The Antagonistic Effects of Selenium Yeast (SeY) on Cadmium-Induced Inflammatory Factors and the Heat Shock Protein Expression Levels in Chicken Livers

Histopathology and changes in the expression of metallothioneins, heat shock proteins and inducible nitric oxide synthase in Prochilodus costatus from a neotropical river contaminated by heavy metals

The most recent dam rupture in Brazil released tons of mining tailings into the upper course of the Paraopeba River, affecting this river in an unprecedented way. The present study aimed to evaluate the influence of heavy metals on Prochilodus costatus, an important commercial species in Brazil, four years after the dam colapse. To this end, biomarkers of heavy metals, oxidative stress, and environmental stress were analyzed, and histological analyses of target organs were performed. The results demonstrated critical contamination of fish from the Paraopeba River. Increased expression of Metallothioneins - MTs, Heat Shock Protein - HSP70, and inducible nitric oxide synthase - iNOS, as well as greater rates of histological changes in the liver, spleen, and gonads, were observed in P. costatus. These findings demonstrate that, despite past contamination, the metals present in mining tailings have significantly increased the contamination of the Paraopeba River basin.

Selenomethionine modulates the JAK2 / STAT3 / A20 pathway through oxidative stress to alleviate LPS-induced pyroptosis and inflammation in chicken hearts

Selenium (Se) is involved in many physiopathologic processes in humans and animals and is strongly associated with the development of heart disease. Lipopolysaccharides (LPS) are cell wall components of gram-negative bacteria that are present in large quantities during environmental pollution. To investigate the mechanism of LPS-induced cardiac injury and the efficacy of the therapeutic effect of SeMet on LPS, a chicken model supplemented with selenomethionine (SeMet) and/or LPS treatment, as well as a primary chicken embryo cardiomyocyte model with the combined effect of SeMet / JAK2 inhibitor (INCB018424) and/or LPS were established in this experiment. CCK8 kit, Trypan blue staining, DCFH-DA staining, oxidative stress kits, immunofluorescence staining, LDH kit, real-time fluorescence quantitative PCR, and western blot were used. The results proved that LPS exposure led to ROS explosion, hindered the antioxidant system, promoted the expression of the JAK2 pathway, and increased the expression of genes involved in the pyroptosis pathway, inflammatory factors, and heat shock proteins (HSPs). Upon co-treatment with SeMet and LPS, SeMet reduced LPS-induced pyroptosis and inflammation and restored the expression of HSPs by inhibiting the ROS burst and modulating the antioxidant capacity. Co-treatment with INCB018424 and LPS resulted in inhibited of the JAK2 pathway, attenuating pyroptosis, inflammation, and high expression of HSPs. Thus, LPS induced pyroptosis, inflammation, and changes in HSPs activity by activating of the JAK2 / STAT3 / A20 signaling axis in chicken hearts. Moreover, SeMet has a positive effect on LPS-induced injury. This work further provides a theoretical basis for treating cardiac injury by SeMet.

Detoxification of Selenium Yeast on Mycotoxins and Heavy Metals: a Review

Mycotoxins are secondary metabolites produced by specific fungi. More than 400 different mycotoxins are known in the world, and the concentration of these toxins in food and feed often exceeds the acceptable limit, thus causing serious harm to animals and human body. At the same time, modern industrial agriculture will also bring a lot of environmental pollution in the development process, including the increase of heavy metal content, and often the clinical symptoms of low/medium level chronic heavy metal poisoning are not obvious, thus delaying the best treatment opportunity. However, the traditional ways of detoxification cannot completely eliminate the adverse effects of these toxins on the body, and sometimes bring some side effects, so it is essential to find a new type of safe antidote. Trace element selenium is among the essential mineral nutrient elements of human and animal bodies, which can effectively remove excessive free radicals and reactive oxygen species in the body, and has the effects of antioxidant, resisting stress, and improving body immunity. Selenium is common in nature in inorganic selenium and organic selenium. In previous studies, it was found that the use of inorganic selenium (sodium selenite) can play a certain protective role against mycotoxins and heavy metal poisoning. However, while it plays the role of antioxidant, it will also have adverse effects on the body. Therefore, it was found in the latest study that selenium yeast could not only replace the protective effect of sodium selenite on mycotoxins and heavy metal poisoning, but also improve the immunity of the body. Selenium yeast is an organic selenium source with high activity and low toxicity, which is produced by selenium relying on the cell protein structure of growing yeast. It not only has high absorption rate, but also can be stored in the body after meeting the physiological needs of the body for selenium, so as to avoid selenium deficiency again in the short term. However, few of these studies can clearly reveal the protective mechanism of yeast selenium. In this paper, the detoxification mechanism of selenium yeast on mycotoxins and heavy metal poisoning was reviewed, which provided some theoretical support for further understanding of the biological function of selenium yeast and its replacement for inorganic selenium. The conclusions suggest that selenium yeast can effectively alleviate the oxidative damage by regulating different signaling pathways, improving the activity of antioxidant enzymes, reversing the content of inflammatory factors, regulating the protein expression of apoptosis-related genes, and reducing the accumulation of mycotoxins and heavy metals in the body.

