Evaluation of the effect of pentoxifylline on sleep‐deprivation induced memory impairment

In this study, we examined the ability of Pentoxifylline (PTX) to prevent sleep deprivation induced memory impairment probably through decreasing oxidative stress. Sleep deprivation was chronically induced 8 h/day for 6 weeks in rats using modified multiple platform model. Concurrently, PTX (100 mg/kg) was administered to animals on daily basis. After 6 weeks of treatment, behavioral studies were conducted to test the spatial learning and memory using the Radial Arm Water Maze. Additionally, the hippocampus was dissected; and levels/activities of antioxidant defense biomarkers glutathione reduced (GSH), glutathione oxidized (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), were assessed. The results show that chronic sleep deprivation impaired short‐ and long‐term memories, which was prevented by chronic treatment with PTX. Additionally, PTX normalized sleep deprivation‐induced reduction in the hippocampus GSH/GSSG ratio (P < 0.05), and activities of GPx, catalase, and SOD (P < 0.05). In conclusion, chronic sleep deprivation induces memory impairment, and treatment with PTX prevented this impairment probably through normalizing antioxidant mechanisms in the hippocampus. © 2013 Wiley Periodicals, Inc.     

The Combined Effect of Sleep Deprivation and Western Diet on Spatial Learning and Memory: Role of BDNF and Oxidative Stress

Either sleep deprivation or Western diet can impair learning and memory via induction of oxidative stress, which results in neuronal damage and interference with the neurotransmission. In this study, we examined the combined effect of sleep deprivation and Western diet on hippocampus-dependent spatial learning and memory. In addition, possible molecular targets for sleep deprivation and Western diet-induced cognitive impairments were investigated. Sleep deprivation was induced in rats using the modified multiple platform model simultaneous with the administration of Western diet for 6 weeks. Thereafter, spatial learning and memory were tested using radial arm water maze. At the molecular level, BDNF protein and antioxidant markers including superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG, and thiobarbituric acid reactive substances (TBARS) were assessed. The results of this study revealed that sleep deprivation, Western diet, or a combination of both impair short- and long-term memory (P?<?0.05). The magnitude of the impairment induced by the combined treatment at the 24-h long-term memory was higher than that caused by each factor alone (P?<?0.05). In addition, the combined treatment reduced the levels of hippocampal BDNF, a reduction that was not detected with each factor alone. Moreover, the combined treatment reduced the hippocampal activities of SOD, catalase, GPx, ratio of GSH/GSSG, and elevated TBARS level (P?<?0.05). In conclusion, the combination of sleep deprivation and Western diet decreases BDNF levels and increases oxidative stress in the hippocampus, thus inducing memory impairment that is greater than the impairment produced by each factor alone.     

Antioxidant intervention attenuates oxidative stress in children and teenagers with Down syndrome

We previously demonstrated that systemic oxidative stress is present in Down syndrome (DS) patients. In the present study we investigated the antioxidant status in the peripheral blood of DS children and teenagers comparing such status before and after an antioxidant supplementation. Oxidative stress biomarkers were evaluated in the blood of DS patients (n = 21) before and after a daily antioxidant intervention (vitamin E 400 mg, C 500 mg) during 6 months. Healthy children (n = 18) without DS were recruited as control group. The activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), gamma-glutamyltransferase (GGT), glucose-6-phosphate dehydrogenase (G6PD) and myeloperoxidase (MPO), as well as the contents of reduced glutathione (GSH), uric acid, vitamin E, thiobarbituric acid reactive substances (TBARS), and protein carbonyls (PC) were measured. Before the antioxidant therapy, DS patients presented decreased GST activity and GSH depletion; elevated SOD, CAT, GR, GGT and MPO activities; increased uric acid levels; while GPx and G6PD activities as well as vitamin E and TBARS levels were unaltered. After the antioxidant supplementation, SOD, CAT, GPx, GR, GGT and MPO activities were downregulated, while TBARS contents were strongly decreased in DS. Also, the antioxidant therapy did not change G6PD and GST activities as well as uric acid and PC levels, while it significantly increased GSH and vitamin E levels in DS patients. Our results clearly demonstrate that the antioxidant intervention with vitamins E and C attenuated the systemic oxidative damage present in DS patients.     

