Immunohistochemical detection of oxidative DNA damage induced by ischemia-reperfusion insults in gerbil hippocampus in vivo

Evaluation of brain injury in goats naturally infected with Coenurus cerebralis; brain specific biomarkers, acute inflammation, and DNA oxidation

This investigate goals are to establish the utility of brain-specific biomarkers (GFAP and S100B) in vivo and to assess the brain damage in C. cerebralis-infected goats using histopathological and immunopathological methods. The animal material of the study consisted of 10 healthy and 20 Coenurus cerebralis infected female hair goats. Serum GFAP and S100B concentrations were measured to determine brain damage. Serum S100B (p < 0.037), GFAP (p < 0.012), urea (p < 0.045), GGT (p < 0.001) and ALT (p < 0.001) concentrations in the C.cerebralis group were significantly higher than the control group. There was no significant difference between the C.cerebralis group and the control group for hsTnI (p > 0.078), creatinine (p > 0.099) and CK-MB (p > 0.725). In the histopathological examination, pressure atrophy and related inflammatory changes were observed due to mechanical damage of the parasite. Immunohistochemical examinations revealed that the parasite stimulated inflammation with the expression of TNF-α and caused DNA damage with the expression of 8-OHdG. As a result, when the data collected for this study are assessed as a whole, it is thought that the use of brainspecific GFAP and S100B biomarkers may be beneficial in determining brain damage in naturally infected hair goats with C.cerebralis. Changes in the levels of brain-specific biomarkers contribute significantly to determining the prognosis of the disease in vivo. Measurement of GFAP and S100B concentrations from serum offers an important alternative to the CSF method.

Erinacine A-Enriched Hericium erinaceus Mycelium Delays Progression of Age-Related Cognitive Decline in Senescence Accelerated Mouse Prone 8 (SAMP8) Mice

There have been many reports on the neuroprotective effects of Hericium erinaceus mycelium, in which the most well-known active compounds found are diterpenoids, such as erinacine A. Previously, erinacine A-enriched Hericeum erinaceus mycelium (EAHEM) was shown to decrease amyloid plaque aggregation and improve cognitive disability in Alzheimer’s disease model APP/PS1 mice. However, its effects on brain aging have not yet been touched upon. Here, we used senescence accelerated mouse prone 8 (SAMP8) mice as a model to elucidate the mechanism by which EAHEM delays the aging of the brain. Three-month-old SAMP8 mice were divided into three EAHEM dosage groups, administered at 108, 215 and 431 mg/kg/BW/day, respectively. During the 12th week of EAHEM feeding, learning and memory of the mice were evaluated by single-trial passive avoidance and active avoidance test. After sacrifice, the amyloid plaques, induced nitric oxidase synthase (iNOS) activity, thiobarbituric acid-reactive substances (TBARS) and 8-OHdG levels were analyzed. We found that the lowest dose of 108 mg/kg/BW EAHEM was sufficient to significantly improve learning and memory in the passive and active avoidance tests. In all three EAHEM dose groups, iNOS, TBARS and 8-OHdG levels all decreased significantly and showed a dose-dependent response. The results indicate that EAHEM improved learning and memory and delayed degenerative aging in mice brains.

Pyridoxine Deficiency Exacerbates Neuronal Damage after Ischemia by Increasing Oxidative Stress and Reduces Proliferating Cells and Neuroblasts in the Gerbil Hippocampus

We investigated the effects of pyridoxine deficiency on ischemic neuronal death in the hippocampus of gerbil (n = 5 per group). Serum pyridoxal 5′-phosphate levels were significantly decreased in Pyridoxine-deficient diet (PDD)-fed gerbils, while homocysteine levels were significantly increased in sham- and ischemia-operated gerbils. PDD-fed gerbil showed a reduction in neuronal nuclei (NeuN)-immunoreactive neurons in the medial part of the hippocampal CA1 region three days after. Reactive astrocytosis and microgliosis were found in PDD-fed gerbils, and transient ischemia caused the aggregation of activated microglia in the stratum pyramidale three days after ischemia. Lipid peroxidation was prominently increased in the hippocampus and was significantly higher in PDD-fed gerbils than in Control diet (CD)-fed gerbils after ischemia. In contrast, pyridoxine deficiency decreased the proliferating cells and neuroblasts in the dentate gyrus in sham- and ischemia-operated gerbils. Nuclear factor erythroid-2-related factor 2 (Nrf2) and brain-derived neurotrophic factor (BDNF) levels also significantly decreased in PDD-fed gerbils sham 24 h after ischemia. These results suggest that pyridoxine deficiency accelerates neuronal death by increasing serum homocysteine levels and lipid peroxidation, and by decreasing Nrf2 levels in the hippocampus. Additionally, it reduces the regenerated potentials in hippocampus by decreasing BDNF levels. Collectively, pyridoxine is an essential element in modulating cell death and hippocampal neurogenesis after ischemia.

Cuprizone Affects Hypothermia-Induced Neuroprotection and Enhanced Neuroblast Differentiation in the Gerbil Hippocampus after Ischemia

In the present study, we investigated the effects of cuprizone on cell death, glial activation, and neuronal plasticity induced by hypothermia after ischemia in gerbils. Food was supplemented with cuprizone at 0.2% ad libitum for eight weeks. At six weeks after diet feeing, gerbils received transient forebrain ischemia with or without hypothermic preconditioning. Cuprizone treatment for 8 weeks increased the number of astrocytes, microglia, and pro-inflammatory cytokine levels in the hippocampus. In addition, cuprizone treatment significantly decreased the number of proliferating cells and neuroblasts in the dentate gyrus. Brain ischemia caused cell death, disruption of myelin basic proteins, and reactive gliosis in CA1. In addition, ischemia significantly increased pro-inflammatory cytokines and the number of proliferating cells and differentiating neuroblasts in the dentate gyrus. In contrast, hypothermic conditioning attenuated these changes in CA1 and the dentate gyrus. However, cuprizone treatment decreased cell survival induced by hypothermic preconditioning after ischemia and increased the number of reactive microglia and astrocytes in CA1 as well as that of macrophages in the subcallosal zone. These changes occurred because the protective effect of hypothermia in ischemic damage was disrupted by cuprizone administration. Furthermore, cuprizone decreased ischemia-induced proliferating cells and neuroblasts in the dentate gyrus.

Transduced Tat-aldose Reductase Protects Hippocampal Neuronal Cells against Oxidative Stress-induced Damage

Aldose reductase (AR) protein, a member of the NADPH-dependent aldo-keto reductase family, reduces a wide range of aldehydes and enhances cell survival by inhibition of oxidative stress. Oxidative stress is known as one of the major pathological factor in ischemia. Since the precise function of AR protein in ischemic injury is fully unclear, we examined the function of AR protein in hippocampal neuronal (HT-22) cells and in an animal model of ischemia in this study. Cell permeable Tat-AR protein was produced by fusion of protein transduction domain in Tat for delivery into the cells. Tat-AR protein transduced into HT-22 cells and significantly inhibited cell death and regulated the mitogen-activate protein kinases (MAPKs), Bcl-2, Bax, and Caspase-3 under oxidative stress condition. In an ischemic animal model, Tat-AR protein transduced into the brain tissues through the blood-brain barrier (BBB) and drastically decreased neuronal cell death in hippocampal CA1 region. These results indicate that transduced Tat-AR protein has protective effects against oxidative stress-induced neuronal cell death in vitro and in vivo, suggesting that Tat-AR protein could be used as potential therapeutic agent in ischemic injury.