Involvement of the heat shock response (HSR) regulatory pathway in cadmium-elicited cerebral damage

The heat shock response (HSR) is a cellular protective mechanism that is characterized by the induction of heat shock transcription factors (HSFs) and heat shock proteins (HSPs) in response to diverse cellular and environmental stressors, including cadmium (Cd). However, little is known about the relationship between the damaging effects of Cd and the HSR pathway in the chicken cerebrum following Cd exposure. To explore whether Cd exposure elicits cerebral damage and triggers the HSR pathway, chicks were exposed to Cd in the daily diet at different concentrations (35, 70, or 140 mg/kg feed) for 90 days, while a control group was fed the standard diet without Cd. Histopathological examination of cerebral tissue from Cd-exposed chickens showed neuronal damage, as evidenced by swelling and degeneration of neurons, loss of neurons, and capillary damage. Cd exposure significantly increased mRNA expression of HSF1, HSF2, and HSF3, and mRNA and protein expression of three major stress-inducible HSPs (HSP60, HSP70, and HSP90). Moreover, Cd exposure differentially modulated mRNA expression of small HSP (sHSPs), most notably reducing expression of HSP27 (HSPB1). Furthermore, Cd exposure increased TUNEL-positive neuronal apoptotic cells and up-regulated protein expression of caspase-1, caspase-8, caspase-3, and p53, leading to apoptosis. Taken together, these data demonstrate that activation of the HSR and apoptotic pathways by Cd exposure is involved in Cd-elicited cerebral damage in the chicken. Synopsis for the graphical abstract Cadmium (Cd)-induced neuronal damage triggers the heat shock response (HSR) by activating heat shock transcription factors (HSFs) and subsequent induction of major heat shock proteins (notably, HSP60, HSP70, and HSP90). Moreover, Cd exposure activates caspase-1, caspase-8, caspase-3, and p53 protein, thereby resulting in neuronal apoptosis in the chicken brain.

Astilbin Attenuates Cadmium-Induced Adipose Tissue Damage by Inhibiting NF-κB Pathways and Regulating the Expression of HSPs in Chicken

Cadmium (Cd) can damage tissues by inducing oxidative stress, lymphocyte infiltration, and inflammation in these sites. Meanwhile, astilbin (Ast) is an antioxidant agent. At present, only a few mechanisms of Cd-induced adipose tissue damage have been described. Herein, we assessed the potential protective effects and the molecular mechanism underlying the antioxidant properly of Ast after Cd intake in chicken adipose tissue. In this study, a total of 160 7-day-old roosters were randomly divided into four groups. Roosters were fed with a basic diet (C group), Ast 40 mg/kg (Ast group), CdCl₂ 150 mg/kg + Ast 40 mg/kg (Cd/Ast group), and CdCl₂ 150 mg/kg (Cd group) for 60 days. We found that Cd intake changed the morphology and structure of adipose tissues and decreased the expression of several antioxidants, including total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (T-AOC), but increased those of oxidative stress markers including malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), NO, and H2O2. Cd further activated the nuclear factor kappa B (NF-κB) signaling pathway and increased the expression of the inflammation-related mediators, interleukin 1beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10), cyclooxygenase-2 (COX-2), iNOS, prostaglandin E synthase (PTGES), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). Cd-induced oxidative stress upregulated the expression of three heat shock proteins (HSPs), including HSP27, HSP70, and HSP90. Summarily, Cd causes oxidative stress-mediated tissue damage by activating the NF-κB pathway, promoting inflammation and upregulating the expression of HSPs. However, Ast supplementation modulates oxidative stress in adipose tissue by inhibiting inflammation mediated by the NF-κB pathway and regulating the expression of HSPs.

