Alterations In Superoxide Dismutase Activities Research Articles

Neurotoxic effects of low dose ranges of environmental metal mixture in a rat model: The benchmark approach

Metals exert detrimental effects on various systems within the body, including the nervous system. Nevertheless, the dose-response relationship concerning the administration of low doses of metal mixtures remains inadequately explored. The assessment of neurotoxic effects of lead, cadmium, mercury, and arsenic mixture (MIX) administered at low dose ranges, was conducted using an in vivo approach. A subacute study was conducted on a rat model consisting of a control and five treatment groups subjected to oral exposure with gradually increasing doses (from MIX 1 to MIX 5). The results indicated that behavioural patterns in an already developed nervous system displayed a reduced susceptibility to the metal mixture exposure with tendency of higher doses to alter short term memory. However, the vulnerability of the mature brain to even minimal amounts of the investigated metal mixture was evident, particularly in the context of oxidative stress. Moreover, the study highlights superoxide dismutase's sensitivity as an early-stage neurotoxicity marker, as indicated by dose-dependent induction of oxidative stress in the brain revealed through Benchmark analysis. The narrowest Benchmark Dose Interval (BMDI) for superoxide dismutase (SOD) activity (1e-06 - 3.18e-05 mg As/kg b.w./day) indicates that arsenic may dictate the alterations in SOD activity when co-exposed with the other examined metals. The predicted Benchmark doses for oxidative stress parameters were very low, supporting “no-threshold” concept. Histopathological alterations were most severe in the groups treated with higher doses of metal mixture. Similarly, the brain acetylcholinesterase (AChE) activity demonstrated a dose-dependent decrease significant in higher doses, while BMDI suggested Cd as the main contributor in the examined metal mixture. These findings imply varying susceptibility of neurotoxic endpoints to different doses of environmentally relevant metal mixtures, advocating for risk assessment and regulatory measures to address metal pollution and enhance remediation strategies.

Mandibular lateral deviation induces alteration in vascular endothelial growth factor expression and oxidative stress/nitric oxide generation in rat condyle, synovial membrane and masseter muscle

ObjectiveWe aimed to investigate alteration in cellular signaling mediated by vascular endothelial growth factor (VEGF) and parameters of oxidative stress/nitric oxide generation, superoxide dismutase (SOD) and neuronal nitric oxide synthase (nNOS), underlying altered functional mechanical loading of TMJ (temporomandibular joint) during lateral mandibular deviation. DesignThirty-eight 5-week-old male Wistar rats were divided into experimental group, which received acrylic resin appliance that shifted mandible to the left during closure, and control group. Computed tomography and histomorphometry were used for condyle analyses, while samples of condyle, synovial membrane and m. masseter were analyzed with enzyme–linked immunosorbent assay and spectrophotometry to determine VEGF and nNOS protein concentrations, and SOD activity. ResultsExperimental group of rats developed smaller and asymmetrical mandibles. Less of new bone and cartilage formation and larger bone marrow cavities area were found in the experimental group. Higher VEGF expression in condyle and m. masseter as well as higher nNOS expression in m. masseter and synovial membrane were found in the experimental compared to the control group. Alteration of SOD activity was found in m. masseter and synovial membrane in the experimental group. ConclusionsLateral mandibular deviation induces mandibular and condylar morphological changes as well as significant cellular signaling alterations in condyle, synovial membrane and masticatory muscle. Cellular VEGF protein overexpression and oxidative stress/nitric oxide disbalance could be the mechanisms underlying unbalanced functional TMJ loading due to mandibular deviation.

Effects of alpha lipoic acid on acrylamide-induced hepatotoxicity in rats.

Acrylamide (ACR) is a neurotoxicant, reproductive toxicant, and carcinogen in animal species. It is used in many industries and has been found to form naturally in foods cooked at high temperatures. Alpha-lipoic acid (ALA) is a naturally occurring antioxidant whose therapeutic effect has been related to its antioxidant activity. This study was carried out to study the protective effect of alpha lipoic acid on acrylamide induced perturbations in rat liver. Four groups of rats were studied viz., control rats, acrylamide treated rats, alpha lipoic acid treated rats, and alpha lipoic acid plus acrylamide treated rats. ACR and ALA treatment alone and together caused a signifi-cant increase in hepatic reduced glutathione content while a decrease in hepatic ascorbic content was observed when compared to control group. ALA pretreatment of acrylamide exposed rats caused no a signifi-cant alteration in superoxide dismutase activity but resulted in a tendency towards restoration of glutathione peroxidase and catalase activity to near normal levels. Gel electrophoresis showed fragmentation of DNA in the treated groups. The dose of ALA used in the present study afforded partial restoration of oxidative indices altered by ACR in rat liver.

