Cadmium induced hepatotoxicity in chickens (Gallus domesticus) and ameliorative effect by selenium

A new insight into the mechanism of cadmium-induced nephrotoxicity and antagonism of selenium nanoparticles: modulation of MTF1-MT axis dependent metal homeostasis

Cadmium (Cd) is a highly toxic pollutant that causes direct harm to the kidney. Cellular metal homeostasis is one of the key targets of heavy metal toxicity and may represent an alleviation pathway for environmentally-related kidney disease. Selenium nanoparticles (SeNPs) is a antioxidant and is considered to be involved in the regulation of cellular metal transport. However, the impact of Cd on renal metal homeostasis and the protective role of SeNPs against Cd-induced nephrotoxicity have not been fully elucidated. Chickens were treated with CdCl2 and SeNPs during this 90-day trial. SeNPs alleviated Cd-induced kidney injury, preserved filter barrier, and restored disrupted metal transport and selenoprotein biosynthesis, thereby normalizing the renal Cd, Se, Zn, Fe, and Cu levels. Further investigation identified that SeNPs increased nuclear translocation of MTF1 and the transcription of downstream genes MT1 and MT2. JNK activated MTF1 under a low dose of Cd exposure in response to metal stress. However, high doses of Cd exposure led to MTF1 dysfunction and Cd accumulation. Interestingly, SeNPs upregulated MTF1 expression despite down-regulation of JNK phosphorylation, suggesting that SeNPs activated the MTF1-MT axis in a non-JNK-dependent pathway. These results support the key role of SeNPs in responding to metal stress.

Polystyrene Microplastics and Cadmium Drive the Gut-Liver Axis Through the TLR4/MyD88/NF-κB Signaling Pathway to Cause Toxic Effects on Broilers

Nowadays, the risk of oral intake of microplastics (MPs) and cadmium (Cd) by poultry is high. In some industrially polluted areas, the chicken feed samples contain 9.60 × 102 ± 1.09 × 102 MPs per kilogram (mean ± std) in wet weight, and the Cd content in chicken feed has been detected to reach up to 5.61 mg/kg. But scholars still focus more on the toxic effects of MPs and Cd on the liver and intestines of aquatic animals. There are few studies that use poultry as research animals and consider these two organs as an integrated system to investigate the toxicity of MPs and Cd on the gut-liver axis and the mechanisms of inflammation. Therefore, in this research, broilers were used as experimental subjects, and experimental models were established by single or combined exposure of MPs (100 mg/L) and Cd (140 mg/kg) to explore the effects of MPs and Cd on the intestinal mucosae and liver of broilers, as well as the mechanisms behind these toxic effects. In this study, the degree of adverse effects (decreased expression of tight junction proteins, changes in intestinal morphology, abundance and diversity of intestinal flora, liver inflammation) caused by the single exposure group was higher than that of the combined exposure group. The results showed that MPs and Cd induced intestinal damage and liver inflammation in broilers by interfering with the TLR4/MyD88/NF-κB pathway and intestinal flora homeostasis. The toxicity of combined exposure was lower than that of single exposure.

Rutin Nanoparticles Alleviate Cadmium-Induced Oxidative and Immune Damage in Broilers' Bursa of Fabricius via Modulating Hsp70/TLR4/NF-κB Signaling Pathway

Cadmium (Cd) is a serious environmental pollutant affecting various tissues/organs in broilers and compromising their immunological function and productivity. Therefore, the current study aimed to investigate Cd-induced immunotoxicity and potential immunoprotective effect of rutin nanoparticles (RNPs) in the bursal tissue of broilers. A total number of 150 chicks from the Hubbard breed were randomly divided into 5 groups. Group I was fed on standard basal diet (SD) with normal drinking water (DW), Group II received SD containing RNPs (50 mg/kg feed) with DW, Group III fed on SD and DW containing Cd (150 mg/L), Group IV co-treated with rutin-enforced SD (50 mg/kg diet) and DW containing Cd (150 mg/L), and finally, Group V co-supplemented with RNP-enhanced SD (50 mg/kg diet) DW containing Cd (150 mg/L). Productive performance, economic efficiency, oxidative biomarkers, histopathological changes, and the expression level of TLR-4, HSP-70, caspase 3, NF-κB, Bcl-2, and Bax were assessed in the BF tissue. Cd led to severe production and economic losses in exposed birds with a marked surge of oxidative biomarkers, pro-inflammatory cytokines, and histopathological changes in the bursal tissue which could be explained through upregulation of the Hsp70/TLR4/NF-κB molecular pathway in the BF tissue. Meanwhile, RNPs could alleviate most of these changes and prevail optimistic immunomodulatory properties which subsequently could enhance broilers' productivity when incorporated in their diets.

Chlorogenic acid alleviates cadmium-induced neuronal injury in chicken cerebral cortex by inhibiting incomplete autophagy mediated by AMPK-ULK1 pathway

Cadmium (Cd) is an environmental pollutant that has neurotoxic properties, which poses serious threats to human health and the development of poultry farming. Chlorogenic acid (CGA) is a dietary polyphenol exhibit various biological activities such as antioxidant, anti-inflammatory, and autophagy regulation. In addition, CGA can penetrate the blood-brain barrier and exert neuroprotective effects. This study explored the mechanism of CGA in alleviating Cd-induced cerebral cortical neuron injury in chickens. The results showed that in vivo, CGA reduced the Cd level and alleviated Cd-induced histopathological and ultrastructural damages in the chicken cerebral cortex. Further research has found that CGA alleviated Cd-induced incomplete autophagy and activation of the AMPK-ULK1 pathway. In vitro, AMPK inhibitors (Compound C) could alleviate Cd-induced incomplete autophagy in chicken cerebral cortical neurons. In addition, CGA alleviated the decreased viability, incomplete autophagy, and activation of the AMPK-ULK1 pathway induced by Cd in chicken cerebral cortical neurons. In summary, CGA can alleviate Cd-induced cerebral cortical neuron injury in chickens, which is related to CGA alleviating Cd-induced incomplete autophagy by inhibiting the AMPK-ULK1 pathway.

Selenium mitigated cadmium-induced ovarian retardation in female Procambarus clarkii by regulating vitellogenin synthesis and transfer in the hepatopancreas

Cadmium (Cd) is prevalent in aquatic ecosystems and accumulates in various tissues of aquatic organisms, leading to severe biological toxicity. Selenium (Se) is recognized for mitigating heavy metal toxicity, though its protective effects against Cd in aquatic crustaceans remain underexplored. This study, therefore, assessed the effects of dietary Cd (15 mg/kg) exposure and Se (6 mg/kg) supplementation on the hepatopancreas and ovaries of female crayfish to uncover the mechanisms of Cd toxicity and the protective role of Se. The results showed that Cd accumulation in the hepatopancreas caused a reduced hepatopancreas index (HPI), decreased protein content, histopathological damage, and oxidative stress, while Se supplementation reduced Cd levels, mitigated damage, and restored tissue integrity and antioxidant defenses. Transcriptomic analysis further revealed significant alterations in gene expression related to detoxification, lipid metabolism, and energy production in response to Cd exposure, which were partially or fully restored by Se supplementation. Additionally, Se alleviated Cd-induced inhibition of ovarian development, as evidenced by improved ovary index, enhanced oocyte development, and normalization of essential trace element levels. Mechanistically, Se restored the Cd-disrupted vitellogenin (Vtg) synthesis in the hepatopancreas via regulating the mRNA expression of hsp70 and genes related to the molt-inhibiting hormone (MIH) (mih, rxr, and ecr). Overall, these findings indicate that Se supplementation mitigated Cd-induced hepatopancreatic dysfunction, restored Vtg synthesis, and consequently counteracted the inhibition of ovarian development in adult female crayfish.

Therapeutic Efficacy of Selenium Pre-treatment in Mitigating Cadmium-Induced Cardiotoxicity in Zebrafish (Danio rerio)

Cardiovascular diseases are a rampant public health threat. Environmental contaminants, such as Cadmium (Cd), a toxic metal, are risk factors for cardiovascular diseases. Given that human exposure to Cd is increasing, there is a need for therapies to ameliorate Cd toxicity. Selenium (Se), an essential trace element, has been proposed to rescue the effects of Cd toxicity, with mixed effects. Se's narrow therapeutic window necessitates precise dosing to avoid toxicity. Here, we assessed the effects of various waterborne Cd and Se concentrations and sequences on cardiac function using zebrafish (Danio rerio). We showed that Cd induced pericardial edemas and modified heart rates in zebrafish larvae in a concentration-dependent manner. To identify the therapeutic range of Se for Cd-induced cardiotoxicity, zebrafish embryos were treated with 0, 10, 50, 100, 150, or 200 μg/L Se for 1-4 days prior to exposure to 2.5 and 5 μg/L Cd. We found that a 50 µg/L Se pre-treatment before 2.5 μg/L Cd, but not 5 μg/L Cd, reduced the prevalence of pericardial edemas and ameliorated Cd-induced bradycardia in zebrafish. Zebrafish exposed to 10 and 50 μg/L of Se for up to 4 days showed typical heart morphology, whereas other Se-exposed and control fish presented pericardial edemas. Longer Se pre-treatment durations led to fewer incidences of pericardial edemas. Overall, this study highlights the importance of optimizing Se concentrations and pre-treatment periods to harness its protective effects against Cd-induced cardiotoxicity. These findings provide insights into potential therapeutic strategies for reducing Cd-related cardiovascular damage in humans.

Therapeutic Efficacy of Selenium Pre-treatment in Mitigating Cadmium-Induced Cardiotoxicity in Zebrafish (Danio rerio)

Cardiovascular diseases are a rampant public health threat. Environmental contaminants, such as Cadmium (Cd), a toxic metal, have been linked to increased risk for cardiovascular diseases. Given that human exposure to Cd is increasing overtime, there is a need to develop new therapies to ameliorate Cd toxicity. Selenium (Se), an essential trace element, has been proposed to rescue the effects of Cd toxicity, with mixed effects. Se's narrow therapeutic window necessitates precise dosing to avoid toxicity. Here, we assessed the effects of various waterborne Cd and Se concentrations and sequences on cardiac function using zebrafish (Danio rerio). We showed that Cd induced pericardial edemas and modified heart rates in a concentration-dependent manner. To identify the therapeutic range of Se for Cd-induced cardiotoxicity, zebrafish embryos were treated with 0, 10, 50, 100, 150, or 200 μg/L Se for 1-4 days prior to exposure to Cd at 2.5, and 5 μg/L. We found that a 50 μg/L Se pre-treatment prior to Cd at 2.5 μg/L, but not at 5 μg/L, reduced the prevalence of pericardial edemas and ameliorated Cd-induced bradycardia in zebrafish. Embryos exposed to 10 and 50 μg/L of Se showed typical heart morphology, whereas other Se-exposed and Se-deficient fish presented pericardial edemas. Longer Se pre-treatment durations led to fewer incidences of pericardial edemas. Overall, this study highlights the importance of optimizing Se concentration and pre-treatment periods to harness its protective effects against Cd-induced cardiotoxicity. These findings provide insights into potential therapeutic strategies for reducing Cd-related cardiovascular damage in humans.

