Rat liver antioxidant response to iron and copper overloads

Biochemical regulatory processes in the control of oxidants and antioxidants production in the brain of rats with iron and copper chronic overloads

Iron [Fe(II)] and copper [Cu(II)] overloads in rat brain are associated with oxidative stress and damage. The purpose of this research is to study whether brain antioxidant enzymes are involved in the control of intracellular redox homeostasis in the brain of rats male Sprague-Dawley rats (80-90 g) that received drinking water supplemented with either 1.0 g/L of ferrous chloride (n = 24) or 0.5 g/L cupric sulfate (n = 24) for 42 days. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione transferase (GT) activities in brain were determined by spectrophotometric methods and NO production by the content of nitrite concentration in the organ. Chronic treatment with Fe(II) and Cu(II) led to a significant decrease of nitrite content and SOD activity in brain. Activity of NADPH oxidase increased with Cu(II) treatment. Concerning Fe(II), catalase and GT activities increased in brain after 28 and 4 days of treatment, respectively. In the case of Cu(II), catalase activity decreased whereas GT activity increased after 2 and 14 days, respectively. The regulation of redox homeostasis in brain involves changes of the activity of these enzymes to control the steady state of oxidant species related to redox signaling pathways upon Cu and Fe overload. NO may serve to detoxify cells from superoxide anion and hydrogen peroxide with the concomitant formation of peroxynitrite. However, the latest is a powerful oxidant which leads to oxidative modifications of biomolecules. These results suggest a common pathway to oxidative stress and damage in brain for Cu(II) and Fe(II).

Autonomous Bionanorobots via a Cage-Shaped Silsesquioxane Vehicle for In Vivo Heavy Metal Detoxification

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by in vivo experiments that the bionanorobot can inhibit persistent enlargement of the liver caused by zinc ion poisoning.

Protective Mechanism of Gandou Decoction in a Copper-Laden Hepatolenticular Degeneration Model: In Vitro Pharmacology and Cell Metabolomics

Gandou decoction (GDD) is a classic prescription for the treatment of hepatolenticular degeneration (HLD) in China; however, the liver-protecting mechanism of this prescription needs further evaluation. In the present study, we explored the protective mechanisms of GDD in a copper-laden HLD model using integrated pharmacology and cellular metabolomics in vitro. The results revealed that GDD could significantly promote copper excretion in copper-laden HLD model cells and improve the ultrastructural changes in hepatocytes. In addition, GDD could decrease the extent of lipid peroxidation, levels of reactive oxygen species, and the release rate of lactate dehydrogenase while increasing the activity of superoxide dismutase and the ratio of glutathione to oxidized glutathione in the copper-laden HLD model cells. On conducting statistical analysis of significant metabolic changes, 47 biomarkers and 30 related metabolic pathways were screened as pharmacological reactions induced by GDD in HLD model cells. d-glutamate and d-glutamine metabolic pathways showed the highest importance and significance among the 30 metabolic pathways, and the differential expression levels of the glutamine synthetase (GS) and the renal type and liver type GLS (GLS1 and GLS2) proteins were verified by Western blotting. Collectively, our data established the underlying mechanism of GDD therapy, such as the promotion of copper excretion and improvement in oxidative stress by regulating the expressions of GS, GLS1, and GLS2 protein to protect hepatocytes from injury.

Nitric oxide, chronic iron and copper overloads and regulation of redox homeostasis in rat liver

Iron [Fe(II)] and copper [Cu(II)] ions produced liver oxidative stress and damage, and as a consequence, changes in the antioxidant protection. The objective of this work is to evaluate whether control of redox homeostasis in chronic overload of Fe(II) and Cu(II) is associated with nitric oxide (NO) and antioxidant enzymes protection in liver. Male Sprague-Dawley rats of 80-90 g received the standard diet ad libitum and drinking water supplemented with either 1.0 g/L of ferrous chloride (0.1% w/v, n = 24) or 0.5 g/L cupric sulfate (0.05% w/v, n = 24) for 42 days. The activities of the enzymes involved in the control of cellular redox homeostasis, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), were determined by spectrophotometric methods, and NO production was determined by the determination of nitrite levels in liver. Chronic overload with Fe(II) and Cu(II) led to a significant increase of NO production while hampering the activity of NADPH oxidase. Meanwhile, the animals supplemented with Fe(II) showed a decrease in SOD and Gpx activities in liver homogenates with respect to baseline activity after 7 days of treatment, whereas the rats which received Cu(II) showed an increased SOD and catalase activity after 28 and 7 days of chronic overload. Further research is required to understand whether the modulation of the activity of these enzymes upon Cu and Fe overload is involved in a common toxic pathway or may serve to control the steady state of oxidant species related to redox signaling pathways.