Tissue-specific response of metallothionein and superoxide dismutase in the clam Mactra veneriformis under sublethal mercury exposure

To identify the relationship between mercury (Hg) and stress responses in the clam Mactra veneriformis, metallothionein (MT) and superoxide dismutase (SOD) mRNA expression in the digestive gland, gill, and mantle as well as MT protein content and SOD activity in the digestive gland were examined under sublethal Hg exposure at doses of 10, 20, and 40 μg/L for 21 days. The ranking of the tissues in decreasing order of their basal MvMT and MvSOD mRNA expression is as follows: digestive gland > mantle > gill > adductor muscle > foot and digestive gland > mantle > gill > foot > adductor muscle, respectively. Hg exposure significantly elevated MvMT and MvSOD mRNA transcripts in the digestive gland, gill, and mantle in a tissue-specific way. In the digestive gland, a dose-dependent increase of MvMT and MvSOD mRNA expression, stimulation of MT protein, and alteration of SOD activity were observed under Hg stress. MT protein responded later than MT mRNA to Hg exposure and no clear relationship was found between them, indicating the occurrence of posttranscriptional events. All of the results suggest that MT and SOD cooperate in resisting Hg toxicity and maintaining cellular metabolic homeostasis in M. veneriformis. MT and SOD mRNA expressions have great potential as biomarkers of Hg pollution in the aquatic environment for the studied species.

Effect of age‐dependent exposure to lead on hepatotoxicity and nephrotoxicity in male rats

Lead is known to induce a broad range of physiological, biochemical, and behavioral dysfunctions in laboratory animals and humans. This includes age-specific variations in absorption, retention, and tissue distribution of lead. This study was carried out to investigate the effects of chronic exposure to lead (50 mg/L) on liver and kidneys of two different age groups of male rats treated with lead from delivery until puberty period (40 days) and postpuberty period (65 days). For this purpose, the concentrations of thiobarbituric acid reactive substance (TBARS), total thiol groups (SH), and superoxide dismutase (SOD) activity were measured in the liver and kidney of rats. Renal function was analyzed by determining creatinine, acid uric, and urea. Plasma activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and albumin were determined spectrophotometrically to evaluate hepatic function. These markers of damage were determined to assess the level of toxicity in these animals. Our results clearly show that the administration of lead produces oxidative damage in liver and kidney, as strongly suggested by the significant increase in TBARS, decrease in total SH, and the alteration of SOD activity. In young lead-exposed animals, lead-induced perturbations on the synthetic function of the liver and the kidney were more pronounced. However, nephropathy is evident for adult lead-exposed animals. It is concluded that lead induces severe hepatic and renal toxicity, which depends on the age of the animals and the target organ.

Acute exposure to diphenyl ditelluride causes oxidative damage in rat lungs

The present study evaluated the effect of acute exposure to diphenyl ditelluride [(PhTe)2] on oxidative status in lungs of rats. Rats were exposed to a single subcutaneous application of (PhTe)2 at the doses of 0.3, 0.6, 0.9μmol/kg or vehicle. After 72h of exposure to (PhTe)2, biochemical parameters of oxidative stress were carried out in lungs of rats. The lungs of rats exposed to (PhTe)2 showed an increase in the levels of lipid peroxidation, reactive species and non-protein thiol. Alterations in superoxide dismutase activity were observed at all tested doses. (PhTe)2 caused an increase in catalase activity and a reduction in ascorbic acid levels at the dose of 0.9μmol/kg. The oxidative damage was more pronounced in animals treated with the highest dose of (PhTe)2. Thus, this study demonstrated that acute exposure to (PhTe)2 induced oxidative damage and an adaptive response of antioxidants in pulmonary tissue of rats.