The FAK/occludin/ZO-1 complex is critical for cadmium-induced testicular damage by disruption of the integrity of the blood-testis barrier in chickens

Cadmium (Cd) is a well-known testis toxicant. The blood-testis barrier (BTB) is a crucial component of the testis. Cd can disrupt the integrity of the BTB and reproductive function. However, the mechanism of Cd-induced disruption of BTB and testicular damage has not been fully elucidated. Here, our study investigates the effects of Cd on BTB integrity and testicular dysfunction. 80 (aged 1 day) Hy-Line white variety chickens were randomly designed into 4 groups and treated for 90 days, as follows: control group (essential diet), 35 Cd, 70 Cd and 140 Cd groups (35, 70 and 140 mg/kg Cd). The results found that Cd exposure diminished volume of the testes and induced histopathological lesions in the testes. Exposure to Cd induced an inflammatory response, disrupted the structure and function of the FAK/occludin/ZO-1 protein complex and disrupted the tight junction and adherens junction in the BTB. In addition, Cd exposure reduced the expression of steroid-related proteins and inhibited testosterone synthesis. Taken together, these data elucidate that Cd disrupts the integrity of the BTB and further inhibits spermatogenesis by dissociating the FAK/occludin/ZO-1 complex, which provides a basis for further investigation into the mechanisms of Cd-induced impairment of male reproductive function and pharmacological protection.

The antagonism mechanism of astilbin against cadmium-induced injury in chicken lungs via Treg/Th1 balance signaling pathway

The purpose of this study was to investigate the effect of Treg/Th1 imbalance in cadmium-induced lung injury and the potential protective effect of astilbin against cadmium-induced lung injury in chicken. Cadmium exposure significantly decreased T-AOC and GSH-Px levels and SOD activity in the chicken lung tissues. In contrast, it significantly increased the MDA and NO levels. These results indicate that cadmium triggers oxidative stress in lungs. Histopathological analysis revealed that cadmium exposure further induced infiltration of lymphocytes in the chicken lungs, indicating that cadmium causes pulmonary damage. Further analysis revealed that cadmium decreased the expression of IL-4 and IL-10 but increased those of IL-17, Foxp3, TNF-α, and TGF-β, indicating that the exposure of cadmium induced the imbalance of Treg/Th1. Moreover, cadmium adversely affected chicken lung function by activating the NF-kB pathway and inducing expression of genes downstream to these pathways (COX-2, iNOS), associated with inflammatory injury in the lung tissue. Astilbin reduced cadmium-induced oxidative stress and inflammation in the lungs by increasing antioxidant enzyme activities and restoring Treg/Th1 balance. In conclusion, our results suggest that astilbin treatment alleviated the effects of cadmium-mediated lung injury in chickens by restoring the Treg/Th1 balance.

Molecular mechanism of selenium against lead-induced apoptosis in chicken brainstem relating to heat shock protein, selenoproteins, and inflammatory cytokines

Extensive application of lead (Pb) brought about environmental pollution and toxic reactions of organisms. Selenium (Se) has the effect of antagonizing Pb poisoning in humans and animals. However, it is still unclear how Pb causes brainstem toxicity. In the present study, we wanted to investigate whether Se can alleviate Pb toxicity in chicken brainstems by reducing apoptosis. One hundred and eighty chickens were randomly divided into four groups, namely the control group, the Se group, the Pb group, and the Se/Pb group. Morphological examination, ultrastructural observation, relative mRNA expressions of genes on heat shock proteins (HSPs); selenoproteins; inflammatory cytokines; and apoptosis-related factors were investigated. The results showed that Pb exposure led to tissue damage and apoptosis in chicken brainstems. Furthermore, an atypical expression of HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90); selenoprotein family glutathione peroxidase (GPx) 1, GPx2, GPx3, and GPx4), thioredoxin reductases (Txnrd) (Txnrd1, Txnrd2, and Txnrd3), dio selenoprotein famliy (diodothyronine deiodinases (Dio)1, Dio2, and Dio3), as well as other selenoproteins (selenoprotein (Sel)T, SelK, SelS, SelH, SelM, SelU, SelI, SelO, Selpb, selenoprotein n1 (Sepn1), Sepp1, Sepx1, Sepw1, 15-kDa selenoprotein (Sep15), and selenophosphate synthetases 2 (SPS2)); inflammatory cytokines (Interleukin 2 (IL-2), IL-4, IL-6, IL-12β, IL-17, and Interferon-γ (IFN-γ)); and apoptosis-related genes (B-cell lymphoma-2 (Bcl-2), tumor protein 53 (p53), Bcl-2 Associated X (Bax), Cytochrome c (Cyt c), and Caspase-3) were identified. An inflammatory reaction and apoptosis were induced in chicken brainstems after exposure to Pb. Se alleviated the abnormal expression of HSPs, selenoproteins, inflammatory cytokines, and apoptosis in brainstem tissues of chickens treated with Pb. The results indicated that HSPs, selenoproteins, inflammatory, and apoptosis were involved in Se-resisted Pb poisoning. Overall, Se had resistance effect against Pb poisoning, and can be act as an antidote for Pb poisoning in animals.

A study on the effectiveness of sodium selenite in treating cadmium and perfluoro octane sulfonic (PFOS) poisoned zebrafish (Danio rerio)

Perfluoro octane sulfonate (PFOS) and cadmium (Cd) are toxic elements in the environment. As a micronutrient trace element, selenium (Se) can mitigate the adverse effects induced by PFOS and Cd. However, few studies have examined the correlation between Se, PFOS and Cd in fish. The present study focused on the antagonistic effects of Se on PFOS+Cd-induced accumulation in the liver of zebrafish. The fish was exposed to PFOS (0.08mg/L), Cd (1mg/L), PFOS+ Cd (0.08 mg/L PFOS+1 mg/L Cd), L-Se (0.07mg/L Sodium selenite +0.08mg/L PFOS+1mg/L Cd), M-Se (0.35mg/L Sodium selenite + 0.08mg/L PFOS+ 1 mg/L Cd), H-Se (1.75 mg/L Sodium selenite + 0.08 mg/L PFOS+ 1mg/L Cd) for 14d. The addition of selenium to fish exposed to PFOS and Cd has been found to have significant positive effects. Specifically, selenium treatments can alleviate the adverse effects of PFOS and Cd on fish growth, with a 23.10% improvement observed with the addition of T6 compared to T4. In addition, selenium can alleviate the negative effects of PFOS and Cd on antioxidant enzymes in zebrafish liver, thus reducing the liver toxicity caused by PFOS and Cd. Overall, the supplementation of selenium can reduce the health risks to fish and mitigate the injuries caused by PFOS and Cd in zebrafish.

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.

Autophagy protects against Cd-induced cell damage in primary chicken hepatocytes via mitigation of oxidative stress and endoplasmic reticulum stress

Cadmium (Cd) is widespread globally in the environment as a toxic metal. Although it is well known to induce hepatotoxicity in the cells, defense mechanisms against the detrimental effects of Cd are still unknown. We examined the role of autophagy (a cellular defense mechanism) on Cd-induced cytotoxicity in bird hepatocytes. Primary chicken hepatocytes were cultured with different concentrations (0, 1, 2.5, 5, and 10 μM) of cadmium chloride (CdCl₂) for 12 h. We assessed the effects of CdCl₂ on the cell viability, antioxidant status, reactive oxygen species (ROS) generation, autophagy response and endoplasmic reticulum (ER) stress. Further, it is also evaluated that insight into underling molecular mechanisms involved in the study. In this study, CdCl₂-induce hepatotoxicity was caused by drastically increased ROS generation as well as a reduction level of antioxidant enzymes. It was also demonstrated that marked activation of ER stress markers (GRP78, IRE1, PERK, ATF4, ATF6 and XBP-1 s) was observed. Simultaneously, increased activation of autophagy in low-dose CdCl₂ (1 μM) exposed group was observed, but high-dose CdCl₂ (10 μM) inhibited autophagy and significantly promoted apoptosis, as indicated by the expression of the autophagy related genes for P62, Beclin-1, ATG3, ATG5, ATG9, and the detection of autophagic vacuoles. Pretreatment with autophagy agonist Rapamycin (RAP) has successfully reduced ROS production, attenuated ER stress and enhanced hepatocytes viability, while the autophagy inhibitor 3-Methyladenine (3-MA) had the opposite effect. Hence, these findings stipulate that Cd could inhibit viability of hepatocytes in a dose-dependent manner. Autophagy relieves hepatotoxicity of Cd via reducing ROS generation and regulating ER stress. We identified autophagy as a novel protective mechanism involved in Cd-mediated chicken hepatotoxicity.

Resveratrol protects against cadmium-induced cerebrum toxicity through modifications of the cytochrome P450 enzyme system in microsomes

BACKGROUND

Cadmium (Cd), known as a vital contaminant in the environment, penetrates the blood-brain barrier and accumulates in the cerebrum. Acute toxicosis of Cd, which leads to lethal cerebral edema, intracellular accumulation and cellular dysfunction, remains to be illuminated with regard to the exact molecular mechanism of cerebral toxicity. Resveratrol (RES), present in the edible portions of numerous plants, is a simply acquirable and correspondingly less toxic natural compound with neuroprotective potential, which provides some theoretical bases for antagonizing Cd-induced cerebral toxicity.

RESULTS

This work was executed to research the protective effects of RES against Cd-induced toxicity in chicken cerebrum. Markedly, these lesions were increased in the Cd group, which also exhibited a thinner cortex, reduced granule cells, vacuolar degeneration, and an enlarged medullary space in the cerebrum. Furthermore, Cd induced CYP450 enzyme metabolism disorders by disrupting the nuclear xenobiotic receptor response (NXRs), enabling the cerebrum to reduce the ability to metabolize exogenous substances, eventually leading to Cd accumulation. Meanwhile, accumulated Cd promoted oxidative damage and synergistically promoted the damage to neurons and glial cells.