Cerebellar injury induced by cadmium via disrupting the heat-shock response

Cadmium (Cd) is a food contaminant that poses serious threats to animal health, including birds. It is also an air pollutant with well-known neurotoxic effects on humans. However, knowledge on the neurotoxic effects of chronic Cd exposure on chicken is limited. Thus, this study assessed the neurotoxic effects of chronic Cd on chicken cerebellum. Chicks were exposed to 0 (control), 35 (low), and 70 (high) mg/kg of Cd for 90 days, and the expression of genes related to the heat-shock response was investigated. The chickens showed clinical symptoms of ataxia, and histopathology revealed that Cd exposure decreased the number of Purkinje cells and induced degeneration of Purkinje cells with pyknosis, and some dendrites were missing. Moreover, Cd exposure increased the expression of heat-shock factors, HSF1, HSF2, and HSF3, and heat-shock proteins, HSP60, HSP70, HSP90, and HSP110. These changes indicate that HSPs improve the tolerance of the cerebellum to Cd. Conversely, the expressions of HSP10, HSP25, and HSP40 were decreased significantly, which indicated that Cd inhibits the expression of small heat-shock proteins. However, HSP27 and HSP47 were upregulated following low-dose Cd exposure, but downregulated under high-dose Cd exposure. This work sheds light on the toxic effects of Cd on the cerebellum, and it may provide evidence for health risks posed by Cd. Additionally, this work also identified a novel target of Cd exposure in that Cd induces cerebellar injury by disrupting the heat-shock response. Cd can be absorbed into chicken's cerebellum through the food chain, which eventually caused cerebellar injury. This study provided a new insight that chronic Cd-induced neurotoxicity in the cerebellum is associated with alterations in heat-shock response-related genes, which indicated that Cd through disturbing heat-shock response induced cerebellar injury.

Genes and Signaling Pathways Involved in the Regulation of Selenium-Enriched Yeast on Liver Metabolism and Health of Broiler (Gallus gallus)

Selenium-enriched yeast (SeY) plays an important role in the liver health and metabolism of the broiler. However, the mechanism by which it regulates liver metabolism and the health of broilers is largely unknown. Therefore, this study was conducted to elucidate the key genes and signaling pathways involved in regulating SeY in liver metabolism and bird's health. Thus, the mRNA expression microarray, GSE25151, was downloaded from Gene Expression Omnibus (GEO) database. GSE25151 consists of liver samples from SeY-treated and the control broilers. Six hundred four differentially expressed genes (DEGs) were identified in livers between SeY-treated and control. Gene ontology (GO) enrichment analysis indicated that those DEGs are mainly involved in metabolism-related biological processes, such as biological regulation, molecular processes, responses to stimuli, cell communication and proliferation, and growth. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the DEGs mainly enriched in metabolism-related signaling pathways, including PI3K, Akt, Wnt, calcium, IGF1 receptor, and MAPK signaling pathways. Moreover, many genes, such as NMUR1, NMU, and GPRC6A, might contribute to the regulation of SeY to broiler liver metabolism and health. In conclusion, the current study enhances our understanding of the regulation of SeY in liver metabolism and health of the birds and will assist studies of the molecular mechanisms of SeY regulation in chicken liver.

Selenium-enriched yeast modulates the metal bioaccumulation, oxidant status, and inflammation in copper-stressed broiler chickens

Copper (Cu) could be seriously hazardous when present at excessive levels, despite its vital contribution to various cellular processes. Selenium-enriched yeast (SeY) was reported to improve the health and metabolic status in broiler chicken. Hence, our study was endeavored to illustrate the mitigating efficacy of SeY on Cu-induced hepatic and renal damage. Cobb chicks aged 1 day were allocated into four experimental groups and offered a basal diet, SeY (0.5 mg/kg), CuSO₄ (300 mg/kg), or SeY plus CuSO₄ in their diets for 42 days. Our results revealed that SeY supplement antagonized significantly the Cu accumulation in livers and kidneys of exposed birds. Marked declines were also detected in the AST, ALT, urea, and creatinine levels, besides marked increases in total protein, glycerides, and cholesterol in the SeY-supplemented group. Moreover, enhancement of cellular antioxidant biomarkers (superoxide dismutase, CAT, GPx, and GSH) along with lowered MDA contents were achieved by SeY in hepatic and renal tissues. Further, SeY exerted a noteworthy anti-inflammatory action as indicated by decreased inflammatory biomarkers (IL-1β and TNF-α) and NO levels in both organs. Noticeable histopathological alterations of both organs further validated the changes in the markers mentioned above. To sum up, our findings indicate that SeY can be considered a potential feed supplement for alleviating Cu-induced hepatic and renal damage in broilers, possibly via activation of antioxidant molecules and lessening the inflammatory stress.

