Thyroid hormone-induced haemoglobin changes and antioxidant enzymes response in erythrocytes

Thyroid hormones modulate haemoglobin and reactive oxygen species (ROS) production, leading to antioxidant changes. This study evaluated the antioxidant response to ROS in erythrocytes in hypothyroid and hyperthyroid rats. Wistar rats were divided into four groups: control; hyperthyroid (T4-12 mg 1(-1) in drinking water); sham operated (simulation of thyroidectomy); and hypothyroid (thyroidectomized). Four weeks after, blood was collected and haemoglobin and T(4) levels, lipid peroxidation (LPO), protein oxidation, superoxide dismutase (SOD), catalase (CAT) , glutathione S-transferase (GST) and glutathione peroxidase (GPx) activities, and total radical antioxidant potential (TRAP) were measured. SOD, CAT and GST immunocontent was evaluated. Haemoglobin levels were increased in hyperthyroid erythrocytes. LPO and carbonyls were augmented (65% and 55%, respectively) in hyperthyroid and reduced (31% and 56%, respectively) in hypothyroid group. SOD and CAT activities have not changed, as well as CAT immunocontent. TRAP was diminished in both hyperthyroid and hypothyroid groups (36% and 37%, respectively). GST activity and immunocontent, as well as GPx activity, were increased in hyper and hypothyroid rats. The data suggest that thyroid hormone changes determine ROS concentration changes and decrease of some antioxidant defences that would lead to a compensatory answer of the GST and GPx enzymes, which could be consider as credible biomarkers.     

Antioxidant levels from different Antarctic fish caught around South Georgia Island and Shag Rocks

Antarctic fish have been isolated for over several million years in an environment with a very low and constant temperature and high oxygen concentration. In such conditions the oxidative stress might be an important factor affecting their metabolic adaptive strategies. Activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), vitamin E levels and total antioxidant capacity (TRAP) were measured in liver, gill, heart and muscle homogenates of red-blooded (Nototheniidae) and white-blooded (Channichthyidae) Antarctic fish. SOD activity was also measured in blood samples. Gill SOD activity was threefold higher in channichthyids than in nototheniids while CAT and GPx were significantly higher in the gills of channichthyids. The increased SOD activity of channichthyids probably reflects the large PO₂ gradient across their gills. The H₂O₂ produced seems to be preferentially eliminated by diffusion, according to the low levels of CAT and GPx found in the gills of these species. In contrast, blood SOD was about fivefold higher in the latter group, which possesses erythrocytes and thus a much higher oxygen-carrying capacity. CAT activity was always higher in nototheniids except in muscle. However, vitamin E did not show clear differences between families except for the pattern observed in muscle. The higher content of vitamin E in this tissue shown in channichthyids is related to the higher volume density of mitochondria reported for this group, since vitamin E is responsible for preventing membrane lipid peroxidation. Accordingly, TRAP (representative of hydrosoluble antioxidant capacity) was also higher in muscle of channichthyids. This is probably related to the role of ascorbic (a hydrosoluble compound) acid in regenerating vitamin E. Accepted: 4 September 1999     

Antioxidant defence system during exponential and stationary growth phases of Phycomyces blakesleeanus: Response to oxidative stress by hydrogen peroxide

An analysis of the components of the antioxidant defence system in exponential and stationary growth phases of filamentous fungus Phycomyces blakesleeanus and the response to the oxidative stress hydrogen peroxide were performed. There is a strong positive correlation between mycelial antioxidant capacity and the contents of gallic acid, d-erythroascorbate (d-EAA) or d-erythroascorbate monoglucoside (d-EAAG). These secondary metabolites are specifically synthesized by this fungus and reach maximal values in the stationary growth phase, suggesting that they can play some role in the antioxidant defence system of this fungus. There is a differential expression of the two more notable antioxidant activities, catalase (CAT) and superoxide dismutase (SOD), depending of the growth stage of P. blakesleeanus, CAT being expressed in the exponential and SOD in the stationary phase. Phycomyces blakesleeanus showed a high resistance to the oxidative stress caused by H₂O₂ (50 and 200 mM) which was higher in exponential phase. This higher resistance can be explained by the presence of CAT, glutathione peroxidase (GPx), and the probable contribution of glutathione-S-transferase (GST) and high levels of reduced form of glutathione (GSH). The transition to stationary phase was accompanied with a higher physiological oxidative damage illustrated by the higher protein carbonylation. In this growth stage the resistance of the fungus to the oxidative stress caused by H₂O₂ could be explained by the presence of SOD, GPx, and the probable contribution of GST as well as of secondary metabolites, mainly d-EAA and d-EAAG. These results highlight a specific response to oxidative stress by H₂O₂ depending on the growth phase of P. blakesleeanus.     