CONCLUSION

RES initiated NXRs (especially for aromatic receptor and pregnancy alkane X receptor), decreasing the expression of CYP450 genes, changing the content of CYP450, maintaining CYP450 enzyme normal activities, and exerting antagonistic action against the Cd-induced abnormal response of nuclear receptors. These results suggest that the cerebrum toxicity caused by Cd was reduced by pretreatment with RES. © 2023 Society of Chemical Industry.

Antagonism of cadmium-induced liver injury in ducks by α-bisabolol

Cadmium (Cd) is an ecological pollutant which causes hazardous effects in animals and humans. The aim of this study was to investigate the role of α-bisabolol (BISA) in antagonizing the Cd-induced hepatotoxicity in ducks. Two-week old ducks were allocated into 8 groups (10 ducks/group): Group I received basal diet and was gavaged with sunflower oil (BISA vehicle, 1.1 mL/kg/day); group II was administered BISA orally (50 mg/kg/day; diluted with sunflower oil); groups III, IV, and V were fed the basal diet mixed with CdCl2 at 37.5, 75, and 150 mg/kg diet, respectively, and were gavaged with sunflower oil; group VI, VII, and VIII were given basal diet containing CdCl2 at the aforementioned consecutive doses plus BISA. All treatments were provided daily for 4 weeks. Exposure to CdCl2 induced mortality in ducks, increased hepatic Cd content and serum levels of hepatopathic biomarkers, and caused oxidative stress and morphological alterations in ducks' liver. Furthermore, exposure to Cd caused upregulation of the mRNA of proinflammatory cytokine tumor necrosis factor-α and apoptotic gene Bax, and that of cyclooxygenase-2 protein in the liver. All effects of Cd were dose-dependent. BISA antagonized all of the aforementioned CdCl2-induced changes. These findings suggested that BISA exert the hepatoprotective effect against Cd toxicity through reducing the hepatic content of Cd as well as antagonizing oxidative insults, inflammation, and apoptosis. Thus, BISA has a great potential to be used as an antidote in the control of Cd poisoning.

Protective Effects of Astilbin Against Cadmium-Induced Apoptosis in Chicken Kidneys via Endoplasmic Reticulum Stress Signaling Pathway

Cadmium (Cd) can cause endoplasmic reticulum stress (ERS) and apoptosis in animals. The kidney is an organ seriously affected by Cd because it can accumulate metal ions. Astilbin (ASB) is a dihydroflavonol rhamnoside, which has an anti-renal injury effect. This study aimed to evaluate the protective effect of ASB on Cd-induced ERS and apoptosis in the chicken kidney. In this study, a total of 120 1-day-old chickens were randomly divided into 4 groups. Chickens were fed with a basic diet (Con group), ASB 40 mg/kg (ASB group), CdCl₂ 150 mg/kg + ASB 40 mg/kg (ASB/Cd group), and CdCl₂ 150 mg/kg (Cd group) for 90 days. The results showed that Cd exposure induced pathological and ultrastructural damages and apoptosis in chicken kidneys. Compared with the Con group, metallothionein (MT1/MT2) level, nitric oxide (NO) content, inducible nitric oxide synthase (iNOS) activity, ERS-related genes 78-kDa glucose-regulated protein (Grp78), protein kinase PKR-like endoplasmic reticulum kinase (Perk), activating transcription factor 4 (Atf4) and CAAT/enhancer-binding protein (C/EBP) homologous protein (Chop), and pro-apoptotic gene B-cell lymphoma 2 (Bcl-2)-associated X (Bax), caspase-12, caspase-9, caspase-3 expression levels, and apoptotic rate were significantly increased in the Cd group. The expression level of Bcl-2 was significantly decreased in the Cd group. ASB/Cd combined treatment significantly improves the damage of chicken kidneys by ameliorating Cd-induced kidney ERS and apoptosis. Cd can cause the disorder of the GRP78 signal axis, activate the PERK-ATF4-CHOP pathway, aggravate the structural damage and dysfunction of ER, and promote the apoptosis of chicken kidneys, while the above changes were significantly alleviated in the ASB/Cd group. The results showed that ASB antagonizes the negative effects of Cd and against Cd-induced apoptosis in chicken kidneys via ERS signaling pathway.

Effects of exposure to cadmium (Cd) and selenium-enriched Lactobacillus plantarum in Luciobarbus capito: Bioaccumulation, antioxidant responses and intestinal microflora

Cadmium (Cd) is a dangerous pollutant with multiple toxic effects on aquatic animals, and it exists widely in the environment. Selenium (Se) is a biologically essential trace element. Interactions between heavy metals and selenium can significantly affect their biological toxicity, although little is known about the mechanism of this antagonism. Lactobacillus is one of the dominant probiotics, given that a certain dose promotes host health. In this study, we evaluated the protective effect of a dietary probiotic supplementation, Se-enriched Lactobacillus plantarum (L. plantarum), on the bioaccumulation, oxidative stress and gut microflora of Luciobarbus capito exposed to waterborne Cd. Fish were exposed for 28 days to waterborne Cd at 0.05 mg/L and/or dietary Se-enriched L. plantarum. Exposure to Cd in water leads to Cd accumulation in tissues, oxidative stress and significant changes in gut microflora composition. Adding Se-enriched L. plantarum to the diet can reduce the accumulation of Cd in tissues, enhance the activity of antioxidant enzymes, and reverse changes in intestinal microbial composition after Cd exposure. The results obtained indicate that Se-enriched L. plantarum provides significant protection against the toxicity of Cd by inhibiting bioaccumulation. Selenium reduced oxidative stress by increasing the activity of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and malondialdehyde (MDA). Se-enriched L. plantarum can reduce the increase in the number of pathogenic Aeromonas caviae bacteria in the intestine caused by Cd stress and increase the number of Gemmobacter to regulate the microbial population. The results of this study show that Se-enriched L. plantarum dietary supplements can effectively protect Luciobarbus capito against Cd toxicity at subchronic levels.

Antagonistic Interaction of Selenium and Cadmium in Human Hepatic Cells Through Selenoproteins

Cadmium (Cd) is a highly toxic heavy metal for humans and animals, which is associated with acute hepatotoxicity. Selenium (Se) confers protection against Cd-induced toxicity in cells, diminishing the levels of ROS and increasing the activity of antioxidant selenoproteins such as glutathione peroxidase (GPx). The aim of this study was to evaluate the antagonistic effect of selenomethionine (SeMet) against Cd toxicity in HepG2 cells, through the modulation of selenoproteins. To this end, the cells were cultured in the presence of 100 µM SeMet and 5 μM, 15 µM, and 25 µM CdCl₂ and a combination of both species for 24 h. At the end of the experiment, cell viability was determined by MTT assay. The total metal content of Cd and Se was analyzed by triple-quadrupole inductively coupled plasma–mass spectrometry (ICP-QqQ-MS). To quantify the concentration of three selenoproteins [GPx, selenoprotein P (SELENOP), and selenoalbumin (SeAlb)] and selenometabolites, an analytical methodology based on column switching and a species-unspecific isotopic dilution approach using two-dimensional size exclusion and affinity chromatography coupled to ICP-QqQ-MS was applied. The co-exposure of SeMet and Cd in HepG2 cells enhanced the cell viability and diminished the Cd accumulation in cells. Se supplementation increased the levels of selenometabolites, GPx, SELENOP, and SeAlb; however, the presence of Cd resulted in a significant diminution of selenometabolites and SELENOP. These results suggested that SeMet may affect the accumulation of Cd in cells, as well as the suppression of selenoprotein synthesis induced by Cd.

Rutin Ameliorates Cadmium-Induced Necroptosis in the Chicken Liver via Inhibiting Oxidative Stress and MAPK/NF-κB Pathway

Cadmium (Cd) is a recognized toxic metal and exerts serious hepatotoxicity in animals and humans. Rutin (RUT) is a dietary bioflavonoid with strong antioxidant and anti-inflammatory potential. However, little is known about the alleviating effect of RUT against Cd-induced liver necroptosis. The aim of this study was to ascertain the ameliorative mechanism of RUT on necroptosis triggered by Cd in chicken liver. One hundred twenty-eight 100-day-old Isa hens were randomly divided into four groups: the control group, RUT group, Cd + RUT cotreated group, and Cd group. Cd exposure prominently elevated Cd accumulation and the activities of liver function indicators (ALT and AST). Furthermore, the histopathological results, the overexpression of genes (RIPK1, RIPK3, and MLKL) related to the necroptosis pathway, and low Caspase 8 levels in Cd-exposed chicken liver indicated that Cd intoxication induced necroptosis in chicken liver. Meanwhile, Cd administration drastically increased the levels of oxidizing stress biomarkers (ROS production, MDA content, iNOS activity, and NO generation), and obviously reduced the activities of antioxidant enzymes (SOD, GPx, and CAT) and total antioxidant capacity (T-AOC) in chicken liver. Cd treatment promoted the expression of the main members of the MAPK and NF-κB pathways (JNK, ERK, P38, NF-κB, and TNF-α) and activated heat shock proteins (HSP27, HSP40, HSP60, HSP70, and HSP90). However, RUT application remarkably alleviated these Cd-induced variations and necroptosis injury. Overall, our study demonstrated that RUT might prevent Cd-induced necroptosis in the chicken liver by inhibiting oxidative stress and MAPK/NF-κB pathway.

Tissue Bioaccumulation and Toxicopathological Effects of Cadmium and Its Dietary Amelioration in Poultry-a Review

Cadmium (Cd) has been recognized as one of the most toxic heavy metals, which is continuously discharged into environments through anthropogenic (industrial activities, fertilizer production, and waste disposal) and natural sources with anthropogenic sources contributing greater than the natural sources. Therefore, Cd concentration sometimes increases in feeds, fodders, water bodies, and tissues of livestock including poultry in the vicinity of the industrial areas, which causes metabolic, structural, and functional changes of different organs of all animals. In poultry, bioaccumulation of Cd occurs in several organs mainly in the liver, kidney, lung, and reproductive organs due to its continuous exposure. Intake of Cd reduces growth and egg laying performance and feed conversion efficiency in poultry. Chronic exposure of Cd at low doses can also alter the microscopic structures of tissues, particularly in the liver, kidney, brain, pancreas, intestine, and reproductive organs due to increased content of Cd in these tissues. Continuous Cd exposure causes increased oxidative stress at cellular levels due to over-production of reactive oxygen species, exhausting antioxidant defense mechanisms. This leads to disruption of biologically relevant molecules, particularly nucleic acid, protein and lipid, and subsequently apoptosis, cell damage, and necrotic cell death. The histopatholocal changes in the liver, kidneys, and other organs are adversely reflected in hemogram and serum biochemical and enzyme activities. The present review discusses about Cd bioaccumulation and histopathological alterations in different tissues, pathogenesis of Cd toxicity, blood-biochemical changes, and its different ameliorative measures in poultry.