Gandou Decoction Decreases Copper Levels and Alleviates Hepatic Injury in Copper-Laden Hepatolenticular Degeneration Model Rats

Objective: This study was designed to investigate the therapeutic efficacy and underlying mechanisms of Gandou Decoction (GDD) in copper-laden hepatolenticular degeneration (HLD) model rats. Methods: In this study, high-performance liquid chromatography (HPLC) fingerprint analysis and eight representative active components were simultaneously measured for quality control of GDD. The therapeutic effect of GDD in HLD was studied by constructing a rat model of copper-laden HLD. The copper levels in the liver, serum, urine, and feces were quantified by atomic absorption spectrophotometry (AAS). Subsequently, UV-Vis spectrophotometry was used to study the coordination ability of copper ion (Cu2+) with six representative active components in GDD to explore its potential copper expulsion mechanism. Serological indexes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (AKP) were evaluated. Hepatic indicators including superoxide dismutase (SOD), glutathione (GSH), and the total antioxidant capacity (T-AOC) were determined. Moreover, the liver tissue was stained with hematoxylin-eosin to observe the histological changes. Results: Thirty characteristic fingerprint peaks were used to assess the similarities among 10 samples and showed the similarity was >0.98, indicating a good correlation among the common peaks. Simultaneous quantification of eight markers in GDD was then performed to determine the consistency of quality. GDD could decrease the serum and hepatic copper levels by increasing the urinary and fecal copper content in copper-laden rats. Meanwhile, the results of UV-Vis absorption studies show that six representative active ingredients in GDD can coordinate with Cu2+, indicating that complexing copper removal may be a potential mechanism for GDD to play a role in copper removal. Serum hepatic enzyme markers AST, ALT, and AKP activities and antioxidant enzyme SOD, T-AOC activities, and GSH level in hepatic tissue showed the protection of GDD against liver injury induced by excessive copper. Additionally, the hepatoprotective effect of GDD was also evidenced by the results of the liver histological evaluation. Conclusions: This study suggested that GDD could reduce the serum and hepatic copper levels through promoting urinary and fecal copper excretion in copper-laden rats. At the same time, GDD could alleviate hepatic injury by inhibition of oxidative stress.

Copper-induced cell death and the protective role of glutathione: the implication of impaired protein folding rather than oxidative stress

Copper (Cu) is a bioelement essential for a myriad of enzymatic reactions, which when present in high concentration leads to cytotoxicity. Whereas Cu toxicity is usually assumed to originate from the metal's ability to enhance lipid peroxidation, the role of oxidative stress has remained uncertain since no antioxidant therapy has ever been effective. Here we show that Cu overload induces cell death independently of the metal's ability to oxidize the intracellular milieu. In fact, cells neither lose control of their thiol homeostasis until briefly before the onset of cell death, nor trigger a consistent antioxidant response. As expected, glutathione (GSH) protects the cell from Cu-mediated cytotoxicity but, surprisingly, fully independent of its reactive thiol. Moreover, the oxidation state of extracellular Cu is irrelevant as cells accumulate the metal as cuprous ions. We provide evidence that cell death is driven by the interaction of cuprous ions with proteins which impairs protein folding and promotes aggregation. Consequently, cells mostly react to Cu by mounting a heat shock response and trying to restore protein homeostasis. The protective role of GSH is based on the binding of cuprous ions, thus preventing the metal interaction with proteins. Due to the high intracellular content of GSH, it is depleted near the Cu entry site, and hence Cu can interact with proteins and cause aggregation and cytotoxicity immediately below the plasma membrane.

The Resveratrol Alleviates the Hepatic Toxicity of CuSO4 in the Rat

Cu is toxic to humans and other animals. Oxidative stress is an important mechanism involved in Cu toxicity. Resveratrol (RSV) is an antioxidative compound, so could counteract Cu toxicity. The aim of this study was to determine whether RSV protects the liver from the effects of CuSO₄. Forty male Sprague-Dawley rats (5 weeks old, 110-120 g) were divided into four groups (n = 10 per group), a control group and groups treated with CuSO₄ at a dose of 200 mg/kg body weight (BW), RSV at a dose of 15 mg/kg BW, and CuSO₄ at a dose of 200 mg/kg BW and RSV at a dose of 15 mg/kg BW. The treatments were orally administered for 30 days. The livers were removed from the rats at the end of the study, and the cytochrome P450, cytochrome b5, Cu, Fe, Zn, glutathione peroxidase, superoxide dismutase, reactive oxygen species, aspartate aminotransferase, and alanine aminotransferase concentrations in the livers were determined. CuSO₄ decreased the BW, liver weight, and cytochrome P450, cytochrome b5, Fe, Zn, glutathione peroxidase, and superoxide dismutase concentrations but increased the Cu, aspartate aminotransferase, alanine aminotransferase, and reactive oxygen species concentrations relative to the control group. RSV alleviated the toxic effects of CuSO₄ on the liver, indicating that RSV attenuates CuSO₄-induced liver injury by decreasing the liver transaminase concentration and oxidative stress, promoting antioxidative activity and cytochrome P450 enzymes, and maintaining balance in the trace element concentrations. The results indicate that RSV could be used to treat CuSO₄ toxicity.

