Schisandrin B, attenuates cisplatin-induced oxidative stress, genotoxicity and neurotoxicity through modulating NF-κB pathway in mice

This study aimed to investigate the potential beneficial effect of an antioxidant lignan, Schisandrin B (Sch B), against cisplatin (cDDP) induced oxidative stress mediated geno- and neuro-toxicities. A dose of 10 mg/kg cDDP induced considerable genotoxicity in mice, and Sch B treatment attenuated the cDDP-induced DNA damage as assessed by the comet assay in the brain. The frequency of micro-nucleated erythrocyte production in bone marrow was also significantly reduced by Sch B treatment in cDDP-treated mice. In neurobehavioral studies, Sch B significantly prevented the memory deficits induced by cDDP, and had an anxiolytic effect in the elevated plus maze task. Sch B treatment significantly attenuated lipid peroxidation, acetylcholinesterase activity and nitrite levels induced by cDDP. Furthermore, Sch B effectively inhibited NF-κB and p53 activation, and cleaved caspase-3 expression in cDDP-treated mice. Hence, Sch B with potent antioxidant and neuro-protective property with no mutagenic activity would be beneficial complementary food factor against cDDP induced oxidative stress.     

Neuroprotective Effects of Bacopa monnieri in Experimental Model of Dementia

Alzheimer disease (AD) is characterized by dementia that begins as mild short term memory deficit and culminates in total loss of cognitive and executive functions. The present study was conducted to evaluate the neuroprotective potential of Bacopa monnieri (BM), an Indian traditional medicinal plant effective against cognitive impairment, in colchicine-induced dementia. Intracerebroventricular administration of colchicine (15?μg/5?μl) induced cognitive impairment in rats as assessed by elevated plus maze. This was accompanied by a significant increase in oxidative stress in term of enhanced levels of lipid peroxidation and protein carbonyls. Concomitantly, decrease in activity of antioxidant enzymes was observed in colchicine treated animals. BM (50?mg/kg body weight) supplementation reversed memory impairment observed in the colchicine treated rats. BM administration attenuated oxidative damage, as evident by decreased LPO and protein carbonyl levels and restoration in activities of the antioxidant enzymes. The activity of membrane bound enzymes (Na(+)K(+) ATPase and AChE) was altered in colchicine treated brain regions and BM supplementation was able to restore the activity of enzymes to comparable values observed in controls. The results suggest therapeutic potential of BM in the treatment of AD associated cognitive decline.     

Protective effects of aloe-emodin on scopolamine-induced memory impairment in mice and H2O2-induced cytotoxicity in PC12 cells

Aloe-emodin (AE) is one of the most important active components of Rheum officinale Baill. The present study aimed to investigate that AE could attenuate scopolamine-induced cognitive deficits via inhibiting acetylcholinesterase (AChE) activity and modulating oxidative stress. Kunming (KM) mice were received intraperitoneal injection of scopolamine (2 mg/kg) to induce cognitive impairment. Learning and memory performance were assessed in the Morris water maze (MWM). After behavioral testing, the mice were sacrificed and their hippocampi were removed for biochemical assays (superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), AChE and acetylcholine (ACh)). In vitro, we also performed the AChE activity assay and H₂O₂-induced PC12 cells toxicity assay. After 2 h exposure to 200 μM H₂O₂ in PC12 cells, the cytotoxicity were evaluated by cell viability (MTT), nitric oxide (NO)/lactate dehydrogenase (LDH) release and intracellular reactive oxygen species (ROS) production. Our results confirmed that AE showed significant improvement in cognitive deficit in scopolamine-induced amnesia animal model. Besides, it increased SOD, GPx activities and ACh content, while decreased the level of MDA and AChE activity in AE treated mice. In addition, AE was found to inhibit AChE activity (IC₅₀ = 18.37 μg/ml) in a dose-dependent manner. Furthermore, preincubation of PC12 cells with AE could prevent cytotoxicity induced by H₂O₂ and reduce significantly extracellular release of NO, LDH and intracellular accumulation of ROS. The study indicated that AE could have neuroprotective effects against Alzheimer’s disease (AD) via inhibiting the activity of AChE and modulating oxidative stress.     

