Effects of selenium on apoptosis and abnormal amino acid metabolism induced by excess fatty acid in isolated rat hepatocytes

Selenium Nanoparticles Ameliorate Adverse Impacts of Aflatoxin in Nile Tilapia with Special Reference to Streptococcus agalactiae Infection

Aflatoxin B1 (AFB1) is a plant-origin toxin that could induce oxidative stress in fish. The micromineral selenium (Se) possesses well-documented antioxidant properties. To assess the ameliorative effects of SeNPs (1 mg/kg fish feed) on oxidative stress induced by AFB1 (500 μg/kg fish feed), Nile tilapia (32.2±1.7 g body weight) were distributed randomly and even in six groups for 8-week feeding trial. Live enzymes, AST, ALT, and ALP levels were increased in the serum of fish fed AFB1-contaminated diet, and the addition of SeNPs could restore normal values compared to the control. The gene expression of antioxidant enzymes, superoxide dismutase (SOD) enzyme and catalase (CAT) enzyme, and DNA fragmentation were significantly increased in response to aflatoxin exposure, while dietary SeNPs could mitigate the generated oxidative stress. The innate immunity, serum antibacterial activity (SAA), oxidative burst activity (OBA), phagocytic activities (PA and PI), and gene expression of cytokines (interleukin (IL)-1β, heat shock protein70 (Hsp), and tumor necrosis factor (TNF)-α) revealed a status of immunosuppression in Nile tilapia fed on AFB1-contaminated diet. These findings showed that fish became more vulnerable to Streptococcus agalactiae infection with a high mortality rate while dietary SeNPs provided a high relative protection level (RPL). From the obtained findings, SeNPs could mitigate the oxidative stress induced by feeding the AFB1 diet and could boost the immunity of stressed Nile tilapia.

Hexavalent-Chromium-Induced Disruption of Mitochondrial Dynamics and Apoptosis in the Liver via the AMPK-PGC-1α Pathway in Ducks

Hexavalent chromium (Cr(VI)) is a hazardous substance that poses significant risks to environmental ecosystems and animal organisms. However, the specific consequences of Cr(VI) exposure in terms of liver damage remain incompletely understood. This study aims to elucidate the mechanism by which Cr(VI) disrupts mitochondrial dynamics, leading to hepatic injury in ducks. Forty-eight healthy 8-day-old ducks were divided into four groups and subjected to diets containing varying doses of Cr(VI) (0, 9.28, 46.4, and 232 mg/kg) for 49 days. Our results demonstrated that Cr(VI) exposure resulted in disarranged liver lobular vacuolation, along with increasing the serum levels of ALT, AST, and AKP in a dose-dependent manner, which indicated liver damage. Furthermore, Cr(VI) exposure induced oxidative stress by reducing the activities of T-SOD, SOD, GSH-Px, GSH, and CAT, while increasing the contents of MDA and H2O2. Moreover, Cr(VI) exposure downregulated the activities of CS and MDH, resulting in energy disturbance, as evidenced by the reduced AMPK/p-AMPK ratio and PGC-1α protein expression. Additionally, Cr(VI) exposure disrupted mitochondrial dynamics through decreased expression of OPA1, Mfn1, and Mfn2 and increased expression of Drp-1, Fis1, and MFF proteins. This disruption ultimately triggered mitochondria-mediated apoptosis, as evidenced by elevated levels of caspase-3, Cyt C, and Bax, along with decreased expression of Bcl-2 and the Bcl-2/Bax ratio, at both the protein and mRNA levels. In summary, this study highlights that Cr(VI) exposure induces oxidative stress, inhibits the AMPK-PGC-1α pathway, disrupts mitochondrial dynamics, and triggers liver cell apoptosis in ducks.

Use of Microbial Consortia in Bioremediation of Metalloid Polluted Environments

Metalloids are released into the environment due to the erosion of the rocks or anthropogenic activities, causing problems for human health in different world regions. Meanwhile, microorganisms with different mechanisms to tolerate and detoxify metalloid contaminants have an essential role in reducing risks. In this review, we first define metalloids and bioremediation methods and examine the ecology and biodiversity of microorganisms in areas contaminated with these metalloids. Then we studied the genes and proteins involved in the tolerance, transport, uptake, and reduction of these metalloids. Most of these studies focused on a single metalloid and co-contamination of multiple pollutants were poorly discussed in the literature. Furthermore, microbial communication within consortia was rarely explored. Finally, we summarized the microbial relationships between microorganisms in consortia and biofilms to remove one or more contaminants. Therefore, this review article contains valuable information about microbial consortia and their mechanisms in the bioremediation of metalloids.

Inhibition of the Nrf2 signaling pathway involved in imidacloprid-induced liver fibrosis in Coturnix japonica

Imidacloprid (IMI) is a kind of widely used neonicotinoid insecticide. However, the toxicity of IMI is not only applied to target pests but also causes serious negative effects on birds and other creatures. Our previous studies have shown that long-term exposure to IMI can induce liver fibrosis in quails. However, the specific mechanism of quail liver fibrosis induced by IMI is not completely clear. Accordingly, the purpose of this study is to further clarify the potential molecular mechanism of IMI-induced liver fibrosis in quails. Japanese quails (Coturnix japonica) were treated with/without IMI (intragastric administration with 6 mg/kg body weight) in the presence/absence of luteolin (Lut) (fed with 800 mg/kg) for 90 days. The results reveal that IMI can induce hepatic fibrosis, oxidative stress, fatty degeneration, inflammation, and the down-expression of nuclear factor-E2-related factor-2 (Nrf2). Furthermore, the treatment of Lut, a kind of Nrf2 activator, increased the expression of Nrf2 in livers and alleviated liver fibrosis in quails. Altogether, our study demonstrates that inhibition of the Nrf2 pathway is the key to liver fibrosis induced by IMI in quails. These results provide a new understanding for the study of the toxicity of IMI and a practical basis for the treatment of liver fibrosis caused by IMI.