Redox dyshomeostasis in the experimental chronic hepatic overloads with iron or copper

Male rats of 80-90 g were overloaded with either Fe(II) or Cu(II) for 42 days by high concentrations of FeCl₂ or CuSO₄ in the drinking water. The animals were fed with a commercial rodent diet of 2780 kcal/100 g. Both metal treatments led to a liver redox imbalance and dyshomeostasis with oxidative stress and damage and the concomitant enhancement of oxidative processes as indicated by in vivo surface liver chemiluminescence, the sensitive and organ non-invasive assay for oxidative free radical reactions, and by ex vivo determined processes of phospholipid peroxidation and protein oxidation. In parallel, marked decreases in the antioxidant defense were observed. Liver reduced glutathione (GSH) content and the reduced/oxidized glutathione ratio (GSH/GSSG) were early indicators of oxidative metabolic disturbance upon the metal overloads. Thus, GSH plays a central role in the defense reactions involved in the chronic toxicity of Fe and Cu. Chronic overloads of Fe or Cu in rats afford an experimental animal model of hemochromatosis and of Wilson's disease, respectively. These two animal models could be useful in the study and development of the beneficial effects of pharmacological interventions in the two human diseases.

Oxidative damage induced by copper in mouse primary hepatocytes by single-cell analysis

Copper can disturb the intracellular redox balance, induce oxidative stress, and subsequently cause irreversible damage, leading to a variety of diseases. In the present study, mouse primary hepatocytes were chosen to elucidate the in vitro oxidative damage of short-term copper exposure (10-200 μM) by single-cell analysis. We evaluated the toxicity of copper by reactive oxygen species (ROS), glutathione (GSH), and oxidative DNA damage at the single-cell level. Oxidative damage induced by copper was verified by the morphological changes, persistent elevations of excessive ROS and malondialdehyde (MDA), a decrease in GSH level, and the oxidative DNA damage. Furthermore, the average ROS generation, GSH consumption, and the indicators in DNA damage did not significantly change at relatively low concentrations (10 or 50 μM), but we can find the alterations of parameters in some single cells clearly. Emphasis on the analysis of single cells is conducive to gain a better understanding on the toxicity of copper. This study will also complement studies on the environmental risk assessment of copper pollution.

Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine

Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.

Effects of gluten-free breads, with varying functional supplements, on the biochemical parameters and antioxidant status of rat serum

This paper examines the effects of gluten-free bread enriched with functional ingredients (milk powder, poppy, sunflower and pumpkin seeds, egg yolk, carum, hazel nuts and amaranth) on the morphological and biochemical parameters and antioxidant status of rats serum. Rats were provided test diets--gluten-free breads and water ad libitum. After 14 days, the animals were weighed and killed. A hazel nut-amaranth bread diet significantly increased the level of thrombocytes when compared to control bread. A mixed bread diet significantly decreased cholesterol levels in rats. All fortified breads decreased triglyceride levels and alanine transaminase activity and caused an increase in antiradical activity of the serum. In rats fed with poppy-milk bread, milk-seed bread and mixed bread, a marked decrease in superoxide dismutase activity was found. Enriched breads reduced the levels of triglyceride and improved the antiradical properties of serum, although the physiological relevance of this needs to be confirmed by human studies.

Sulforaphane alleviates muscular dystrophy in mdx mice by activation of Nrf2

Sulforaphane (SFN), one of the most important isothiocyanates in the human diet, is known to have chemo-preventive and antioxidant activities in different tissues via activation of nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated induction of antioxidant/phase II enzymes, such as heme oxygenase-1 and NAD(P)H quinone oxidoreductase 1. However, its effects on muscular dystrophy remain unknown. This work was undertaken to evaluate the effects of SFN on Duchenne muscular dystrophy. Four-week-old mdx mice were treated with SFN by gavage (2 mg·kg body wt(-1)·day(-1) for 8 wk), and our results demonstrated that SFN treatment increased the expression and activity of muscle phase II enzymes NAD(P)H quinone oxidoreductase 1 and heme oxygenase-1 with a Nrf2-dependent manner. SFN significantly increased skeletal muscle mass, muscle force (∼30%), running distance (∼20%), and GSH-to-GSSG ratio (∼3.2-fold) of mdx mice and decreased the activities of plasma creatine phosphokinase (∼45%) and lactate dehydrogenase (∼40%), gastrocnemius hypertrophy (∼25%), myocardial hypertrophy (∼20%), and malondialdehyde levels (∼60%). Furthermore, SFN treatment also reduced the central nucleation (∼40%), fiber size variability, and inflammation and improved the sarcolemmal integrity of mdx mice. Collectively, these results show that SFN can improve muscle function and pathology and protect dystrophic muscle from oxidative damage in mdx mice associated with Nrf2 signaling pathway, which indicate Nrf2 may have clinical implications for the treatment of patients with muscular dystrophy.

Brain antioxidant responses to acute iron and copper intoxications in rats

The response of brain antioxidant system to the oxidative stress following Fe and Cu overloads involves: antioxidant consumption and an adaptive increase in antioxidant enzyme activities and protein expression.