Exercise prevents sleep deprivation-associated anxiety-like behavior in rats: potential role of oxidative stress mechanisms

Our previous work suggests that pharmacological induction of oxidative stress causes anxiety-like behavior in rats. Interestingly, sleep deprivation is reported to cause oxidative damage in the brain and is also reported to be anxiogenic. Minimal mechanistic insights are available. In this study, using a behavioral and biochemical approach, we investigated involvement of oxidative stress mechanisms in sleep deprivation-induced anxiety-like behavior of rats and the protective role of treadmill exercise in this process. We report that acute sleep deprivation (SD) increases oxidative stress in the cortex, hippocampus and amygdala while prior treadmill exercise prevents this increase. Serum corticosterones also increase with SD but its levels are normalized in exercised sleep-deprived rats. Also, anxiety-like behavior of rats significantly increases with SD while prior treadmill exercise prevents this increase. Protein expression of two enzymes involved in antioxidant defense, glyoxalase (GLO)-1 and glutathione reductase (GSR)-1 increased after 24 h SD in the hippocampus, cortex and amygdala while their levels were normalized in exercised sleep-deprived rats. It is plausible that oxidative stress via regulation of GLO1 and GSR1 is involved in sleep deprivation-induced anxiety-like behavior of rats.     

PCB (Aroclor 1254) enhances oxidative damage in rat brain regions: protective role of ascorbic acid

PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Oxidative stress is a contributing factor to alteration caused in neurodegenerative processes. The ability of Vitamin C to retard oxidative processes has been recognized for many years. Therefore, the present experiment was carried out to determine the antioxidant role of ascorbate on Aroclor 1254 induced oxidative stress in brain regions of albino rats. One group of rats received corn oil as vehicle for 30 days as control. The other group of rats were administered Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received Vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. The brain was dissected to cerebral cortex (Cc), cerebellum (C) and hippocampus (H). Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), reduced glutathione (GSH) and Vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase activity (AchE) were determined. Activities of SOD, CAT, GPx, GST, AchE and the concentration of GSH, Vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in brain regions of PCB treated animals. Vitamin C administration retrieved all the parameters except GST, significantly. These results suggest that PCB induces oxidative stress in rat brain by decreasing the activities of antioxidant enzymes, which can be protected by Vitamin C treatment.     

Sleep deprivation decreases superoxide dismutase activity in rat hippocampus and brainstem

Sleep deprivation by the disk-over-water technique results in a predictable syndrome of physiological changes in rats. It has been proposed that reactive oxygen species (ROS) may be responsible for some of these effects. A variety of antioxidative enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) help to regulate the level of ROS. In this study we investigated the effects of prolonged (5-11 days) sleep deprivation on the activities of SOD and GPx as well as the metabolic activity of the mitochondria (using alamar blue) in several brain regions (cortex, hippocampus, hypothalamus, brainstem and cerebellum). We show that prolonged sleep deprivation significantly decreased Cu/Zn-SOD activity in the hippocampus and brainstem, suggesting an alteration in the metabolism of ROS resulting in oxidative stress.     

Persistence of the benefit of an antioxidant therapy in children and teenagers with Down syndrome