Risperidone Treatment after Transient Ischemia Induces Hypothermia and Provides Neuroprotection in the Gerbil Hippocampus by Decreasing Oxidative Stress

Compelling evidence from preclinical and clinical studies has shown that mild hypothermia is neuroprotective against ischemic stroke. We investigated the neuroprotective effect of post-risperidone (RIS) treatment against transient ischemic injury and its mechanisms in the gerbil brain. Transient ischemia (TI) was induced in the telencephalon by bilateral common carotid artery occlusion (BCCAO) for 5 min under normothermic condition (37 ± 0.2 °C). Treatment of RIS induced hypothermia until 12 h after TI in the TI-induced animals under uncontrolled body temperature (UBT) compared to that under controlled body temperature (CBT) (about 37 °C). Neuroprotective effect was statistically significant when we used 5 and 10 mg/kg doses (p < 0.05, respectively). In the RIS-treated TI group, many CA1 pyramidal neurons of the hippocampus survived under UBT compared to those under CBT. In this group under UBT, post-treatment with RIS to TI-induced animals markedly attenuated the activation of glial cells, an increase of oxidative stress markers [dihydroethidium, 8-hydroxy-2' -deoxyguanosine (8-OHdG), and 4-Hydroxynonenal (4-HNE)], and a decrease of superoxide dismutase 2 (SOD2) in their CA1 pyramidal neurons. Furthermore, RIS-induced hypothermia was significantly interrupted by NBOH-2C-CN hydrochloride (a selective 5-HT_2A receptor agonist), but not bromocriptine mesylate (a D₂ receptor agonist). Our findings indicate that RIS-induced hypothermia can effectively protect neuronal cell death from TI injury through attenuation of glial activation and maintenance of antioxidants, showing that 5-HT_2A receptor is involved in RIS-induced hypothermia. Therefore, RIS could be introduced to reduce body temperature rapidly and might be applied to patients for hypothermic therapy following ischemic stroke.

MAPK pathway mediates the anti-oxidative effect of chicoric acid against cerebral ischemia-reperfusion injury in vivo

The aim of the present study was to investigate the protective effect of chicoric acid on oxidative stress and inflammation in rats with cerebral ischemia-reperfusion injury. A cerebral ischemia-reperfusion injury rat model was created via transient middle cerebral artery occlusion (MCAO) and rats were treated with various doses of chicoric acid (0, 1, 10 and 100 mg/kg). Neurological deficits and infarct volume were used to estimate the protective effects of chicoric acid treatment. Levels of reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, nitric oxide (NO) and prostaglandin E2 (PGE2) were assessed. Western blot analysis was also used to measure the expression of cyclooxygenase (COX)-2, p38-mitogen activated protein kinase (MAPK), c-Jun, phosphorylated protein kinase B (p-AKT) and AKT. Chicoric acid exposure was observed to reduce neurological deficits and infarct volume in rats with cerebral ischemia-reperfusion injury. In addition, ROS production and inflammation were significantly suppressed following treatment with chicoric acid. Chicoric acid was demonstrated to significantly inhibit the upregulation of NO and PGE2 levels in rats following MCAO. Furthermore, chicoric acid significantly suppressed the MCAO-induced promotion of COX-2, p38-MAPK and c-Jun protein expression and enhanced the inhibition of p-AKT/AKT. These results suggest that chicoric acid has a protective effect, preventing oxidative stress and inflammation in rats with cerebral ischemia-reperfusion injury via the p38-MAPK, c-Jun and AKT signaling pathways.

Beneficial effects of Panax ginseng for the treatment and prevention of neurodegenerative diseases: past findings and future directions

In recent years, several therapeutic drugs have been rationally designed and synthesized based on the novel knowledge gained from investigating the actions of biologically active chemicals derived from foods, plants, and medicinal herbs. One of the major advantages of these naturalistic chemicals is their ability to interact with multiple targets in the body resulting in a combined beneficial effect. Ginseng is a perennial herb (Araliaceae family), a species within the genus Panax, and a highly valued and popular medicinal plant. Evidence for the medicinal and health benefits of Panax ginseng and its components in preventing neurodegeneration has increased significantly in the past decade. The beneficial effects of P. ginseng on neurodegenerative diseases have been attributed primarily to the antioxidative and immunomodulatory activities of its ginsenoside components. Mechanistic studies on the neuroprotective effects of ginsenosides revealed that they act not only as antioxidants but also as modulators of intracellular neuronal signaling and metabolism, cell survival/death genes, and mitochondrial function. The goal of the present paper is to provide a brief review of recent knowledge and developments concerning the beneficial effects as well as the mechanism of action of P. ginseng and its components in the treatment and prevention of neurodegenerative diseases.

56Fe irradiation-induced cognitive deficits through oxidative stress in mice

The rapid growth of manned space flight results in more concerns about health risks and an urgent need for health assessment for space travel. The cosmic environment is complicated and full of radiation. Because of their strong biological effects, heavy ions such as ⁵⁶Fe ions are considered to be an important component of these lethal galactic rays. Due to the importance of brain function to astronauts, we explored the long-term effects and potential mechanisms of ⁵⁶Fe ion radiation on mice brains containing the hippocampus. In our study, radiation doses were carried out with 0.5 Gy, 1 Gy or 2 Gy. One month after whole-body ⁵⁶Fe ion exposure, the Morris water maze test was performed to assess the ability of spatial learning and memory. A histological study was used for pathology analysis of the hippocampus. Alteration of oxidative stress was reflected by MDA and GSH and oxidative DNA damage marked by 8-OHdG was detected by biochemical and immunofluorescence methods. In our results, irradiated groups exhibited significant changes in behavioral performance and also showed loose and edematous arrangement in the pathological characteristics. Furthermore, whole brain levels of MDA, GSH and 8-OHdG increased in the irradiated groups. In addition, increased expression of 8-OHdG can also be detected by immunofluorescence in the hippocampus. Our findings revealed a linkage between radiation-induced oxidative stress and behavioral deficits. This may suggest an underlying mechanism of brain tissue protection and risk assessment in manned space flight.

Synergistic cardioprotective effects of Danshensu and hydroxysafflor yellow A against myocardial ischemia-reperfusion injury are mediated through the Akt/Nrf2/HO-1 pathway

In clinical practice, the traditional Chinese medicinal herbs, Radix Salvia Miltiorrhiza and Carthamus tinctorius L., are usually prescribed in combination due to their significant cardioprotective effects. However, the mechanisms responsible for these combined effects remain unknown. Thus, in this study, we investigated the mechanisms responsible for the combined effects of Danshensu (DSS) and hydroxysafflor yellow A (HSYA) by establishing a rat model of myocardial ischemia/reperfusion (MI/R), as well as a model of hypoxia/reoxygenation (H/R) using H9c2 cells. The combination index (CI) was calculated using the median-effect method. DSS and HSYA in combination led to a CI value of <1 as regards infarct size in vivo and cell viability in vitro. The rats with MI/R injury that were treated with DSS and/or HSYA were found to have significantly lower levels of creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) and malondialdehyde (MDA), and a lower expressoin of 8-hydroxydeoxyguanosine (8-OHdG), and markedly enhanced superoxide dismutase (SOD) activity. Our in vitro experiments revealed that the cells treated with DSS and/or HSYA had a reduced lactate dehydrogenase (LDH) activity and a decreased percentage of cell apoptosis (increased Bcl-2/Bax ratio, decreased expression of cleaved caspase-3). DSS and HSYA increased the expression of heme oxygenase-1 (HO-1), the phosphorylation of Akt and the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Furthermore, the Akt inhibitor, LY294002, partially hampered the expression of Nrf2 and HO-1. The HO-1 inhibitor, zinc protoporphyrin IX (ZnPP‑IX), did not decrease the expression of p-Akt and Nrf2, although it abolished the anti-apoptotic and antioxidant effects of DSS and HSYA. The findings of our study thus demonstrate that DSS and HSYA confer synergistic cardioprotective effects through the Akt/Nrf2/HO-1 signaling pathway, to certain extent, by enhancing the antioxidant defense system and exerting anti-apoptotic effects.