Effect of salicylic acid potentiates cadmium-induced oxidative damage in <Emphasis Type="Italic">Oryza sativa</Emphasis> L. leaves

In the present investigation, we studied the possible potentiating effect of salicylic acid (SA) under Cd toxicity in Oryza sativa L. leaves. Cd treatments for 24 h reduced the shoot length, dry biomass and total chlorophyll content followed by high Cd accumulation in shoots. About 16 h presoaking with SA resulted in partial protection against Cd, as observed by minor changes in length, biomass and total chlorophyll. SA priming resulted in low Cd accumulation. Enhanced thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H₂O₂) and superoxide anion (O₂ ⁻) content were seen when Cd was applied alone, while under SA priming the extent of TBARS, H₂O₂ and O₂ ⁻ were significantly low, suggesting SA-regulated protection against oxidative stress. The antioxidant enzymes like Catalase (CAT), guaiacol peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) showed varied activities under Cd alone. CAT activity increased after Cd treatment, followed by a decline in GPX and GR activity. SOD also declined at the highest concentrations with an initial increase. Under SA-priming conditions, the efficiency of the antioxidant enzymes was significantly elevated. GPx and SOD activity showed significant increase in activity. The ascorbate activity increased after Cd treatment, followed by a decline in glutathione under SA-free condition. SA priming showed gradual increase in these non-enzymic antioxidants. Our results indicate that Cd-induced oxidative stress can be regulated by SA.     

Parameters related to oxygen free radicals in erythrocytes,plasma and epidermis of the hairless rat

The following parameters related to oxygen free radicals (OFR) were determined in erythrocytes and the epidermis of hairless rats: catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced (GSH) and oxidized (GSSG) glutathione, glutathione S-transferase (GST), superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS). GSH, GSSG and TBARS were also analyzed in plasma. In erythrocytes, the Pearson correlation coefficients (r) were significant (p < 0.001) between glutathione and other parameters as follows: GSH correlated negatively with GSSG (r = -0.665) and TBARS (r = -0.669); GSSG correlated positively with SOD (r = 0.709) and TBARS (r = 0.752). Plasma GSSG correlated negatively with erythrocytic thermostable GST activity (r = -0.608; p=0.001) and with erythrocytic total GST activity (r = -0.677; p < 0.001). In epidermis (p < 0.001 in all cases), GSH content correlated with GSSG (r = 0.682) and with GPx (r = 0.663); GSSG correlated with GPx (r = 0.731) and with GR (r = 0.794). By multiple linear regression analysis some predictor variables (R(2)) were found: in erythrocytes, thermostable GST was predicted by total GST activity and GSSG, GSSG content was predicted by GSH and by the GSH/GSSG ratio and GPx activity was predicted by GST, CAT and SOD activities; in epidermis, GSSG was predicted by GR and SOD activities and GR was predicted by GSSG, TBARS and GPx. It is concluded that the hairless rat is a good model for studying OFR-related parameters simultaneously in blood and skin, and that it may provide valuable information about other animals under oxidative stress.     

Reduced glucose‐induced insulin secretion in low‐protein‐fed rats is associated with altered pancreatic islets redox status

In the present study, we investigated the relationship between early life protein malnutrition‐induced redox imbalance, and reduced glucose‐stimulated insulin secretion. After weaning, male Wistar rats were submitted to a normal‐protein‐diet (17%‐protein, NP) or to a low‐protein‐diet (6%‐protein, LP) for 60 days. Pancreatic islets were isolated and hydrogen peroxide (H₂O₂), oxidized (GSSG) and reduced (GSH) glutathione content, CuZn‐superoxide dismutase (SOD1), glutathione peroxidase (GPx1) and catalase (CAT) gene expression, as well as enzymatic antioxidant activities were quantified. Islets that were pre‐incubated with H₂O₂ and/or N‐acetylcysteine, were subsequently incubated with glucose for insulin secretion measurement. Protein malnutrition increased CAT mRNA content by 100%. LP group SOD1 and CAT activities were 50% increased and reduced, respectively. H₂O₂ production was more than 50% increased whereas GSH/GSSG ratio was near 60% lower in LP group. Insulin secretion was, in most conditions, approximately 50% lower in LP rat islets. When islets were pre‐incubated with H₂O₂ (100 μM), and incubated with glucose (33 mM), LP rats showed significant decrease of insulin secretion. This effect was attenuated when LP islets were exposed to N‐acetylcysteine.     