This study examined the effect of an antioxidant intervention in biomarkers of inflammation and oxidative stress (OS) in the blood of Down syndrome (DS) children and teenagers during four different stages. A control group was composed by healthy children (n = 18), assessed once, and a Down group composed by DS patients (n = 21) assessed at the basal period (t₀), as well as after 6 months of antioxidant supplementation (t₁), after 12 months (after interruption of the antioxidant intervention for 6 months) (t₂), and again after further 6 months of antioxidant supplementation (t₃). Biomarkers of inflammation (myeloperoxidase activity – MPO and levels of IL-1β and TNF-α) and OS (thiobarbituric acid reactive substances – TBARS, protein carbonyls – PC), reduced glutathione (GSH), uric acid (UA) and vitamin E levels, as well as antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and gamma-glutamyltransferase (GGT) activities, were measured after each period. After the antioxidant supplementation, the activities of SOD, CAT, GPx, GR, GGT and MPO were downregulated, while TBARS contents were strongly decreased, the contents of GSH and vitamin E were significantly increased, and no changes in G6PD and GST activity as well as in UA and PC levels were detected. After the interruption of the antioxidant therapy for 6 months, DS patients showed elevated GPx and GGT activities and also elevated UA and TBARS levels. No changes in SOD, CAT, GR, GST, G6PD and MPO activities as well as in GSH, vitamin E, PC, TNF-α and IL-1β levels were detected. The results showed that the antioxidant intervention persistently attenuated the systemic oxidative damage in DS patients even after a relatively long period of cessation of the antioxidant intervention.     

Low plasma antioxidant status in patients with epilepsy and the role of antiepileptic drugs on oxidative stress

Background:

Oxidative stress has been implicated in various disorders including epilepsy. We studied the antioxidant status in patients with epilepsy and aimed at determining whether there was any difference in the antioxidant levels between patients and controls, patients who are not on antiepileptic drugs (AEDs), and on treatment, between individual AEDs and patients on monotherapy and polytherapy.

Materials and Methods:

Antioxidant levels like catalase, glutathione peroxidase (GPx), vitamin E, glutathione (GSH), thiol group (SH), uric acid, and total antioxidant capacity (TAC) were compared between 100 patients with epilepsy and equal number of controls. Twenty-five patients who were not on AEDs were compared with patients on AEDs and the control group. Patients were divided into monotherapy and polytherapy group and antioxidant status was compared between the two groups and between individual drugs.

Results:

Catalase, SH, vitamin E, and TAC were significantly low in patients with epilepsy than those in the control group (P < 0.001). GSH and uric acid did not show any difference; GPx in patients was significantly higher than those in the control group There were no differences in the antioxidant levels between the treated and the untreated groups; however, it was lower in untreated patients than controls (P < 0.001), suggesting that AEDs do not modify the oxidative stress. Patients on Valproate (VPA) showed higher catalase and GPx levels. Catalase was higher in the monotherapy than polytherapy group (P < 0.04).

Conclusion:

Our study found significantly low levels of antioxidant in patients as compared to controls. AED did not influence the antioxidant status suggesting that seizures induce oxidative stress.     

Regular treadmill exercise prevents sleep deprivation-induced disruption of synaptic plasticity and associated signaling cascade in the dentate gyrus

Study objectivesEvidence suggests that regular exercise can protect against learning and memory impairment in the presence of insults such as sleep deprivation. The dentate gyrus (DG) area of the hippocampus is a key staging area for learning and memory processes and is particularly sensitive to sleep deprivation. The purpose of this study was to determine the effect of regular exercise on early-phase long-term potentiation (E-LTP) and its signaling cascade in the presence of sleep deprivation.Experimental designRats were exposed to 4 weeks of regular treadmill exercise then subsequently sleep-deprived for 24 h using the modified multiple platform model before experimentation. We tested the effects of exercise and/or sleep deprivation using electrophysiological recording in the DG to measure synaptic plasticity; and Western blot analysis to quantify the levels of key signaling proteins related to E-LTP.Measurements and resultsRegular exercise prevented the sleep deprivation-induced impairment of E-LTP in the DG area as well as the sleep deprivation-associated decrease in basal protein levels of phosphorylated and total α calcium/calmodulin-dependent protein kinase II (P/total-CaMKII) and brain-derived neurotrophic factor (BDNF). High frequency stimulation (HFS) to the DG area was used to model learning stimuli and increased the P-CaMKII and BDNF levels in normal animals: yet failed to change these levels in sleep-deprived rats. However, HFS in control and sleep-deprived rats increased the levels of the phosphatase calcineurin. In contrast, exercise increased BDNF and P-CaMKII levels in exercised/sleep-deprived rats.ConclusionsRegular exercise appears to exert a protective effect against sleep deprivation-induced spatial memory impairment by inducing hippocampal signaling cascades that positively modulate basal and stimulated levels of key effectors such as P-CaMKII and BDNF, while attenuating increases in the protein phosphatase calcineurin.     