Yeast Selenium Exerts an Antioxidant Effect by Regulating the Level of Selenoprotein to Antagonize Cd-Induced Pyroptosis of Chicken Liver

Cadmium (Cd) exposure can cause multiple organ damage in humans and animals by causing oxidative stress. Organic selenium can antagonize the toxic damage of heavy metals by exerting antioxidant effects. Oxidative stress can activate NLRP3/Caspase1-dependent pyroptosis, but it is not clear whether yeast selenium (Se Y) can antagonize Cd-induced pyroptosis in the chicken liver. In this experiment, we studied the effects of CdCl₂ single, Se Y single, and combined exposure on the pyroptosis of chicken liver. The results showed that Cd exposure induced oxidative stress in the chicken liver, and the expression of Sepx1, SelU, SelT, GPx1, GPx4, Dio1, Dio2, Dio3, TrxR1, TrxR2, TrxR3, SelH, SelI, SelO, SelK, SelPb, Selpp, and Sel15 decreased. In addition, NLRP3 inflammasome complex (NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing (ASC), and pro-Caspase1), Cysteinyl aspartate specific proteinase (Caspase1), Interleukin-β (IL-1β), and Interleukin-18 (IL-18) were upregulated. The combined treatment of Se Y and Cd found that the antioxidant level and the expression level of selenoprotein recovered to the Se group, and the liver pyroptosis decreased. Principal component analysis and correlation analysis screened out that selenoprotein O (SelO) is negatively correlated with pyroptosis-related genes. In short, our data shows that Se Y exerts an antioxidant effect by increasing the expression of selenoproteins and antagonizing the pyroptosis of chicken liver induced by Cd. This study provides new ideas for the field of heavy metal toxicology research. And the selected SelO has an important reference significance for follow-up research.

Comparative study on protective effect of different selenium sources against cadmium-induced nephrotoxicity via regulating the transcriptions of selenoproteome

Cadmium (Cd) is a ubiquitous environmental pollutant, which mainly input to the aquatic environment through discharge of industrial and agricultural waste, can be a threat to human and animal health. Selenium (Se) possesses a beneficial role in protecting animals and ameliorating the toxic effects of Cd. However, the comparative antagonistic effects of different Se sources such as inorganic, organic Se and nano-form Se on Cd toxicity are still under-investigated. Hence, the purpose of this study was to evaluate the comparative of Se sources antagonism on Cd-induced nephrotoxicity via oxidative stress and selenoproteome transcription. In the present study, Cd-diet disturbed in the system balance of 5 trace elements (Zinc (Zn), copper (Cu), Iron (Fe), Se, Cd) and impaired renal function. Se sources, including nano- Se (NS), Se- yeast (SY), sodium selenite (SS) and mixed selenium (MS) significantly recovered the balance of 4 trace elements (Zn, Cu, Cd, Se) and renal impaired indexes (blood urea nitrogen (BUN) and creatinine (CREA)). Histological appearance of Cd-treated kidney indicated renal tubular epithelial vacuoles, particle degeneration and enlarged capsular space. Ultrastructure observation results illustrated that Cd-induced mitochondrial cristae reduction, membrane disappearance, and nuclear deformation. Treatment with Se sources, NS appeared a better impact on improving kidney tissues against the pathological alterations resulting from Cd administration. Meanwhile, NS reflected a significant impact on relieving Cd-induced kidney oxidative damage, and significantly restored the antioxidant defense system of the body. Our findings also showed NS ameliorated the Cd-induced downtrends expression of selenoproteome and selenoprotein synthesis related transcription factors. Overall, NS was the most effective Se source in avoiding of Cd cumulative toxicity, improving antioxidant capacity and regulating of selenoproteome transcriptome and selenoprotein synthesis related transcription factors expression, which contributes to ameliorate Cd-induced nephrotoxicity in chickens. These results demonstrated diet supplement with NS may prove to be an effective approach for alleviating Cd toxicity and minimizing Cd -induced health risk.