Cognitive enhancing effects of alpha asarone in amnesic mice by influencing cholinergic and antioxidant defense mechanisms

The effect of α-asarone on impairment of cognitive performance caused by amnesic drug scopolamine was investigated. Treatment with α-asarone attenuated scopolamine-induced cognitive deficits as evaluated by passive avoidance and Y-maze test. Administration of α-asarone for 15 d improved memory and cognitive function as indicated by an increase in transfer latency time and spontaneous alternation in passive avoidance and the Y-maze test respectively. To understand the action of α-asarone, the levels of acetylcholinesterase (AChE), malondialdehyde (MDA), and superoxide dismutase (SOD) in the hippocampus (Hippo) and cerebral cortex (CC) of scopolamine-induced amnesic mice were evaluated. The mice treated with Scopolamine showed increased activity of AChE, MDA and SOD levels in both the Hippo and the CC area. Treatment with α-asarone attenuated the increased activity of AChE and normalized the MDA and SOD levels in the Hippo and the CC area in the scopolamine treated amnesic mice. These results suggest that α-asarone has a beneficial effect in cognitive impairment induced by dysfunction of cholinergic system in brain through inhibition of AChE activity and by influencing the antioxidant defense mechanism.     

Anthocyanins as a potential pharmacological agent to manage memory deficit,oxidative stress and alterations in ion pump activity induced by experimental sporadic dementia of Alzheimer's type

Anthocyanins (ANT) are polyphenolic flavonoids with antioxidant and neuroprotective properties. This study evaluated the effect of ANT treatment on cognitive performance and neurochemical parameters in an experimental model of sporadic dementia of Alzheimer's type (SDAT). Adult male rats were divided into four groups: control (1 ml/kg saline, once daily, by gavage), ANT (200 mg/kg, once daily, by gavage), streptozotocin (STZ, 3 mg/kg) and STZ plus ANT. STZ was administered via bilateral intracerebroventricular (ICV) injection (5 μl). ANT were administered after ICV injection for 25 days. Cognitive deficits (short-term memory and spatial memory), oxidative stress parameters, and acetylcholinesterase (AChE) and Na⁺-K⁺-ATPase activity in the cerebral cortex and hippocampus were evaluated. ANT treatment protected against the worsening of memory in STZ-induced SDAT. STZ promoted an increase in AChE and Na⁺-K⁺-ATPase total and isoform activity in both structures; ANT restored this change. STZ administration induced an increase in lipid peroxidation and decrease in the level of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), in the cerebral cortex; ANT significantly attenuated these effects. In the hippocampus, an increase in reactive oxygen species (ROS), nitrite and lipid peroxidation levels, and SOD activity and a decrease in CAT and GPx activity were seen after STZ injection. ANT protected against the changes in ROS and antioxidant enzyme levels. In conclusion, the present study showed that treatment with ANT attenuated memory deficits, protected against oxidative damage in the brain, and restored AChE and ion pump activity in an STZ-induced SDAT in rats.     

Protective Effects of Mangosteen Extract on H2O2-Induced Cytotoxicity in SK-N-SH Cells and Scopolamine-Induced Memory Impairment in Mice

Mangosteen extracts (ME) contain high levels of polyphenolic compounds and antioxidant activity. Protective effects of ME against β-amyloid peptide (Aβ), induced cytotoxicity have been reported. Here, we further studied the protective effects of ME against oxidative stress induced by hydrogen peroxide (H₂O₂) and polychlorinated biphenyls (PCBs), and demonstrated the protection against memory impairment in mice. The cytoprotective effects of ME were measured as cell viability and the reduction in ROS activity. In SK-N-SH cell cultures, 200 μg/ml ME could partially antagonize the effects of 150 or 300 µM H₂O₂ on cell viability, ROS level and caspase-3 activity. At 200, 400 or 800 µg/ml, ME reduced AChE activity of SK-N-SH cells to about 60% of the control. In vivo study, Morris water maze and passive avoidance tests were used to assess the memory of the animals. ME, especially at 100 mg/kg body weight, could improve the animal’s memory and also antagonize the effect of scopolamine on memory. The increase in ROS level and caspase-3 activity in the brain of scopolamine-treated mice were antagonized by the ME treatment. The study demonstrated cytoprotective effects of ME against H₂O₂ and PCB-52 toxicity and having AChE inhibitory effect in cell culture. ME treatment in mice could attenuate scopolamine-induced memory deficit and oxidative stress in brain.     