Temporal patterns of lipoperoxidation and antioxidant enzymes are modified in the hippocampus of vitamin A‐deficient rats

Animals can adapt their behavior to predictable temporal fluctuations in the environment through both, memory‐and‐learning processes and an endogenous time‐keeping mechanism. Hippocampus plays a key role in memory and learning and is especially susceptible to oxidative stress. In compensation, antioxidant enzymes activity, such as Catalase (CAT) and Glutathione peroxidase (GPx), has been detected in this brain region. Daily rhythms of antioxidant enzymes activity, as well as of glutathione and lipid peroxides levels, have been described in brain. Here, we investigate day/night variations in lipoperoxidation, CAT, and GPx expression and activity, as well as the temporal fluctuations of two key components of the endogenous clock, BMAL1 and PER1, in the rat hippocampus and evaluate to which extent vitamin A deficiency may affect their amplitude or phase. Holtzman male rats from control, vitamin A‐deficient, and vitamin A‐refed groups were sacrificed throughout a 24‐h period. Daily levels of clock proteins, lipoperoxidation, CAT and GPx mRNA, protein, and activity, were determined in the rat hippocampus obtained every 4 or 5 h. Gene expression of RARα and RXRβ was also quantified in the hippocampus of the three groups of rats. Our results show significant daily variations of BMAL1 and PER1 protein expression. Rhythmic lipoperoxidation, CAT, and GPx, expression and activity, were also observed in the rat hippocampus. Vitamin A deficiency reduced RXRβ mRNA level, as well as the amplitude of BMAL1 and PER1 daily oscillation, phase‐shifted the daily peak of lipoperoxidation, and had a differential effect on the oscillating CAT and GPx mRNA, protein, and activity. Learning how vitamin A deficiency affects the circadian gene expression in the hippocampus may have an impact on the neurobiology, nutritional and chronobiology fields, emphasizing for the first time the importance of nutritional factors, such as dietary micronutrients, in the regulation of circadian parameters in this brain memory‐and‐learning‐related region. © 2009 Wiley‐Liss, Inc.     

Sleep deprivation impairs spatial memory and decreases extracellular signal-regulated kinase phosphorylation in the hippocampus

Loss of sleep may result in memory impairment. However, little is known about the biochemical basis for memory deficits induced by sleep deprivation. Extracellular signal-regulated kinase (ERK) is involved in memory consolidation in different tasks. Phosphorylation of ERK is necessary for its activation and is an important step in mediating neuronal responses to synaptic activities. The aim of the present study was to determine the effects of total sleep deprivation (TSD) on memory and ERK phosphorylation in the brain. Rats were trained in Morris water maze to find a hidden platform (a spatial task) or a visible platform (a nonspatial task) after 6 h TSD or spontaneous sleep. TSD had no effect on spatial learning, but significantly impaired spatial memory tested 24 h after training. Nonspatial learning and memory were not impaired by TSD. Phospho-ERK levels in the hippocampus were significantly reduced after 6 h TSD compared to the controls and returned to the control levels after 2 h recovery sleep. Total ERK1 and ERK2 were slightly increased after 6 h TSD and returned to the control levels after 2 h recovery sleep. These alterations were not observed in the cortex after TSD. Protein phosphotase-1 and mitogen-activated protein kinase phosphatase-2, which dephosphorylates phospho-ERK, were also measured, but they were not altered by TSD. The impairments of both spatial memory and ERK phosphorylation indicate that the hippocampus is vulnerable to sleep loss. These results are consistent with the idea that decreased ERK activation in the hippocampus is involved in sleep deprivation-induced spatial memory impairment.     