The Alleviative Effects of Quercetin on Cadmium-Induced Necroptosis via Inhibition ROS/iNOS/NF-κB Pathway in the Chicken Brain

Cadmium (Cd), a ubiquitous environmental pollutant, has neurotoxicity to humans and animals. Quercetin (QE), the main component of flavonoids, has strong antioxidant and anti-inflammatory effects. However, little is reported about the influence of Cd exposure on necroptosis in the chicken brain and the antagonistic impacts of QE against Cd-induced brain necroptosis. The aim of this study was to ascertain the alleviative mechanism of QE on Cd-induced necroptosis in the chicken brain. Two hundred 3.5-month-old Isa hens were randomly divided into four groups, control group, QE group, Cd group, and Cd + QE co-administration group. The histopathological analysis indicated that necrosis features were observed in the Cd-intoxicated chicken brains. Meanwhile, the expression levels of RIPK1, RIPK3, and MLKL were elevated and the level of Caspase 8 was reduced in the Cd group, which further testified Cd triggered the occurrence of necroptosis in the chicken brain. Cd exposure obviously increased Cd accumulation, ROS generation, and MDA level; weakened the activities of antioxidase (SOD, GPx, and CAT); enhanced iNOS activity and NO production; promoted the expression of inflammatory factors (NF-κB, TNFα, COX-2, iNOS, PTGEs, and IL-1β); and activated HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90). But, these Cd-caused variations were obviously attenuated in the Cd + QE group. This study indicated that QE had an alleviative effect on Cd-induced necroptosis in the chicken brain through inhibition ROS/iNOS/NF-κB pathway.

Cadmium Toxicity on Chondrocytes and the Palliative Effects of 1α, 25-Dihydroxy Vitamin D3 in White Leghorns Chicken's Embryo

Cadmium (Cd) can causes osteoporosis and joint swelling. However, the mechanism of Cd toxicity in chondrocytes and how to alleviate Cd poisoning to chondrocytes are still unclear. Herein, we evaluated the toxicity of Cd to chicken chondrocytes, and whether vitamin D can relieve the toxicity of Cd to chondrocytes. Primary chondrocytes were collected from knee-joint cartilage of 15-day-old chicken embryos. They were treated with (0, 1, 2, and 4) μM Cd alone, 10^-8 M 1α,25-(OH)₂D₃ alone, or 2 μM Cd combined with 10^-8 M 1α,25-(OH)₂D₃. We found that Cd significantly inhibited Sox9 and ACAN mRNA expression, which are markers for chondrocyte differentiation, downregulated the mitochondrial membrane potential, upregulated the Bax/B-cell lymphoma 2 ratio. Furthermore, Cd significantly promoted matrix metalloproteinase (MMP)-9 expression, thus accelerating the degradation of extracellular matrix. And Cd also inhibited the expression of main macromolecular protein of extracellular matrix, Collagen type IIα1 (COL2A1) and acid mucopolysaccharide. However, 1α,25-(OH)₂D₃ pretreatment significantly alleviated the toxicity effects of Cd on the differentiation, apoptosis and extracellular matrix gene expression in primary chondrocytes. Conclusively, Cd exposure could inhibited chicken embryo chondrocytes differentiation, extracellular matrix gene expression, and induced chondrocyte apoptosis. However, these toxic effects of Cd are alleviated by the pretreatment of chondrocytes with 1α,25-(OH)₂D₃.