Oxidative damage induced in A549 cells by physically and chemically characterized air particulate matter (PM2.5) collected in Abidjan, Côte d'Ivoire

Exposure to high levels of air pollution particulate matter (PM) is strongly associated with increased pulmonary morbidity and mortality. However, the underlying mechanisms of action whereby PM cause adverse health effects are still unclear. In developing countries, like in the sub-Saharian region of Africa, people are often exposed to high PM levels. Hence, three PM(2.5) samples were collected in the District of Abidjan (Côte d'Ivoire), under rural, urban or industrial influences. Their most toxicologically relevant physical and chemical characteristics were determined--thereby showing that most of them were equal or smaller than 2.5 microm--and the influence of both natural (Ca, Na, Mg, Ti, etc.) and anthropic (Al, Fe, Mn, Cr, Pb, Zn, Cu, Ni, benzene and its derivatives, paraffins, etc.) emission sources. The toxicity induced by the three PM samples was studied through 5-bromodeoxyuridine incorporation to DNA, mitochondrial dehydrogenase activity and extracellular lactate dehydrogenase activity. Hence, effect concentrations at 10 and 50% (EC(10) and EC(50), respectively) were as follows: (i) rural PM--EC(10) = 5.91 microg cm(-2) and EC(50) = 29.55 microg cm(-2); (ii) urban PM--EC(10) = 5.45 microg cm(-2) and EC(50) = 27.23 microg cm(-2); and (iii) industrial PM--EC(10) = 6.86 microg cm(-2) and EC(50) = 34.29 microg cm(-2). Moreover, PM-induced oxidative damage in A549 cells was observed through the induction of lipid peroxidation, the alteration of superoxide dismutase activity, and the disruption of glutathione status. Both the transition metals and the organic chemicals within the three collected PM samples under study might be involved in the oxidative damage and, therefore, the toxicity they induced in A549 cells.

Deficiency in frataxin homologue YFH1 in the yeast Pichia guilliermondii leads to missregulation of iron acquisition and riboflavin biosynthesis and affects sulfate assimilation

Pichia guilliermondii is a representative of yeast species that overproduce riboflavin (vitamin B2) in response to iron deprivation. P. guilliermondii YFH1 gene coding for frataxin homologue, eukaryotic mitochondrial protein involved in iron trafficking and storage, was identified and deleted. Constructed P. guilliermondii Δyfh1 mutant grew very poorly in a sucrose-containing synthetic medium supplemented with sulfate or sulfite as a sole sulfur source. Addition of sodium sulfide, glutathione, cysteine, methionine, N-acetyl-L-cysteine partially restored growth rate of the mutant suggesting that it is impaired in sulfate assimilation. Cellular iron content in Δyfh1 mutant was ~3-3.5 times higher as compared to the parental strain. It produced 50-70 times more riboflavin in iron sufficient synthetic media relative to the parental wildtype strain. Biomass yield of the mutant in the synthetic glutathione containing medium supplemented with glycerol as a sole carbon source was 1.4- and 2.6-fold increased as compared to sucrose and succinate containing media, respectively. Oxygen uptake of the Δyfh1 mutant on sucrose, glycerol or succinate, when compared to the parental strain, was decreased 5.5-, 1.7- and 1.5-fold, respectively. Substitution of sucrose or glycerol in the synthetic iron sufficient medium with succinate completely abolished riboflavin overproduction by the mutants. Deletion of the YFH1 gene caused hypersensitivity to hydrogen peroxide and exogenously added riboflavin and led to alterations in superoxide dismutase activities. Thus, deletion of the gene coding for yeast frataxin homologue has pleiotropic effect on metabolism in P. guilliermondii.