Monocarboxylate transporter 4 plays a significant role in the neuroprotective mechanism of ischemic preconditioning in transient cerebral ischemia

Monocarboxylate transporters (MCTs), which carry monocarboxylates such as lactate across biological membranes, have been associated with cerebral ischemia/reperfusion process. In this study, we studied the effect of ischemic preconditioning (IPC) on MCT4 immunoreactivity after 5 minutes of transient cerebral ischemia in the gerbil. Animals were randomly designated to four groups (sham-operated group, ischemia only group, IPC + sham-operated group and IPC + ischemia group). A serious loss of neuron was found in the stratum pyramidale of the hippocampal CA1 region (CA1), not CA2/3, of the ischemia-only group at 5 days post-ischemia; however, in the IPC + ischemia groups, neurons in the stratum pyramidale of the CA1 were well protected. Weak MCT4 immunoreactivity was found in the stratum pyramidale of the CA1 in the sham-operated group. MCT4 immunoreactivity in the stratum pyramidale began to decrease at 2 days post-ischemia and was hardly detected at 5 days post-ischemia; at this time point, MCT4 immunoreactivity was newly expressed in astrocytes. In the IPC + sham-operated group, MCT4 immunoreactivity in the stratum pyramidale of the CA1 was increased compared with the sham-operated group, and, in the IPC + ischemia group, MCT4 immunoreactivity was also increased in the stratum pyramidale compared with the ischemia only group. Briefly, present findings show that IPC apparently protected CA1 pyramidal neurons and increased or maintained MCT4 expression in the stratum pyramidale of the CA1 after transient cerebral ischemia. Our findings suggest that MCT4 appears to play a significant role in the neuroprotective mechanism of IPC in the gerbil with transient cerebral ischemia.

Ischemic preconditioning maintains the immunoreactivities of glucokinase and glucokinase regulatory protein in neurons of the gerbil hippocampal CA1 region following transient cerebral ischemia

Glucokinase (GK) is involved in the control of blood glucose homeostasis. In the present study, the effect of ischemic preconditioning (IPC) on the immunoreactivities of GK and its regulatory protein (GKRP) following 5 min of transient cerebral ischemia was investigated in gerbils. The gerbils were randomly assigned to four groups (sham-operated group, ischemia-operated group, IPC + sham-operated group and IPC + ischemia-operated group). IPC was induced by subjecting the gerbils to 2 min of ischemia, followed by 1 day of recovery. In the ischemia-operated group, a significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) at 5 days post-ischemia; however, in the IPC+ischemia-operated group, the neurons in the SP were well protected. Following immunohistochemical investigation, the immunoreactivities of GK and GKRP in the neurons of the SP were markedly decreased in the CA1, but not the CA2/3, from 2 days post-ischemia, and were almost undetectable in the SP 5 days post-ischemia. In the IPC + ischemia-operated group, the immunoreactivities of GK and GKRP in the SP of the CA1 were similar to those in the sham-group. In brief, the findings of the present study demonstrated that IPC notably maintained the immunoreactivities of GK and GKRP in the neurons of the SP of CA1 following ischemia-reperfusion. This indicated that GK and GKRP may be necessary for neuron survival against transient cerebral ischemia.

p63 Expression in the Gerbil Hippocampus Following Transient Ischemia and Effect of Ischemic Preconditioning on p63 Expression in the Ischemic Hippocampus

p63 is a transcription factor of p53 gene family, which are involved in development, differentiation and cell response to stress; however, its roles in ischemic preconditioning (IPC) in the brain are not clear. In the present study, we investigated the effect of IPC on p63 immunoreactivity caused by 5 min of transient cerebral ischemia in gerbils. IPC was induced by subjecting the gerbils to 2 min of transie ischemia 1 day prior to 5 min of transient ischemia. The animals were randomly assigned to four groups (sham-operated-group, ischemia-operated-group, IPC plus (+)-sham-operated-group and IPC + ischemia-operated-group). The number of viable neurons in the stratum pyramidale of the hippocampal CA1 region (CA1) was significantly increased by IPC + ischemia-operated-group compared with that in the ischemia-operated-group 5 days after ischemic insult. We found that strong p63 immunoreactivity was detected in the CA1 pyramidal neurons in the sham-operated-group, and the immunoreactivity was decreased with time after ischemia-reperfusion. In addition, strong p63 immunoreactivity was newly expressed in microglial cells of the CA1 region from 2 days after ischemia-reperfusion. In all the IPC + sham-operated-groups, p63 immunoreactivity in the CA1 pyramidal neurons was similar to that in the sham-operated-group, and the immunoreactivity was well maintained in the IPC + ischemia-operated-groups after cerebral ischemia. In brief, our present findings show that IPC dramatically protected the reduction of p63 immunoreactivity in the pyramidal neurons of the CA1 region after ischemia-reperfusion, and this result suggests that the expression of p63 may be necessary for neurons to survive after transient cerebral ischemia.

Enhancement of the neuroprotective activity of Hericium erinaceus mycelium co-cultivated with Allium sativum extract

This study investigated the neuroprotective effects of Hericium erinaceus mycelium enriched with garlic extract (HGE) on rat pheochromocytoma nerve cells (PC12). The survival rates of the PC12 nerve cells and the neurite-bearing cells after the addition of HGE were estimated as 3.5 × 10(3) viable cells/ml and 2.3 × 10(3) viable cells/ml, respectively, which were 50% and 30% higher, respectively, compared with the untreated group. For the in vivo ischemia experiments, after treatment with the HGE extract, the hippocampal CA1 region was more strongly stained (>20%) than the control group, and the HGE extract also promoted higher staining levels than HFB, HM and HGEF, and even the garlic extract. This result indicates that HGE must have neuroprotective effects. Furthermore, HGE greatly decreased p21 gene expression to approximately 70% of the control and decreased p21 gene expression to even lower levels compared with HM, HGEF and the garlic extract. This work suggests that a synergistic effect of the H. erinaceus mycelium and the garlic extract (mainly allicin) exist because the amount of allicin in HGE (5.81 µg/ml) was lower than the garlic extract itself (6.89 µg/ml).