Vitamin E deficiency does not induce compensatory antioxidant increases in central nervous system tissue of apolipoprotein E-deficient mice

Compensatory upregulation in endogenous antioxidants has been shown to accompany certain genetic and dietary deficiencies that promote oxidative stress, including that related to Alzheimer's disease. We compared antioxidant levels in brain tissue of normal and transgenic mice lacking apolipoprotein E following dietary deprivation of vitamin E or folate. As described previously, ApoE-deficient mice displayed increased levels of the endogenous antioxidant glutathione as compared to normal mice, and increased these levels further following folate deprivation. By contrast, glutathione was depleted following vitamin E deprivation in brain tissue of normal and ApoE-deficient mice. TBAR analyses confirmed increased oxidative damage following vitamin E deprivation. However, combined deprivation of folate and vitamin E resulted in levels of glutathione intermediate between those observed following deprivation of either agent, indicating that the lack of compensatory increase in glutathione following vitamin E deprivation was not due to overt neurotoxicity. Similar results were observed for total antioxidant levels in brain tissue. The differential response to vitamin E and folate deprivation is consistent with the possibility that specific differences in oxidative damage may result from deficiencies in either of these agents. The lack of a compensatory response to vitamin E deprivation highlights the importance of dietary vitamin E in prevention of chronic neurodegeneration.     

Oxidative stress status and RNA expression in hippocampus of an animal model of Alzheimer's disease after chronic exposure to aluminum

It is well established that aluminum (Al) is a neurotoxic agent that induces the production of free radicals in brain. Accumulation of free radicals may cause degenerative events of aging such as Alzheimer's disease. On the other hand, melatonin (Mel) is a known antioxidant, which can directly act as free radical scavenger, or indirectly by inducing the expression of some genes linked to the antioxidant defense. In this study, AβPP female transgenic (Tg2576) (Tg) and wild‐type mice (5 months of age) were fed with Al lactate supplemented in the diet (1 mg Al/g diet). Simultaneously, animals received oral Mel (10 mg/kg) dissolved in tap water until the end of the study at 11 months of age. Four treatment groups were included for both Tg and wild‐type mice: control, Al only, Mel only, and Al+Mel. At the end of the period of treatment, hippocampus was removed and processed to examine the following oxidative stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and thiobarbituric acid reactive substances (TBARS). Moreover, the gene expression of Cu‐ZnSOD, GR, and CAT was evaluated by real‐time RT‐PCR. Aluminum concentration in hippocampus was also determined. The biochemical changes observed in this tissue suggest that Al acts as a pro‐oxidant agent. Melatonin exerts an antioxidant action by increasing the mRNA levels of the antioxidant enzymes SOD, CAT, and GR evaluated in presence of Al and Mel, with independence of the animal model. © 2009 Wiley‐Liss, Inc.     

Sciatic nerve transection increases gluthatione antioxidant system activity and neuronal nitric oxide synthase expression in the spinal cord

Glutathione (GSH) is a major non-enzymatic antioxidant which is present in all tissues. Its protective actions occur through different pathways such its role as a substrate of antioxidant enzymes, such as glutathione peroxidase (GPx) and glutathione-S-transferase (GST). Nitric oxide (NO) is involved in many physiological processes in the central nervous system, including nociception. In spite of much evidence concerning oxidative and nitrosative stress and neuropathic pain, the exact role of these molecules in pain processing is still unknown. Sciatic nerve transection (SNT) was employed to induce neuropathic pain in rats. Glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities, glutathione (GSH) content, GSH/GSSG ratio, nitric oxide metabolites (NOx) and neuronal nitric oxide synthase (nNOS) protein expression in the lumbosacral spinal cord were determined. All of these analyses were performed in the SNT and sham groups 1, 3, 7 and 15 days after surgery. There was an increase in GPx activity and in GSH content 3 days after surgery in both sham and SNT groups, but the GSH/GSSG ratio increased only in the SNT group in this time point. nNOS expression was upregulated 7 days post SNT. NOx was detected 1 day after surgery in sham and SNT groups, but at 7 and 15 days, the increase occurred only in SNT animals. These results support the role of the gluthatione system in pain physiology and highlight the involvement of NO as an important molecule related to nociception.     