Albicanol antagonizes Cd-induced apoptosis through a NO/iNOS-regulated mitochondrial pathway in chicken liver cells

Cadmium (Cd) induces hepatocyte injury by oxidative stress. Albicanol is a sesquiterpenoid extracted from the medicinal plant Dryopteris fragrans that has previously been shown to exhibit anti-aging and antioxidant activity. In this study, we explored the mechanism of albicanol inhibition of the Cd-induced apoptosis of chicken hepatoma cells (LMH) by treating these cells with CdCl2 (25 μM) and/or albicanol (2.5 × 10-5 μg mL-1) for 24 h. Under Cd treatment, the research results showed that the apoptosis rate markedly increased in LMH cells. In addition, the iNOS activity and NO content increased significantly, which promoted the expressions of genes associated with the mitochondrial apoptosis pathway (Bax, CytC, Caspase-3 and Caspase-9) and inhibited the expression of Bcl-2 in this pathway. However, Cd + albicanol co-treatment significantly reduced the apoptosis rate and the expressions of iNOS and genes associated with the mitochondrial apoptosis pathway (Bax, CytC, Caspase-3 and Caspase-9), and promoted the expression of Bcl-2 in this pathway. In addition, molecular docking supported a link between the albicanol ligand and the iNOS receptor. These results indicated that albicanol can inhibit Cd-induced apoptosis by regulating the NO/iNOS-mediated mitochondrial pathway.

Effects of Flaxseed and Multi-Carbohydrase Enzymes on the Cecal Microbiota and Liver Inflammation of Laying Hens

Simple Summary

Wheat and flaxseed are used worldwide to produce omega-3 (ω-3) enriched poultry meat and eggs, however, wheat and flaxseed contain some anti-nutritional factors (ANFs). In addition, the supplementation of feed additive including enzymes usually alleviate the deleterious influence of ANFs. Therefore, we conducted the current study of laying hens fed with two diets (corn/flaxseed and wheat/flaxseed, supplemented with three enzymes), for a period of 10 weeks. Here, we found a clear increase in the fat weight of birds fed with corn diet as compared with wheat diet. Moreover, a high level of secretory IL-1β, IL-6, and IL-10 and comparatively higher inflammatory changes in the liver tissue were found in birds fed with corn diet as compared with wheat diet. The gut microbial composition of hens fed with corn diet was clearly different than that of birds fed a wheat diet. In conclusion, our findings suggest that inflammatory changes in laying birds were mediated by a corn diet with flaxseed and enzymes instead of a wheat diet. Additionally, in the wheat-fed group, enzyme-b and -c showed more encouraging results as compared to enzyme-a indicating that wheat diet might be a preferable diet for commercial layers poultry farms.

Abstract

Background: The use of wheat and flaxseed to produce omega-3 (ω-3) enriched poultry meat and eggs is very popular in the world. However, wheat and flaxseed contain some anti-nutritional factors (ANFs), and enzymes are usually used to alleviate the deleterious influence of ANFs. Method: A 2 × 3 two factors design was used in the experiment. A total of 540 twenty-week-old Nongda-3 laying hens were randomly allocated to six dietary treatments, two diets (corn/flaxseed and wheat/flaxseed), and three enzymes (enzyme-a contains neutral protease 10,000, xylanase 35,000, β-mannanase 1500, β-glucanase 2000, cellulose 500, amylase 100, and pectinase 10,000 (U g⁻¹); enzyme-b contains alkaline protease 40,000 and neutral protease 10,000 (U g⁻¹); enzyme-c contains alkaline protease 40,000, neutral protease 10,000, and cellulase 4000 (U g⁻¹). Results: There was an interaction between dietary treatment and supplemental enzymes for liver weight and liver inflammatory cytokines of broilers. A significant increase was observed in the fat weight of birds fed a corn diet as compared with a wheat diet. A corn diet and wheat diet with the addition of enzyme-a (p < 0.001) showed the highest level of liver fat followed by enzyme-c (p < 0.01) and enzyme-b. Moreover, a high level of secretory IL-1β, IL-6, and IL-10 and comparatively higher inflammatory changes in the liver tissue were found in birds fed a corn diet as compared with a wheat diet, and enzyme-b showed more beneficial effects as compared with enzyme-a and -c. The gut microbial composition of hens fed a corn diet was significantly different than that of birds fed a wheat diet. Bacteroides were significantly (p < 0.05) abundant in the corn-fed birds as compared with wheat-fed birds. However, Firmicutes were less abundant in the wheat-fed birds than the corn-fed birds (16.99 vs. 31.80%, respectively). The microbial community at the genus level differed significantly in the dietary groups and we observed that Bacteroides are the predominant cecal microbiota. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of co-factors, carbohydrates, vitamins, protein, and energy were expressed at slightly higher levels in the microbiota of the wheat-fed birds, whereas, metabolic pathways for nucleotides, lipids, and glycine were expressed at higher levels in the wheat-fed birds. Furthermore, expression of the growth and cellular processes pathway and endocrine system pathway levels were predicted to be higher for the wheat-fed group as compared with the corn-fed group. Conclusions: In conclusion, our findings suggest that inflammatory changes in laying birds were mediated by a corn diet with flaxseed and enzymes instead of a wheat diet. Additionally, in the wheat-fed group, enzyme-b and -c showed more encouraging results as compared to enzyme-a.

Antagonistic effect of N-acetyl-L-cysteine against cadmium-induced cytotoxicity and abnormal immune response on chicken peritoneal macrophages

Cadmium is a highly toxic metal threatening human and animal health. N-acetyl-L-cysteine (NAC) was reported to play a positive role in disease treatment and immune regulation. The present study aimed to explore the effect of NAC administration on Cd-induced cytotoxicity and abnormal immune response on chicken peritoneal macrophages. Peritoneal macrophages isolated from Isa Brown male chickens were exposed to CdCl₂ (20 or 50 μM) and/or NAC (500 μM) for different time periods. Results showed that Cd caused dose-dependent damage on chicken peritoneal macrophages characterized by morphologic and ultrastructural alterations, increased cell apoptosis, reactive oxygen species accumulation and mitochondrial injury. Cd exposure inhibited phagocytic activity of chicken peritoneal macrophages, and promoted transcriptional status of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) in both unactivated macrophages and cells in response to lipopolysaccharide (LPS) stimuli. Pretreatment with 500 μM NAC did not affect growth of normal chicken peritoneal macrophages, while remarkably inhibiting Cd-caused cell death, oxidative stress, and mitochondrial membrane depolarization. NAC pretreatment significantly prevented intracellular Cd²⁺ accumulation in the Cd-exposed macrophages. Inhibitory effects of NAC on Cd-induced ROS accumulation and mitochondrial injury on chicken macrophages were confirmed in HD-11 macrophage cell line. In addition, NAC pretreatment promoted the phagocytic activity of Cd-exposed chicken peritoneal macrophages, and significantly inhibited expression of pro-inflammatory factors (IL-1β, IL-6 and TNF-α) in both Cd-exposed macrophages and Cd-treated cells in response to LPS stimuli. In conclusion, the present study firstly demonstrated the antagonistic effect of NAC against Cd-caused damage and abnormal immune response on chicken peritoneal macrophages. Protective effect of NAC on chicken macrophages was highly related to its suppression on Cd-induced ROS overproduction, pro-inflammatory reaction and intracellular Cd²⁺ accumulation.

Ameliorative effects of resveratrol against cadmium-induced nephrotoxicity via modulating nuclear xenobiotic receptor response and PINK1/Parkin-mediated Mitophagy

Cadmium (Cd) is a toxic pollutant with high nephrotoxicity in the agricultural environment. Resveratrol has been found to have a renoprotective effect but the underlying mechanisms of this have not yet been fully elucidated. The aim of this study is to illustrate the antagonism of resveratrol against Cd-induced nephrotoxicity. A total of 80 birds were divided randomly into 4 groups and treated via diet for 90 days as follows: control group (Con); 400 mg kg-1 resveratrol group (Resv); 140 mg kg-1 Cd group (Cd 140); and 140 mg kg-1 Cd + 400 mg kg-1 resveratrol group (Cd + Resv). It was observed that resveratrol treatment dramatically alleviated Cd-induced histopathological lesions of the kidney. Simultaneously, resveratrol mitigated Cd-induced oxidative stress by reducing MDA and H2O2 production, alleviating GSH depletion and restoring the activity of antioxidant enzymes (T-SOD, Cu-Zn SOD, CAT, GST and GSH-Px). Resveratrol activated NXRs (CAR/PXR/AHR/Nrf2) signaling pathways and exerted antidotal roles by enhancing the phase I and II detoxification systems to relieve oxidative damage. Moreover, resveratrol ameliorated Cd-induced ultrastructural abnormality and mitochondria dysfunction by recovering mitochondrial function-related factors VDAC1, Cyt C and Sirt3 upregulation and Sirt1, PGC-1α, Nrf1 and TFAM transcription restrictions. Resveratrol attenuated Cd-induced excessive mitochondrial fission and promoted mitochondrial fusion, which reversed PINK1/Parkin-mediated mitophagy initiation. Collectively, our findings explicate the potential protection against Cd-induced nephrotoxicity and mitochondria damage.