Ischemic preconditioning protects hippocampal pyramidal neurons from transient ischemic injury via the attenuation of oxidative damage through upregulating heme oxygenase-1

Ischemic preconditioning (IPC) provides neuroprotection against subsequent severe ischemic injury by activating specific mechanisms. In this study, we tested the hypothesis that IPC attenuates postischemic neuronal death via heme oxygenase-1 (HO-1). Animals used in this study were randomly assigned to 4 groups; sham-operated group, ischemia-operated group, IPC plus (+) sham-operated group and IPC+ischemia-operated group. IPC was induced by subjecting gerbils to 2min of ischemia followed by 1 day of recovery. A significant loss of neurons was observed in pyramidal neurons of the hippocampal CA1 region (CA1) in the ischemia-operated groups at 5 days postischemia. In the IPC+ischemia-operated groups, CA1 pyramidal neurons were well protected. The level of HO-1 protein and its activity increased significantly in the CA1 of the IPC+sham-operated group, and the level and activity was maintained in all the time after ischemia-reperfusion compared with the ischemia-operated groups. HO-1 immunoreactivity was induced in the CA1 pyramidal neurons in both IPC+sham-operated- and IPC+ischemia-operated groups. We also found that levels or immunoreactivities of superoxide anion, 8-hydroxy-2'-deoxyguanosine and 4-hydroxy-2-nonenal were significantly decreased in the CA1 of both IPC+sham-operated- and IPC+ischemia-operated groups. Whereas, treatment with zinc protoporphyrin IX (a HO-1 inhibitor) into the IPC+ischemia-operated groups did not preserve the IPC-mediated increase of HO-1 and lost beneficial effects of IPC by inhibiting ischemia-induced DNA damage and lipid peroxidation. In brief, IPC protects CA1 pyramidal neurons from ischemic injury by upregulating HO-1, and we suggest that the enhancement of HO-1 expression by IPC may be a legitimate strategy for a therapeutic intervention of cerebral ischemic damage.

Bmi1 enhances skeletal muscle regeneration through MT1-mediated oxidative stress protection in a mouse model of dystrophinopathy

Enhanced polycomb complex protein Bmi1 expression in adult stem cells of the skeletal muscle leads to improved muscle function in a model of Duchenne Muscular Dystrophy via metallothionein1-mediated protection from oxidative stress.

The Polycomb group (PcG) protein Bmi1 is an essential epigenetic regulator of stem cell function during normal development and in adult organ systems. We show that mild up-regulation of Bmi1 expression in the adult stem cells of the skeletal muscle leads to a remarkable improvement of muscle function in a mouse model of Duchenne muscular dystrophy. The molecular mechanism underlying enhanced physiological function of Bmi1 depends on the injury context and it is mediated by metallothionein 1 (MT1)–driven modulation of resistance to oxidative stress in the satellite cell population. These results lay the basis for developing Bmi1 pharmacological activators, which either alone or in combination with MT1 agonists could be a powerful novel therapeutic approach to improve regeneration in muscle wasting conditions.

Effects of ischemic preconditioning on VEGF and pFlk-1 immunoreactivities in the gerbil ischemic hippocampus after transient cerebral ischemia

Ischemia preconditioning (IPC) displays an important adaptation of the CNS to sub-lethal ischemia. In the present study, we examined the effect of IPC on immunoreactivities of VEGF-, and phospho-Flk-1 (pFlk-1) following transient cerebral ischemia in gerbils. The animals were randomly assigned to four groups (sham-operated-group, ischemia-operated-group, IPC plus (+) sham-operated-group, and IPC+ischemia-operated-group). IPC was induced by subjecting gerbils to 2 min of ischemia followed by 1 day of recovery. In the ischemia-operated-group, a significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) alone 5 days after ischemia-reperfusion, however, in all the IPC+ischemia-operated-groups, pyramidal neurons in the SP were well protected. In immunohistochemical study, VEGF immunoreactivity in the ischemia-operated-group was increased in the SP at 1 day post-ischemia and decreased with time. Five days after ischemia-reperfusion, strong VEGF immunoreactivity was found in non-pyramidal cells, which were identified as pericytes, in the stratum oriens (SO) and radiatum (SR). In the IPC+sham-operated- and IPC+ischemia-operated-groups, VEGF immunoreactivity was significantly increased in the SP. pFlk-1 immunoreactivity in the sham-operated- and ischemia-operated-groups was hardly found in the SP, and, from 2 days post-ischemia, pFlk-1 immunoreactivity was strongly increased in non-pyramidal cells, which were identified as pericytes. In the IPC+sham-operated-group, pFlk-1 immunoreactivity was significantly increased in both pyramidal and non-pyramidal cells; in the IPC+ischemia-operated-groups, the similar pattern of VEGF immunoreactivity was found in the ischemic CA1, although the VEGF immunoreactivity was strong in non-pyramidal cells at 5 days post-ischemia. In brief, our findings show that IPC dramatically augmented the induction of VEGF and pFlk-1 immunoreactivity in the pyramidal cells of the CA1 after ischemia-reperfusion, and these findings suggest that the increases of VEGF and Flk-1 expressions may be necessary for neurons to survive from transient ischemic damage.

Pomegranate extract protects against cerebral ischemia/reperfusion injury and preserves brain DNA integrity in rats

AIM

Interruption to blood flow causes ischemia and infarction of brain tissues with consequent neuronal damage and brain dysfunction. Pomegranate extract is well tolerated, and safely consumed all over the world. Interestingly, pomegranate extract has shown remarkable antioxidant and anti-inflammatory effects in experimental models. Many investigators consider natural extracts as novel therapies for neurodegenerative disorders. Therefore, this study was carried out to investigate the protective effects of standardized pomegranate extract against cerebral ischemia/reperfusion-induced brain injury in rats.

MAIN METHODS

Adult male albino rats were randomly divided into sham-operated control group, ischemia/reperfusion (I/R) group, and two other groups that received standardized pomegranate extract at two dose levels (250, 500 mg/kg) for 15 days prior to ischemia/reperfusion (PMG250+I/R, and PMG500+I/R groups). After I/R or sham operation, all rats were sacrificed and brains were harvested for subsequent biochemical analysis.

KEY FINDINGS

Results showed reduction in brain contents of MDA (malondialdehyde), and NO (nitric oxide), in addition to enhancement of SOD (superoxide dismutase), GPX (glutathione peroxidase), and GRD (glutathione reductase) activities in rats treated with pomegranate extract prior to cerebral I/R. Moreover, pomegranate extract decreased brain levels of NF-κB p65 (nuclear factor kappa B p65), TNF-α (tumor necrosis factor-alpha), caspase-3 and increased brain levels of IL-10 (interleukin-10), and cerebral ATP (adenosine triphosphate) production. Comet assay showed less brain DNA (deoxyribonucleic acid) damage in rats protected with pomegranate extract.

SIGNIFICANCE

The present study showed, for the first time, that pre-administration of pomegranate extract to rats, can offer a significant dose-dependent neuroprotective activity against cerebral I/R brain injury and DNA damage via antioxidant, anti-inflammatory, anti-apoptotic and ATP-replenishing effects.

Changes and expressions of Redd1 in neurons and glial cells in the gerbil hippocampus proper following transient global cerebral ischemia

Redd1 (known as RTP801/Dig2/DDIT4) is a stress-induced protein, and it is known to be regulated in response to some stresses including hypoxia and oxidative stress. In the present study, we investigated the time-dependent changes in Redd1 immunoreactivity and its protein levels in the gerbil hippocampus proper (CA1-3 regions) after 5 min of transient global cerebral ischemia using immunohistochemistry and Western blot analysis. Redd1 immunoreactivity was apparently changed in the pyramidal neurons of the ischemic CA1 region, not in the pyramidal neurons of the ischemic CA2/3 region. Redd1 immunoreactivity in the CA1 pyramidal neurons was significantly increased at 6 h post-ischemia, decreased until 1 day post-ischemia, increased again at 2 days post-ischemia and weakly observed at 5 days post-ischemia. Especially, at 5 days after ischemic damage, Redd1 immunoreactivity was newly expressed in astrocytes and GABAergic interneurons in the CA1 region. Redd1 protein levels in the ischemic CA1 region were changed like the pattern of the Redd1 immunoreactivity. These results indicate that Redd1 immunoreactivity and protein levels are increased in the ischemic CA1 region at an early time after ischemic damage and that the increased Redd1 expression may be closely related to the delayed neuronal death of the CA1 pyramidal neurons following 5 min of transient global cerebral ischemia.

