects of lycopene against zearalenone-induced reproductive toxicity in early pregnancy through anti-inflammatory, antioxidant and anti-apoptotic effects

Zearalenone is a mycotoxin that is widely present in feed and raw materials and can cause severe reproductive toxicity. Lycopene is a natural carotenoid with antioxidant and anti-inflammatory pharmacological effects, but the protective effects of lycopene against zearalenone-induced uterine damage have not been reported. The aim of this study was to investigate the protective effect of lycopene treatment in early pregnancy on zearalenone-induced uterine damage and pregnancy impairment and its mechanism. Reproductive toxicity was induced by consecutive gavages of zearalenone at 5 mg/kg body weight during gestational days (GDs) 0-10 and in the presence or absence of oral administration of lycopene (20 mg/kg BW). The results showed that lycopene may alleviate zearalenone-induced pathological uterine histological damage and disturbances in oestradiol (E2), follicle-stimulating hormone (FSH), progesterone (P) and luteinizing hormone (LH) secretion. Lycopene increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) production, providing protection against zearalenone-induced oxidative stress in the uterus. Additionally, lycopene significantly reduced levels of pro-inflammatory cytokines, including interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α), and elevated levels of the anti-inflammatory factor interleukin 10 (IL-10), inhibiting the zearalenone-induced inflammatory response. In addition, lycopene improved the homeostasis of uterine cell proliferation and death via the mitochondrial apoptosis pathway. These data provide strong evidence that lycopene can be further developed into a potential new drug for the prevention or treatment of zearalenone-induced reproductive toxicity.

Betulinic acid mitigates zearalenone-induced liver injury by ERS/MAPK/Nrf2 signaling pathways in mice

Zearalenone (ZEA) is a mycotoxin commonly found in cereals and feedstuffs, which can induce oxidative stress and inflammation to cause liver damage in humans and animals. Betulinic acid (BA) is extracted from pentacyclic triterpenoids of many natural plants and has anti-inflammatory, and anti-oxidation biological activities in many studies. However, the protective effect of BA on liver injury induced by ZEA has not been reported. Therefore, this study aims to explore the protective effect of BA on ZEA-induced liver injury and its possible mechanism. In the mice experiment, ZEA exposure increased the liver index and caused histopathological impairment, oxidative damage, hepatic inflammatory responses, and increased hepatocyte apoptosis. However, when combined with BA, it could inhibit the production of ROS, up-regulate the proteins expression of Nrf2 and HO-1 and down-regulate the expression of Keap1, and alleviate oxidative damage and inflammation in the liver of mice. In addition, BA could alleviate ZEA-induced apoptosis and liver injury in mice by inhibiting the endoplasmic reticulum stress (ERS) and MAPK signaling pathways. In conclusion, this study revealed the protective effect of BA on the hepatotoxicity of ZEA for the first time, providing a new perspective for the development of ZEA antidote and the application of BA.

Engineered procyanidin-Fe nanoparticle alleviates intestinal inflammation through scavenging ROS and altering gut microbiome in colitis mice

Inflammatory bowel disease (IBD) is an idiopathic chronic inflammatory bowel disease characterized by inflammation, intestinal barrier injury, and imbalance of gut microbiota. Excess accumulation of reactive oxygen species (ROS) is closely correlated with the development and reoccurrence of IBD. Previous researches demonstrate that procyanidin, as a natural antioxidant, exhibits strong ability of eliminating ROS, thus showing good therapeutic effects in the inflammation-related diseases. Non-etheless, its poor stability and solubility always limits the therapeutic outcomes. Here, we typically designed an antioxidant coordination polymer nanoparticle using the engineering of procyanidin (Pc) and free iron (Fe), named Pc-Fe nanozyme, for effectively scavenging ROS and further inhibiting inflammation while altering the gut microbiome for the treatment of colitis. Furthermore, in vitro experiments uncover that Pc-Fe nanoparticles exert strong multi biomimic activities, including peroxidase, and glutathione peroxidase, for the scavenging of ROS and protecting cells from oxidative injury. In addition, the colon accumulation of Pc-Fe nanozyme effectively protects the intestinal mucosa from oxidative damage while significantly downregulates pro-inflammatory factors, repairs the intestinal barriers and alternates gut microbiome after orally administrated in sodium dextran sulfate (DSS) induced colitis mice. The results collectively illustrate that the multienzyme mimicking Pc-Fe nanozyme owns high potential for treating IBD through scavenging ROS, inhibiting inflammation, repairing gut barriers and alternating gut microbiome, which further promising its clinical translation on IBD treatment and other ROS induced intestinal diseases.