(-)Schisandrin B ameliorates paraquat-induced oxidative stress by suppressing glutathione depletion and enhancing glutathione recovery in differentiated PC12 cells

Exposure to paraquat (PQ; N,N'-dimethyl-4-4'-bipyridium), a potent herbicide, can lead to neuronal cell death and increased risk of Parkinson's disease because of oxidative stress. In this study, we investigated the effect of (-)schisandrin B [(-)Sch B, a potent enantiomer of schisandrin B] on PQ-induced cell injury in differentiated pheochromocytoma cells (PC12). PQ treatment caused cell injury in PC12 cells, as indicated by the significant increase in lactate dehydrogenase (LDH) leakage. Pretreatment with (-)Sch B (5 μM) protected against PQ-induced toxicity in PC12 cells, as evidenced by the significant decrease in LDH leakage. (-)Sch B induced the cytochrome P-450-mediated reactive oxygen species generation in differentiated PC12 cells. The cytoprotection afforded by (-)Sch B pretreatment was associated with an increase in cellular reduced glutathione (GSH) level as well as the enhancement of γ-glutamylcysteine ligase (GCL) and glutathione reductase (GR) activity in PQ-challenged cells. Both GCL and GR inhibitors abrogated the cytoprotective effect of (-)Sch B in PQ-challenged cells. The biochemical mechanism underlying the GSH-enhancing effect of (-)Sch B was further investigated in PC12 cells subjected to an acute peroxide challenge. Although the initial GSH depletion induced by peroxide was reduced through GR-catalyzed regeneration of GSH in (-)Sch B-pretreated cells, the later enhanced GSH recovery was mainly mediated by GCL-catalyzed GSH synthesis. The results suggest that (-)Sch B treatment may increase the resistance of dopaminergic cells against PQ-induced oxidative stress through reducing the extent of oxidant-induced GSH depletion and enhancing the subsequent GSH recovery.     

Hepatoprotective mechanism of schisandrin B: role of mitochondrial glutathione antioxidant status and heat shock proteins

In this study, the time course of schisandrin B- (Sch B-) induced changes in hepatic mitochondrial glutathione antioxidant status (mtGAS) and heat shock protein (HSP) 25/70 induction was examined to study their differential roles in the hepatoprotection afforded by Sch B pretreatment against carbon tetrachloride (CCl(4)) toxicity in mice. Dimethyl diphenyl bicarboxylate (DDB), a nonhepatoprotective analog of Sch B, was also included for comparison. The results indicate that Sch B treatment (2 mmol/kg) produced maximum enhancement in hepatic mtGAS and increases in both hepatic HSP 25 and HSP 70 levels at 24 h after dosing. While the extent of hepatoprotection afforded by Sch B pretreatment against CCl(4) was found to correlate inversely with the elapsed time postdosing, the protective effect was associated with the ability to sustain mtGAS and/or HSP 70 levels in a CCl(4)-intoxicated condition. On the other hand, DDB (2 mmol/kg) treatment, which did not sustain mtGAS and HSP 70 level, could not protect against CCl(4) toxicity. Abolition of the Sch B-mediated enhancement of mtGAS by buthionine sulfoximine/phorone did not completely abrogate the hepatoprotective action of Sch B. The results indicate that Sch B pretreatment independently enhances mtGAS and induces HSP 25/70 production, particularly under conditions of oxidative stress, thereby protecting against CCl(4) hepatotoxicity.     