Epigenetic regulation of survivin by Bmi1 is cell type specific during corticogenesis and in gliomas

Polycomb group proteins are essential regulators of stem cell function during embryonic development and in adult tissue homeostasis. Bmi1, a key component of the Polycomb Repressive Complex 1, is highly expressed in undifferentiated neural stem cells (NSC) as well as in several human cancers including high-grade gliomas--highly aggressive brain tumors. Using a conditional gene activation approach in mice, we show that overexpression of Bmi1 induces repressive epigenetic regulation of the promoter of Survivin, a well-characterized antiapoptotic protein. This phenomenon is cell type-specific and it leads to apoptotic death of progenitor cells exclusively upon commitment toward a neuronal fate. Moreover, we show that this is triggered by increased oxidative stress-induced DNA damage. In contrast, undifferentiated NSC as well as glioma-initiating cells display an open chromatin configuration at the Survivin promoter and do not undergo apoptotic death. These findings raise the possibility that normal and neoplastic stem cells depend on the same mechanism for surviving the hyperproliferative state induced by increased Bmi1 expression.

Repeated short-term daily exercise ameliorates oxidative cerebral damage and the resultant motor dysfunction after transient ischemia in rats

Long-term exercise prior to brain ischemia enhances the activities of antioxidant enzymes and leads to a significant reduction in brain damage and neurological deficits in rats subjected to transient middle cerebral artery occlusion. However, it has not been established whether relatively short-term exercise generates similar results following middle cerebral artery occlusion. We aimed to determine whether short-term exercise could reduce oxidative damage and prevent sensori-motor dysfunction. Male Wistar rats were subjected to perform daily exercise on a treadmill for 30 min at a speed of 15 m/min for 3 weeks, followed by a 90-min middle cerebral artery occlusion. Animals were assessed after middle cerebral artery occlusion for neurological deficits and sensori-motor function. Brain tissues were processed to evaluate infarct volume and oxidative damage. Oxidative stress was assessed using immunohistochemistry for 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Antioxidant enzymes were evaluated using immunohistochemistry for thioredoxin and activity assay for superoxide dismutase. Exercise for 3 weeks decreased the severity of paralysis and impairment in forelimb motor coordination. Furthermore, exercise had effect on superoxide dismutase and reduced the infarct volume and the number of cells immunopositive for 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Our results suggest that pre-conditioning treadmill exercise for 3 weeks is useful for ameliorating ischemia-induced brain injury.

Neuroprotective effects of Alpinia katsumadai against experimental ischemic damage via control of oxidative stress

CONTEXT

Alpinia katsumadai (Zingiberaceae) has been identified by the National Plant Quarantine Service in Korea. The extract of Alpinia katsumadai seed (EAKS) has antioxidant activities.

OBJECTIVE

We investigated the neuroprotective effects of EAKS on ischemic damage in the gerbil hippocampal CA1 region after transient cerebral ischemia.

MATERIALS AND METHODS

The ethanol extract of EAKS was obtained by organic solvent, collected in Kangwon province (South Korea) and orally administered using a feeding needle once a day for one week before transient cerebral ischemia in gerbils.

RESULT

We adapted oral administration of 25 and 50 mg/kg EAKS because there are no data about the absorption and metabolism of EKAS. We found a significant neuroprotection in the 50 mg/kg EAKS-treated ischemia group, not in the 25 mg/kg EAKS-treated ischemia group, at 4 days ischemia-reperfusion (I-R). In the 50 mg/kg EAKS-treated ischemia group, about 68% of pyramidal neurons in the CA1 region were immunostained with neuronal nuclei (NeuN) 4 days after I-R, compared to the vehicle-treated ischemia group. 8-Hydroxy-2'-deoxyguanosine (a marker for DNA damage) and 4-hydroxy-2-nonenal (a marker for lipid peroxidation) immunoreactivity in the CA1 region of the EAKS-treated ischemia group were not markedly changed compared to the vehicle-treated ischemia group. In addition, Cu,Zn- and Mn-SOD immunoreactivity in the CA1 region of the EAKS-treated ischemia group were increased compared to the vehicle-treated ischemia group.

DISCUSSION

Repeated supplements of EAKS could protect neurons against ischemic damage, showing that DNA damage and lipid peroxidation are attenuated and SODs are increased in the ischemic CA1 region.

Effects of transient cerebral ischemia on the expression of DNA methyltransferase 1 in the gerbil hippocampal CA1 region

DNA methylation is a key epigenetic modification of DNA that is catalyzed by DNA methyltransferases (Dnmt). Increasing evidences suggest that DNA methylation in neurons regulates synaptic plasticity as well as neuronal network activity. In the present study, we investigated the changes in DNA methyltransferases 1 (Dnmt1) immunoreactivity and its protein levels in the gerbil hippocampal CA1 region after 5 min of transient global cerebral ischemia. CA1 pyramidal neurons were well stained with NeuN (a neuron-specific soluble nuclear antigen) antibody in the sham-group, Four days after ischemia-reperfusion (I-R), NeuN-positive ((+)) cells were significantly decreased in the stratum pyramidale (SP) of the CA1 region, and many Fluro-Jade B (a marker for neuronal degeneration)(+) cells were observed in the SP. Dnmt1 immunoreactivity was well detected in all the layers of the sham-group. Dnmt1 immunoreactivity was hardly detected only in the stratum pyramidale of the CA1 region from 4 days post-ischemia; however, at these times, Dnmt1 immunoreactivity was newly expressed in GABAergic interneurons or astrocytes in the ischemic CA1 region. In addition, the level of Dnmt1 was lowest at 4 days post-ischemia. In brief, both the Dnmt1 immunoreactivity and protein levels were distinctively decreased in the ischemic CA1 region 4 days after transient cerebral ischemia. These results indicate that the decrease of Dnmt1 expression at 4 days post-ischemia may be related to ischemia-induced delayed neuronal death.

Release of mitochondrial apoptogenic factors and cell death are mediated by CK2 and NADPH oxidase

Activation of the NADPH oxidase subunit, NOX2, and increased oxidative stress are associated with neuronal death after cerebral ischemia and reperfusion. Inhibition of NOX2 by casein kinase 2 (CK2) leads to neuronal survival, but the mechanism is unknown. In this study, we show that in copper/zinc-superoxide dismutase transgenic (SOD1 Tg) mice, degradation of CK2α and CK2α' and dephosphorylation of CK2β against oxidative stress were markedly reduced compared with wild-type (WT) mice that underwent middle cerebral artery occlusion. Inhibition of CK2 pharmacologically or by ischemic reperfusion facilitated accumulation of poly(ADP-ribose) polymers, the translocation of apoptosis-inducing factor (AIF), and cytochrome c release from mitochondria after ischemic injury. The eventual enhancement of CK2 inhibition under ischemic injury strongly increased 8-hydroxy-2'-deoxyguanosine and phosphorylation of H2A.X. Furthermore, CK2 inhibition by tetrabromocinnamic acid (TBCA) in SOD1 Tg and gp91 knockout (KO) mice after ischemia reperfusion induced less release of AIF and cytochrome c than in TBCA-treated WT mice. Inhibition of CK2 in gp91 KO mice subjected to ischemia reperfusion did not increase brain infarction compared with TBCA-treated WT mice. These results strongly suggest that NOX2 activation releases reactive oxygen species after CK2 inhibition, triggering release of apoptogenic factors from mitochondria and inducing DNA damage after ischemic brain injury.