Comparison of intracellular glutathione and related antioxidant enzymes: Impact of two glycosylated whey hydrolysates

The effects of two glycosylated whey hydrolysates (GWH-Gal A and GWH-Gal B) on glutathione (GSH) and related antioxidant enzymes in SGC-7901 cells were evaluated. Two whey glycosylated hydrolysates promoted an increase in reduced glutathione (GSH) in normal SGC-7901 cells. GSH, glutathione peroxidase (GPx), γ-glutamine cysteine synthetaase (γ-GCS), and catalase (CAT) at 1.0 and 2.0 mg/mL in normal SGC-7901 cells were higher in the GWH-Gal A group than in the GWH-Gal B group (P < 0.05). Compared with GWH-Gal B, GWH-Gal A more strongly inhibited decreases in intracellular GSH, GPx, γ-GCS, CAT, and superoxide dismutase (SOD) in H₂O₂-induced SGC-7901 cells. Compared with GWH-Gal B, GWH-Gal A at 1.0 and 2.0 mg/mL effectively inhibited increases in lactate dehydrogenase (LDH) and malondialdehyde (MDA) in H₂O₂-induced SGC-7901 cells (P < 0.05). Therefore, GSH content and related antioxidant enzyme activity levels (GPx, γ-GCS, CAT, SOD) in both normal and H₂O₂-induced SGC-7901 cells were considerably stronger in the GWH-Gal A group than in the GWH-Gal B group.     

Lead-induced oxidative damage in rats/mice: A meta-analysis

BackgroundLead (Pb) is ubiquitous in the environment and is an environmental genotoxic metal. Pb accumulation in the body could cause the oxidative stress.ObjectiveThis meta-analysis aimed to perform a systematic evaluation of the extent of oxidative damage in rats/mice induced by lead.MethodsAll relevant articles in English or Chinese were retrieved from Embase, PubMed, Web of Science, Medline, China National Knowledge Infrastructure, and Chinese Biological Medicine databases from their inception date until July 22, 2018.ResultsA total of 108 eligible articles were included in this study. The indicators of oxidative stress included malondialdehyde (MDA), glutathione disulfide (GSSG), reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced glutathione (GSH), superoxide dismutase (SOD), and glutathione-s-transferase (GST). The meta-analysis showed that lead significantly increased oxidants levels, such as MDA, GSSG, ROS, and H₂O₂ (P < 0.05), and significantly reduced the level of antioxidants, such as CAT, GPx, GR, GSH, SOD, and GST (P < 0.05). The intraperitoneal mode was more effective than water drinking mode in reducing the levels of CAT, GPx, GSH, and SOD (P < 0.05). Other factors that influenced the overall oxidative stress, including species of animals, type of tissues, and intervention dosage and time, were comprehensively evaluated.ConclusionThe results of meta-analysis indicated that mice were more sensitive to lead than rats, and intraperitoneal mode was an effective intervention mean. High doses and long periods of lead treatment can cause serious oxidative damage. Moreover, testicular was more vulnerable to lead than other tissues. These results provided scientific evidence for preventing and treating lead toxicity.     

Effects of repeated desflurane and sevoflurane anesthesia on enzymatic free radical scavanger system