Characterization of tangeretin as an activator of nuclear factor erythroid 2-related factor 2/antioxidant response element pathway in HEK293T cells

Numerous studies have reported that tangeretin is a polymethoxylated flavone with a variety of biological activates, but little research has been done on the antioxidant mechanism of tangeretin. Hence, we investigated the effect of tangeretin on the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway and its potential molecular mechanisms by in vitro and in silico research. The results of molecular docking suggested that tangeretin bound at the top of the central pore of Kelch-like ECH-associated protein 1 (Keap1) Kelch domain, and the hydrophobic and hydrogen bond interactions contributed to their stable binding. Herein, the regulation of Nrf2-ARE pathway by tangeretin was explored in the human embryonic kidney cell line HEK293T, which is relatively easy to be transfected. Upon binding to tangeretin, Nrf2 translocated to the nucleus of HEK293T cells, which in turn activated the Nrf2-ARE pathway. Luciferase reporter gene analysis showed that tangeretin significantly induced ARE-mediated transcriptional activation. Real-time PCR and Western blot assays showed that tangeretin induced the gene and protein expressions of Nrf2-mediated targets, including heme oxygenase 1 (HO-1), nicotinamide adenine dinucleotide phosphate (NADPH) quinone dehydrogenase 1 (NQO1), and glutamate-cysteine ligase (GCLM). In addition, tangeretin could effectively scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. In summary, tangeretin may be a potential antioxidant via activating the Nrf2-ARE pathway.

Chronic exposure to zearalenone induces intestinal inflammation and oxidative injury in adult Drosophila melanogaster midgut

In the past decade, mycotoxin zearalenone (ZEN)-induced gastrointestinal adverse effects have been increasingly attracting worldwide attention. This study aimed to determine the gastrointestinal adverse effects of ZEN in Drosophila melanogaster (D. melanogaster) and reveal possible mechanisms of action of ZEN in insects. Here, chronic exposure of D. melanogaster to ZEN killed flies in a dose-dependent manner (2-20 µM). ZEN (20 µM) decreased the survival rates and climbing ability of flies, and activated immune deficiency-mediated intestinal immunity in midgut, leading to the production of antimicrobial peptides. Meanwhile, ZEN exposure induced morphological alteration of adult midgut. Further study suggested that high levels of oxidative stress was observed in ZEN-treated midgut due to the imbalance between the production of reactive oxygen species and the expression and activities of cellular antioxidant enzyme, including superoxide dismutase and catalase. ZEN-induced oxidative stress then caused cell death, impaired gut barrier function and increased gut permeability, leading to oxidative injury in midgut. Subsequently, ZEN-induce midgut injury further disrupted intestinal stem cell (ISC) homeostasis, stimulating ISC proliferation and tissue regeneration, but did not alter cell fate specification of ISC. Additionally, activation of Jun N-terminal kinase pathway was involved in ZEN-induced oxidative injury and tissue regeneration in midgut. Antioxidant vitamin E alleviated ZEN-induced oxidative injury to midgut epithelium. Collectively, this study provided additional evidences for ZEN-induced gastrointestinal adverse effects from an invertebrate model, extended our understanding of the mechanisms mediating mycotoxin toxicity in organisms.

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.