8-Hydroxydeoxyguanosine: Not mere biomarker for oxidative stress, but remedy for oxidative stress-implicated gastrointestinal diseases

Reactive oxygen species (ROS) attack guanine bases in DNA easily and form 8-hydroxydeoxyguanosine (8-OHdG), which can bind to thymidine rather than cytosine, based on which, the level of 8-OHdG is generally regarded as a biomarker of mutagenesis consequent to oxidative stress. For example, higher levels of 8-OHdG are noted in Helicobacter pylori-associated chronic atrophic gastritis as well as gastric cancer. However, we have found that exogenous 8-OHdG can paradoxically reduce ROS production, attenuate the nuclear factor-κB signaling pathway, and ameliorate the expression of proinflammatory mediators such as interleukin (IL)-1, IL-6, cyclo-oxygenase-2, and inducible nitric oxide synthase in addition to expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX)-1, NOX organizer-1 and NOX activator-1 in various conditions of inflammation-based gastrointestinal (GI) diseases including gastritis, inflammatory bowel disease, pancreatitis, and even colitis-associated carcinogenesis. Our recent finding that exogenous 8-OHdG was very effective in either inflammation-based or oxidative-stress-associated diseases of stress-related mucosal damage has inspired the hope that synthetic 8-OHdG can be a potential candidate for the treatment of inflammation-based GI diseases, as well as the prevention of inflammation-associated GI cancer. In this editorial review, the novel fact that exogenous 8-OHdG can be a functional molecule regulating oxidative-stress-induced gastritis through either antagonizing Rac-guanosine triphosphate binding or blocking the signals responsible for gastric inflammatory cascade is introduced.

Differences in the activities of resveratrol and ascorbic acid in protection of ethanol-induced oxidative DNA damage in human peripheral lymphocytes

Previous studies have shown that ethanol induces oxidative DNA damage in human peripheral lymphocytes. In the present study, protective effect of resveratrol and ascorbic acid on ethanol-induced oxidative DNA damage in human peripheral lymphocytes in vitro were comparatively investigated. Pretreatments with resveratrol at 5, 25, and 50μM, which were in the concentration range of in vitro research, significantly inhibited ethanol-induced oxidative DNA damage in 24h, whereas ascorbic acid showed such DNA protective activity only in 1h. Further study showed that both compounds could directly scavenge hydroxyl radical produced during ethanol metabolism. Resveratrol significantly inhibited ethanol metabolism by regulating alcohol dehydrogenase 1B (ADH1B) and acetaldehyde dehydrogenase 2 (ALDH2) mRNA expressions. Moreover, resveratrol also activated the base excision repair (BER) system in mRNA and protein levels in DNA auto-repair process. However, ascorbic acid showed no effect on ethanol metabolic pathway and BER system. Thus, the present study provided the first evidence that even though both resveratrol and ascorbic acid are anti-oxidants, they possessed differential mechanisms of action in protection against ethanol-induced oxidative DNA damage in human peripheral lymphocytes.

Microfluidic tool based on the antibody-modified paramagnetic particles for detection of 8-hydroxy-2'-deoxyguanosine in urine of prostate cancer patients

Guanosine derivatives are important for diagnosis of oxidative DNA damage including 8-hydroxy-2'-deoxyguanosine (8-OHdG) as one of the most abundant products of DNA oxidation. This compound is commonly determined in urine, which makes 8-OHdG a good non-invasive marker of oxidation stress. In this study, we optimized and tested the isolation of 8-OHdG from biological matrix by using paramagnetic particles with an antibody-modified surface. 8-OHdG was determined using 1-naphthol generated by alkaline phosphatase conjugated with the secondary antibody. 1-Naphthol was determined by stopped flow injection analysis (SFIA) with electrochemical detector using a glassy carbon working electrode and by stationary electrochemical detection using linear sweep voltammetry. A special modular electrochemical SFIA system which needs only 10  μL of sample including working buffer for one analysis was completely designed and successfully verified. The recoveries in different matrices and analyte concentration were estimated. Detection limit (3 S/N) was estimated as 5  pg/mL of 8-OHdG. This method promises to be very easily modified to microfluidic systems as "lab on valve". The optimized method had sufficient selectivity and thus could be used for determination of 8-OHDG in human urine and therefore for estimation of oxidative DNA damage as a result of oxidation stress in prostate cancer patients.

p-Hydroxybenzyl alcohol prevents brain injury and behavioral impairment by activating Nrf2, PDI, and neurotrophic factor genes in a rat model of brain ischemia

The therapeutic goal in treating cerebral ischemia is to reduce the extent of brain injury and thus minimize neurological impairment. We examined the effects of p-hydroxybenzyl alcohol (HBA), an active component of Gastrodia elata Blume, on transient focal cerebral ischemia-induced brain injury with respect to the involvement of protein disulphide isomerase (PDI), nuclear factor-E2-related factor 2 (Nrf2), and neurotrophic factors. All animals were ovariectomized 14 days before ischemic injury. Ischemic injury was induced for 1 h by middle cerebral artery occlusion (MCAO) followed by 24-h reperfusion. Three days before MCAO, the vehicle-treated and the HBA-treated groups received intramuscular sesame oil and HBA (25 mg/kg BW), respectively. 2,3,5-Triphenyltetrazolium chloride (TTC) staining showed decreased infarct volume in the ischemic lesion of HBA-treated animals. HBA pretreatment also promoted functional recovery, as measured by the modified neurological severity score (mNSS; p < 0.05). Moreover, expression of PDI, Nrf2, BDNF, GDNF, and MBP genes increased by HBA treatment. In vitro, H(2)O(2)-induced PC12 cell death was prevented by 24 h HBA treatment, but bacitracin, a PDI inhibitor, attenuated this cytoprotective effect in a dose-dependent manner. HBA treatment for 2 h also induced nuclear translocation of Nrf2, possibly activating the intracellular antioxidative system. These results suggest that HBA protects against brain damage by modulating cytoprotective genes, such as Nrf2 and PDI, and neurotrophic factors.

Transient cerebral ischemia induces active astrocytosis without distinct neuronal death in the gerbil main olfactory bulb: a long-term analysis

In the present study, we examined ischemia-induced neuronal and glial changes in the gerbil MOB at various time points during 60 days after 5 min of transient cerebral ischemia. The number of neuronal neuclei-immunoreactive neurons was not changed after ischemia/reperfusion (I/R). Myelin basic protein immunoreaction was well preserved after I/R. Five days after I/R, reactive form of GFAP-immunoreactive astrocytes began to increase in the external plexiform layer and granule cell layer: These reactive astrocytes peaked 10 days after I/R, thereafter, they decreased with time after I/R. Iba-1-immunoreactive microglia were ubiquitously distributed in all layers of the MOB. After I/R, significant changes in their morphology and immunoreactivity were not detected. The results of western blot analyses for GFAP, Iba-1 and MBP were similar to the immunohistochemical data. In addition, 8-hydroxy-2'-deoxyguanosine (a marker for DNA damage) immunoreactivity and SOD1, an antioxidant, protein levels were not changed in the ischemic MOB. These results indicate that neurons in the MOB are resistant to ischemic insult, showing that astrocytes are activated late in the ischemic MOB.

