Diel variation in cortisol,glucose, lactic acid and antioxidant system of black sea bass Centropristis striata under natural photoperiod

ABSTRACT

Diel rhythm in activity of antioxidant enzymes, as well as contents of glutathione and lipid peroxides, has been intensively investigated in Mammalia and Aves, however, the relevant studies about fish are few. In the present study, we examined variation in contents of cortisol, glucose and lactic acid in plasma of black sea bass Centropristis striata under natural photoperiod during a 24-h period. In addition, variation in activity of antioxidant enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) and glutathione reductase (GR) as well as contents of total glutathione (T-GSH), reduced glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde (MDA) in liver and plasma of the fish were also determined. The plasma and liver samples were collected from the test fish at 3 h intervals during a 24-h cycle, with the first sampling time set at 03:00 h. No significant differences were found in glucose content and activities of GSH-PX and GR in plasma, as well as activities of SOD and GR in liver among different sampling times. In contrast, apparent variation was observed in contents of cortisol, lactic acid and MDA in plasma, activities of SOD and CAT in plasma, contents of MDA, T-GSH, GSH and GSSG in liver and activities of GSH-PX and CAT in liver between different sampling times. Moreover, contents of cortisol and MDA in plasma, SOD activity in plasma, and contents of MDA, GSH and GSSG in liver exhibited circadian rhythm, and their acrophases occurred at 06:08 h, 18:38 h, 15:09 h, 09:57 h, 23:36 h and 07:30 h, respectively. The present study indicates that some physiological parameters relating to stress response, such as cortisol and MDA contents in plasma, MDA, GSH and GSSG contents in liver and SOD activity in plasma changed at different time throughout a day in black sea bass. Therefore, caution should be taken when evaluating stress response in fish with these physiological parameters measured at different times.     

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.     

Reduction of Brain Antioxidant Defense Upon Treatment with Butylated Hydroxyanisole (BHA) and Sudan III in Syrian Golden Hamster

Treatment with the antioxidant butylated hydroxyanisole (BHA) or the azo dye Sudan III during two weeks led to changes in the brain enzymatic antioxidant defense of Syrian golden hamsters. BHA was able to induce liver superoxide dismutase (SOD) 2-fold but had no effect on the brain SOD activity, whereas SOD activity was reduced to 50% in brain and remained unchanged in liver with Sudan III. These two substances are known inducers of DT-diaphorase and in fact this enzymatic activity was induced 4- and 6-fold in liver with BHA and Sudan III, respectively. However, BHA promoted a significant 40% reduction, whereas no change was observed with Sudan III in brain DT-diaphorase activity. Glutathione(GSH)-related enzymatic activities were also assayed in brain and liver. No induction was observed with BHA or Sudan III for any of the activities tested in hamster brain: GSH S-transferase (GST), GSH peroxidase (GSH-Px) and glutathione disulfide (GSSG) reductase (GR). Only 1.3- and 1. 4-fold increases of GST and GR activities were observed in liver and no change in any of these enzymatic activities in brain with BHA; a partial limitation of permeability to BHA of the blood-brain barrier may explain this results. Furthermore, Sudan III promoted reductions in all these GSH-related enzymatic activities in brain and liver. The possible explanations for these results are discussed.Deceased 4th November 1998     

Induced swimming modified the antioxidant status of gilthead seabream (Sparus aurata)