Antioxidant Activity of Indigo and its Preventive Effect against Ethanol-Induced DNA Damage in Rat Gastric Mucosa

Ethanol-induced oxidative damage is commonly associated with the generation of reactive oxygen molecules, leading to oxidative stress. Considering that antioxidant activity is an important mechanism of action involved in cytoprotection, the aim of this work was to evaluate the antioxidant properties of the alkaloid indigo (1) (2 mg/kg, P. O.), obtained from the leaves of Indigofera truxillensis Kunth (Fabaceae), on rat gastric mucosa submitted to ethanol-induced (100%, 1 mL, P. O.) gastric ulcer. Enzymatic assays and DNA fragmentation analysis were performed. When ethanol was administered to the control group, the sulfhydryl content (SH) and the glutathione peroxidase (GPx) activity decreased by 41% and 50%, respectively; in contrast, superoxide dismutase (SOD) and glutathione reductase (GR) activities increased by 56% and 67%, respectively. Additionally, myeloperoxidase (MPO) activity, a marker for free radical generation caused by polymorphonuclear neutrophil (PMN) tissue infiltration, also increased 4.5-fold after ethanol treatment. Rat gastric mucosa exposed to ethanol showed DNA fragmentation. Indigo alkaloid pretreatment protected rats from ethanol-induced gastric lesions. This effect was determined by the ulcerative lesion area (ULA), indicating an inhibition of around 80% at 2 mg/kg. This alkaloid also diminished GPx activity, which was higher than that observed with ethanol alone. However, this effect was counterbalanced by increased GR activity. Indigo was unable to restore alterations in SOD activity promoted by ethanol. After indigo pretreatment, SH levels and MPO activity remained normal and gastric mucosa DNA damage caused by ethanol was also partially prevented by indigo. These results suggest that the gastroprotective mechanisms of indigo include non-enzymatic antioxidant effects and the inhibition of PMN infiltration which, in combination, partially protect the gastric mucosa against ethanol-induced DNA damage.

Modulatory effects of an algal extract containing astaxanthin on UVA-irradiated cells in culture

UV radiation from sunlight is the most potent environmental risk factor in skin cancer pathogenesis. In the present study the ability of an algal extract to protect against UVA-induced DNA alterations was examined in human skin fibroblasts (1BR-3), human melanocytes (HEMAc) and human intestinal CaCo-2 cells. The protective effects of the proprietary algal extract, which contained a high level of the carotenoid astaxanthin, were compared with synthetic astaxanthin. DNA damage was assessed using the single cell gel electrophoresis or comet assay. In 1BR-3 cells, synthetic astaxanthin prevented UVA-induced DNA damage at all concentrations (10 nM, 100 nM, 10 μM) tested. In addition, the synthetic carotenoid also prevented DNA damage in both the HEMAc and CaCo-2 cells. The algal extract displayed protection against UVA-induced DNA damage when the equivalent of 10 μM astaxanthin was added to all three-cell types, however, at the lower concentrations (10 and 100 nM) no significant protection was evident. There was a 4.6-fold increase in astaxanthin content of CaCo-2 cells exposed to the synthetic compound and a 2.5-fold increase in cells exposed to algal extract. In 1BR-3 cells, exposure to UVA for 2 h resulted in a significant induction of cellular superoxide dismutase (SOD) activity, coupled with a marked decrease in cellular glutathione (GSH) content. However pre-incubation (18 h) with 10 μM of the either the synthetic astaxanthin or the algal extract prevented UVA-induced alterations in SOD activity and GSH content. Similarly, in CaCo-2 cells a significant depletion of GSH was observed following UVA-irradiation which was prevented by simultaneously incubating with 10 μM of either synthetic astaxanthin or the algal extract. SOD activity was unchanged following UVA exposure in the intestinal cell line. This work suggests a role for the algal extract as a potentially beneficial antioxidant.

Interleukin-6–Induced Protection in Hyperoxic Acute Lung Injury

Hyperoxic lung injury is commonly encountered in patients who require treatment with high concentrations of inspired oxygen. To determine whether interleukin (IL)-6 is protective in oxygen toxicity, we compared the effects of 100% O(2) in transgenic mice that overexpress IL-6 in the lung and transgene (-) controls. IL-6 markedly enhanced survival, with 100% of transgene (-) animals dying within 72 to 96 h, 100% of transgene (+) animals living for more than 8 d and more than 90% of transgene (+) animals living longer than 12 d. This protection was associated with markedly diminished alveolar-capillary protein leak, endothelial and epithelial membrane injury, and lung lipid peroxidation. Hyperoxia also caused cell death with DNA fragmentation in the lungs of transgene (-) animals and IL-6 markedly diminished this cytopathic response. The protective effects of IL-6 were not associated with significant alterations in the activities of copper/ zinc superoxide dismutase (SOD) or manganese SOD. They were, however, associated with the enhanced accumulation of the cell-death inhibitor Bcl-2, but not the cell-death stimulator BAX, and with the heightened accumulation of the cell-death regulator tissue inhibitor of metalloproteinase-1 (TIMP-1). These studies demonstrate that IL-6 markedly diminishes hyperoxic lung injury and that this protection is associated with a marked diminution in hyperoxia-induced cell death and DNA fragmentation. They also demonstrate that this protection is not associated with significant alterations in SOD activity, but is associated with the induction of Bcl-2 and TIMP-1.