Redox Homeostasis in Poultry: Regulatory Roles of NF-κB

Redox biology is a very quickly developing area of modern biological sciences, and roles of redox homeostasis in health and disease have recently received tremendous attention. There are a range of redox pairs in the cells/tissues responsible for redox homeostasis maintenance/regulation. In general, all redox elements are interconnected and regulated by various means, including antioxidant and vitagene networks. The redox status is responsible for maintenance of cell signaling and cell stress adaptation. Physiological roles of redox homeostasis maintenance in avian species, including poultry, have received limited attention and are poorly characterized. However, for the last 5 years, this topic attracted much attention, and a range of publications covered some related aspects. In fact, transcription factor Nrf2 was shown to be a master regulator of antioxidant defenses via activation of various vitagenes and other protective molecules to maintain redox homeostasis in cells/tissues. It was shown that Nrf2 is closely related to another transcription factor, namely, NF-κB, responsible for control of inflammation; however, its roles in poultry have not yet been characterized. Therefore, the aim of this review is to describe a current view on NF-κB functioning in poultry with a specific emphasis to its nutritional modulation under various stress conditions. In particular, on the one hand, it has been shown that, in many stress conditions in poultry, NF-κB activation can lead to increased synthesis of proinflammatory cytokines leading to systemic inflammation. On the other hand, there are a range of nutrients/supplements that can downregulate NF-κB and decrease the negative consequences of stress-related disturbances in redox homeostasis. In general, vitagene-NF-κB interactions in relation to redox balance homeostasis, immunity, and gut health in poultry production await further research.

As3+ or/and Cu2+ exposure triggers oxidative stress imbalance, induces inflammatory response and apoptosis in chicken brain

Arsenic (As) and copper (Cu) are common environmental pollutants in nature. When they are excessively present in living organisms, they can cause heavy metal poisoning. There were relatively few studies of the toxicological concentrations of As and Cu in the brain using chicken as a model. Therefore, in this study, arsenic trioxide or/and copper sulfate were added to chicken diets for a 12-week toxicity test. The test results showed that excessive intake of As or/and Cu led to a significant reduction in the total antioxidant capacity (T-AOC), catalase (CAT) and hydroxyl radicals. And significant increase in nitric oxide synthase (NOS) indicates an imbalanced oxidation reaction. In addition, the increase in heat shock protein (HSPs), the increase of NF-κB pathway-related pro-inflammatory mediators, the change of apoptosis factors on the death receptor and mitochondrial apoptosis pathway show that, As or/and Cu exposure induced chicken brain has heat shock response (HSP), tissue inflammation and apoptosis. This damage is inseparable from the oxidative imbalance. It is worth noting that these injury changes are time-dependent, and the combined effect of these two metals is more severe than that of a single group of injuries. Our findings can inform the regulation of animal feed additives and avoid agricultural economic losses or biological health damage.

Selenium relieves oxidative stress, inflammation, and apoptosis within spleen of chicken exposed to mercuric chloride

Mercuric chloride (HgCl₂) is a widely distributed environmental pollutant with multiorgan toxicity including immune organs such as spleen. Selenium (Se) is an essential trace element in animal nutrition and exerts biological activity to antagonize organ toxicity caused by heavy metals. The objective of this study was to explore the underlying mechanism of the protective effects of Se against spleen damage caused by HgCl₂ in chicken. Ninety male Hyline brown chicken were randomly divided into 3 groups namely Cont, HgCl₂, and HgCl₂+Se group. Chicken were provided with the standard diet and nontreated water, standard diet and HgCl₂-treated water (250 ppm), and sodium selenite-treated diet (10 ppm) plus HgCl₂-treated water (250 ppm), respectively. After being fed for 7 wk, the spleen tissues were collected, and spleen index, the microstructure of the spleen, and the indicators of oxidative stress, inflammation, apoptosis as well as heat shock proteins (HSP) were detected. First, the results of spleen index and pathological examination confirmed that Se exerted an antagonistic effect on the spleen injury induced by HgCl₂. Second, Se ameliorated HgCl₂-induced oxidative stress by decreasing the level of malondialdehyde and increasing the levels of glutathione, glutathione peroxidase, and total antioxidant capacity. Third, Se attenuated HgCl₂-induced inflammation by decreasing the protein expression of nuclear factor kappa-B, inducible nitric oxide synthase, and cyclooxygenase-2, and the gene expression of interleukin (IL)-1β, IL-6, IL-8, IL-12β, IL-18 as well as tumor necrosis factor-α. Fourth, Se inhibited HgCl₂-induced apoptosis by downregulating the protein expression of BCL2 antagonist/killer 1 and upregulating the protein expression of B-cell lymphoma-2. Finally, Se reversed HgCl₂-triggered activation of HSP 60, 70, and 90. In conclusion, Se antagonized HgCl₂-induced spleen damage in chicken, partially through the regulation of oxidative stress, inflammatory, and apoptotic signaling.