Sciatic nerve transection increases gluthatione antioxidant system activity and neuronal nitric oxide synthase expression in the spinal cord

Glutathione (GSH) is a major non-enzymatic antioxidant which is present in all tissues. Its protective actions occur through different pathways such its role as a substrate of antioxidant enzymes, such as glutathione peroxidase (GPx) and glutathione-S-transferase (GST). Nitric oxide (NO) is involved in many physiological processes in the central nervous system, including nociception. In spite of much evidence concerning oxidative and nitrosative stress and neuropathic pain, the exact role of these molecules in pain processing is still unknown. Sciatic nerve transection (SNT) was employed to induce neuropathic pain in rats. Glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities, glutathione (GSH) content, GSH/GSSG ratio, nitric oxide metabolites (NOx) and neuronal nitric oxide synthase (nNOS) protein expression in the lumbosacral spinal cord were determined. All of these analyses were performed in the SNT and sham groups 1, 3, 7 and 15 days after surgery. There was an increase in GPx activity and in GSH content 3 days after surgery in both sham and SNT groups, but the GSH/GSSG ratio increased only in the SNT group in this time point. nNOS expression was upregulated 7 days post SNT. NOx was detected 1 day after surgery in sham and SNT groups, but at 7 and 15 days, the increase occurred only in SNT animals. These results support the role of the gluthatione system in pain physiology and highlight the involvement of NO as an important molecule related to nociception.     

Inflammatory markers are associated with inhibitory avoidance memory deficit induced by sleep deprivation in rats

Sleep deprivation (SD) causes detrimental effects to the body, such as memory impairment and weight loss. SD also changes the concentration of inflammatory mediators such as cytokines, which, in turn, can affect cognitive functioning. Thus, the objective of this study was to investigate the involvement of these inflammatory mediators in inhibitory avoidance memory deficit in sleep-deprived rats. Male Wistar rats were deprived of sleep by the modified multiple platform method for 96 h, while their respective controls remained in their housing cages. To assess memory after SD, all animals underwent training, followed by the inhibitory avoidance task test 24 h later. Also, the weight of each animal was recorded daily. In the first experiment, animals received an acute administration of lipopolysaccharide (LPS, 50 or 75 μg/kg i.p.) 3 h before the inhibitory avoidance training. In the experiment 2, the animals received acute or chronic administration of anti-IL-6 antibody (Ab, 2 μg/kg i.p.). The acute administration was performed 3 h before the inhibitory avoidance training, while the chronic treatment administrations were performed daily during the SD period. The 75 μg/kg dose of LPS, but not the 50 μg/kg dose, caused a significant attenuation of memory impairment in the sleep-deprived animals. Although the treatments with the anti-IL-6 Ab did not produce any significant changes in cognitive performance, the Ab attenuated weight loss in sleep-deprived animals. Taken together, these results suggest the involvement of inflammatory mediators in the modulation of memory deficit and weight loss that are observed in sleep-deprived rats.     

Glutathione peroxidase 1 and a high cellular glutathione concentration are essential for effective organic hydroperoxide detoxification in astrocytes

Organic hydroperoxides are produced in the eicosanoid metabolism and by lipid peroxidation. To examine the contribution of glutathione peroxidase-1 (GPx1) and glutathione (GSH) in the disposal of organic hydroperoxides in brain astrocytes, primary astrocyte cultures from wild type or GPx1-deficient (GPx1(-/-)) mice were exposed to cumene hydroperoxide (CHP). After application of 100 microM CHP, the peroxide disappeared quickly from the incubation medium of wild type cells with a half-life of 9 min, whereas CHP clearance was strongly retarded in GPx1(-/-) astrocytes. Depletion of GSH by pre-incubation with buthionine sulfoximine (BSO) significantly slowed CHP clearance by wild type astrocytes, while almost completely preventing peroxide disposal by GPx1(-/-) cells. In contrast, the catalase inhibitor 3-aminotriazole (3AT) had no effect on CHP clearance. Application of CHP to wild type astrocytes was followed by a rapid and transient accumulation of GSSG, whereas in GPx1(-/-) cells no increase in the GSSG content was detected. Astrocytes from both mouse lines remained viable for up to 24 h following CHP exposure, however depletion of cellular GSH by pre-treatment with BSO compromised the viability of astrocytes, an effect that was stronger in GPx1(-/-) than in wild type cells. This cell death was almost completely prevented by iron chelators, whereas pre-incubation with iron increased CHP toxicity. These novel data demonstrate that the toxicity of organic hydroperoxides in astrocytes is iron-mediated, and that an intact GSH system is required for the effective removal of organic hydroperoxides and for protection from these peroxides.     