4,7-Didehydro-neophysalin B Protects Rat Lung Epithelial Cells against Hydrogen Peroxide-Induced Oxidative Damage through Nrf2-Mediated Signaling Pathway

The administration of 4,7-didehydro-neophysalin B is expected to be a promising strategy for mitigating oxidative stress in respiratory diseases. This study was aimed at investigating the efficacy of 4,7-didehydro-neophysalin B for apoptosis resistance of rat lung epithelial cells (RLE-6TN) to oxidative stress and evaluating its underlying mechanism of action. The RLE-6TN cells treated with hydrogen peroxide (H₂O₂) were divided into five groups, and 4,7-didehydro-neophysalin B was administered into it. To evaluate its mechanism of action, the expression of oxidative stress and apoptotic proteins was investigated. 4,7-Didehydro-neophysalin B significantly inhibited H₂O₂-induced RLE-6TN cell damage. It also activated the Nrf2 signaling pathway which was evident from the increased transcription of antioxidant responsive of KLF9, NQO1, Keap-1, and HO-1. Nrf2 was found to be a potential target of 4,7-didehydro-neophysalin B. The protein levels of Bcl-2 and Bcl-xL were increased while Bax and p53 were decreased significantly. Flow cytometry showed that 4,7-didehydro-neophysalin B protected RLE-6TN cells from apoptosis and has improved the oxidative damage. This study provided a promising evidence that 4,7-didehydro-neophysalin B can be a therapeutic option for oxidative stress in respiratory diseases.

Deltamethrin induces apoptosis in cerebrum neurons of quail via promoting endoplasmic reticulum stress and mitochondrial dysfunction

Deltamethrin (DLM) is a widely used and highly effective insecticide. DLM exposure is harmful to animal and human. Quail, as a bird model, has been widely used in the field of toxicology. However, there is little information available in the literature about quail cerebrum damage caused by DLM. Here, we investigated the effect of DLM on quail cerebrum neurons. Four groups of healthy quails were assigned (10 quails in each group), respectively given 0, 15, 30, and 45 mg/kg DLM by gavage for 12 weeks. Through the measurements of quail cerebrum, it was found that DLM exposure induced obvious histological changes, oxidative stress, and neurons apoptosis. To further explore the possible molecular mechanisms, we performed real-time quantitative PCR to detect the expression of endoplasmic reticulum (ER) stress-related mRNA such as glucose regulated protein 78 kD, activating transcription factor 6, inositol requiring enzyme, and protein kinase RNA (PKR)-like ER kinase. In addition, we detected ATP content in quail cerebrum to evaluate the functional status of mitochondria. The study showed that DLM exposure significantly increased the expression of ER stress-related mRNA and decreased ATP content in quail cerebrum tissues. These results suggest that chronic exposure to DLM induces apoptosis of quail cerebrum neurons via promoting ER stress and mitochondrial dysfunction. Furthermore, our results provide a novel explanation for DLM-induced apoptosis of avian cerebrum neurons.

Harmful Effects of Inorganic Mercury Exposure on Kidney Cells: Mitochondrial Dynamics Disorder and Excessive Oxidative Stress

Mercury is widely used in industry and has caused global environmental pollution. Inorganic mercury accumulates in the body causes damage to many organs, and the kidney is the most susceptible to the toxic effects of mercury. However, the underlying specific molecular mechanism of renal injury induced by inorganic mercury remains unclear at the cellular level. Therefore, in order to understand its molecular mechanism, we used in vitro method. We established experimental models by treating human embryonic kidney epithelial cell line (HEK-293 T) cells with HgCl₂ (0, 1.25, 5, and 20 µmol/L). We found that HgCl₂ can lead to a decrease in cell viability and oxidative stress of HEK-293 T, which may be mediated by upregulation mitochondrial fission. In addition, HgCl₂ exposure resulted in the mitochondrial disorder of HEK-293 T cells, which was mediated by downregulating the expression of silent information regulator two ortholog 1 (Sirt1)/peroxisome proliferator-activated receptor coactivator-1α (PGC-1α) signaling pathway. In summary, our results suggest that HgCl₂ induces HEK-293 T cell toxicity through promoting Sirt1/PGC-1α axis-mediated mitochondrial dynamics disorder and oxidative stress. Sirt1/PGC-1α may be an appealing pharmaceutical target curing HgCl₂-induced kidney injury.

Dietary Selenium Alleviated Mouse Liver Oxidative Stress and NAFLD Induced by Obesity by Regulating the KEAP1/NRF2 Pathway

Nonalcoholic fatty liver disease (NAFLD) occurs when excess fat is stored in the liver and it is strongly linked with metabolic syndrome and oxidative stress. Selenium (Se) is an essential micronutrient in animals, which has a variety of biological functions, including antioxidant and anti-inflammatory. However, the exact effect of dietary selenium on NAFLD and the underlying molecular mechanism are not yet clear. Herein, we fed a high-fat diet (HFD) to C57BL/6 mice to construct an in vivo NAFLD model, treated AML-12 cells with palmitic acid (PA) to construct an in vitro NAFLD model, and AML-12 cells were stimulated with H₂O₂ to induce hepatocyte oxidative stress and then treated with adequate selenium. We observed that adequate selenium significantly improved the hepatic injury and insulin resistance in HFD mice, and decreased the fat accumulation and the expression of lipogenic genes in PA-induced AML-12 cells. Meanwhile, selenium significantly inhibited the production of reactive oxygen species (ROS), inhibited apoptosis, and restored mitochondrial number and membrane potential in PA- induced AML-12 cells. In addition, selenium can promote selenoproteinP1 (SEPP1) synthesis to regulate the Kelch-like ECH-associated protein 1 (KEAP1)/NF-E2-related factor 2 (NRF2) pathway, so as to defend against hepatocyte oxidative stress. These findings suggest that dietary selenium supplementation can effectively resist hepatic injury and insulin resistance during NAFLD development, and regulate the KEAP1/NRF2 pathway to resist oxidative stress by promoting SEPP1 synthesis.