Swimming has relevant physiological changes in farmed fish, although the potential link between swimming and oxidative stress remains poorly studied. We investigated the effects of different medium-term moderate swimming conditions for 6 h on the antioxidant status of gilthead seabream (Sparus aurata), analyzing the activity of enzymes related to oxidative stress in the liver and skeletal red and white muscle. Forty fish were induced to swim individually with the following conditions: steady low (SL, 0.8 body length (BL)·s⁻¹), steady high (SH, 2.3 BL·s⁻¹), oscillating low (OL, 0.2–0.8 BL·s⁻¹) and oscillating high (OH, 0.8–2.3 BL·s⁻¹) velocities, and a non-exercised group with minimal water flow (MF, < 0.1 BL·s⁻¹). All swimming conditions resulted in lower activities of superoxide dismutase (SOD), glutathione reductase (GR), and glutathione-S-transferase (GST) in the liver compared to the MF group, while steady swimming (SL and SH) led to higher reduced glutathione/oxidized glutathione ratio (GSH/GSSG) compared to the MF condition. Swimming also differently modulated the antioxidant enzyme activities in red and white muscles. The OH condition increased lipid peroxidation (LPO), catalase (CAT) and glutathione peroxidase (GPx) activities in the red muscle, decreasing the GSH/GSSG ratio, whereas the SL condition led to increased GSH. Oscillating swimming conditions (OL and OH) led to lower CAT activity in the white muscle, although GPx activity was increased. The GSH/GSSG ratio in white muscle was increased in all swimming conditions. Liver and skeletal muscle antioxidant status was modulated by exercise, highlighting the importance of adequate swimming conditions to minimize oxidative stress in gilthead seabream.     

Fulminant Hepatic Failure in Rats Induces Oxidative Stress Differentially in Cerebral Cortex,Cerebellum and Pons Medulla

Hepatic Encephalopathy (HE) is one of the most common complications of acute liver diseases and is known to have profound influence on the brain. Most of the studies, available from the literature are pertaining to whole brain homogenates or mitochondria. Since brain is highly heterogeneous with functions localized in specific areas, the present study was aimed to assess the oxidative stress in different regions of brain-cerebral cortex, cerebellum and pons medulla during acute HE. Acute liver failure was induced in 3-month old adult male Wistar rats by intraperitoneal injection of thioacetamide (300 mg/kg body weight for two days), a well known hepatotoxin. Oxidative stress conditions were assessed by free radical production, lipid peroxidation, nitric oxide levels, GSH/GSSG ratio and antioxidant enzyme machinery in three distinct structures of rat brain-cerebral cortex, cerebellum and pons medulla. Results of the present study indicate a significant increase in malondialdehyde (MDA) levels, reactive oxygen species (ROS), total nitric oxide levels [(NO) estimated by measuring (nitrites + nitrates)] and a decrease in GSH/GSSG ratio in all the regions of brain. There was also a marked decrease in the activity of the antioxidant enzymes-glutathione peroxidase, glutathione reductase and catalase while the super oxide dismutase activity (SOD) increased. However, the present study also revealed that pons medulla and cerebral cortex were more susceptible to oxidative stress than cerebellum. The increased vulnerability to oxidative stress in pons medulla could be due to the increased NO levels and increased activity of SOD and decreased glutathione peroxidase and glutathione reductase activities. In summary, the present study revealed that oxidative stress prevails in different cerebral regions analyzed during thioacetamide-induced acute liver failure with more pronounced effects on pons medulla and cerebral cortex. Murthy Ch.R.K—Deceased while in service.     

Dapsone induces oxidative stress and impairs antioxidant defenses in rat liver

Dapsone (DDS) is currently used in the treatment of leprosy, malaria and in infections with Pneumocystis jirovecii and Toxoplasma gondii in AIDS patients. Adverse effects of DDS involve methemoglobinemia and hemolysis and, to a lower extent, liver damage, though the mechanism is poorly characterized. We evaluated the effect of DDS administration to male and female rats (30 mg/kg body wt, twice a day, for 4 days) on liver oxidative stress through assessment of biliary output and liver content of reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, and expression/activities of the main antioxidant enzymes glutathione peroxidase, superoxide dismutase, catalase and glutathione S-transferase. The influence of DDS treatment on expression/activity of the main DDS phase-II-metabolizing system, UDP-glucuronosyltransferase (UGT), was additionally evaluated. The involvement of dapsone hydroxylamine (DDS-NHOH) generation in these processes was estimated by comparing the data in male and female rats since N-hydroxylation of DDS mainly occurs in males. Our studies revealed an increase in the GSSG/GSH biliary output ratio, a sensitive indicator of oxidative stress, and in lipid peroxidation, in male but not in female rats treated with DDS. The activity of all antioxidant enzymes was significantly impaired by DDS treatment also in male rats, whereas UGT activity was not affected in any sex. Taken together, the evidence indicates that DDS induces oxidative stress in rat liver and that N-hydroxylation of DDS was the likely mediator. Impairment in the activity of enzymatic antioxidant systems, also associated with DDS-NHOH formation, constituted a key aggravating factor.     