Background: To investigate the possible effects of repeated sevoflurane and desflurane anesthesia on hepatocellular system by evaluating the free radical metabolism, hepatocellular enzymes and histopatholgical changes in rats. Methods: Four groups of animals were studied. Sevoflurane 2% (v/v) and desflurane 6% (v/v) in air/O₂ were administered to animals in group II (n = 9) and III (n = 9) respectively. 100% (v/v) O₂ was administered in group IV (n = 9). Administration was done for 60 minutes over 3 days. Nine animals were allocated to control group (group I), superoxide dismutase (SOD), catalase (CAT), glutathion peroxidase (GSH-Px), glutathione-s-transferase (GST) and thiobarbituric acid reactive substances (TBARS) were studied. Also electron microscopy was performed. Results: Catalase, SOD, GSH-Px, GST activities and TBARS levels were significantly higher in groups II and III than in group I (p < 0.05). All parameters were significantly higher in groups II versus group IV (p < 0.05). On the other hand, SOD, GSH-Px and GST activities were significantly elevated in group III than IV, but CAT activity and TBARS levels were not significantly. Catalase, SOD, GSH-Px, GST but not TBARS levels were significantly higher in groups II and III than in group IV (p < 0.05). TBARS levels were higher in group III than in group IV, but this elevation was not statistically significant. CAT, SOD and GSH-Px activities were significantly higher in groups II than in group III (p < 0.05). Conclusion: Although electron microscopy findings were similar for group II and III, we can conclude that sevoflurane might cause more cellular damage than desflurane by causing higher activation of free radical metabolising enzymes.     

Alteration of Antioxidant Enzymes and Associated Genes Induced by Grape Seed Extracts in the Primary Muscle Cells of Goats In Vitro

This study was conducted to investigate how the activity and expression of certain paramount antioxidant enzymes respond to grape seed extract (GSE) addition in primary muscle cells of goats. Gluteal primary muscle cells (PMCs) isolated from a 3-week old goat were cultivated as an unstressed cell model, or they were exposed to 100 µM H₂O₂ to establish a H₂O₂-stimulated cell model. The activities of catalase (CAT), superoxide dismutases (SOD) and glutathione peroxidases (GPx) in combination with other relevant antioxidant indexes [i.e., reduced glutathione (GSH) and total antioxidant capacity (TAOC)] in response to GSE addition were tested in the unstressed and H₂O₂-stimulated cell models, and the relative mRNA levels of the CAT, GuZu-SOD, and GPx-1 genes were measured by qPCR. In unstressed PMCs, GSE addition at the dose of 10 µg/ml strikingly attenuated the expression levels of CAT and CuZn-SOD as well as the corresponding enzyme activities. By contrast, in cells pretreated with 100 µM H₂O₂, the expression and activity levels of these two antioxidant enzymes were enhanced by GSE addition at 10 µg/ml. GSE addition promoted GPx activity in both unstressed and stressed PMCs, while the expression of the GPx 1 gene displayed partial divergence with GPx activity, which was mitigated by GSE addition at 10 µg/ml in unstressed PMCs. GSH remained comparatively stable except for GSE addition to H₂O₂-stimulated PMCs at 60 µg/ml, in which a dramatic depletion of GSH occurred. Moreover, GSE addition enhanced TAOC in unstressed (but not H₂O₂-stimulated) PMCs. GSE addition exerted a bidirectional modulating effect on the mRNA levels and activities of CAT and SOD in unstressed and stressed PMCs at a moderate dose, and it only exhibited a unidirectional effect on the promotion of GPx activity, reflecting its potential to improve antioxidant protection in ruminants.     

Pistacia lentiscus fruit oil reduces oxidative stress in human skin explants caused by hydrogen peroxide

We investigated the efficacy of Pistacia lentiscus fruit oil (PLFO) for protecting human skin from damage due to oxidative stress. PLFO contains natural antioxidants including polyphenols, sterols and tocopherols. We compared the antioxidant potential of PLFO with extra virgin olive oil (EVOO). Explants of healthy adult human skin were grown in culture with either PLFO or EVOO before adding hydrogen peroxide (H₂O₂). We also used cultured skin explants to investigate the effects of PLFO on lipid oxidation and depletion of endogenous antioxidant defense enzymes including glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) one day after 2 h exposure to H₂O₂. We found that PLFO scavenged radicals and protected skin against oxidative injury. PLFO exhibited greater antioxidant and free radical scavenging activity than EVOO. Skin explants treated with PLFO inhibited H₂O₂ induced MDA formation by inhibition of lipid oxidation. In addition, the oil inhibited H₂O₂ induced depletion of antioxidant defense enzymes including GPx, SOD and CAT. We found that treatment with PLFO repaired skin damage owing to its antioxidant properties.     