Increased oxidative stress alters nucleosides metabolite levels in sickle cell anemia

Objectives: This study was conducted to assess the markers of oxidative stress, myeloperoxidase (MPO), acetylcholinesterase (AChE) and xanthine oxidase (XO) activities as well as the levels of nucleotide metabolites in sickle cell anemia (SCA) patients.

Methods: Fifteen SCA treated patients and 30 health subjects (control group) were selected. The markers of oxidative stress (levels of reactive oxygen species (ROS), plasma proteins, carbonyl content, lipid peroxidation (TBARS), total thiols (T-SH), glutathione and catalase activity), MPO, AChE and XO activities as well as the levels of nucleotide metabolites were measured in SCA patients.

Results: ROS, thiobarbituric acid-reactive substances (TBARS) and T-SH levels as well as the activities of catalase and MPO were significantly increased while glutathione level was reduced in SCA patients. Furthermore, a significant (P?P?P?P?Discussion: The altered parameters in SCA patients suggest that the generation and impairment of oxidative stress in this disease as well as antioxidant markers are contributory factors towards cellular redox homeostasis and alteration of purine metabolites.     

Synthesis of aminoalkyl-substituted coumarin derivatives as acetylcholinesterase inhibitors

Alzheimer’s disease, one of the most common forms of dementia, is a progressive neurodegenerative disorder symptomatically characterized by declines in memory and cognitive abilities. To date, the successful therapeutic strategy to treat AD is maintaining levels of acetylcholine by inhibiting acetylcholinesterase (AChE). In the present study, coumarin derivatives were designed and synthesized as AChE inhibitors based on the lead structure of scopoletin. Of those synthesized, pyrrolidine-substituted coumarins 3b and 3f showed ca. 160-fold higher AChE inhibitory activities than scopoletin. These compounds also ameliorated scopolamine-induced memory deficit in mice when administered orally at the dose of 1 and 2 mg/kg.     

Changes of rat plasma total low molecular weight antioxidant level after tabun exposure and consequent treatment by acetylcholinesterase reactivators

These experiments were performed on a rat model. The rats were divided into eight groups and consequently exposed to either a saline solution (control), atropine or a combination of atropine and tabun. The reactivation efficacy of the oximes was estimated on the rats exposed to tabun, atropine and a reactivator of AChE. The oximes HI-6, obidoxime, trimedoxime, K203 and KR-22836 were used as representative compounds of commonly available and new AChE reactivators. Besides the positive effect of the administered reactivators on blood AChE activity, the sizable modulation of low molecular weight antioxidant (LMWA) levels was also determined. The LMWA levels in the the animals treated with the oxime reactivators were decreased in comparison with the animals treated by atropine alone. It was found that the levels of LMWA returned to the level found in the control animals when either trimedoxime, K203 or KR-22836 were administered. The principle of oxime reactivator function and a novel insight into AChE activity regulation and oxidative stress is discussed.     

Erythrocyte antioxidants in aging and dementia

Age of patients and oxidative stress in brain cells may contribute to pathogenesis of Alzheimer’s disease (AD). Erythrocytes (red blood cells, RBC) are considered as passive “reporter cells” for the oxidative status of the whole body and remain poorly investigated in AD. The aim of this study was to assess whether the antioxidant status of RBC changes in aging and AD. Blood was taken from AD and non-Alzheimer’s dementia patients, aged-matched and younger controls. The antioxidant status of RBC was evaluated in each person participated in the study by measuring levels of H₂O₂, organic hydroperoxides, glutathione (GSH) and glutathione disulfide (GSSG), activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, and glucose-6-phosphate dehydrogenase. In both aging and dementia, oxidative stress in RBC was shown to increase as evidenced by elevated concentrations of H₂O₂, organic hydroperoxides, decreased GSH/GSSG ratio, and decreased glutathione S-transferase activity. Decreased glutathione peroxidase activity in RBC may be considered as a new peripheral marker for Alzheimer’s disease while changes of other parameters of oxidative stress reflect age-related events.     