Cyclin D1 immunoreactivity changes in CA1 pyramidal neurons and dentate granule cells in the gerbil hippocampus after transient forebrain ischemia

OBJECTIVES

Cyclin D1, a member of the G1 cyclin family, plays a critical role in the progression of the cell cycle. In the present study, we investigated chronological alterations in cyclin D1 immunoreactivity and its protein levels in the gerbil hippocampus after ischemia/reperfusion.

METHODS

Chronological alterations in cyclin D1 immunoreactivity and its levels were examined in the gerbil hippocampus after ischemia/reperfusion using immunohistochemistry and western blot analysis.

RESULTS

Changes in cyclin D1 immunoreactivity in the ischemic hippocampus were distinct in pyramidal neurons of the CA1 region and granule cells of the dentate gyrus. Cyclin D1 immunoreactivity in pyramidal neurons of the CA1 region was increased up to 1 day after ischemia/reperfusion, although a transient decrease of cyclin D1 immunoreactivity was detected at 12 hour after ischemia/reperfusion. Thereafter, cyclin D1 immunoreactivity in the CA1 pyramidal neurons was very weak 2 days and disappeared nearly 4 and 7 days after ischemia/reperfusion. However, 4 days after ischemia/reperfusion, the cyclin D1 immunoreactivity in non-pyramidal neurons of the CA1 region was very strong. In the CA2/3 region, cyclin D1 immunoreactivity was higher than that in the CA1 region and not changed after ischemia/reperfusion. In the dentate gyrus, chronological change in cyclin D1 immunoreactivity was observed. Cells in the granule cell layer showed distinct change in cyclin D1 immunoreactivity after ischemia/reperfusion: the cyclin D1 immunoreactivity was lowest at 12 hours and strong 1 and 4 days after ischemia/reperfusion. In addition, change in cyclin D1 protein level was found in the ischemic hippocampus.

CONCLUSION

Our results indicate that cyclin D1 may play an important role in cellular events related with neuronal damage following ischemia/reperfusion.

Transduced human PEP-1-catalase fusion protein attenuates ischemic neuronal damage

Antioxidant enzymes are considered to have beneficial effects against various diseases mediated by reactive oxygen species (ROS). Ischemia is characterized by both oxidative stress and changes in the antioxidant defense system. Catalase (CAT) and superoxide dismutase (SOD) are major antioxidant enzymes by which cells counteract the deleterious effects of ROS. To investigate the protective effects of CAT, we constructed PEP-1-CAT cell-permeative expression vectors. When PEP-1-CAT fusion proteins were added to the culture medium of neuronal cells, they rapidly entered the cells and protected them against oxidative stress-induced neuronal cell death. Immunohistochemical analysis revealed that PEP-1-CAT prevented neuronal cell death in the hippocampus induced by transient forebrain ischemia. Moreover, we showed that the protective effect of PEP-1-CAT was observed in neuronal cells treated with PEP-1-SOD. Therefore, we suggest that transduced PEP-1-CAT and PEP-1-SOD fusion proteins could be useful as therapeutic agents for various human diseases related to oxidative stress, including stroke.

Platycodin D and 2''-O-acetyl-polygalacin D2 isolated from Platycodon grandiflorum protect ischemia/reperfusion injury in the gerbil hippocampus

Platycodi radix is used as a folk remedy for several conditions. In this study, we investigated the neuroprotective effects of five major extracts; deapioplatycoside E (DPE), platycoside E (PE), platyconic acid A (PA), platycodin D (PD) and 2''-o-acetyl-polygalacin D2 (PD2) isolated from the P.radix in the hippocampal CA1 region (CA1) 4 or 10 days after ischemia/reperfusion (I/R). Each extract was administered into gerbils with intraperitoneal injection (5 mg/kg/day) 10 days before ischemic surgery and the gerbils were sacrificed 4 or 10 days after I/R. Fluoro-Jade B (F-J B, a marker for neurodegeneration) positive ((+)) neurons increased significantly in the stratum pyramidale of the CA1 region in the vehicle-treated group after I/R. A similar pattern was observed in the DPE-, PE- and PA-treated groups; however, in the PD- and PD2-treated groups, F-J B(+) neurons were small in number. We also observed that activations of astrocytes and microglia in the CA1 region after I/R were blocked by the PD- and PD2 treatments. In addition, we found that Cu,Zn-superoxide dismutase (SOD1) immunoreactivity in the pyramidal layer of the PD- and PD2-treated groups was similar to that of the sham group and COX-2(+) and NF-kappaB(+) cells were significantly lower in the PD- and PD2-treated group than those in the vehicle-treated group after I/R. These results suggest that PD and PD2 rescue neurons in the CA1 region from an ischemic damage.

Folic acid deficiency increases delayed neuronal death, DNA damage, platelet endothelial cell adhesion molecule-1 immunoreactivity, and gliosis in the hippocampus after transient cerebral ischemia

Folic acid deficiency increases stroke risk. In the present study, we examined whether folic acid deficiency enhances neuronal damage and gliosis via oxidative stress in the gerbil hippocampus after transient forebrain ischemia. Animals were exposed to a folic acid-deficient diet (FAD) for 3 months and then subjected to occlusion of both common carotid arteries for 5 min. Exposure to an FAD increased plasma homocysteine levels by five- to eightfold compared with those of animals fed with a control diet (CD). In CD-treated animals, most neurons were dead in the hippocampal CA1 region 4 days after ischemia/reperfusion, whereas, in FAD-treated animals, this occurred 3 days after ischemia/reperfusion. Immunostaining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) was performed to examine DNA damage in CA1 neurons in both groups after ischemia, and it was found that 8-OHdG immunoreactivity in both FAD and CD groups peaked at 12 hr after reperfusion, although the immunoreactivity in the FAD group was much greater than that in the CD group. Platelet endothelial cell adhesion molecule-1 (PECAM-1; a final mediator of neutrophil transendothelial migration) immunoreactivity in both groups increased with time after ischemia/reperfusion: Its immunoreactivity in the FAD group was much higher than that in the CD group 3 days after ischemia/reperfusion. In addition, reactive gliosis in the ischemic CA1 region increased with time after ischemia in both groups, but astrocytosis and microgliosis in the FAD group were more severe than in the CD group at all times after ischemia. Our results suggest that folic acid deficiency enhances neuronal damage induced by ischemia.

Oral administration of grape polyphenol extract ameliorates cerebral ischemia/reperfusion-induced neuronal damage and behavioral deficits in gerbils: comparison of pre- and post-ischemic administration

Oxidative stress has been regarded as an important underlying cause for the delayed neuronal death (DND) after cerebral ischemia. In this study, the effects of short-term oral administration of grape polyphenol extract (GPE) on ischemia/reperfusion (I/R) injury in a gerbil global ischemia model were determined. Ischemia was induced by occlusion of the common carotid arteries for 5 min. GPE (30 mg/ml)-containing formula or formula without GPE was administered daily via gavage for 4 days prior to and/or for 4 days after I/R. I/R resulted in hyperlocomotion, extensive DND, oxidative and fragmented DNA damage, and an increase in reactive astrocytes and microglial cells in the hippocampal CA1 region. GPE administration for 4 days prior to I/R and for 4 days after I/R attenuated DND, DNA damage and glial cell activation. However, neuroprotection was more pronounced when GPE was administered for 4 days after I/R than when administered for 4 days prior to I/R. GPE administration after I/R attenuated I/R-induced hyperlocomotion. These findings indicate that oral GPE intake may confer protection against I/R injury and emphasize that early intervention may be an effective therapeutic measure for ameliorating brain injury in stroke.