Differential domain structure stability of the severe acute respiratory syndrome coronavirus papain-like protease

Recent studies from our laboratory have showed that resveratrol, a polyphenol found predominantly in grapes rendered strong cardioprotection in animal models of heart disease. The cardioprotection which was observed was primarily associated with the ability of resveratrol to reduce oxidative stress in these models. The aim of the current study was to corroborate the role of resveratrol as an inhibitor of oxidative stress and explore the underlying mechanisms of its action in heart disease. For this purpose, we used a cell model of oxidative stress, the hydrogen peroxide (H₂O₂) exposed adult rat cardiomyocytes, which was treated with and without resveratrol (30 μM); cardiomyocytes which were not exposed to resveratrol served as controls. Cell injury, cell death and oxidative stress measurements as well as the activities of the major endogenous antioxidants superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were carried out in control and H₂O₂ exposed cardiomyocytes, treated with and without resveratrol. Pharmacological blockade using specific blockers of the antioxidant enzymes were used to confirm their role in mediating resveratrol action in H₂O₂ exposed cardiomyocytes. The status of H₂O₂ and antioxidant enzymes in serum samples from spontaneously hypertensive rats (SHR) treated with and without resveratrol (2.5 mg/kg body weight) was also examined.Our results showed significant cell injury and death in H₂O₂ exposed cardiomyocytes which was prevented upon resveratrol treatment. SOD and CAT activities were decreased in H₂O₂ exposed adult rat cardiomyocytes; treatment with resveratrol significantly prevented this reduction. However, GPx activity was not altered in the H₂O₂ exposed cardiomyocytes in comparison to controls. Pharmacological blockade of SOD and/or CAT prevented the beneficial effect of resveratrol. In SHR, H₂O₂ levels were increased, but CAT activity was decreased, while SOD remained unchanged, when compared to WKY rats; resveratrol treatment significantly prevented the increase in H₂O₂ levels and the decrease in CAT activities in SHR.Based on our results, we conclude that treatment with resveratrol prevents oxidative stress induced cardiomyocyte injury mainly by preserving the activities of critical antioxidant enzymes. This may be a crucial mechanism by which resveratrol confers cardioprotection.     

Effects of Chronic Restraint Stress and 17-β-Estradiol Replacement on Oxidative Stress in the Spinal Cord of Ovariectomized Female Rats

Previous studies have shown sex-specific oxidative changes in spinal cord of rats submitted to chronic stress, which may be due to gonadal hormones. Here, we assessed total radical-trapping potential (TRAP), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and lipid peroxidation (evaluated by the TBARS test) in the spinal cord of ovariectomized (OVX) female rats. Female rats were subjected to OVX, and half of the animals received estradiol replacement. Animals were subdivided into controls and chronically stressed (for 40 days). Our findings demonstrate that chronic stress decreased TRAP, and increased SOD activity in spinal cord homogenates from ovariectomized female rats and had no effect on GPx activity. On the other hand, groups receiving 17β-estradiol replacement presented a decreased GPx activity, but no alteration in TRAP and in SOD activity. No differences in the TBARS test were found in any of the groups analyzed. In conclusion, our results support the idea that chronic stress induces an imbalance between SOD and GPx activities, additionally decreasing TRAP. Estradiol replacement did not reverse the effects of chronic stress, but induced a decrease in GPx activity. Therefore, estradiol replacement in ovariectomized chronically stressed rats could make the spinal cord more susceptible to oxidative injury.     

Induction in the antioxidative systems and lipid peroxidation in suspension culture roots of Panax ginseng induced by oxygen in bioreactors

Roots of mountain ginseng (Panax ginseng) were exposed to various levels of oxygen (O₂) (30, 40 and 50%) for 15, 30 and 45 days in 5 L (working volume 4 L) airlift bioreactors. Ginsenoside accumulation and dry weight was enhanced up to 40% O₂; but thereafter declined ginsenoside and dry weight of the roots by increasing level of O₂. Gradual increase in H₂O₂ content and lipoxygenase activity (LOX), resulting in cellular damage and oxidative stress as indicated by increased malondialdehyde (MDA) content after 30 and 45 days at all O₂ levels was shown. Increased levels of O₂ (above ambient) resulted in increases in non-protein thiol (NP-SH) and cysteine content. Higher activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), catalase (CAT), guaiacol peroxidase (G-POD), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S transferase (GST) activities indicated that antioxidant enzymes played an important role in protecting the roots from O₂ up to 45 days, except at 50% O₂ where GR, GST and GPx decreased compared to the control. However, after 45 days, SOD activity decreased significantly compared to the control in the O₂-treated roots. This reflects the sensitivity of enzymes to O₂ toxicity. In stress related experiment, roots showed increased synthesis of ginsenosides when 25 and 50 μM H₂O₂ was applied. However, higher dose and increasing treatment inhibited ginsenoside synthesis. The results indicate that plant roots could grow and protect themselves from O₂ stress by coordinated induction of various antioxidant enzymes and metabolite contents. These results suggest that O₂ supplementation is useful for ginsenoside accumulation using 5-L bioreactors.     