Schisandrin B protects against tert-butylhydroperoxide induced cerebral toxicity by enhancing glutathione antioxidant status in mouse brain

Schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from Fructus Schisandrae, has been shown to produce antioxidant effect on rodent liver and heart. A mouse model of tert-butylhydroperoxide (t-BHP) induced cerebral toxicity was adopted for examining the antioxidant potential of Sch B in the brain. Intracerebroventricular injection of t-BHP caused a time-dependent increase in mortality rate in mice. The t-BHP toxicity was associated with an increase in the extent of cerebral lipid peroxidation and an impairment in cerebral glutathione antioxidant status, as evidenced by the abrupt decrease in reduced glutathione (GSH) level and the inhibition of Se-glutathione peroxidase activity at 5 min following t-BHP challenge. Sch B pretreatment (1 or 2 mmol/kg/day × 3) produced a dose-dependent protection against t-BHP induced mortality. The protection was associated with a decrease in the extent of lipid peroxidation and an enhancement in glutathione antioxidant status in brain tissue detectable at 5 min post t-BHP challenge, with the assessed biochemical parameters being returned to normal values at 60 min in Sch B pretreated mice at a dose of 2 mmol/kg. The ensemble of results suggests the antioxidant potential of Sch B pretreatment in protecting against cerebral oxidative stress.     

Central regulation of gastric acetylcholine metabolism and acid output: Analysis using stress and 2-deoxy-d-glucose administration in rats

The stress of immobilization in water caused a significant increase in the activity of choline acetyltransferase (CAT) and acetylcholinesterase (AChE), acetylcholine (ACh) content in the stomach and gastric acid secretion, but a decrease of choline content in rats. The increase in CAT activity began 1 h after the application of stress, peaked in 3 h and gradually decreased to normal within 7 h. Similar alterations in gastric acid secretion were observed. The ACh content in stomach tissue increased 30 min after the application of stress and remained elevated for 2.5 h. The content decreased to control levels after 5 h, and significantly increased again after 7 h. The choline content in stomach tissue significantly decreased 1 and 2 h after stress but returned to normal 3 h after the application. An increase in AChE activity was observed 2 and 7 h after the application of stress but normal levels were found after 4 h. Increases in CAT activity and acid output were also observed following administration of 2-deoxy-d-glucose (2-DG), but no changes in ACh and choline contents or AChE activity were observed. The increases in CAT activity and the acid secretion caused by stress and 2-DG administration were blocked by administration of hexamethonium. These results suggest that increases in gastric CAT, AChE activities and ACh content and a decrease of choline content in the early stages are results of increased vagus nerve activity, which influences gastric acid secretion. Furthermore, they suggest that alterations in ACh content and AChE activity at a later stage are less directly related to the increase in vagus nerve activity.     

Cognition Enhancing and Neuromodulatory Propensity of <Emphasis Type="Italic">Bacopa monniera</Emphasis> Extract Against Scopolamine Induced Cognitive Impairments in Rat Hippocampus

Cognition-enhancing activity of Bacopa monniera extract (BME) was evaluated against scopolamine-induced amnesic rats by novel object recognition test (NOR), elevated plus maze (EPM) and Morris water maze (MWM) tests. Scopolamine (2 mg/kg body wt, i.p.) was used to induce amnesia in rats. Piracetam (200 mg/kg body wt, i.p.) was used as positive control. BME at three different dosages (i.e., 10, 20 and 40 mg/kg body wt.) improved the impairment induced by scopolamine by increasing the discrimination index of NOR and by decreasing the transfer latency of EPM and escape latency of MWM tests. Our results further elucidate that BME administration has normalized the neurotransmitters (acetylcholine, glutamate, 5-hydroxytryptamine, dopamine, 3,4 dihydroxyphenylacetic acid, norepinephrine) levels that were altered by scopolamine administration in hippocampus of rat brain. BME administration also ameliorated scopolamine effect by down-regulating AChE and up-regulating BDNF, muscarinic M1 receptor and CREB expression in brain hippocampus confirms the potent neuroprotective role and these results are in corroboration with the earlier in vitro studies. BME administration showed significant protection against scopolamine-induced toxicity by restoring the levels of antioxidant and lipid peroxidation. These results indicate that, cognition-enhancing and neuromodulatory propensity of BME is through modulating the expression of AChE, BDNF, MUS-1, CREB and also by altering the levels of neurotransmitters in hippocampus of rat brain.     