萝卜硫素对急性低温暴露鼠骨骼肌Nrf2介导的抗氧化能力的影响

萝卜硫素(sulforaphane,SFN)是一种在十字花科植物中含量丰富,且具有抗氧化效应的天然物质。本文基于核因子E2相关因子2(nuclear factor E2-related factor 2,Nrf2)介导的抗氧化系统,探究不同时长低温暴露对骨骼肌抗氧化酶的影响及SFN对低温暴露骨骼肌抗氧化能力的作用。首先,30只雄性C57BL/6N小鼠随机分为常温对照组(0 h组)、低温暴露1 h组(1 h组)和低温暴露3 h组(3 h组)。其次,40只雄性C57BL/6N小鼠随机分为PBS常温对照组(PBS+Con),PBS低温暴露3 h组(PBS+Cold),SFN常温对照组(SFN+Con)和SFN低温暴露3 h组(SFN+Cold)。小鼠在急性温度干预前腹腔注射4次SFN或等体积PBS。急性低温暴露后,取小鼠骨骼肌,试剂盒检测活性氧(ROS)水平、总抗氧化能力(T-AOC)、还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)含量;荧光实时定量PCR检测Nrf2介导的抗氧化酶和参与生成谷胱甘肽相关酶的mRNA转录水平;Western blot检测Nrf2介导的抗氧化酶蛋白表达。结果显示,与0和1 h组相比,3 h组小鼠骨骼肌Nrf 2和抗氧化酶基因(Gpx 1、Hmox1、Cat、Sod 1和Nqo 1)的mRNA转录水平显著降低,ROS水平显著增加。与PBS+Con组相比,PBS+Cold组小鼠骨骼肌Nrf2和抗氧化酶(HMOX1和CAT)蛋白表达、GSH/GSSG比值及T-AOC水平显著降低,而GSSG含量和ROS水平增加。与PBS+Cold组相比,SFN+Cold组小鼠骨骼肌Nrf 2 mRNA及其蛋白表达、抗氧化酶(HMOX1和SOD1)蛋白表达、抗氧化酶基因(Gpx 1、Hmox 1、Cat、Sod 1和Nqo 1)mRNA转录水平、参与GSH生成的酶基因(Gclm和Gss)mRNA转录水平、GSH/GSSG比值以及T-AOC水平显著提高,而GSSG含量和ROS水平显著降低。综上,3 h急性低温暴露降低了Nrf2介导的抗氧化作用。而低温暴露前给予SFN补充,则激活了Nrf2介导的抗氧化酶和谷胱甘肽抗氧化系统,增强了骨骼肌抗氧化能力。     

Effect of gender differences and voluntary exercise on antioxidant capacity in rats

The effects of gender difference and voluntary exercise on antioxidant capacity in rats were evaluated. The subjects were divided into two groups, physically active and sedentary. In the sedentary group, the level of hydroxyl radical in the liver was higher (P<0.001) in male rats than in female rats, however, in the physically active group, the level in male rats was lower (P<0.05) than in female rats. The levels of reduced glutathione (GSH) in physically active males and females were higher compared to those in the sedentary group. The physically active group also showed an increase in antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase activities. The level of liver GSH was higher in physically active females than in physically active males. For both groups, GPx and GR activities in females were significantly higher than in males. These results indicate that female rats have an intrinsically higher antioxidant capacity, which resulted in increased levels of GSH via the glutathione redox cycle and gamma-glutamyl cycle enzymes. The adaptation to altered antioxidant capacity, induced by physical activity, appeared to be affected by gender differences.     