Limitation of Dietary Copper and Zinc Decreases Superoxide Dismutase Activity in the Onion Fly, Delia antiqua

Larvae of the onion fly, Delia antiqua, have lower superoxide dismutase (SOD) activity when they are fed a defined synthetic diet that contains no copper or zinc. SOD activity was rapidly recovered when these larvae were fed onion bulbs. Addition of copper and zinc to the synthetic diet also led to the recovery of SOD activity. Results of an immunoblotting analysis using anti-D. antiqua CuZnSOD mouse monoclonal antibody suggest that this alteration of SOD activity is dependent on the amount of CuZnSOD.

Mitochondrial respiratory enzyme function and superoxide dismutase activity following brain glutathione depletion in the rat

In substantia nigra from patients with Parkinson's disease, there are decreased levels of reduced glutathione (GSH) and diminished activities of mitochondrial complex I and α-ketoglutarate dehydrogenase (α-KGDH), along with increased activity of superoxide dismutase (SOD). However, the interrelationship among these events is uncertain. We now report the effect of decreased brain GSH levels on SOD and mitochondrial respiratory enzyme activity in rat brain. In addition, we have investigated the ability of thioctic acid, an endogenous antioxidant, to alter these parameters. Unilateral or bilateral intracerebroventricular (ICV) administration of buthionine sulphoximine (BSO; 1 × 3.2 mg or 2 × 1.6 mg) over a 48-hr period reduced cortical GSH by 55–70%. There was no change in the activity of complex I, II/III, or IV or of citrate synthase in cortex. Similarly, there was no alteration of mitochondrial or cytosolic SOD activity. Thioctic acid (50 or 100 mg/kg IP) alone had no effect on cortical GSH levels in control animals and did not reverse the decrease in GSH levels produced by unilateral or bilateral ICV BSO administration. Thioctic acid (50 or 100 mg/kg IP) had no overall effect on complex I, II/III, or IV or on citrate synthase activity in control animals. Thioctic acid also did not alter cortical mitochondrial respiratory enzyme activity in BSO-treated rats. At the lower dose, thioctic acid tended to increase mitochondrial and cytosolic SOD activity in control animals and in BSO-treated rats. However, at the higher dose, thioctic acid tended to decrease mitochondrial SOD activity. Overall, there was no consistent effect of thioctic acid (50 or 100 mg/kg IP) on SOD activity in control or BSO-treated animals. This study shows that BSO-induced glutathione deficiency does not lead to alterations in mitochondrial respiratory enzyme activity or to changes in SOD activity. GSH depletion in Parkinson's disease therefore may not account for the alterations occurring in complex I and mitochondrial SOD in substantia nigra. Thioctic acid did not alter brain GSH levels or mitochondrial function. Interestingly, however, it did produce some alterations in SOD activity, which may reflect either its antioxidant activity or its ability to act as a thiol-disulphide redox couple.

Effect of MPTP and l‐Deprenyl on Antioxidant Enzymes and Lipid Peroxidation Levels in Mouse Brain

Excessive free radical formation or antioxidant enzyme deficiency can result in oxidative stress, a mechanism proposed in the toxicity of MPTP and in the etiology of Parkinson's disease (PD). However, it is unclear if altered antioxidant enzyme activity is sufficient to increase lipid peroxidation in PD. We therefore investigated if MPTP can alter the activity of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX) and the level of lipid peroxidation. L-Deprenyl, prior to MPTP administration, is used to inhibit MPP+ formation and its subsequent effect on antioxidant enzymes. MPTP induced a threefold increase in SOD activity in the striatum of C57BL/6 mice. No parallel increase in GSH-PX or CAT activities was observed, while striatal lipid peroxidation decreased. At the level of the substantia nigra (SN), even though increases in CAT activity and reduction in SOD and GSH-PX activities were detected, lipid peroxidation was not altered. Interestingly, L-deprenyl induced similar changes in antioxidant enzymes and lipid peroxidation levels, as did MPTP. Taken together, these results suggest that an alteration in SOD activity, without compensatory increases in CAT or GSH-PX activities, is not sufficient to induce lipid peroxidation.