Risperidone reverses phencyclidine induced decrease in glutathione levels and alterations of antioxidant defense in rat brain

Perinatal phencyclidine (PCP) administration to rats represents one of the actual animal models of schizophrenia. Numerous data suggest redox dysregulation in this disease. We have previously demonstrated decreased content of the reduced glutathione (GSH) and complex disbalance of antioxidant enzymes in the brain of rats perinatally treated with PCP. The aim of this study was to elucidate whether chronic risperidone treatment can reverse these changes. The Wistar rats were perinatally treated with either PCP (10mg/kg; PCP, two groups) or saline (0.9% NaCl, two groups). At postnatal day (PN) 35, two groups of rats one NaCl and one PCP have started to receive risperidone in drinking water for nine weeks (NaCl-RSP and PCP-RSP groups). Animals were sacrificed on PN100 and the levels of GSH, the activities of γ-glutamate cysteine ligase (GCL), glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD), as well as, the concentration of lipid peroxides were determined in the different brain structures. Risperidone restored decreased GSH levels, as well as decreased γ-GCL activity in cortex and hippocampus of animals perinatally treated with PCP. Alterations in GPx and GR activities caused by perinatal PCP treatment were also reversed by risperidone in most investigated brain structures. Furthermore, chronic risperidone treatment caused the decrease in SOD activity both in control and in PCP perinatally treated groups. Increased levels of lipid peroxides noticed in hippocampus and thalamus were reversed after chronic risperidone treatment. The results of the present study demonstrate that risperidone treatment restores GSH levels and to great measure reverses antioxidant defense alterations in the brain of perinatally PCP treated rats. Further studies are necessary in order to clarify the significance of risperidone influence on oxidative stress parameters in schizophrenia.     

Differential vulnerability of immature murine neurons to oxygen-glucose deprivation

In vivo studies support selective neuronal vulnerability to hypoxia-ischemia (HI) in the developing brain. Since differences in intrinsic properties of neurons might be responsible, pure cultures containing immature neurons (6-8 days in vitro) isolated from mouse cortex and hippocampus, regions chosen for their marked vulnerability to oxidative stress, were studied under in vitro ischemic conditions-oxygen-glucose deprivation (OGD). Twenty-four hours of reoxygenation after 2.5 h of OGD induced significantly greater cell death in hippocampal than in cortical neurons (67.8% vs. 33.4%, P = 0.0068). The expression of neuronal nitric oxide synthase (nNOS) protein, production of nitric oxide (NO), and reactive oxygen species (ROS), as well as glutathione peroxidase (GPx) activity and intracellular levels of reduced glutathione (GSH), were measured as indicators of oxidative stress. Hippocampal neurons had markedly higher nNOS expression than cortical neurons by 24 h of reoxygenation, which coincided with an increase in NO production, and significantly greater ROS accumulation. GPx activity declined significantly in hippocampal but not in cortical neurons at 4 and 24 h after OGD. The decrease in GSH level in hippocampal neurons correlated with the decline of GPx activity. Our data suggest that developing hippocampal neurons are more sensitive to OGD than cortical neurons. This finding supports our in vivo studies showing that mouse hippocampus is more vulnerable than cortex after neonatal HI. An imbalance between excess prooxidant production (increased nNOS expression, and NO and ROS production) and insufficient antioxidant defenses created by reduced GPx activity and GSH levels may, in part, explain the higher susceptibility to OGD of immature hippocampal neurons.