N-Acetylcysteine Alleviated the Deltamethrin-Induced Oxidative Cascade and Apoptosis in Liver and Kidney Tissues

Deltamethrin (DLM) is a synthetic pyrethroid with anti-acaricide and insecticidal properties. It is commonly used in agriculture and veterinary medicine. Humans and animals are exposed to DLM through the ingestion of polluted food and water, resulting in severe health issues. N-acetylcysteine (NAC) is a prodrug of L-cysteine, the precursor to glutathione. It can restore the oxidant-antioxidant balance. Therefore, this research aimed to examine whether NAC may protect broiler chickens against oxidative stress, at the level of biochemical and molecular alterations caused by DLM intoxication. The indicators of liver and kidney injury in the serum of DLM-intoxicated and NAC-treated groups were examined. Furthermore, lipid peroxidation, antioxidant markers, superoxide dismutase activity, and apoptotic gene expressions (caspase-3 and Bcl-2) were investigated. All parameters were significantly altered in the DLM-intoxicated group, suggesting that DLM could induce oxidative damage and apoptosis in hepato-renal tissue. The majority of the changes in the studied parameters were reversed when NAC therapy was used. In conclusion, by virtue of its antioxidant and antiapoptotic properties, NAC enabled the provision of significant protection effects against DLM-induced hepato-renal injury.

Effect of inorganic mercury exposure on reproductive system of male mice: Immunosuppression and fibrosis in testis

Mercury as a toxic heavy metal will accumulate in the body and induce various diseases through the food chain. However, it is unknown that the detailed mechanism of reproductive disorder induced by inorganic mercury in male mice to date. This study investigated the toxicological effect of mercuric chloride (HgCl₂ ) exposure on reproductive system in male mice. Male Kunming mice received normal saline daily or HgCl₂ (3 mg/kg bodyweight) by intraperitoneal injection for a week. The reproductive function was evaluated, and the HgCl₂ exposure induced the decline of sperm quality, pregnancy rate, mean litter size, and survival rate. Notably, we firstly found the HgCl₂ -induced immunosuppression and fibrosis in mice testis according to the results of RNA sequencing. Collectively, these findings demonstrate that HgCl₂ exposure disrupts the reproductive system and induces testicular immunosuppression and fibrosis via inhibition of the CD74 signaling pathway in male mice.

Addition of Bamboo Charcoal to Selenium (Se)-Rich Feed Improves Growth and Antioxidant Capacity of Blunt Snout Bream (Megalobrama amblycephala)

Simple Summary

In our previous studies, we determined that juvenile blunt snout bream (Megalobrama amblycephala) require a selenium (Se) dietary intake of 0.958–0.959 mg/kg based on the quadratic fitting method. Nevertheless, growth rates were significantly affected, and the expression of anti-inflammatory factors was inhibited when the feed contained excessively high Se concentrations. Given its activity as an insoluble carrier, bamboo charcoal can be used as a dietary supplement in fish feed to absorb and slowly release excess nutrients. However, these hypotheses have not been evaluated in diets containing excess Se. The present study determined that 2–3 g/kg bamboo charcoal inclusion in Se-rich feed could improve the growth performance of blunt snout bream. Dietary bamboo charcoal supplementation mobilized the antioxidant system and inhibited the inflammatory response by activating Nrf2-Keap1 signaling while suppressing NF-κB signaling.

Abstract

The ability of bamboo charcoal to reduce the negative effects of high dietary selenium (Se) concentrations was assessed by feeding juvenile blunt snout bream (Megalobrama amblycephala) one of five Se-rich diets (1.5 mg/kg Se; 36% protein, 8.7% lipid) containing graded levels (0–4 g/kg) of bamboo charcoal powder for eight weeks. There were four tanks (350 L) of fish (initial weight 16.0 ± 0.5 g) for each treatment, and the fish were fed to satiation four times each day. At the end of the feeding trial, all of the fish from each tank were weighed to calculate the growth performance. Blood samples were firstly obtained to collect plasma for the biochemical indexes determination. Liver tissues were then collected to determine the antioxidant enzyme activities and gene expression. Dorsal muscles were also collected to determine the nutrient composition. The results show that when the bamboo charcoal content in the Se-rich feed ranged between 0 and 3 g/kg, the weight growth rate (WGR) and specific growth rate (SGR) values increased with the higher dietary bamboo charcoal content, and the maximum WGR and SGR values were achieved when the bamboo charcoal content in the Se-rich feed was 2–3 g/kg (p < 0.05). The Se content in muscle tissues decreased significantly with the increased bamboo charcoal content (p < 0.05) in the Se-rich feed, which ranged from 0 to 4 g/kg. When the bamboo charcoal content in the Se-rich feed was 2–3 g/kg, the levels of glucose (GLU) and albumin (ALB) in plasma reached a maximum (p < 0.05), whereas the level of alkaline phosphatase (ALP) reached a minimum (p < 0.05). Additionally, the activities of catalase (CAT), total superoxide dismutase (T-SOD), total antioxidative capacity (T-AOC), and glutathione peroxidase (GSH-Px) were significantly enhanced (p < 0.05) when the bamboo charcoal content was 3 g/kg. In contrast, the malondialdehyde (MDA) level increased sharply when the bamboo charcoal content in the Se-rich feed was 1 g/kg, compared to the control group and the groups supplemented with 2–3 g/kg bamboo charcoal (p < 0.05). Regarding mRNA-level gene expression, the results show that dietary supplementation with 0 to 3 g/kg of bamboo charcoal increased the expression of keap1 and nrf2, whereas nfkb expression was inhibited (p < 0.05). The mRNA expression of the antioxidant enzymes cat, gpx, and mn-sod was consistently enhanced in the group fed with the 3 g/kg bamboo charcoal diet (p < 0.05). The expression of the pro-inflammatory cytokines tnfα and tgfβ was inhibited in the groups supplemented with 2–3 g/kg bamboo charcoal, whereas the expression of anti-inflammatory cytokines (il10) increased in the bamboo charcoal supplementation groups compared to the control group (p < 0.05). Generally, supplementation with 2–3 g/kg of bamboo charcoal in Se-rich feed improved the growth performance, physiological status, and antioxidant enzyme activities of blunt snout bream. Moreover, bamboo charcoal supplementation in Se-rich diets stimulated the antioxidant system and inhibited the inflammatory response by activating Nrf2-Keap1 and suppressing NF-κB.