Alteration of superoxide dismutase activity in the anterior horn in motoneuron disease patients

Studies on anterior horn dissected from MND patients have demonstrated that MnSOD activity is increased when expressed as a percentage of total SOD activity when compared to controls. Total SOD activity (mean ± SD) in controls = 414 ± 105 U mg −1 tissue and in MND patients = 373 ± 115 U mg −1 tissue, whereas CuZnSOD activity was higher in controls (290 ± 91 U mg −1 tissue) than in MND patients (197 ± 81 U mg −1 tissue). The reduction in CuZnSOD was compensated for by a concomitant elevation of MnSOD activity (control = 123 ± 40.5 U mg −1 tissue, MND patients = 175 ± 47 U mg −1 tissue). These data not only show an important deficit in anterior horn cell body protection against free radical-mediated cell damage, but are also are the first measurements of SOD isoenzymes in anterior horn neurones.

Reduced superoxide dismutase activity in UVB-induced hyperproliferative pig epidermis

Decreased superoxide dismutase (SOD) activity has been reported in various hyperproliferative keratinocytes. In order to elucidate the relationship between epidermal SOD activity and keratinocyte proliferation, we employed in vivo UVB irradiation. Following UVB irradiation at twice the minimum erythema dose, pig epidermis revealed an initial decrease in thymidine incorporation and mitotic counts for at least 48 h, followed by a marked increase, the peak of which was observed at 96 h after irradiation, and a return to basal levels by 5-7 days. The SOD activity remained constant during the initial 48 h and then decreased to about 50% at 96 h, mainly due to a decreased Cu,Zn-SOD activity. Our results indicate that the increased keratinocyte proliferation induced by UVB irradiation is accompanied by a decrease in SOD activity, and that this decrease is mainly due to a decreased Cu,Zn-SOD activity. No alteration in SOD activity was noted during the initial hypoproliferative phase following irradiation.

Superoxide Dismutase in Epidermis: Its Relation to Keratinocyte Proliferation

AbstractDecreased superoxide dismutase (SOD) activity has been reported in various hyperproliferative tissues. In order to elucidate the significance of SOD activity in keratinocyte proliferation, we measured the SOD activity in several pathologic epidermal conditions. The SOD activity was significantly decreased in psoriatic hyperproliferative epidermis as well as in basal cell epithelioma, squamous cell carcinoma and seborrheic keratosis.Following tape stripping in vivo, pig epidermis revealed a marked increase in thymidine uptake and mitotic counts. The peak of the thymidine uptake was observed at 24 h, which was followed by the increased mitotic counts (peak at 48 h). The pig skin revealed a decreased epidermal SOD activity following the tape stripping. A decline of SOD activity was observed within 7 days after the tape stripping and about a 50% decrease was observed at 48 h. Epidermis is known to contain both Cu, Zn‐SOD and Mn‐SOD activities; the decreased SOD activity after tape stripping was mainly due to decreased Cu, Zn‐SOD activity without any significant alteration of Mn‐SOD activity.Following UVB irradiation (2MED) in vivo, pig epidermis revealed decreased thymidine incorporation as well as decreased mitotic counts. Epidermal SOD activity, however, was not altered by the UVBirradiation. Pig epidermis is also known to indicate decreased cell proliferative activity in the presence of various chemicals in vitro. These modalities, which include retinoid (Ro 10‐1670), colchicine and protein synthesis inhibitors (puromycin, actinomycin D, cycloheximide), had no effect on the epidermal SOD activity.Our results indicate that, although the decreased SOD activity appears to be comcomitant with keratinocyte hyperproliferation, no alteration of SOD activity is observed in hypoproliferative epidermis. The significance of the altered SOD activity in the regulatory mechanism of keratinocyte proliferation remains unknown at present.