Carbaryl-induced effects on glutathione content, glutathione reductase and superoxide dismutase activity of the cyanobacterium Nostoc muscorum

The carbamate insecticide carbaryl, at concentrations of 10 mg/l and above, significantly stimulated glutathione reductase (GR) and superoxide dismutase (SOD) activity in the cyanobacterium Nostoc muscorum. A low content of total glutathione (GSH + GSSG), decreased photosynthetic activity, and an increased level of H₂O₂ was observed in pesticide treated cyanobacteria. As no glutathione peroxidase was observed in this species, stimulation of GR and SOD activity, higher production of H₂O₂, and low glutathione level was attributed to the utilization of GSH to remove H₂O₂ spontaneously and nonenzymatically under conditions of pesticide toxicity.     

Increased recovery of brain acetylcholinesterase activity in dichlorvos-intoxicated European eels Anguilla anguilla by bath treatment with N-acetylcysteine

Organophosphate (OP) pesticides are widely used as antiparasitic chemicals in finfish aquaculture. However, current antidotes cannot be applied to treat intoxicated fish. We showed in previous studies the importance of glutathione (GSH) metabolism in pesticide resistance of the European eel Anguilla anguilla L. The present work studied the effects of the antioxidant and glutathione pro-drug N-acetyl-L-cysteine (NAC) on the recovery of European eels exposed for 96 h to a sublethal concentration (0.17 mg l(-1); 20% of its 96 h LC50) of the OP pesticide dichlorvos (2,2-dichlorovinyl dimethyl phosphate; DDVP). This insecticide and acaricide decreased muscular GSH content and increased oxidised glutathione (GSSG), lowering the GSH:GSSG ratio, which is indicative of a condition of oxidative stress. Acetylcholinesterase (AChE) and glutathione reductase (GR) activities in the brain, which were biomarkers of neurotoxicity and oxidative stress, respectively, were also highly inhibited. Recovery in a 0.5 mM (81.6 mg l(-1)) NAC concentration ameliorated muscular GSH depletion, GSH:GSSG ratio, and the inhibition of brain AChE and GR activities. Hence, this is the first evidence of improved recovery of organophosphate-poisoned fish by bath treatments.     

Response of hepatic antioxidant system to exercise training in aging female rat

This study was undertaken to investigate the effect of exercise training on aging in the hepatic oxidative status and antioxidant defense of female albino rat. Two age groups of 3 months and 12 months old Wistar strain female albino rats were given chronic exercise training for a period of 12 weeks. The antioxidant enzyme assays were carried out by the standard methods. Lower (P<0.01) activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) by 21%, 44% and 63% respectively was observed in the older rats when compared to younger rats. Also, glutathione (GSH) levels were 42% lower (P<0.01) in older than younger animals. Exercise training to the 12 months aged rats significantly (P<0.01) elevated these antioxidant enzyme activities and GSH content, when compared to older control rats. These levels are almost equal to the values observed in the younger control rats. The levels of lipid peroxidation end product, malondialdehyde (MDA) the major indicator of oxidative stress, was found to increase with age (11%) and exercise training caused further elevation (28% of control). The present findings imply that the reactive oxygen species that are generated due to aging process were detoxified by the exercise induced antioxidant system in the liver tissue. These findings are also in agreement with similar changes in male animals, which clearly envisage no gender difference in the amelioration of the antioxidant enzyme system in older age due to exercise. In conclusion, it can be stated that twelve weeks treadmill exercise training has beneficial effect in improving antioxidant defense capacity by augmenting SOD, CAT and GR activities and GSH levels of older rats, thereby preventing oxidative damage to the liver tissue.     