Selenium mitigates cadmium-induced crosstalk between autophagy and endoplasmic reticulum stress via regulating calcium homeostasis in avian leghorn male hepatoma (LMH) cells

Cadmium (Cd) is a toxic heavy metal and widespread in environment and food, which is adverse to human and animal health. Food intervention is a hot topic because it has no side effects. Selenium (Se) is an essential trace element, found in various fruits and vegetables. Many previous papers have described that Se showed ameliorative effects against Cd. However, the underlying mechanism of antagonistic effect of Se against Cd-induced cytotoxicity in avian leghorn male hepatoma (LMH) cells is unknown, the molecular mechanism of Se antagonistic effect on Cd-induced and calcium (Ca²⁺) homeostasis disorder and crosstalk of ER stress and autophagy remain to be explored. In order to confirm the antagonistic effect of Se on Cd-induced LMH cell toxicity, LMH cells were treated with CdCl₂ (2.5 μM) and Na₂SeO₃ (1.25 and 2.5 μM) for 24 h. In this study, Cd exposure induced cell death, disrupted intracellular Ca²⁺ homeostasis and Ca²⁺ homeostasis related regulatory factors, interfered with the cycle of cadherin (CNX)/calreticulin (CRT), and triggered ER stress and autophagy. Se intervention inhibited Cd-induced LDH release and crosstalk of ER stress and autophagy via regulating intracellular Ca²⁺ homeostasis. Moreover, Se mitigated Cd-induced Intracellular Ca²⁺ overload by Ca²⁺/calmodulin (CaM)/calmodulin kinase IV (CaMK-IV) signaling pathway. Herein, CNX/CRT cycle played a critical role for the protective effect of Se on Cd-induced hepatotoxicity. Based on these findings, we demonstrated that the application of Se is beneficial for prevention and alleviation of Cd toxicity.

Biosynthesis of selenium nanoparticles and their protective, antioxidative effects in streptozotocin induced diabetic rats

Green synthesis of selenium nanoparticles (Se NPs) was performed by mixing Hibiscus sabdariffa (roselle plant) leaf extract with the solution of selenious acid (H₂SeO₃) under continuous stirring conditions resulting the roselle plant secondary metabolites conjugated Se NPs. The existence of functional groups of roselle plant secondary metabolites on the surface of prepared Se NPs was confirmed by Fourier transform infrared spectroscopy (FTIR). The formation of crystalline nanoparticles with anisotropic shape was confirmed by transmission electron microscopy (TEM) images. Furthermore, we also studied anti-oxidative and protective effects of Se NPs in streptozotocin (STZ) induced diabetes rats. These STZ induced diabetic rats were daily exposed to Se NPs or/and insulin treatment and the effect of Se NPs on the factors correlated to oxidative damage in the rat testes were evaluated. The biochemical studies showed that the Se NPs are capable to enhance the serum testosterone reduction caused due to STZ induced diabetes. In addition, Se NPs can significantly reduce the oxidative stress indicators of the testicular tissue such as nitric oxide and lipid peroxidation. However, the treatment of Se NPs on the STZ induced diabetic rats increased the activities of antioxidant enzyme as well as the glutathione content in testicular tissues. Furthermore, microscopic studies revealed that the Se NPs are capable of preventing the histological damage in the testes of STZ induced diabetic rats. Altogether, these results explained the possible effects of Se NPs in attenuating oxidative damage induced by diabetes, especially in the testicular tissue.

`Cadmium induced cardiac inflammation in chicken (Gallus gallus) via modulating cytochrome P450 systems and Nrf2 mediated antioxidant defense

Cadmium (Cd) has been implicated in the pathogenesis of inflammation, myocardial infarction, angiocardiopathy, even cancers. However, it is unknown that Cd-induced cardiac toxicity through Nrf2-mediate antioxidant defense and Cytochrome P450 (CYP450) system. To ascertain the chemoprevention of Cd-induced cardiac toxicity, total 60 newborn chicks were fed with different doses of Cd (0 mg/kg, 35 mg/kg and 70 mg/kg) for a period of 90 days feed administration. Results indicated Cd exposure caused cardiac histopathology changed and functions abnormal, induced NOS activities raised and cardiac inflammation, triggering inflammation factors (IL-6, IL-8, TNF-α, and NF-κb) upregulation and inhabitation of IL-10. Cd caused increase of total CYP450 and Cytochrome b5 (Cyt b5) contents, while erythromycin N-demethylase (ERND), aminopyrin N-demethylase (APND), aniline-4-hydeoxylase (AH) and NADPH-cytochrome c reductase (NCR) indicated opposite situations with different degrees of reduction in microsomes. The mRNA level of most CYP450s isoforms (CYP1A1, CYP1A2, CYP1A5, CYP1B1, CYP2C18, CYP2C45, CYP3A4, CYP3A7 and CYP3A9) were significantly increase but CYP2D6 expression level changed not obvious. Furthermore, Cd treatment caused increased the peroxidation product (MDA) and H₂O₂ over accumulation, the decreased of T-AOC accompanied by decreased activity of antioxidant enzymes (T-SOD, GST and GPX). Over accumulation of Cd lead to oxidative stress and activated Nrf2 signal pathway through upregulating pivotal target genes (HO-1, NQO1, GCLC, GCLM and SOD). These findings suggested Cd exposure caused cardiotoxicity through CYP450s enzymes homeostasis disturbance and Nrf2-mediated oxidative stress signal pathways defense. These results may provide new evidence on molecular mechanism of Cd-induced cardiac toxicity.

Histological changes, lipid metabolism, and oxidative and endoplasmic reticulum stress in the liver of laying hens exposed to cadmium concentrations

The objective of this study was to determine the effects of cadmium (Cd) on histological changes, lipid metabolism, and oxidative and endoplasmic reticulum (ER) stress in the liver of layers. A total of 480 hens at 38 wk of age were randomly assigned in 5 groups that were fed a basal diet or basal diet supplemented with CdCl₂ 2.5H₂O at 7.5, 15, 30, and 60 mg Cd/kg feed for 9 wk. The results showed that accumulation of Cd was the greatest in the kidney, followed by the liver, pancreas, and lung. Diet contaminated with 30 mg Cd/kg induced antioxidant defenses accompanied by the increase of the activities of antioxidant enzymes in the liver, while dietary supplementation with 60 mg Cd/kg decreased the antioxidant levels significantly (P < 0.05). Immunofluorescence assay showed Cd induced reactive oxygen species production and endoplasmic reticulum stress in hepatocytes. Exposure to 60 mg Cd/kg significantly upregulated the expression of cytochrome C, caspase 3, caspase 9, caspase 7, Grp78, and Chop (P < 0.05). Histopathology and quantitative real-time PCR results presented periportal fibrosis, bile duct hyperplasia, and periportal inflammatory cell infiltration in the liver accompanied by upregulating the expression of tumor necrosis factor-α, IL-6 and IL-10 in the 30- or 60-mg Cd/kg groups. Oil Red O staining and RT-qPCR results showed dietary supplementation with 7.5, 15, and 30 mg Cd/kg promoted the synthesis of lipid droplets and upregulated the expression of fatty acid synthase, while dietary supplementation with 60 mg Cd/kg attenuated the synthesis of lipid droplets and downregulated the expression of acyl-CoA oxidase 1, carnitine palmitoyltransferase-1, and perixisome proliferation-activated receptor α (P < 0.05). Besides, the expression of vitellogenin (VTG) II and microsomal triglyceride transfer protein were upregulated in the 7.5-mg Cd/kg group, and the expressions of apolipoprotein B, vitellogenin II, and apolipoprotein very-low-density lipoprotein-II were downregulated in the 30- and/or 60-mg Cd/kg groups (P < 0.05). Conclusively, although low-dose Cd exposure promoted the synthesis of lipids and lipoproteins in the liver, the increase of Cd exposure could trigger liver injury through inducing oxidative and endoplasmic reticulum stress and negatively affect lipid metabolism and yolk formation in laying hens.

Astilbin protects chicken peripheral blood lymphocytes from cadmium-induced necroptosis via oxidative stress and the PI3K/Akt pathway

Astilbin (ASB), a dihydroflavonol glycoside, is widely found in a variety of plants and in functional foods and acts as a powerful antioxidant. The aim of this study was to investigate the underlying mechanisms involved in the antagonistic effects of ASB on cadmium (Cd)-induced necroptosis in chicken peripheral blood lymphocytes. Peripheral blood lymphocytes were aseptically collected from Roman white hens and then randomly divided into five groups: the control group was incubated without additional reagents, while the other groups were incubated with Cd, ASB, a combination of Cd and ASB, and 0.1% DMSO. After a 24 h treatment, cell samples were collected. The results showed that some morphological changes consistent with necroptosis were observed in the Cd-treated groups, suggesting the occurrence of necroptosis. Simultaneously, antioxidant activity markers (CAT, SOD, GSH, GSH-px, and T-AOC) decreased and indicators of oxidative stress (MDA, iNOS, NO, H₂O₂, ·OH and ROS) increased. The production of ROS induced the activation of the PI3K/Akt signaling pathway, as the expression levels of PI3K, Akt and PDK1 were significantly elevated. Additionally, the expression levels of RIPK3, RIPK1, MLKL, TAK1, TAB2 and TAB3 were increased and that of Caspase-8 was decreased, which could cause the necroptosis. However, the most important our results was that ASB supplements remarkably attenuated the Cd-induced effects. We conclude that the Cd treatment promoted an imbalance of the antioxidant status and activated the PI3K/Akt pathway, leading to necroptosis in chicken peripheral blood lymphocytes, and that ASB was able to partially ameliorate the effect of Cd-induced necroptosis.

Prediction of Lead Intake and Tissue Lead Concentrations in Broiler Chickens Using Feather Lead Concentrations

The present experiment was conducted to derive equations for predicting daily lead (Pb) intake and tissue Pb concentrations in broiler chickens using feather Pb concentrations. A total of 800 3-day-old broiler chickens were allotted to one of five dietary treatments with 16 replicates, each replicate consisting of 10 birds, in a completely randomized design. Dietary Pb concentrations were set to 0, 50, 100, 200, or 400 mg/kg by adding a lead acetate. The experimental diets were provided ad libitum for 32 days. Results indicated that growth performance and serum measurements were not affected by increasing concentrations of Pb in diets, which represented that the toxic level of dietary Pb may exceed over 400 mg/kg in broiler diets. Increasing concentrations of Pb in diets increased Pb concentrations in the liver (linear and quadratic, P < 0.05), breast (linear, P < 0.01), and feather (linear, P < 0.01). Feather Pb concentrations were greater than Pb concentrations in the liver and breast, indicating that the feather is highly responsive tissue of broiler chickens to various dietary Pb concentrations. Consequently, the equations for predicting daily Pb intake and Pb concentrations in the liver and breast were derived from Pb concentrations in the feather. Resulting equations indicated that feather Pb concentrations in broiler chickens can be used to predict both daily Pb intake and Pb concentrations in the liver and breast.

