metallothionein and cobaltous-chloride

Training under hypoxia has several advantages over normoxic training in terms of enhancing the physical performance. Therefore, we tested the protective effect of hypoxia preconditioning by hypoxia mimetic cobalt chloride against exercise-induced oxidative damage in the skeletal muscles and improvement of physical performance.. Male Sprague-Dawley rats were randomly divided into four groups (n=8), namely control, cobalt-supplemented, training and cobalt with training. The red gastrocnemius muscle was examined for all measurements, viz. free radical generation, lipid peroxidation, muscle damage and antioxidative capacity.. Hypoxic preconditioning with cobalt along with training significantly increased physical performance (33%, P<0.01) in rats compared with training-only rats. Cobalt supplementation activated cellular oxygen sensing system in rat skeletal muscle. It also protected against training-induced oxidative damage as observed by an increase in the GSH/GSSG ratio (36%, P<0.001; 28%, P<0.01 respectively) and reduced lipid peroxidation (15%, P<0.01; 31%, P<0.01 respectively) in both trained and untrained rats compared with their respective controls. Cobalt supplementation along with training enhanced the expression of antioxidant proteins haem oxygenase-1 (HO-1; 1.2-fold, P<0.05) and metallothionein (MT; 4.8-fold, P<0.001) compared with training only. A marked reduction was observed in exercise-induced muscle fibre damage as indicated by decreased necrotic muscle fibre, decreased lipofuscin content of muscle and plasma creatine kinase level (16%, P<0.01) in rats preconditioned with cobalt.. Our study provides strong evidence that hypoxic preconditioning with cobalt chloride enhances physical performance and protects muscle from exercise-induced oxidative damage via GSH, HO-1 and MT-mediated antioxidative capacity.

Topics: Animals; Antioxidants; Cell Hypoxia; Cobalt; Creatine Kinase, MM Form; Cytoprotection; Disease Models, Animal; Dose-Response Relationship, Drug; Glutathione; Heme Oxygenase (Decyclizing); Lactic Acid; Lipid Peroxidation; Lipofuscin; Male; Metallothionein; Mitochondria, Muscle; Mitochondrial Proteins; Muscle, Skeletal; Muscular Diseases; Necrosis; Oxidative Stress; Physical Endurance; Physical Exertion; Rats; Rats, Wistar; Reactive Oxygen Species

Acute systemic hypoxia induces delayed cardioprotection against ischaemia-reperfusion injury in the heart. As cobalt chloride (CoCl₂) is known to elicit hypoxia-like responses, it was hypothesized that this chemical would mimic the preconditioning effect and facilitate acclimatization to hypobaric hypoxia in rat heart.. Male Sprague-Dawley rats treated with distilled water or cobalt chloride (12.5 mg Co/kg for 7 days) were exposed to simulated altitude at 7622 m for different time periods (1, 2, 3 and 5 days).. Hypoxic preconditioning with cobalt appreciably attenuated hypobaric hypoxia-induced oxidative damage as observed by a decrease in free radical (reactive oxygen species) generation, oxidation of lipids and proteins. Interestingly, the observed effect was due to increased expression of the antioxidant proteins hemeoxygenase and metallothionein, as no significant change was observed in antioxidant enzyme activity. Hypoxic preconditioning with cobalt increased hypoxia-inducible factor 1α (HIF-1α) expression as well as HIF-1 DNA binding activity, which further resulted in increased expression of HIF-1 regulated genes such as erythropoietin, vascular endothelial growth factor and glucose transporter. A significant decrease was observed in lactate dehydrogenase activity and lactate levels in the heart of preconditioned animals compared with non-preconditioned animals exposed to hypoxia.. The results showed that hypoxic preconditioning with cobalt induces acclimatization by up-regulation of hemeoxygenase 1 and metallothionein 1 via HIF-1 stabilization.

Topics: Acclimatization; Animals; Cardiotonic Agents; Cobalt; DNA-Binding Proteins; Erythropoietin; Heart; Heme Oxygenase-1; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Metallothionein; Myocardium; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Up-Regulation; Vascular Endothelial Growth Factor A