Changes in ascorbate, glutathione, and related enzyme activities during thidiazuron-induced bud break of apple

The changes of ascorbic acid, dehydroascorbic acid, and glutathione content and related enzyme activities were studied in apple buds during dormancy and thidiazuron-induced bud break. An increase in ascorbic acid, reduced form of glutathione (GSH), total glutathione, total non-protein thiol (NPSH) and non-glutathione thiol (RSH) occurred as a result of induction by thidiazuron during bud break, whereas dehydroascorbic acid and oxidized glutathione (GSSG) decreased during the same period. Thidiazuron also enhanced the ratio of GSH/GSSG, and activities of ascorbate free radical reductase (AFR; EC 1.6.5.4), ascorbate peroxidase (EC 1.11.1.11). dehydroascorbate reductase (DHAR; EC 1.8.5.1) and glutathione reductase (GR; EC 1.6.4.2). The ascorbic acid content and the activities of AFR, ascorbate peroxidase, and DHAR peaked when buds were in the side green or green tip stage just prior to the start of rapid expansion, and declined thereafter. The GSH, NPSH, RSH, ratio of GSH/GSSG, and activities of GR increased steadily during bud development.     

Antioxidant Enzymatic System in Neuronal and Glial Cells Enriched Fractions of Rat Brain After Aluminum Exposure

The aim of this work was to investigate as to how neurons and glial cells separated from the brain cortex respond to oxidative stress induced by aluminum. Female SD rats were exposed to aluminum at the dose level of 100 mg/kg b.w. for 8 weeks. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex by sieving the trypsinated homogenate through a series of nylon meshes, followed by centrifugation on ficoll density gradient. Total glutathione content, glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-s-transferase (GST) along with antioxidant enzymes superoxide dismutase (SOD), catalase were estimated in neuronal and glial-enriched fractions in both control (N-c and G-c) and aluminum exposed animals (N-a and G-a). Secondary products of lipid peroxidation that is MDA levels were estimated by measuring the (TBARS) levels. Our results indicate that TBARS levels were significantly higher in glial cell fraction of unexposed controls (Gc) than the neuronal cells (Nc). Correspondingly the glial cells had higher levels of GSH, GSSG, GPx and GST where as neurons had higher levels of catalase, SOD and GR. Following aluminum exposures significant increase in the TBARS levels was observed in neurons as compared to glial cells which also showed a significant decrease in SOD and catalase activity. The decrease in the TBARS levels in the glial cells could be related to the increase in the GSH levels, GR activity, and GST activity which were found to be increased in glial enriched fractions following aluminum exposure. The increase in activity of various enzymes viz GR, GST in glial cells as compared to neurons suggests that glial cells are actively involved in glutathione homeostasis. Our conclusion is that glial and neurons isolated from rat cerebral cortex show a varied pattern of important antioxidant enzymes and glial cells are more capable of handling the oxidative stress conditions.     

Protective effect of silymarin on oxidative stress in rat brain

Brain is susceptible to oxidative stress and it is associated with age-related brain dysfunction. Previously, we have pointed out a dramatic decrease of glutathione levels in the rat brain after acetaminophen (APAP) oral administration overdose. Silymarin (SM) is a mixture of bioactive flavonolignans isolated from Silybum marianum (L.) Gaertn., employed usually in the treatment of alcoholic liver disease and as anti-hepatotoxic agent in humans. In this study, we have evaluated the effect of SM on enzymatic and non enzymatic antioxidant defensive systems in rat brain after APAP-induced damage. Male albino Wistar rats were treated with SM (200 mg/kg/die orally) for three days, or with APAP single oral administration (3 g/kg) or with SM (200 mg/kg/die orally) for 3 days and APAP single oral administration (3 g/kg) at third day. Successively the following parameters were measured: reduced and oxidized glutathione (GSH and GSSG), ascorbic acid (AA), enzymatic activity variations of superoxide dismutase (SOD) and malondialdehyde levels (MDA). Our results showed a significant decrease of GSH levels, AA levels and SOD activity and an increase of MDA and GSSG levels after APAP administration. After SM administration GSH and AA significantly increase and SOD activity was significantly enhanced. In the SM+APAP group, GSH values significantly increase and the others parameters remained unchanged respect to control values. These results suggest that SM may to protect the SNC by oxidative damage for its ability to prevent lipid peroxidation and replenishing the GSH levels.     