The Role of Selenium in Arsenic and Cadmium Toxicity: an Updated Review of Scientific Literature

Arsenic (As) and cadmium (Cd) are elements arousing major public health concerns associated with environmental pollution, high toxicity potential, and carcinogenic nature. However, selenium (Se) at low doses and incorporated into enzymes and proteins has antioxidant properties and protects animals and humans from the risk of various diseases. It also has an exceptionally narrow range between necessary and toxic concentrations, which is a well-known hindrance in its use as a dietary supplement. The present article aims to update and expand the role of Se in As and Cd toxicity discussed in our earlier paper. In general, recent reports show that Se, regardless of its form (as selenite, selenomethionine, nanoSe, or Se from lentils), can reduce As- or Cd-mediated toxicity in the liver, kidney, spleen, brain, or heart in animal models and in cell culture studies. As was suggested in our earlier review, Se antagonizes the toxicity of As and Cd mainly through sequestration of these elements into biologically inert complexes and/or through the action of Se-dependent antioxidant enzymes. An increase in the As methylation efficiency is proposed as a possible mechanism by which Se can reduce As toxicity. However, new studies indicate that Se may also diminish As or Cd toxicity by activation of the Nrf2 pathway. In addition, this paper discusses possible signs of Se toxic effects, which may be a challenge for its future use in the therapy of As and Cd poisoning and provide future directions to address this issue.

Selenium Mitigates Cadmium-Induced Adverse Effects on Trace Elements and Amino Acids Profiles in Chicken Pectoral Muscles

Cadmium (Cd), as one of the most toxic heavy metals, has become a widespread environmental contaminant and threats the food quality and safety. The protective effect of selenium (Se) on Cd-induced tissue lesion and cytotoxicity in chicken has been extensively reported. The objective of this study was to investigate the antagonistic effect of Se on Cd-induced damage of chicken pectoral muscles via analyzing the trace elements and amino acids profiles. Firstly, 19 trace elements contents were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that under Cd exposure, the contents of Cd, lead (Pb), mercury (Hg), aluminum (Al), and lithium (Li) were significantly elevated, and the contents of Se, iron (Fe), and chromium (Cr) were significantly reduced. However, supplementing Se significantly reversed the effects induced by Cd. Secondly, the amino acids contents were detected by L-8900 automatic amino acid analyzer. The results showed that supplementing Se increased significantly Cd-induced decrease of valine (Val), leucine (Leu), arginine (Arg), and proline (Pro). Thirdly, the results of principal component analysis (PCA) showed that cobalt (Co), manganese (Mn), silicium (Si), and Pro may play special roles in response to the process of Se antagonizes Cd-induced damage of pectoral muscles in chickens. In summary, these results indicated that different trace elements and amino acids possessed and exhibited distinct responses to suffer from Se and/or Cd in chicken pectoral muscles. Notably, Se alleviated Cd-induced adverse effects by regulating trace elements and amino acids profiles in chicken pectoral muscles.

Allam A, A. El-Serehy H, N. Maodaa S, M. Mahmoud A. Use of Spilopelia senegalensis as a Biomonitor of Heavy Metal Contamination from Mining Activities in Riyadh (Saudi Arabia)

Simple Summary

Bioindicators and biomonitors are living organisms utilized to appraise the health of the environment or natural ecosystem. Mining, which refers to extraction of valuable materials from the earth, represents a source of heavy metals that can impact the environment, biodiversity, and human health. We investigated the value of the laughing dove (Spilopelia senegalensis) as a biomonitor of environmental contamination with heavy metals from mining practices. Our results revealed the accumulation of heavy metals in the liver, kidneys, and lungs of the laughing dove collected from the mining site. The doves exhibited tissue dysfunction and injury, and decreased antioxidants. These results show the value of the laughing dove as a biomonitor of environmental pollution with heavy metals.

Abstract

Environmental pollution with heavy metals (HMs) is of serious ecological and public health concern worldwide. Mining is one of the main sources of HMs and can impact the environment, species diversity, and human health. This study assessed the value of Spilopelia senegalensis as a biomonitor of environmental contamination with metal(loid)s caused by mining activities. S. senegalensis was collected from a gold mining site and a reference site, and metal(loid)s and biochemical parameters were determined. Lead, cadmium, mercury, vanadium, arsenic, copper, zinc, and iron were significantly increased in the liver, kidney, and lung of S. senegalensis from the mining site. Serum transaminases, alkaline phosphatase, creatinine, and urea were significantly elevated in S. senegalensis from the mining site. Lipid peroxidation and nitric oxide were increased, whereas glutathione and antioxidant enzymes were diminished in the liver and kidney of S. senegalensis from the mining site. In addition, multiple histological alterations were observed in the liver, kidney, and lung of S. senegalensis. In conclusion, mining activities provoke the accumulation of metal(loid)s, oxidative stress, and tissue injury in S. senegalensis. Therefore, S. senegalensis is a valuable biomonitor of environmental pollution caused by mining activities and could be utilized in epidemiological avian studies of human health.

Cadmium exposure triggers mitochondrial dysfunction and oxidative stress in chicken (Gallus gallus) kidney via mitochondrial UPR inhibition and Nrf2-mediated antioxidant defense activation

Cadmium (Cd) is a widespread environmental pollutant that accumulates in living systems and represents a significant global health hazard. Cd poses a toxicity threat to both human and animal health, including that of birds. Further knowledge of Cd toxicology pathways will allow for a better understanding of Cd-induced nephrotoxicity. To evaluate Cd-induced nephrotoxicity through potential oxidative damage, male chickens were treated with 0 mg/kg, 35 mg/kg or 70 mg/kg CdCl₂ in diet for 90 days. Markedly, histopathology indicated renal tubular epithelial cell swelling, renal function CREA content abnormalities, biochemical and morphologic indices indicative of Cd-induced kidney injury. Cd toxicity induced the up-regulation of Nrf2 and downstream target genes that relieve oxidative stress. Meanwhile, Cd disrupted the homeostasis of trace elements and promoted oxidative damage. Cd interfered with mitochondrial unfolded protein response (UPR^mt)-related factors (SIRT1, SIRT3, PGC-1α, TFAM, Nrf1, and HTRA2) and disrupted the homeostasis of mitochondrial dynamics (OPA1, MFN1, MFN2, Fis1 and MFF), thereby exacerbating mitochondrial structural damage and mitochondrial dysfunction. In conclusion, our study demonstrated that the nephrotoxicity of Cd exposure results in oxidative stress and mitochondrial dysfunction by activating the Nrf2 signaling pathway and inhibiting UPR^mt in the kidneys.

The Protection of Selenium Against Cadmium-Induced Mitochondrial Damage via the Cytochrome P450 in the Livers of Chicken

Cadmium (Cd) is a heavy metal in natural environment and has extreme toxicity. Selenium (Se) has protective effect against heavy metal-induced injury or oxidative stress. Cytochrome P450 (CYP450) enzymes are a family of hemoproteins primarily responsible for detoxification functions. In order to investigate whether CYP450 is related to the damage of livers caused by Cd exposure, we chose forty-eight 28-day-old healthy Hailan cocks for four groups: control group, Se group, Cd group, and Se + Cd group. After 90-day treatment, euthanized for experiment. Based on an established subchronic Cd poisoning model in chicken, this experiment was designed to detect mitochondrial structure, malondialdehyde (MDA), glutathione (GSH), DNA and protein crosslink (DPC) and protein carbonyl (PCO) content, the CYP450 and b₅ contents, the aminopyrine-N-demethylase (AND), erythromycin N-demethylase (ERND), aniline 4-hydroxylase (AH) and NADPH-cytochrome C reducatase (CR) activities, and mRNA expression level in the livers. The present results indicated that the MDA content, PCO content, and DPC index in Cd group were higher than those observed in other three groups. Most of the mitochondrial structure is incomplete in Cd group. The contents of CYP450 and b₅ were decreased in Cd group. The activities of AND, ERND, AH, and CR got reduced after Cd exposure, as observed in CYP450 gene expression. Our results showed that CYP450 system was involved in the entire process of injury and protection. This research provides a comprehensive evaluation of the oxidative stress effects of Cd related to CYP450 in chicken.

Di-(2-ethylhexyl) phthalate (DEHP)-induced hepatotoxicity in quail (Coturnix japonica) via suppression of the heat shock response

Di-(2-ethylhexyl) phthalate (DEHP) is a widespread environmental toxicant that severely impacts agricultural production and animal and human health. Nevertheless, DEHP-induced hepatotoxicity at the molecular level in quail remains unexplored. The heat shock response (HSR), involving heat shock proteins (HSPs) and heat shock transcription factors (HSFs), is a highly conserved molecular response that is triggered by stressors, especially exposure to toxicants. To explore the DEHP-induced hepatotoxicity that occurs via regulation of HSR in birds, female quail were dosed with DEHP by oral gavage (0, 250, 500 and 1000 mg/kg) for 45 days. Based on histopathological analysis, the livers of the DEHP-treated groups exhibited structural alterations of hepatocytes, including mitochondrial swelling, derangement of hepatic plates, inflammatory cell infiltration and adipose degeneration. Ultrastructural evaluation of the livers of DEHP-treated quail revealed swollen mitochondria, partial disappearance of mitochondrial membranes and cristae, nuclear chromatin margination and nuclear condensation. The expression of HSF1 and HSF3 significantly decreased after DEHP exposure. The levels of HSPs (HSP10, HSP25, HSP27, HSP40, HSP47, HSP60, HSP70 and HSP90) were significantly downregulated in the livers of DEHP-treated quail. In this study, we concluded that DEHP exposure resulted in liver function damage and hepatotoxicity by reducing the expression of HSFs and HSPs in quail liver, which inhibited the protective effect of the HSR signaling pathway.