Inhibition of the Nrf2/p38MAPK pathway involved in deltamethrin-induced apoptosis and fibrosis in quail kidney

Deltamethrin (DLM) is a broad-spectrum and effective pyrethroid insecticide. However, DLM has good residual activity on most surfaces and many insects, so it poses a threat to the environment and health of animals and human. Exposure to DLM can cause kidney injury, but the mechanism is not well understood. Therefore, we investigated the possible mechanism of quail kidney injury induced by chronic exposure to different doses of DLM for 12 weeks. The results showed that chronic exposure to DLM induced apoptosis and fibrosis of quail kidney through the promotion of oxidative stress by down-regulating nuclear factor erythroid 2 related factor 2 (Nrf2), up-regulating the phosphorylation of p38 mitogen-activated protein kinases (p38MAPK). Furthermore, DLM-induced kidney apoptosis in quails as evidenced by increased expression of B-cell lymphoma gene 2-associated X while decreased expression of B-cell lymphoma-extra large. Simultaneously, DLM-induced kidney fibrosis in quails as evidenced by increased expression of fibrosis maker proteins. Overall, the results demonstrate that chronic DLM exposure induces kidney apoptosis and fibrosis via inhibition of the Nrf2/p38MAPK pathway. This study provides a new understanding for the mechanism of DLM-induced quail kidney injury and also provides a theoretical basis for treatment of the DLM poisoning.

Exploring the liver fibrosis induced by deltamethrin exposure in quails and elucidating the protective mechanism of resveratrol

Deltamethrin (DLM) is widely used in agriculture and the prevention of human insect-borne diseases. However, the molecular mechanism of DLM induced liver injury remains unclear to date. This study investigated the potential molecular mechanism that DLM induced liver fibrosis in quails. Japanese quails received resveratrol (500 mg/kg) daily with or without DLM (45 mg/kg) exposure for 12 weeks. Histopathology, transmission electron microscopy, biochemical indexes, TUNEL, quantitative real-time PCR, and western blot analysis were performed. DLM exposure induced hepatic steatosis, oxidative stress, inflammation, and apoptosis. Most importantly, the Nrf2/TGF-β1/Smad3 signaling pathway played an important role on DLM-induced liver fibrosis in quails. Interestingly, the addition of resveratrol, an Nrf2 activator, alleviates oxidative stress and inflammation response by activating Nrf2, thereby inhibits the liver fibrosis induced by DLM in quails. Collectively, these findings demonstrate that chronic exposure to DLM induces oxidative stress via the Nrf2 expression inhibition and apoptosis, and then results in liver fibrosis in quails by the activation of NF-κB/TNF-α and TGF-β1/Smad3 signaling pathway.

Melatonin inhibits the apoptosis of rooster Leydig cells by suppressing oxidative stress via AKT-Nrf2 pathway activation

Oxidative stress has been described as a key driver of Leydig cell apoptosis. Melatonin has antioxidative and antiapoptotic effects, but the potential effects and mechanism of melatonin on oxidative stress and apoptosis in rooster Leydig cells remain unclear. Our results showed that melatonin biosynthetic enzymes and melatonin receptors were expressed in rooster Leydig cells and their expression were locally inhibited as rooster sexual maturation. We found that melatonin inhibited H₂O₂-induced apoptosis of rooster Leydig cell by activating the melatonin receptors Mel-1a and Mel-1b. Additionally, melatonin protects mitochondria from damage by reducing the level of oxidative stress in Leydig cells. Melatonin relieved H₂O₂-induced oxidative stress by significantly reducing intracellular ROS, MDA and 8-OHdG levels and increasing SOD and GSH-Px activities. Simultaneously, melatonin significantly reduced H₂O₂-induced depolarization of ΔΨm and decreased the release of Cytochrome C and Ca²⁺. We also observed that melatonin activated the Nrf2 pathway, while Nrf2 silencing abrogated the anti-oxidative and anti-apoptotic effects of melatonin in rooster Leydig cells. Furthermore, melatonin promoted the phosphorylation of AKT, while AKT inhibitor suppressed the Nrf2 pathway activated by melatonin and alleviated the inhibitory effects of melatonin on apoptosis and oxidative stress. In conclusion, melatonin could inhibit apoptosis in rooster Leydig cells by suppressing oxidative stress via activation of the AKT-Nrf2 pathway.

Hexavalent chromium induces renal apoptosis and autophagy via disordering the balance of mitochondrial dynamics in rats

The use of hexavalent chromium (Cr(VI)) in many industrial processes has resulted in serious environmental pollution problems. Cr(VI) causes organ toxicity in animals after ingestion or inhalation. However, the exact mechanism by which Cr(VI) produces kidney damage remains elusive. Herein, we investigated whether Cr(VI)-induced kidney damage is related to the disorder of mitochondrial dynamics. In this study, 28 male rats were divided into four groups and intraperitoneally injected with 0, 2, 4, and 6 mg/kg body weight potassium dichromate for 5 weeks. Experiment included analysis of renal histopathology and ultrastructure, determination of biochemical indicators, and measurement of related protein content. The results showed that Cr(VI) induced kidney injury through promotion of oxidative stress, apoptosis, and disorder of mitochondrial dynamics in a dose-dependent manner. The protein levels of the silent information regulator two ortholog 1 (Sirt1), peroxisome proliferation-activated receptor-g coactivator-1a (PGC-1a), and autophagy-related proteins were significantly decreased after Cr(VI) exposure. These findings suggest that Cr(VI) leads to the disorder of mitochondrial dynamics by inhibiting the Sirt1/PGC-1a pathway, which leads to renal apoptosis and autophagy in rats.