The role of Acanthamoeba castellanii (T4 genotype) antioxidant enzymes in parasite survival under H2O2-induced oxidative stress

Acanthamoeba castellanii (A. castellanii) is an important opportunistic parasite. Induction of oxidative stress by the host immune system is one of the most important defense strategies against parasites. Hence, parasites partly deal with oxidative stress by different mechanisms. Identifying resistance mechanisms of A. castellanii parasites against oxidative stress is important to achieve a new therapeutic approach. Thus, this study aimed to understand the resistance mechanisms of A. castellanii, against oxidative stress. Trophozoites of A. castellanii were treated with different concentrations of H₂O₂. The half maximal inhibitory concentration (IC₅₀) of H₂O₂ was determined using the MTT assay. The induction of oxidative stress was confirmed by flow cytometer. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) were determined. The gene expression levels of CAT and SOD were measured by qRT-PCR. Furthermore, 3-amino-1:2:4-triazole (3-AT) and potassium cyanide (KCN) were used as specific inhibitors of CAT and SOD, respectively. Cell cycle assay and the apoptosis were evaluated by flow cytometer. The activities of SOD, CAT, GR, and GPx, showed an increase in oxidative stress. The cell cycle analysis revealed that most of the cellular population was in G0 and G1 phases. The apoptosis increased in oxidative stress conditions. Moreover, the apoptosis significantly increased after the specific inhibition of CAT and SOD under oxidative stress. The gene expression levels of CAT and SOD significantly increased under oxidative stress. A. castellanii can resist the host immune system through various mechanisms, including evoking its antioxidant enzymes. Therefore, by reducing or inhibiting the activity of the parasite's antioxidant enzymes such as SOD and CAT, it is possible to cope with A. castellanii.     

Abscisic acid improves drought tolerance of triploid bermudagrass and involves H2O2- and NO-induced antioxidant enzyme activities

Drought is a major limiting factor for turfgrass growth. Protection of triploid bermudagrass against drought stress by abscisic acid (ABA) and its association with hydrogen peroxide (H₂O₂) and nitric oxide (NO) were investigated. ABA treatment increased relative water content, decreased ion leakage and the percentage of dead plants significantly under drought stress. Superoxide dismutase (SOD) and catalase (CAT) activities increased in both ABA-treated and control plants, but more in ABA-treated plants, under drought stress. Malondialdehyde, an indicator of plant lipid peroxidation, was lower in ABA-treated plants than in control plants, indicating that ABA alleviated drought-induced oxidative injury. ABA treatment increased H₂O₂ and NO contents. ABA-induced SOD and CAT activities could be blocked by scavengers of H₂O₂ and NO, and inhibitors of H₂O₂ and NO generation. The results indicated that H₂O₂ and NO were essential for ABA-induced SOD and CAT activities. Both H₂O₂ and NO could induce SOD and CAT activities individually. SOD and CAT induced by H₂O₂ could be blocked by scavenger of NO and inhibitors of NO generation, while SOD and CAT induced by NO could not be blocked by scavenger of H₂O₂ and inhibitor of H₂O₂. The results revealed that ABA-induced SOD and CAT activities were mediated sequentially by H₂O₂ and NO, and NO acted downstream of H₂O₂.     