Shukla, Dhananjay, Saurabh Saxena, Purushotman Jayamurthy, Mustoori Sairam, Mrinalini, Singh, Swatantra Kumar Jain, Anju Bansal, and Govindaswamy Ilavazaghan. High Alt. Med. Biol. 10:57-69, 2009.-Hypoxic preco759nditioning (HPC) provides robust protection against injury from subsequent prolonged hypobaric hypoxia, which is a characteristic of high altitude and is known to induce oxidative injury in lung by increasing the generation of reactive oxygen species (ROS) and decreasing the effectiveness of the antioxidant defense system. We hypothesize that HPC with cobalt might protect the lung from subsequent hypobaric hypoxia-induced lung injury. HPC with cobalt can be achieved by oral feeding of CoCl(2) (12.5 mg kg(-1)) in rats for 7 days. Nonpreconditioned rats responded to hypobaric hypoxia (7619 m) by increased reactive oxygen species (ROS) generation and a decreased GSH/GSSG ratio. They also showed a marked increase in lipid peroxidation, heat-shock proteins (HSP32, HSP70), metallothionins (MT), levels of inflammatory cytokines (TNF-alpha, IFN-gamma, MCP-1), and SOD, GPx, and GST enzyme activity. In contrast, rats preconditioned with cobalt were far less impaired by severe hypobaric hypoxia, as observed by decreased ROS generation, lipid peroxidation, and inflammatory cytokine release and an inceased GSH/GSSG ratio. Increased expression of antioxidative proeins Nrf-1, HSP-32, and MT was also observed in cobalt- preconditioned animals. A marked increase in the protein expression and DNA binding activity of hypoxia-inducible transcriptional factor (HIF-1alpha) and its regulated genes, such as erythropoietin (EPO) and glucose transporter-1 (glut-1), was observed after HPC with cobalt. We conclude that HPC with cobalt enhances antioxidant status in the lung and protects from subsequent hypobaric hypoxia-induced oxidative stress.

Topics: Animals; Antimutagenic Agents; Cobalt; Cytokines; Glutathione; Glutathione Disulfide; Heme Oxygenase-1; HSP70 Heat-Shock Proteins; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Ischemic Preconditioning; Lipid Peroxidation; Lung; Lung Injury; Male; Metallothionein; NF-E2-Related Factor 1; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; RNA, Messenger; Superoxide Dismutase; Vascular Endothelial Growth Factor A

Hypobaric hypoxia, characteristic of high altitude is known to increase the formation of reactive oxygen and nitrogen species (RONS), and decrease effectiveness of antioxidant enzymes. RONS are involved and may even play a causative role in high altitude related ailments. Brain is highly susceptible to hypoxic stress and is involved in physiological responses that follow. Exposure of rats to hypobaric hypoxia (7619 m) resulted in increased oxidation of lipids and proteins due to increased RONS and decreased reduced to oxidized glutathione (GSH/GSSG) ratio. Further, there was a significant increase in superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) levels. Increase in heme oxygenase 1 (HO-1) and heat shock protein 70 (HSP70) was also noticed along with metallothionein (MT) II and III. Administration of cobalt appreciably attenuated the RONS generation, oxidation of lipids and proteins and maintained GSH/GSSH ratio similar to that of control cells via induction of HO-1 and MT offering efficient neuroprotection. It can be concluded that cobalt reduces hypoxia oxidative stress by maintaining higher cellular HO-1 and MT levels via hypoxia inducible factor 1alpha (HIF-1alpha) signaling mechanisms. These findings provide a basis for possible use of cobalt for prevention of hypoxia-induced oxidative stress.

Topics: Altitude Sickness; Animals; Antimutagenic Agents; Antioxidants; Atmospheric Pressure; Brain; Cobalt; Enzymes; Glutathione; Heme Oxygenase (Decyclizing); Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia, Brain; Lipid Peroxidation; Male; Metallothionein; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Nitrogen Species; Reactive Oxygen Species

The nature of hepatic metallothionein (MT) induction by several metals and its relationship to an inflammatory response was studied in chicks. Intraperitoneal (ip) injection of chromium (Cr), managanese, and iron (Fe) caused a much greater increase in hepatic MT (10.2-, 9.0-, and 6.8-fold) compared with cobalt and nickel (2.5- and 2.9-fold); thus not all transition metals are effective. Cr3+ caused markedly greater hepatic MT accumulation than Cr6+, suggesting that the ionic nature of the metal is an important factor. Small organic complexes of Fe (ferrous gluconate or lactate, 6.2-fold) caused significantly greater accumulation of hepatic MT than ferric dextran (1.4-fold), a large organic aggregate. In vitro data from chick hepatocytes and/or fibroblasts clearly indicated that Fe does not effect the induction of MT directly. The role of inflammation, as measured by recruitment of peritoneal exudate cells (PEC), was examined. Endotoxin (LPS), Sephadex (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S = Fe greater than LPS much greater than control). The percentage of heterophils but not macrophages was significantly correlated with the accumulation and induction of hepatic MT. In a similar experiment with Cr, we demonstrated that Cr3+ but not Cr6+ stimulated MT messenger RNA accumulation and concomitant hetereophil infiltration at 3 h after injection. Our results indicate that the induction of hepatic MT by the parenteral administration of a number of metals is dependent on the chemical nature of the metal and is associated with an inflammatory response.

Topics: Animals; Cells, Cultured; Chick Embryo; Chickens; Chlorides; Chromium; Chromium Compounds; Cobalt; Ferric Compounds; Fibroblasts; Inflammation; Injections, Intraperitoneal; Kinetics; Liver; Male; Manganese Compounds; Manganese Poisoning; Metallothionein; Metals; Nickel