Effects of Selenium and Cadmium on Breast Muscle Fatty-Acid Composition and Gene Expression of Liver Antioxidant Proteins in Broilers

The present work was part of a project intended to evaluate whether organic selenium (Se) has the potential to protect against toxic effects exerted by cadmium (Cd). For this reason, 300 as-hatched, one-day-old broiler chickens were randomly allocated in four dietary treatments with five replicate pens per treatment. Chickens in T1 treatment, were offered a diet supplemented with 0.3 ppm Se (as Se-yeast), without added Cd; in T2 treatment, they were offered a diet with 0.3 ppm Se and 10 ppm Cd; in T3 treatment, they were offered a diet with 0.3 ppm Se and 100 ppm Cd; in T4 treatment, chickens were offered a diet supplemented with 3 ppm Se and 100 ppm Cd. Cadmium was added to the diets in T2, T3, and T4 as CdCl₂. On the fourth and sixth weeks, liver and breast samples were obtained from two broilers per replicate pen. Relative gene expression levels of catalase (CAT), superoxide dismutase 1 (SOD1) and 2 (SOD2), methionine sulfoxide reductase A (MSRA) and B3 (MSRB3), iodothyronine deiodinase 1 (DIO1), 2 (DIO2), and 3 (DIO3), glutathione peroxidase 1 (GPX1) and 4 (GPX4), thioredoxin reductase 1 (TXNRD1) and 3 (TXNRD3), and metallothionein 3 (MT3) were analyzed by real-time quantitative PCR in liver, whereas the fatty-acid (FA) profile of breast muscle was determined by gas chromatography. Broilers supplemented with 0.3 ppm Se could tolerate low levels of Cd present in the diets, as there were no significant changes in the breast muscle FA profile, whereas excess Cd led to decreased polyunsaturated fatty acids (PUFAs), and in particular n-6 PUFA. Furthermore, treatments mainly affected the messenger RNA (mRNA) expression of SOD2, TXNRD3, and MT3, while age affected CAT, MSRB3, DIO2, DIO3, GPX4, TXNRD1, and MT3. In conclusion, dietary Se may help against the negative effects of Cd, but cannot be effective when Cd is present at excessive amounts in the diet.

Di(2-ethylhexyl) phthalate induced hepatotoxicity in quail (Coturnix japonica) via modulating the mitochondrial unfolded protein response and NRF2 mediated antioxidant defense

Among ubiquitously found environmental contaminants in the ecosystem, di(2-ethylhexyl) phthalate (DEHP) is an important environmental contaminant used as plasticizer in medical and consumer goods. The bioaccumulation and environmental persistence of DEHP cause serious global health effects in wildlife animals and human, especially hepatotoxicity. Herein, to explore the mechanisms of DEHP induced hepatotoxicity, quail were exposed with 0, 250, 500 and 1000 mg/kg BW/day DEHP by gavage administration daily for 45 days. Notably, the adipose tissue degeneration was observed in the liver of DEHP-exposed quail under the histopathological analysis. DEHP exposure increased the peroxidation product (MDA), GSH and GST, but decreased antioxidant function (T-AOC, SOD and GPX). DEHP induced the oxidative stress and pulsed on NRF2 signal pathway through activating downstream genes. Furthermore, DEHP induced mitochondrial ultrastructural abnormalities and mitochondrial dysfunctions. Mitochondrial unfolded protein response (mtUPR) was activated to relieve mitochondrial dysfunctions and mitigated oxidative stress. These findings showed that mitochondrial functions and redox homeostasis were affected by DEHP and resulted in irreversible hepatic injury. In Conclusion, this study suggested that DEHP-induced hepatotoxicity in quail was associated with activating the NRF2 mediated antioxidant defense and mtUPR. These results provided new evidence on molecular mechanism of DEHP induced hepatotoxicity.

Cadmium-mediated miR-30a-GRP78 leads to JNK-dependent autophagy in chicken kidney

Cadmium-mediated microRNAs have become a heavily researched topic. Few studies mention the regulation of autophagy by cadmium through microRNAs, especially regarding poultry. The kidney is one of the organs most severely affected by cadmium, as it is involved in the accumulation of metal ions; causing such types of damage as apoptosis, necrosis and autophagy to the body. However, the relationship between miR-30a and GRP78 in the chicken kidney during ER stress and autophagy via JNK has not been thoroughly elucidated to date. In our research, we randomly assigned 128 Hy-Line Brown laying chickens to four groups with different diet treatments. The four groups consisted of the control group (0.2 mg Se kg-1), the Se group (2 mg kg-1 of Na₂SeO₃), the Se + Cd group (150 mg kg-1 of CdCl₂ and 2 mg kg-1 of Na₂SeO₃) and the Cd group (150 mg kg-1 of CdCl₂). On the 90th day, we detected the expression of miR-30a, GRP78, ER stress-related genes, IRE-1-JNK and autophagy-related genes. Compared with the control group, the mRNA levels of IRE-1-JNK, ER stress-related genes, autophagy-related genes and GRP78 were significantly increased (P < 0.05), while the expression of miR-30a was significantly decreased (p < 0.05) in the Cd group. However, those changes were clearly alleviated in the Se + Cd group (p < 0.05). In summary, we demonstrated that Cd triggered an miR-30a-GRP78 signaling axis disorder, increasing ER stress and activating the IRE-1-JNK pathway, thereby promoting autophagy in the chicken kidney. Moreover, Se could antagonize the negative impact of Cd.

Protective effects of zinc and N-acetyl-L-cysteine supplementation against cadmium induced erythrocyte cytotoxicity in Arbor Acres broiler chickens (Gallus gallus domesticus)

Cadmium (Cd) is one of the most toxic metals released into the environment. Here, we investigated the protective role of Zn²⁺ and/or N-acetyl-L-cysteine (NAC) against Cd cytotoxicity in the erythrocytes of Arbor Acres (AA) broiler chickens. Four hundred one-day-old AA chickens were divided into 12 groups for in vitro and in vivo studies. Zn²⁺ and/or NAC was given to the Cd exposed AA chickens to assess their protective roles. This was accomplished by investigating nuclear morphological abnormalities, oxidative stress (SOD, CAT, GPx, GSH and T-AOC), cell apoptosis, ROS accumulation and mitochondrial membrane potential (MMP). Results showed that Cd led to dose- and time-dependent cytotoxicity in the erythrocytes of AA chickens characterized by morphological abnormalities, nucleus damage, increased apoptosis rate and antioxidants depletion. Zn²⁺ or NAC significantly decreased the erythrocyte apoptosis, ROS production and mitochondrial membrane depolarization caused by Cd. SOD, CAT, GPx, GSH and T-AOC activities significantly decreased both in serum and erythrocytes of Cd exposed AA chickens. The supplementation with Zn²⁺ or NAC alleviated Cd induced oxidative stress through promoting SOD or GPx/GSH activities respectively. NAC presented a better role in reducing apoptosis, improving antioxidant activities more than Zn²⁺ in vitro. The combined use of Zn²⁺ and NAC enhanced cytoprotection in Cd exposed erythrocytes of AA chickens compared to Zn²⁺ or NAC alone. In conclusion, Zn²⁺ and NAC exerted remarkable protective roles in Cd exposed erythrocytes of AA chickens by inhibiting cell apoptosis and oxidative stress, and this provides a promising approach to antagonize Cd poisoning in poultry.

The protective role of selenium against cadmium-induced hepatotoxicity in laying hens: Expression of Hsps and inflammation-related genes and modulation of elements homeostasis

The purpose of this study was to examine the potential role of high selenium (Se) diets in alleviating chronic cadmium (Cd) hepatic toxicity in laying hens. In the present study, 128 healthy 31-week-old laying hens were fed a diet supplemented with Se (Na₂SeO₃, 2 mg/kg), Cd (CdCl₂, 150 mg/kg), or both Se and Cd (150 mg/kg of CdCl₂ and 2 mg/kg of Na₂SeO₃) for 90 days. The expression levels of heat shock proteins (Hsps, including Hsp60, Hsp70 and Hsp90) and inflammation-related factors, including nuclear factor-kappa B p50 (NF-κB), cyclooxygenase-2 (COX-2), prostaglandin E synthases (PTGES), interleukin 1-beta (IL-1β), and tumor necrosis factor-α (TNF-α) were investigated. The concentrations of 28 elements were also determined. The results indicated that Cd treatment significantly increased the mRNA and protein expression levels of Hsps and significantly improved the expression of inflammation-related genes. Moreover, Cd addition to the diets resulted in disturbances in the systemic balance of 13 elements, leading to decrease in the concentrations of Cr, Mn, Sr, Ba, and Hg and increase in Li, B, Ca, Ti, Fe, Cu, Mo, and Cd concentrations. Treatment with Se significantly alleviated Cd-induced hepatic toxicity, as evidenced by a reduction in Hsp60, Hsp70, Hsp90, NF-κB, COX-2, PTGES, TNF-α, and IL-1β expression. Additionally, Se and Cd co-treatment alleviated the changes in Li, B, Ca, Fe, Ti, Cu, Mo, Cd, Cr, Se, Sr, Ba, and Hg concentrations, which was in contrast to that upon Cd induction. The study indicated that Se could help against the negative effects of Cd and may be related to the alleviation of Cd-induced Hsps stress and the inflammatory responses along with modulating the element homeostasis.

The Antagonistic Effect of Selenium on Lead-Induced Immune Dysfunction via Recovery of Cytokine and Heat Shock Protein Expression in Chicken Neutrophils

Lead (Pb) is a ubiquitous and toxic heavy metal and it can damage the immune system in humans and animals. Many researchers have reported that Selenium (Se) could possess various pharmacological effects in mammals. However, few studies have been carried out to investigate the protective role of Se in birds, especially in chickens. In this study, we investigated the protective effects of Se against Pb-induced inflammatory responses and the expression of heat shock proteins (HSPs) in peripheral blood neutrophils. One hundred eighty Hy-Line brown chickens were randomly divided into the control group (Con group), Se supplementation group (+Se group), Pb supplementation group (+Pb group), and the Se and Pb compound group (Se+Pb group). On the 90th day of the experiment, the peripheral blood was collected to extract neutrophils, and then, the levels of HSPs and cytokines were examined. The results showed that, after Pb treatment, the levels of IL-(1β, 1R, 4, 8, 10, and 12β), TGF-β4, and HSP (27, 40, 60, 70, and 90) mRNA were significantly increased and levels of IL-2 and IFN-γ mRNA were decreased compared with those in the control group. Compared with the control group, the protein levels of HSP60 and HSP70 were also increased in the Pb treatment group. Co-administration of Se (1 mg/kg/day) and Pb resulted in a reversal of the Pb-induced cytokine changes in neutrophils accompanied by a significant decrease in HSPs. Our study demonstrated that Pb could decrease the immune function via changing the expression of cytokines and HSPs in chicken neutrophils, but Se could relieve the toxic effect induced by Pb.