Glutathione and antioxidant enzymes in skeletal muscle: effects of fiber type and exercise intensity.

Glutathione status and antioxidant enzymes in various types of rat skeletal muscle were studied after an acute bout of exercise (Ex) at different intensities. Glutathione (GSH) and glutathione disulfide (GSSG) concentrations were the highest in soleus (SO) muscle, followed by those in deep (DVL) and then superficial (SVL) portions of vastus lateralis. In DVL, but not in SO or SVL, muscle GSH increased proportionally with Ex intensity and reached 1.8 +/- 0.08 mumol/g wet wt compared with 1.5 +/- 0.03 (P < 0.05) in resting controls (R). GSSG in DVL was increased from 0.10 +/- 0.01 mumol/g wet wt in R to 0.14 +/- 0.01 (P < 0.05) after Ex. Total glutathione (GSH + GSSG) contents in DVL were also significantly elevated with Ex, whereas GSH/GSSG ratio was unchanged. Activities of GSH peroxidase (GPX), GSSG reductase (GR), and catalase (CAT) were significantly higher in SO than in DVL and SVL, but there was no difference in superoxide dismutase activity between the three muscle types. Furthermore, Ex at moderate intensities elicited significant increases in GPX, GR, and CAT activities in DVL muscle. None of the antioxidant enzymes was affected by exercise in SO. It is concluded that rat DVL muscle is particularly vulnerable to exercise-induced free radical damage and that a disturbance of muscle GSH status is indicative of an oxidative stress.     

Acute phase immune response to exercise coexists with decreased neutrophil antioxidant enzyme defences

Long-duration or damaging exercise initiates reactions that resemble the acute phase response to infection and induces neutrophil priming for oxidative activity. Our objective was to establish the status of the antioxidant defences and of the oxidative equilibrium in the neutrophils of sportsmen prior to and after intense physical exercise. Nine voluntary male professional cyclists participated in this study. The exercise was a cycling mountain stage (171 km) and the cyclists took a mean ±SEM of 270 ±12 min to complete it. We determined the activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), the levels and activity of superoxide dismutase (SOD), the concentrations of ascorbate, glutathione and glutathione disulphide (GSSG) and DNA levels in neutrophils. The cycling stage decreased enzyme activities expressed per DNA units: CAT (33%), SOD (38%), GPx (65%); increased ascorbate concentration in neutrophils and decreased the GSH/GSSG ratio and the enzyme activities expressed per DNA units. Neutrophils could contribute to plasma antioxidant defences against oxidative stress induced by exercise because they probably provide antioxidant enzymes and ascorbate.     

Acute Phase Immune Response to Exercise Coexists with Decreased Neutrophil Antioxidant Enzyme Defences

Long-duration or damaging exercise initiates reactions that resemble the acute phase response to infection and induces neutrophil priming for oxidative activity. Our objective was to establish the status of the antioxidant defences and of the oxidative equilibrium in the neutrophils of sportsmen prior to and after intense physical exercise. Nine voluntary male professional cyclists participated in this study. The exercise was a cycling mountain stage (171 km) and the cyclists took a mean &#45 SEM of 270 &#45 12 min to complete it. We determined the activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), the levels and activity of superoxide dismutase (SOD), the concentrations of ascorbate, glutathione and glutathione disulphide (GSSG) and DNA levels in neutrophils. The cycling stage decreased enzyme activities expressed per DNA units: CAT (33%), SOD (38%), GPx (65%); increased ascorbate concentration in neutrophils and decreased the GSH/GSSG ratio and the enzyme activities expressed per DNA units. Neutrophils could contribute to plasma antioxidant defences against oxidative stress induced by exercise because they probably provide antioxidant enzymes and ascorbate.     