Immobilization of cell membrane onto a glucose-Zn-based porous coordination polymer and its application to rapid screening of potentially active compounds from Vaccinium corymbosum L. leaves

A novel glucose-Zn-based porous coordination polymer (PCP) was selected as a carrier of cell membranes (CMs) to fabricate CM-coated PCP (CMPCP) for rapid screening of potentially active compounds from natural products. The cell disruption and the amount of maximum CMs adsorbed on PCP were optimized according to the amount of immobilized protein. This new kind of matrix exhibited good reproducibility and stability, and was applied for fishing potentially active compounds from the extracts of Vaccinium corymbosum L. leaves (VCL). Using LC-MS/MS, chlorogenic acid and quercetin were identified as the potentially active compounds through comparison of normal and non-alcoholic fatty liver disease (NAFLD)-modeled CMPCP. Our results suggested that the proposed approach based on CMPCP was environmentally friendly, cost-effective, and convenient in terms of green porous material, stable protein loading capacity, and accessible operation process. The developed method could provide a promising platform for efficient drug discovery from natural product resources.Graphical abstract.

Hexavalent chromium induces mitochondrial dynamics disorder in rat liver by inhibiting AMPK/PGC-1α signaling pathway

Occupational exposure to hexavalent chromium (Cr(VI)) can cause cytotoxicity and carcinogenicity. In this study, we established a liver injury model in rats via intraperitoneal injection of potassium dichromate (0, 2, 4, and 6 mg/kg body weight) for 35 d to investigate the mechanism of Cr(VI)-induced liver injury. We found that Cr(VI) induced hepatic histopathological lesions, oxidative stress, and apoptosis and reduced the expression of mitochondrial-related regulatory factors such as adenosine 5'-monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in a dose-dependent manner. Furthermore, Cr(VI) promoted mitochondrial division and inhibited fusion, leading to increased expression of caspase-3 and production of mitochondrial reactive oxygen species. Our study demonstrates that long-term exposure to Cr(VI) induces mitochondrial dynamics disorder by inhibiting AMPK/PGC-1α signaling pathway in rat liver.

Dietary selenium enhances the growth and anti-oxidant capacity of juvenile blunt snout bream (Megalobrama amblycephala)

Sodium selenite was added to basal diet at five levels (0.10, 0.42, 0.67, 1.06 and 1.46 mg Se/kg) and fed fish for 8 weeks. The dietary selenium requirement of juvenile blunt snout bream (Megalobrama amblycephala) was quantified. Dietaryseleniums at 0.67-1.06 mg Se/kg improved weight gain rate, specific growth rate and feed efficiency. The optimal amount was 0.96 mg/kg, for which the specific growth rate was 1.798%/day and the weight gain rate was 173.852% (p < 0.05). Se deposition in muscle was increased (p < 0.05) at ≥0.67 mg/kg, but moisture, protein, lipid and ash content were not affected. Physiological status and lipid metabolism were improved by 1.06-1.46 mg/kg dietary selenium based on total protein and albumin in plasma, and total cholesterol and triglycerides (p < 0.05). Activities of hepatic anti-oxidant enzymes catalase, total superoxide dismutase, glutathione peroxidase and reduced glutathione were enhanced at Se1.06 (p < 0.05). However, malondialdehyde content was lowered at Se1.06 (p < 0.05). Expression of anti-inflammatory cytokines, nuclear factor erythroid 2-related factor 2 (Nrf2) and kelch-like ECH-associated protein 1 (Keap-1) in liver were elevated at Se1.06 (p < 0.05), as were mRNA levels of glutathione peroxidase, copper zinc superoxide dismutase and catalase. Expression of pro-inflammatory cytokines, interleukin 8, tumour necrosis factor-α and transforming growth factor-β were inhibited at 0.67-1.46 mg/kg (p < 0.05). In general, 0.96 mg/kg was optimal, and optimal selenium enhanced antioxidant stress tolerance and anti-inflammatory ability.

Deltamethrin induces liver fibrosis in quails via activation of the TGF-β1/Smad signaling pathway

Deltamethrin (DLM) is an important member of the pyrethroid pesticide family, and its widespread use has led to serious environmental and health problems. Exposure to DLM causes pathological changes in the liver of animals and humans and can lead to liver fibrosis. However, the mechanism of DLM-induced liver fibrosis remains unclear. Therefore, to address its potential molecular mechanisms, we used both in vivo and in vitro methods. Quails were treated in vivo by intragastric administration of different concentrations of DLM (0, 15, 30, or 45 mg kg^-1), and the chicken liver cancer cell line LMH was treated in vitro with various doses of DLM (0, 50, 200, or 800 μg mL^-1). We found that DLM treatment in vivo induced liver fibrosis in a dose-dependent manner through the promotion of oxidative stress, activation of transforming growth factor-β1 (TGF-β1) and phosphorylation of Smad2/3. Treatment of LMH cells with different concentrations of DLM similarly induced oxidative stress and also decreased cell viability. Collectively, our study demonstrates that DLM-induced liver fibrosis in quails occurs via activation of the TGF-β1/Smad signaling pathway.

Sulforaphane prevents chromium-induced lung injury in rats via activation of the Akt/GSK-3β/Fyn pathway

Chromium (Cr) is an internationally recognized carcinogenic hazard that causes serious pulmonary toxicity. However, Cr-induced pulmonary toxicity lacks effective treatment to date. Sulforaphane (SFN), a well-known organosulfur compound, has gained increasing attention because of its unique biological function. This study investigates if SFN could decrease K₂Cr₂O₇-induced pulmonary toxicity and a potential mechanism involved using a rat 35-day Cr-induced pulmonary toxicity model and the mouse alveolar type II epithelial cell line (MLE-12). The results showed that SFN prevented Cr-induced oxidative stress, histopathological lesions, inflammation, apoptosis, and changes in protein kinase B (Akt) and glycogen synthase kinase 3 beta (GSK-3β) levels in vivo and in vitro. However, SFN can not play the protective effect against K₂Cr₂O₇-induced cell injury after treating by an Akt-specific inhibitor (MK-2206 2HCl) in MLE-12 cells. Furthermore, SFN increased the expression of nuclear factor-E2-related factor-2 (Nrf2) phase II detoxification enzymes. Collectively, this study demonstrates that SFN prevents K₂Cr₂O₇-induced lung toxicity in rats through enhancing Nrf2-mediated exogenous antioxidant defenses via activation of the Akt/GSK-3β/Fyn signaling pathway. SFN may be a novel natural substance to cure Cr-induced lung toxicity.