Agaricus blazei Murill Polysaccharides Protect Against Cadmium-Induced Oxidative Stress and Inflammatory Damage in Chicken Spleens

Agaricus blazei Murill polysaccharide (ABP) has exhibited antioxidant and immunoregulatory activity. The aim of this study was to investigate the effect of ABP on cadmium (Cd)-induced antioxidant functions and inflammatory damage in chicken spleens. In this study, groups of 7-day-old chickens were fed with normal saline (0.2 mL single/day), CdCl₂ (140 mg/kg/day), ABP (30 mg/mL, 0.2 mL single/day), and Cd + ABP (140 mg/kg/day + 0.2 mL ABP). Spleens were separated on the 20th, 40th, and 60th day for each group. The Cd contents, expression of melanoma-associated differentiation gene 5 (MDA5) and its downstream signaling molecules (interferon promoter-stimulating factor 1 (IPS-1), transcription factors interferon regulatory factor 3 (IRF3), and nuclear factor kappa-light chain-enhancer of activated B cells (NF-κB)), the content of cytokines (interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and beta interferon (IFN-β)), protein levels of heat shock proteins (HSPs), levels of malondialdehyde (MDA), activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), and histopathological changes of spleens were detected on the 20th, 40th, and 60th day. The results showed that ABP significantly reduced the accumulation of Cd in the chicken spleens and reduced the expression of MDA5, IPS-1, IRF-3, and NF-κB; their downstream inflammatory cytokines, IL-1β, IL-6, TNF-α, and IFN-β; and the protein levels of HSPs (HSP60, HSP70, and HSP90) in spleens. The activities of antioxidant enzymes (SOD and GSH-Px) significantly increased, and the level of MDA decreased in the ABP + Cd group. The results indicate that ABP has a protective effect on Cd-induced damage in chicken spleens.

Effects of Se and Cd Co-treatment on the Morphology, Oxidative Stress, and Ion Concentrations in the Ovaries of Laying Hens

This study aims at revealing the effects of the combined treatment of selenium and cadmium on ovary morphology, oxidative stress, and 28 kinds of ion concentrations in laying hens. In this experiment, 128 healthy 31-week-old chickens were selected and divided into four treatment groups, three of which were separately fed the basic diets supplemented with either Se or Cd or both Se and Cd for 90 days, and the remaining group was fed the basic diet and treated as a control. The chickens were sacrificed for collecting ovarian tissues. Morphological structure and ultrastructure analysis of ovaries in the Cd-treated group revealed ovarian damage, with decreased activities of SOD and GPx, along with increased levels of MDA and H₂O₂. Cd treatment also resulted in disturbances in ion balance. The concentrations of Ca, Ti, Cu, Zn, and Ba were significantly reduced, while the concentrations of Fe, Mo, and Cd were significantly increased when compared with the control group. Interestingly, the damages caused by cadmium were alleviated in the Se+Cd-treated group. These results indicate that selenium can alleviate cadmium-induced ovarian damages.

Cadmium induces BNIP3-dependent autophagy in chicken spleen by modulating miR-33-AMPK axis

Cadmium (Cd), a widespread environmental pollutant, has toxic effects on organs including spleen. However, the underlying mechanisms of Cd induced spleen toxicity and the roles of micro-RNA (miRNA) in this process remain poorly understood. To investigate this, cadmium chloride (CdCl₂, 10 mg/kg) was administered in the diet of chickens for 90 days. Electron microscopy, qPCR and Western blot were performed. Results showed that Cd exposure suppressed miR-33-5q which increased the levels of AMPK. Subsequently, significant decrease in AKT/mTOR signaling and HSP70 were observed. Concurrently, levels of NF-κB, p-JNK/JNK increased significantly. Moreover, the expression of BNIP3 and other autophagy markers (LC3-I, LC3-II, Beclin-1) increased significantly. Additionally, the levels of ions (Ca, Cr, Se, Sr, Sn, Ba) and (Na, Mg, V, Fe, Mo, Cu, Zn, Cd) significantly decreased and increased, respectively. Taken together, we conclude that Cd induced the deregulation of miR-33-AMPK axis led to BNIP3-dependent autophagy in chicken spleen through AKT/mTOR and HSP70-NF-κB/JNK signal pathways. In-addition Cd could affect ion homeostasis in chicken spleen.

Selenium Antagonizes the Lead-Induced Apoptosis of Chicken Splenic Lymphocytes In Vitro by Activating the PI3K/Akt Pathway

Lead (Pb) pollution has become one of the most serious global ecological problems. In animals, Pb ingestion induces apoptosis in many tissues. However, the mechanisms by which Pb induces apoptosis in chicken splenic lymphocytes in vitro via the PI3K/Akt pathway and the antagonistic effect of selenium (Se) on Pb remain unclear. Therefore, we established the in vitro Se-Pb interaction model in chicken splenic lymphocytes and examined the frequency of apoptotic cells using acridine orange/ethidium bromide (AO/EB) staining and the TdT-mediated dUTP nick end labeling assay and detected the activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT), as well as the levels of malondialdehyde (MDA) and reactive oxygen species (ROS). The expression of PI3K/Akt pathway-related genes was also examined by qRT-PCR and western blotting. MDA and ROS levels were markedly increased, whereas the activities of GPx, SOD, and CAT were significantly decreased; the levels of the PI3K, Akt, and Bcl-2 messenger RNAs (mRNAs) and proteins were decreased; and the levels of the p53, Bax, cytochrome c (Cyt-c), caspase 3, and caspase 9 mRNAs and proteins were increased in the Pb group. In addition, the frequency of apoptotic cells was also significantly increased by the Pb treatment. However, Se supplementation during Pb exposure observably attenuated Pb-induced apoptosis; increased the levels of the PI3K, Akt, and Bcl-2 mRNAs and proteins; and decrease the levels of the p53, Bax, Cyt-c, caspase 3, and caspase 9 mRNAs and proteins in the chicken spleen. In conclusion, Pb exposure causes oxidative stress, inhibits the PI3K/Akt pathway, and subsequently induces apoptosis in chicken splenic lymphocytes in vitro, and these effects are partially attenuated by Se supplementation. To the best of our knowledge, this study is the first to reveal the antagonistic effect of Se on Pb-induced apoptosis of chicken splenic lymphocytes in vitro via the activation of the PI3K/Akt pathway.

The Antagonistic Effect of Selenium on Cadmium-Induced Damage and mRNA Levels of Selenoprotein Genes and Inflammatory Factors in Chicken Kidney Tissue

Selenium (Se) is a necessary trace mineral in the diet of humans and animals. Cadmium (Cd) is a toxic heavy metal that can damage animal organs, especially the kidneys. Antagonistic interactions between Se and Cd have been reported in previous studies. However, little is known about the effects of Se against Cd toxicity and on the mRNA levels of 25 selenoprotein genes and inflammatory factors in chicken kidneys. In the current study, we fed chickens with a Se-treated, Cd-treated, or Se/Cd treated diet for 90 days. We then analyzed the mRNA expression of inflammatory factors (including prostaglandin E synthase (PTGES), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2)) and 25 selenoprotein genes (Gpx1, Gpx2, Gpx3, Gpx4, Txnrd1, Txnrd2, Txnrd3, Dio1, Dio2, Dio3, SPS2, Sepp1, SelPb, Sep15, Selh, Seli, Selm, Selo, Sels, Sepx1, Selu, Selk, Selw, Seln, Selt). The results demonstrated that Cd exposure increased the Cd content in the chicken kidneys, renal tubular epithelial cells underwent denaturation and necrosis, and the tubules became narrow or disappeared. However, Se supplementation reduced the Cd content in chicken kidneys and induced normal development of renal tubular epithelial cells. In addition, we also observed that Se alleviated the Cd-induced increase in the mRNA levels of inflammatory factors and ameliorated the Cd-induced downtrend in the mRNA levels of 25 selenoprotein genes in chicken kidneys.

Bioaccumulation of selected heavy metals and histopathological and hematobiochemical alterations in backyard chickens reared in an industrial area, India

This study was carried out to determine the concentrations of four heavy metals, cadmium (Cd), lead (Pb), copper (Cu), and cobalt (Co), and histopathological lesions in tissues of chickens reared in an industrial area of West Bengal, India. In particular, Mejhia Block was selected as a heavy metal-exposed area and Vatar Block (120 km away from industrially polluted areas) as a reference site. Samples were collected from the backyard chickens in these areas. Concentrations of heavy metals in soil, water, feedstuffs, tissues (liver, kidney, spleen, lung, and muscle), and droppings were greater (p < 0.05) in the polluted site than in the reference site. The greatest tissue concentrations of Cd and Pb were noted in the kidney, followed by the liver, lung, spleen, and muscle, whereas Cu and Co concentrations accumulated in these tissues resulted in the following: liver > kidney > lung > spleen > muscle. Heavy metal concentrations were greater in older chickens (> 1 year) than in young chickens (< 1 year). Packed cell volume, total erythrocyte counts, hemoglobin, total protein, and total leucocyte counts were significantly (p < 0.01) lower in the blood picture of chickens in the exposed area. Different serum enzymes and biochemical profiles were altered due to heavy metal exposure. Histological changes revealed necrotic lesions and tubulitis in the kidney, degeneration and necrosis in liver parenchyma, and periarteriolitis, peribronchiolitis, and presence of hemosiderin pigment in the lung of chickens in the exposed site. Results indicated that backyard chickens in heavy metal-exposed site may show pathological lesions in different tissues due to accumulation of heavy metals, and thus, the consumption of chicken meat from the industrially exposed site may pose a potential health risk to local residents of polluted sites.

Alterations in antioxidant function and cell apoptosis in duck spleen exposed to molybdenum and/or cadmium

To investigate the effects of molybdenum (Mo) and/or cadmium (Cd) on antioxidant function and the apoptosis-related genes in duck spleens. Sixty healthy 11-day-old ducks were randomly divided into six groups of 10 ducks (control, low Mo group, high Mo, Cd, low Mo + Cd, and high Mo + Cd groups). All were fed a basal diet containing low or high dietary doses of Mo and/or Cd. Relative spleen weight, antioxidant indices, apoptosis-related gene mRNA expression levels, and ultrastructural changes were evaluated after 120 days. The results showed that the relative spleen weight decreased significantly in the high Mo + Cd treatment group which compared with control group. Malondialdehyde levels increased and xanthine oxidase and catalase activities decreased in the Mo and/or Cd groups compared with levels in the control group. Bak-1 and Caspase-3 expressions were upregulated in the high Mo + Cd group, while Bcl-2 was downregulated. In addition, mitochondrial crest fracture, swelling, vacuolation, deformed nuclei, and karyopyknosis in both Mo + Cd treated groups were more severe than in the other groups. The results suggest that Mo and/or Cd can induce oxidative stress and apoptosis of spleen via effects on the mitochondrial intrinsic pathway. Moreover, the results indicate the two elements have a possible synergistic relationship.