Schisandrin B protects against menadione-induced hepatotoxicity by enhancing DT-diaphorase activity

Pretreating mice with schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis, at a daily dose of 1 mmol/kg for 3 days protected against menadione-induced hepatic oxidative damage in mice, as evidenced by decreases in plasma alanine aminotransferase activity (78%) and hepatic malondialdehyde level (70%), when compared with the menadione intoxicated control. In order to define the biochemical mechanism involved in the hepatoprotection afforded by Sch B pretreatment, we examined the activity of DT-diaphorase (DTD) in hepatocytes isolated from Sch B pretreated rats. Hepatocytes isolated from Sch B pretreated (a daily dose of 1 mmol/kg for 3 days) rats showed a significant increase (25%) in DTD activity. The increase in DTD activity was associated with the enhanced rate of menadione elimination in the hepatocyte culture. The ensemble of results suggests that the ability of Sch B pretreatment to enhance hepatocellular DTD activity may at least in part be attributed to the protection against menadione hepatotoxicity.     

Glutathione loading prevents free radical injury in red blood cells after storage

We have previously demonstrated that the loss of glutathione (GSH) and GSH-peroxidase (GSH-PX) in banked red blood cells (RBCs) is accompanied by oxidative modifications of lipids, proteins and loss of membrane integrity^[1]. The objective of this study was to determine whether artificial increases in antioxidant (GSH) or antioxidant enzyme (catalase) content could protect membrane damage in the banked RBCs following an oxidant challenge. RBCs stored at 1–6°C for 0, 42 and 84 days in a conventional additive solution (Adsol®) were subjected to oxidative stress using ferric/ascorbic acid (Fe/ASC) before and after enriching them with GSH or catalase using a hypotonic lysis-isoosmotic resealing procedure. This lysis-resealing procedure in the presence of GSH/catalase raised intracellular GSH and catalase concentrations 4–6 fold, yet produced only a small reduction in mean cell volume (MCV), mean cell hemoglobin (MCH) and mean cell hemoglobin concentrations (MCHC). Indicators of oxidative stress and membrane integrity were measured, including acetylcholinesterase (AChE) activity, GSH concentration, phosphatidylserine (PS) externalization (prothrombin-converting activity) and transmembrane lipid movements (¹⁴C-lyso phosphatidylcholine flip-flop and PS transport). GSH-enrichment protected AChE activity in fresh (0 day) and stored (42 and 84 days) RBCs from Fe/ASC oxidation by 10, 23 and 26%, respectively, compared with not-enriched controls. Following oxidative stress, the rate of transbilayer lipid flip-flop did not increase in fresh cells, but increased 9.3% in 42-day stored cells. Phosphatidylserine exposure, as measured by prothrombinase activity, increased 2.4-fold in fresh and 5.2-fold in 42-day stored cells exposed to Fe/ASC. Previous studies have shown that 42-day storage causes a moderate decrease in PS transport (～ 50 %), whereas transport rates declined by up to 75% in stored RBCs when challenged with Fe/ASC. GSH-enrichment prevented the increase in passive lipid flip-flop and the increase in prothrombinase activity, but offered no protection against oxidative damage of PS transport. In contrast to these effects, catalase-enrichment failed to protect GSH levels and AChE activity upon oxidative stress. Membrane protein thiol oxidation was assessed by labeling reactive protein thiols with 5-acetalamidofluorescein followed by immunoblotting with antifluorescein antibodies. Significant oxidation of membrane proteins was confirmed by a greater loss of thiols in stored RBCs than in fresh RBCs. These results demonstrate that it may be possible to prevent storage-mediated loss of AChE, increased lipid flip-flop, and increased PS exposure, by maintaining or increasing GSH levels of banked RBCs.     