Selenium and selenoprotein P in nonalcoholic fatty liver disease

Conflicting data link nonalcoholic fatty liver disease (NAFLD), a disease with no currently approved treatment, with selenium (Se) and selenoprotein P (SELENOP), a glycoprotein synthesized and primarily secreted by the hepatocytes, functioning as a Se transporter from the liver to other tissues. This review aims to summarize the evidence between Se, SELENOP, and NAFLD, which may hopefully clarify whether current data on Se and SELENOP in NAFLD warrant further investigation for their diagnostic and therapeutic potential. Most, albeit not all, experimental data show a favorable effect of Se on hepatic steatosis, inflammation, and fibrosis. It seems that Se may exert an antioxidant effect on the liver, at least partly via increasing the activity of glutathione peroxidase, whose depletion contributes to the pathogenesis of hepatic inflammation and fibrosis. Se may also affect metalloproteinases, cytokines, and growth factors participating in the pathogenesis of NAFLD and, most importantly, may induce the apoptosis of hepatic stellate cells, the key players in hepatic fibrosis. However, the association between Se or SELENOP and insulin resistance, which is a principal pathogenetic factor of NAFLD, remains inconclusive. Clinical studies on Se or SELENOP in NAFLD are conflicting, apart from those in advanced liver disease (cirrhosis or hepatocellular carcinoma), in which lower circulating Se and SELENOP are constant findings. Existing data warrant further mechanistic studies in valid animal models of human NAFLD. Prospective cohort studies and possibly randomized controlled trials are also needed to elucidate the diagnostic and therapeutic potential of Se supplementation in selected NAFLD individuals with Se deficiency.

Imidacloprid-induced liver fibrosis in quails via activation of the TGF-β1/Smad pathway

Imidacloprid (IMI) is one of the most frequently used neonicotinoid insecticide, and its potential toxicity and environmental hazards have gradually attracted people's attention. Liver fibrosis caused by long-term inflammation or oxidative stress can lead to cirrhosis and liver failure, even death. However, the mechanism of liver fibrosis induced by neonicotinoid insecticide remains unclear. This study investigates whether IMI could induce liver fibrosis in quails and a potential mechanism. Our study used a quail 90-day IMI-induced liver fibrosis model. The results showed that IMI induced histopathological lesions, oxidative stress, inflammation, fibrosis, and changes in nuclear factor-kappa B (NF-κB), nuclear factor-E2-related factor-2 (Nrf2), and transforming growth factor (TGF-β1) levels. Furthermore, IMI enhanced the expression of liver fibrosis marker proteins, including collagen I, α-smooth muscle actin (α-SMA), and fibronectin 1 (FN-1), by activating the TGF-β1/Smad signaling pathway. In conclusion, our study demonstrated that IMI exposure induces liver fibrosis via activation of the TGF-β1/Smad signaling pathway in quails.

Exploring the kidney hazard of exposure to mercuric chloride in mice:Disorder of mitochondrial dynamics induces oxidative stress and results in apoptosis

Mercury is one of the 10 toxic chemicals with major public health concerns. Continuous exposure to low levels of heavy metals including mercury is related to renal injury, especially in children. This study investigated the possible molecular mechanism of inorganic mercury-induced kidney injury. Twenty eight Kunming mice were divided into four groups (n = 7), and treated with 0, 20, 40, 80 mg/L mercuric chloride (HgCl₂) in drinking water for 16 weeks respectively. All the HgCl₂ exposure mice displayed different degrees of renal injury, which was diagnosed by hematoxylin and eosin stain, biochemical analysis, and ultrastructure examination. The treatment of HgCl₂ inhibited the silent information regulator two ortholog 1 (Sirt1)/peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) signaling pathway and resulted the disorder of mitochondrial dynamics, as evidenced by the increasing expression of dynamin-related protein 1 and decreasing expression of mitofusin 2. Meanwhile, HgCl₂ inhibited the nuclear factor erythroid 2-related factor 2 (Nrf2) axis. The abnormality of mitochondrial dynamics and the suppression of Nrf2 axis exacerbated oxidative stress, and then induced cell apoptosis. These findings demonstrated that the disorder of mitochondrial dynamics induced by HgCl₂ activated oxidative stress, and further resulted in renal apoptosis through inhibiting the Sirt1/PGC-1α signaling pathway and the Nrf2 axis.

Dietary melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway

Exposure to chromium (Cr) causes a number of respiratory diseases, including lung cancer and pulmonary fibrosis. However, there is currently no safe treatment for Cr-induced lung damage. Here, we used in vivo and in vitro approaches to examine the protective effects of melatonin (MEL) on Cr-induced lung injury and to identify the underlying molecular mechanisms. We found that treatment of rats or a mouse lung epithelial cell MLE-12 with MEL attenuated K₂Cr₂O₇-induced lung injury by reducing the production of oxidative stress and inflammatory mediators and inhibiting cell apoptosis. MEL treatment upregulated the expression of silent information regulator 1 (Sirt1), which deacetylated the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc-1α). In turn, this increased the expression of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and key anti-oxidant target genes. These results suggest that melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway. Dietary MEL supplement may be a potential new strategy for the treatment of Cr poisoning.