Oxidation Products and Antioxidant Markers in Plasma of Patients with Graves' Disease and Toxic Multinodular Goiter: Effect of Methimazole Treatment

Oxidative stress plays an important role in hyperthyroidism-induced tissue damage, as well as in development of autoimmune disorders. To clarify influence of thyroid metabolic status and autoimmune factors on blood extracellular indices of reactive oxygen species (ROS) generation and free radical scavenging in hyperthyroidism, we studied patients with newly diagnosed and untreated Graves' disease without infiltrative ophthalmopathy (17 female and 8 male, aged 41.8±8.9) and toxic multinodular goiter (15 female and 9 male, aged 48.4±10.1) under the same antithyroid treatment protocol. Initially and after achievement of stable euthyroidism with methimazole, plasma levels of hydrogen peroxide (H²O²), lipid hydroperoxides (ROOH) and ceruloplasmin (CP) and serum concentrations of thiobarbituric acid-reacting substances (TBARS) were determined. Similarly, activities of plasma superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were assayed. The results were compared to those of age- and sex-matched controls. Average duration of hyperthyroidism and treatment period were similar in both patients groups. H²O², ROOH and TBARS concentrations were significantly higher in hyperthyroid patients compared to controls. Hyperthyroidism caused an evident increase in SOD and CAT activities and CP level, as well as a decrease in GPx and GR activities. Achievement of euthyroidism resulted in normalization of all analyzed parameters in both hyperthyroid patients groups. These findings suggest that the changes in blood extracellular indices of oxidative stress and free radical scavenging in hyperthyroid patients are influenced by thyroid metabolic status, and are not directly dependent on autoimmune factors present in Graves' disease.     

Age-related changes in antioxidant enzyme activities and lipid peroxidation in lungs of control and sulfur dioxide exposed rats

Antioxidant defenses within the lung are pivotal in preventing damage from oxidative toxicants. There have also been several reports with conflicting results on the antioxidant system during aging. In this study, we attempted to investigate age-related alterations in both antioxidant enzyme activities and thiobarbituric acid-reactive substances (TBARS), a product of lipid peroxidation, in the whole lung of control and sulfur dioxide (SO₂) exposed rats of different age groups (3-, 12-, and 24-months-old). Swiss-Albino Male rats were exposed to 10 ppm SO₂ 1 hr/day, 7 days/week for 6 weeks. The antioxidant enzymes examined include Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST). A mixed pattern of age-associated alterations in antioxidant activities was observed. SOD, GSH-Px and GST activities were increased with age, but CAT activity was decreased. Lung SOD, GSH-Px and GST activities were also increased in response to SO₂. The level of TBARS was increased with age. SO₂ exposure stimulated lipid peroxide formation in the lung as indicated by an increase in the level of TBARS. These findings suggest that both aging and SO₂ exposure may impose an oxidative stress to the body. We conclude that the increase in the activities of the antioxidant enzymes of the lung during aging, could be interpreted as a positive feedback mechanism in response to rising lipid peroxidation.     

Bromelain from Ananas comosus stem attenuates oxidative toxicity and testicular dysfunction caused by aluminum in rats

BACKGROUNDAluminum (Al) has been reported to induce testicular injury via oxidative stress. Ananas comosus stem extract is an inexpensive byproduct waste rich in bromelain which is a group of sulfur-containing enzymes known for its biological activities and medicinal applications. So, the current investigation aims to evaluate the efficacy of bromelain in counteracting oxidative injury and testicular dysfunction stimulated by aluminum in rats.METHODSMale adult Wistar rats were divided into four groups. The first group used as control, however, the second and third groups were received bromelain (250 mg/kg) and AlCl₃ (34 mg/Kg, 1/25 LD₅₀), and the fourth group supplemented with bromelain one hour before AlCl₃ intoxication, respectively. Bromelain was administered daily while AlCl₃ was given every other day by oral gavages for one month.RESULTSAl intoxicated animals revealed an elevation in lipid peroxidation (TBARS and H₂O₂) level and lactate dehydrogenase (LDH) activity. However, reduced glutathione (GSH) and protein contents, antioxidant enzymes (SOD, CAT, GPx, GR, GST), phosphatases (ALP, AcP) and aminotransferases (AST, ALT) activities were significantly reduced. Additionally, considerable amendments in hormonal levels (testosterone, luteinizing and follicle-stimulating hormone) and sperm characteristics were spotted. Further, histological variations in the testes section were detected and this supports the biochemical observations. Otherwise, rats supplemented with bromelain alone diminished TBARS and H₂O₂ and augmented mostly other parameters. Furthermore, supplementation with bromelain before Al intoxication in rats exhibited worthy betterment in oxidative stress markers, hormones, and sperm quality compared to Al treated group.CONCLUSIONIn conclusion, bromelain had a powerful protective role against Al-induced testicular dysfunction so, it represents a novel approach in metal toxicity processing.