Lead-induced lipid peroxidation and antioxidant defense components of developing chick embryos.

Administration of lead (1.25 and 2.5 mumol/kg egg weight) to 14-day-old chick embryos enhanced the level of lipid peroxides (LPO) in tissues of liver, brain, and heart. Accumulation of LPO was maximum at 9 h after treatment with lead and returned to normal level by 72 h. Further, we have studied the levels of glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase. At 9 h posttreatment, the hepatic GR was reduced significantly with the induction of GST and considerable depletion of GSH. However, in brain and heart, both GR and GST activities were unaltered with significant reduction of GSH. Further, an increase of non-Se-dependent GPx and SOD activities were observed in liver, brain, and heart. Similarly, at 72 h, although the GPx activity was found decreased in liver and brain, the GST, catalase, and SOD activities were significantly increased in all the three tissues alike, suggesting tissue-specific changes of antioxidant defense components in response to lead treatment. Our results suggests that the elevated levels of GST, SOD, and catalase at 72 h were successful in bringing LPO levels back to normal.     

Lidocaine affects the redox environment and the antioxidant enzymatic system causing oxidative stress in the hippocampus and amygdala of adult rats

AIMS: Our objective was to investigate if oxidative stress is involved in the neural damage caused by lidocaine. MAIN METHODS: Male Wistar rats were used. The control group received 0.9% saline ip and the treated group received a single 60 mg/kg lidocaine dose ip. On days 1, 2, 5, and 10 after dosing, ten rats were sacrificed and their brains were quickly removed. The amygdala and hippocampus were dissected. Five samples were used to determine lipid peroxidation, reactive oxygen species (ROS), reduced glutathione (GSH), and oxidized glutathione (GSSG). Another five were used to measure antioxidant activities of glutathione peroxidase (GPX), catalase, Cu-Zn SOD (superoxide dismutase), Mn SOD, and total SOD. KEY FINDINGS: Ten days after injection of lidocaine, lipid peroxidation increases in the hippocampus because the ROS are enhanced from day 5, whereas in the amygdala lipid peroxidation and the ROS were enhanced only on the first day postinjection. Lidocaine causes an increased concentration of GSH and GSSG in the hippocampus from the first day. In the amygdala the GSH and GSSG content were increased at day 10. In the hippocampus the catalase activity was enhanced, whereas the total SOD and Cu-Zn SOD activities were decreased. In the amygdala the lidocaine enhances the activities of catalase and GPX, but no SOD isoenzymes were modified. SIGNIFICANCE: In this research we demonstrated that lidocaine affects the redox environment and promotes increases of the oxidative markers both in the hippocampus and amygdala but in a different pattern.     

Micromethods in single muscle fibers. 2. Determination of glutathione reductase and glutathione peroxidase

This paper extends the previous study for systems which control intracellular oxidative events in muscle and describes procedures suitable to assay glutathione peroxidase (GSHPx), glutathione reductase (GR), and total glutathione (GSH + GSSG) after fiber typing of individual muscle fibers. In human skeletal muscle, both GR and GSHPx activities were relatively low when compared to those of other tissue. No difference was found among fiber types (I, IIA, and IIB) with regard to GR activity, but in contrast GSHPx activity was significantly lower in type IIB fibers than in the other types. These results suggest that type IIB fibers may have a reduced ability to cope with hydroperoxides generated during oxidative stress, which, in turn, could lead to increased damage to membrane structures by lipid peroxidation or oxidation of sensitive intracellular thiol (-SH) enzymes by hydrogen peroxide. The Km of skeletal muscle GR for GSSG was 27 microM and for NADPH was 22 microM. If one assumes approximately 95% of total glutathione is present in the reduced state, then GSSG concentration would be of the order of 0.3 mmol/kg and under these conditions skeletal muscle GR would be efficient in all muscle fiber types.