Melatonin protects against chromium(VI)-induced cardiac injury via activating the AMPK/Nrf2 pathway

Chromium (Cr) threatens health by causing oxidative stress. However, effective therapy for cardiac damage mediated by potassium dichromate (K₂Cr₂O₇) still has not been defined. Melatonin (MT) possesses a number of biological activities. Our study was performed to explore the effect and mechanism of MT on Cr(VI)-induced cardiac damage by conducting both in vitro and in vivo studies. Twenty eight male Wistar rats were randomly assigned to four groups: control, MT (20 mg/kg subcutaneously), K₂Cr₂O₇ (4 mg/kg intraperitoneally), and K₂Cr₂O₇ + MT. We measured biomarkers of oxidative stress and cardiac function, and performed histopathological analysis, assay of terminal deoxynucleotidyl transferase-mediated deoxyuracil nucleoside triphosphate nick end labeling and protein levels, and the viability assay of cultured cardiomyocytes in vitro. Our results showed that MT ameliorated K₂Cr₂O₇-induced oxidative stress, apoptosis, and the release of inflammatory mediators in the rat heart. MT also promoted adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, upregulated expression of proteins that nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1, and nicotinamide adenine dinucleotide phosphatase: quinone-acceptor 1, and inhibited nuclear factor kappa B in the heart of rats exposed to K₂Cr₂O₇. Furthermore, MT increased B-cell lymphoma gene 2 (Bcl-2) and B-cell lymphoma extra large protein levels and decreased cleaved caspase 3, P53, and Bcl-2-associated X protein levels. Furthermore, the experiment in vitro showed that MT increased the cells viability and protein levels of Nrf2 and phosphorylated-AMPK in H9C2 cells treated with K₂Cr₂O₇. Collectively, our results demonstrate that MT protects against Cr-induced cardiac damage via activating the AMPK/Nrf2 pathway.

Role of A2B adenosine receptor-dependent adenosine signaling in multi-walled carbon nanotube-triggered lung fibrosis in mice

Background

Multi-walled carbon nanotube (MWCNT)-induced lung fibrosis leads to health concerns in human. However, the mechanisms underlying fibrosis pathogenesis remains unclear. The adenosine (ADO) is produced in response to injury and serves a detrimental role in lung fibrosis. In this study, we aimed to explore the ADO signaling in the progression of lung fibrosis induced by MWCNT.

Results

MWCNT exposure markedly increased A_2B adenosine receptor (A_2BAR) expression in the lungs and ADO level in bronchoalveolar lavage fluid, combined with elevation of blood neutrophils, collagen fiber deposition, and activation of myeloperoxidase (MPO) activity in the lungs. Furthermore, MWCNT exposure elicited an activation of transforming growth factor (TGF)-β1 and follistatin-like 1 (Fstl1), leading to fibroblasts recruitment and differentiation into myofibroblasts in the lungs in an A_2BAR-dependent manner. Conversely, treatment of the selective A_2BAR antagonist CVT-6883 exhibited a significant reduction in levels of fibrosis mediators and efficiently decreased cytotoxicity and inflammatory in MWCNT treated mice.

Conclusion

Our results reveal that accumulation of extracellular ADO promotes the process of the fibroblast-to-myofibroblast transition via A_2BAR/TGF-β1/Fstl1 signaling in MWCNT-induced lung fibrosis.

Luteolin-mediated PI3K/AKT/Nrf2 signaling pathway ameliorates inorganic mercury-induced cardiac injury

Inorganic mercury is a toxic metal of worldwide concern, and causes serious cardiac injury. However, effective treatment for cardiac injury induced by mercuric chloride (HgCl₂) has not been fully identified. Luteolin (Lut) is a novel natural antioxidant. This study aimed to investigate the role of Lut on HgCl₂-induced cardiac injury. Male Wistar rats were randomly assigned to 4 groups, control, Lut (80 mg/kg intragastrically), HgCl₂ (80 mg/L, in drinking water), and HgCl₂ + Lut groups. The results indicated that Lut significantly ameliorated cardiac histopathological damage, oxidative stress, and apoptosis induced by HgCl₂ in the rat heart. Furthermore, Lut evidently increased levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and nuclear factor-erythroid-2-related factor 2 (Nrf2) and its downstream proteins, and inhibited NF-κB activation in the heart of rats treated by HgCl₂. Taken together, our findings suggest that activating PI3K/AKT/Nrf2 signaling pathway is involved in the protective effect of Lut against HgCl₂-induced cardiac damage.

Dietary grape seed procyanidin extract protects against lead-induced heart injury in rats involving endoplasmic reticulum stress inhibition and AKT activation

To investigate the protective role of grape seed procyanidin extract (GSPE) against lead-induced heart injury and the possible molecular mechanism associated with this event, Wistar rats were orally given GSPE (200 mg/kg) daily with or without lead acetate (PbA) (0.5 g/L) in drinking water for 56 d. GSPE attenuated oxidative stress, heart dysfunction, and lead accumulation in lead-exposed rat hearts. Meanwhile, GSPE inhibited the protein kinase RNA-like endoplasmic reticulum (ER) kinase/eukaryotic initiation factor 2α signaling pathway, and promoted protein kinase B (AKT) and glycogen synthase kinase 3β phosphorylation altered by lead, and regulated lead-activated apoptosis and its related signaling pathway. This study suggests that dietary GSPE ameliorates lead-induced heart injury associated with ER stress inhibition and AKT activation. Dietary GSPE may be a protector against lead-induced heart injury and a novel therapy for lead exposure.

Selenium deficiency impaired immune function of the immune organs in young grass carp (Ctenopharyngodon idella)

This study aimed to investigate the effects of dietary selenium on resistance to skin haemorrhages and lesions and on immune function as well as the underlying mechanisms of those effects in the head kidney, spleen and skin of young grass carp (Ctenopharyngodon idella). A total of 540 healthy grass carp with initial body weight (226.48 ± 0.68 g) were randomly divided into six groups and fed six separate diets with graded dietary levels of selenium (0.025, 0.216, 0.387, 0.579, 0.795 and 1.049 mg/kg diet) for 80 days. After the feeding period, an immunization trial was performed by infection with Aeromonas hydrophila for 14 days. The results showed that, compared with the optimal selenium level, (1) selenium deficiency impaired the production of antibacterial compounds and immunoglobulins and down-regulated the transcript abundances of antimicrobial peptides and selenoproteins; (2) selenium deficiency aggravated inflammatory responses in part by up-regulating pro-inflammatory cytokines and down-regulating anti-inflammatory cytokines mRNA levels, which were partially related to [IKKα, β, γ/IκBα/NF-κB] signalling and [TOR/(S6K1, 4E-BP1)] signalling, respectively. Interestingly, selenium deficiency had no effect on the expression of TGF-β2, IL-4/13B, IL-10, IL-12p35, IL-15 (skin only) or 4E-BP2 in the head kidney, spleen and skin of young grass carp. Finally, based on the percent weight gain (PWG), the morbidity of skin haemorrhages and lesions, the ACP activity in the head kidney and the lysozyme activity in spleen, the optimal dietary selenium requirements for young grass carp were estimated to be 0.546-0.604 mg/kg diet. In summary, selenium deficiency decreased the growth performance and impaired the immune function in the head kidney, spleen and skin of young grass carp.