Hypobaric hypoxia induces oxidative stress in rat brain

High altitude exposure results in decreased partial pressure of oxygen and an increased formation of reactive oxygen and nitrogen species (RONS), which causes oxidative damage to lipids, proteins and DNA. Exposure to high altitude appears to decrease the activity and effectiveness of antioxidant enzyme system. The antioxidant system is very less in brain tissue and is very much susceptible to hypoxic stress. The aim of the present study was to investigate the time dependent and region specific changes in cortex, hippocampus and striatum on oxidative stress markers on chronic exposure to hypobaric hypoxia. The rats were exposed to simulated high altitude equivalent to 6100 m in animal decompression chamber for 3 and 7 days. Results indicate an increase in oxidative stress as seen by increase in free radical production, nitric oxide level, lipid peroxidation and lactate dehydrogenase levels. The magnitude of increase in oxidative stress was more in 7 days exposure group as compared to 3 days exposure group. The antioxidant defence system such as reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and reduced/oxidized glutathione (GSH/GSSG) levels were significantly decreased in all the three regions. The observation suggests that the hippocampus is more susceptible to hypoxia than the cortex and striatum. It may be concluded that hypoxia differentially affects the antioxidant status in the cortex, hippocampus and striatum.     

Glutathione loading prevents free radical injury in red blood cells after storage

We have previously demonstrated that the loss of glutathione (GSH) and GSH-peroxidase (GSH-PX) in banked red blood cells (RBCs) is accompanied by oxidative modifications of lipids, proteins and loss of membrane integrity^[1]. The objective of this study was to determine whether artificial increases in antioxidant (GSH) or antioxidant enzyme (catalase) content could protect membrane damage in the banked RBCs following an oxidant challenge. RBCs stored at 1-6°C for 0, 42 and 84 days in a conventional additive solution (Adsol®) were subjected to oxidative stress using ferric/ascorbic acid (Fe/ASC) before and after enriching them with GSH or catalase using a hypotonic lysis-isoosmotic resealing procedure. This lysis-resealing procedure in the presence of GSH/catalase raised intracellular GSH and catalase concentrations 4-6 fold, yet produced only a small reduction in mean cell volume (MCV), mean cell hemoglobin (MCH) and mean cell hemoglobin concentrations (MCHC). Indicators of oxidative stress and membrane integrity were measured, including acetylcholinesterase (AChE) activity, GSH concentration, phosphatidylserine (PS) externalization (prothrombin-converting activity) and transmembrane lipid movements (¹⁴C-lyso phosphatidylcholine flip-flop and PS transport). GSH-enrichment protected AChE activity in fresh (0 day) and stored (42 and 84 days) RBCs from Fe/ASC oxidation by 10, 23 and 26%, respectively, compared with not-enriched controls. Following oxidative stress, the rate of transbilayer lipid flip-flop did not increase in fresh cells, but increased 9.3% in 42-day stored cells. Phosphatidylserine exposure, as measured by prothrombinase activity, increased 2.4-fold in fresh and 5.2-fold in 42-day stored cells exposed to Fe/ASC. Previous studies have shown that 42-day storage causes a moderate decrease in PS transport (∼ 50 %), whereas transport rates declined by up to 75% in stored RBCs when challenged with Fe/ASC. GSH-enrichment prevented the increase in passive lipid flip-flop and the increase in prothrombinase activity, but offered no protection against oxidative damage of PS transport. In contrast to these effects, catalase-enrichment failed to protect GSH levels and AChE activity upon oxidative stress. Membrane protein thiol oxidation was assessed by labeling reactive protein thiols with 5-acetalamidofluorescein followed by immunoblotting with antifluorescein antibodies. Significant oxidation of membrane proteins was confirmed by a greater loss of thiols in stored RBCs than in fresh RBCs. These results demonstrate that it may be possible to prevent storage-mediated loss of AChE, increased lipid flip-flop, and increased PS exposure, by maintaining or increasing GSH levels of banked RBCs.