Dietary grape seed proanthocyanidin extract regulates metabolic disturbance in rat liver exposed to lead associated with PPARα signaling pathway

Lead, a pervasive environmental hazard worldwide, causes a wide range of physiological and biochemical destruction, including metabolic dysfunction. Grape seed proanthocyanidin extract (GSPE) is a natural production with potential metabolic regulation in liver. This study was performed to investigate the protective role of GSPE against lead-induced metabolic dysfunction in liver and elucidate the potential molecular mechanism of this event. Wistar rats received GSPE (200 mg/kg) daily with or without lead acetate (PbA, 0.5 g/L) exposure for 56 d. According to biochemical and histopathologic analysis, GSPE attenuated lead-induced metabolic dysfunction, oxidative stress, and liver dysfunction. Liver gene expression profiling was assessed by RNA sequencing and validated by qRT-PCR. Expression of some genes in peroxisome proliferator-activated receptor alpha (PPARα) signaling pathway was significantly suppressed in PbA group and revived in PbA + GSPE group, which was manifested by Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis and validated by western blot analysis. This study supports that dietary GSPE ameliorates lead-induced fatty acids metabolic disturbance in rat liver associated with PPARα signaling pathway, and suggests that dietary GSPE may be a protector against lead-induced metabolic dysfunction and liver injury, providing a novel therapy to protect liver against lead exposure.

Protective effects of dietary luteolin against mercuric chloride-induced lung injury in mice: Involvement of AKT/Nrf2 and NF-κB pathways

Food-derived compound luteolin possesses multiple pharmacological activities. Accordingly, we focused on exploring the protective effects of luteolin (100 mg/kg) against mercuric chloride (HgCl₂) (5 mg/kg) stimulated lung injury and the molecular mechanisms of lung protection effects in mouse. The influence of luteolin on histologic changes, oxidative stress, proinflammatory cytokine production, neutrophil activation, and apoptosis were assayed in HgCl₂-induced lung injury. Luteolin administration attenuated pulmonary histologic conditions and apoptotic change. The protective effects of luteolin might be attributed to the reduction of myeloperoxidase, inflammatory cytokines, malondialdehyde, and the increase of superoxide dismutase and glutathione. Luteolin promoted protein kinase B (AKT) phosphorylation and translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) into nucleus, and inhibited activation of nuclear factor kappa B (NF-κB) in HgCl₂-induced lung injury. Taken together, dietary luteolin may be an effective candidate for treatment of HgCl₂-induced lung injury by preventing NF-κB activation and activating AKT/Nrf2 pathway.

Dietary luteolin protects against HgCl2-induced renal injury via activation of Nrf2-mediated signaling in rat

Luteolin (Lut) belongs to the flavonoid family with various beneficial bioactivities. Here, we investigated whether Lut attenuate mercuric chloride (HgCl₂)-induced renal injury in rat. We found that oral gavage administration of Lut (80mg/kg) alleviated anemia and renal histology upon HgCl₂ treatment (80mg/L). Lut also significantly reduced HgCl₂-induced oxidative stress and inflammatory, presenting as the reduced malondialdehyde (MDA) formation, increased glutathione (GSH) level, and inhibited activation of nuclear factor kappa B (NF-κB). Moreover, Lut protected renal cells from HgCl₂-induced apoptosis, as assessed by Terminal deoxynucleotidyl transferase dUNT nick end labeling (TUNEL) assay and the protein levels of B-cell lymphoma gene 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), Bcl-2-associated X protein (Bax), and p53. Interestingly, Lut reduced renal mercuric accumulation in rat. Furthermore, Lut increased nuclear translocation of the nuclear factor-erythroid-2-related factor 2 (Nrf2), and subsequent protein expression of the antioxidant enzymes, heme oxygenase-1 (HO-1) and nicotinamide adenine dinucleotide phosphatase: quinone-acceptor 1 (NQO1). Our results suggest that Lut suppress HgCl₂-induced renal injury via activation of Nrf2 signaling pathway.

Grape seed procyanidin extract ameliorates lead-induced liver injury via miRNA153 and AKT/GSK-3β/Fyn-mediated Nrf2 activation

Lead-induced hepatotoxicity is characterized by an extensive oxidative stress. Grape seed procyanidin extract (GSPE) possesses abundant biological activities. Herein, we investigated the protective role of GSPE against lead-induced liver injury and determined the potential molecular mechanisms. In vivo, rats were treated with/without lead acetate (PbAc) (0.05%, w/v) in the presence/absence of GSPE (200 mg/kg). In vitro, hepatocytes were pretreated with/without GSPE (100 μg/ml) in the presence/absence of PbAc (100 μM). PbAc administration to rats resulted in anemia, liver dysfunction, lead accumulation in the bone and liver, oxidative stress, DNA damage and apoptosis. GSPE significantly attenuated these adverse effects, except lead accumulation in liver. GSPE also decreased the expression of miRNA153 and increased the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and levels of its downstream protein, and protein kinase B (AKT) phosphorylation in PbAc-induced liver injury. In primary hepatocytes treated with PbAc, GSPE increased hepatocyte viability and decreased lactate dehydrogenase release and reactive oxygen species levels. Dietary GSPE attenuated PbAc-induced liver injury in rats via an integrated mechanism associated with the miRNA153 and AKT/glycogen synthase kinase 3 beta/Fyn-mediated Nrf2 activation.