Bioenergetics of cerebral ischemia: a cellular perspective

In cerebral ischemia survival of neurons, astrocytes, oligodendrocytes and endothelial cells is threatened during energy deprivation and/or following re-supply of oxygen and glucose. After a brief summary of characteristics of different cells types, emphasizing the dependence of all on oxidative metabolism, the bioenergetics of focal and global ischemia is discussed, distinguishing between events during energy deprivation and subsequent recovery attempt after re-circulation. Gray and white matter ischemia are described separately, and distinctions are made between mature and immature brains. Next comes a description of bioenergetics in individual cell types in culture during oxygen/glucose deprivation or exposure to metabolic inhibitors and following re-establishment of normal aerated conditions. Due to their expression of NMDA and non-NMDA receptors neurons and oligodendrocytes are exquisitely sensitive to excitotoxicity by glutamate, which reaches high extracellular concentrations in ischemic brain for several reasons, including failing astrocytic uptake. Excitotoxicity kills brain cells by energetic exhaustion (due to Na(+) extrusion after channel-mediated entry) combined with mitochondrial Ca(2+)-mediated injury and formation of reactive oxygen species. Many (but not all) astrocytes survive energy deprivation for extended periods, but after return to aerated conditions they are vulnerable to mitochondrial damage by cytoplasmic/mitochondrial Ca(2+) overload and to NAD(+) deficiency. Ca(2+) overload is established by reversal of Na(+)/Ca(2+) exchangers following Na(+) accumulation during Na(+)-K(+)-Cl(-) cotransporter stimulation or pH regulation, compensating for excessive acid production. NAD(+) deficiency inhibits glycolysis and eventually oxidative metabolism, secondary to poly(ADP-ribose)polymerase (PARP) activity following DNA damage. Hyperglycemia can be beneficial for neurons but increases astrocytic death due to enhanced acidosis.

Supplementation with a synthetic polyphenol limits oxidative stress and enhances neuronal cell viability in response to hypoxia-re-oxygenation injury

Oxidative stress is associated with the pathology of acute and chronic neurodegenerative disease. Cultured human neuronal cells exposed to experimental hypoxia-re-oxygenation (H/R) injury responded with an increased production of reactive oxygen species (ROS) and a significant decrease in intracellular ATP. Expression of genes encoding for hypoxia-inducible factor 1-alpha (HIF1-alpha), inducible haemoxygenase-1 (HO-1), glucose transporter-1 (Glut-1), the oxygen-sensor neuroglobin (Nb) and Cu,Zn-superoxide dismutase (SOD1), catalase (CAT) and glutathione peroxidase-1 (Gpx-1) increased significantly in response to the insult. Enhanced expression of HO-1, SOD1 and CAT correlated with an increase in the corresponding protein activity. Despite the cellular response to bolster antioxidant capacity, apoptosis and necrosis increased following H/R injury. In contrast, ROS accumulation, the endogenous gene response and cell death was limited in neuronal cells pre-incubated with 50 or 100, but not 10 microM of the phenolic antioxidant 3,3',5,5'-tetra-t-butyl-biphenyl-4,4'-diol (BP) prior to H/R injury. These data indicate that the early endogenous gene response to H/R injury is unable to inhibit neuronal dysfunction and that increasing cellular antioxidant capacity with a synthetic polyphenol (>10 microM) is potentially neuro-protective.

Tamoxifen neuroprotection in cerebral ischemia involves attenuation of kinase activation and superoxide production and potentiation of mitochondrial superoxide dismutase

The purpose of this study was to enhance our understanding of the mechanisms of neuronal death after focal cerebral ischemia and the neuroprotective effects of tamoxifen (TMX). The phosphorylation state of 31 protein kinases/signaling proteins and superoxide anion (O(2)(-)) production in the contralateral and ipsilateral cortex was measured after permanent middle cerebral artery occlusion (pMCAO) in ovariectomized rats treated with placebo or TMX. The study revealed that pMCAO modulated the phosphorylation of a number of kinases/proteins in the penumbra at 2 h after pMCAO. Of significant interest, phospho-ERK1/2 (pERK1/2) was elevated significantly after pMCAO. TMX attenuated the elevation of pERK1/2, an effect correlated with reduced infarct size. In situ detection of O(2)(-) production showed a significant elevation at 1-2 h after pMCAO in the ischemic cortex with enhanced oxidative damage detected at 24 h. ERK activation may be downstream of free radicals, a suggestion supported by the findings that cells positive for O(2)(-) had high pERK activation and that a superoxide dismutase (SOD) mimetic, tempol, significantly attenuated pERK activation after MCAO. TMX treatment significantly reduced the MCAO-induced elevation of O(2)(-) production, oxidative damage, and proapoptotic caspase-3 activation. Additionally, pMCAO induced a significant reduction in the levels of manganese SOD (MnSOD), which scavenge O(2)(-), an effect largely prevented by TMX treatment, thus providing a potential mechanistic basis for the antioxidant effects of TMX. As a whole, these studies suggest that TMX neuroprotection may be achieved via an antioxidant mechanism that involves enhancement of primarily MnSOD levels, with a corresponding reduction of O(2)(-) production, and downstream kinase and caspase-3 activation.

Ethanol preconditioning protects against ischemia/reperfusion-induced brain damage: role of NADPH oxidase-derived ROS

Ethanol preconditioning (EtOH-PC) refers to a phenomenon in which tissues are protected from the deleterious effects of ischemia/reperfusion (I/R) by prior ingestion of ethanol at low to moderate levels. In this study, we tested whether prior (24 h) administration of ethanol as a single bolus that produced a peak plasma concentration of 42-46 mg/dl in gerbils would offer protective effects against neuronal damage due to cerebral I/R. In addition, we also tested whether reactive oxygen species (ROS) derived from NADPH oxidase played a role as initiators of these putative protective effects. Groups of gerbils were administered either ethanol or the same volume of water by gavage 24 h before transient global cerebral ischemia induced by occlusion of both common carotid arteries for 5 min. In some experiments, apocynin, a specific inhibitor of NADPH oxidase, was administered (5 mg/kg body wt, i.p.) 10 min before ethanol administration. EtOH-PC ameliorated behavioral deficit induced by cerebral I/R and protected the brain against I/R-induced delayed neuronal death, neuronal and dendritic degeneration, oxidative DNA damage, and glial cell activation. These beneficial effects were attenuated by apocynin treatment coincident with ethanol administration. Ethanol ingestion was associated with translocation of the NADPH oxidase subunit p67(phox) from hippocampal cytosol fraction to membrane, increased NADPH oxidase activity in hippocampus within the first hour after gavage, and increased lipid peroxidation (4-hydroxy-2-nonenal) in plasma and hippocampus within the first 2 h after gavage. These effects were also inhibited by concomitant apocynin treatment. Our data are consistent with the hypothesis that antecedent ethanol ingestion at socially relevant levels induces neuroprotective effects in I/R by a mechanism that is triggered by ROS produced through NADPH oxidase. Our results further suggest the possibility that preconditioning with other pharmacological agents that induce a mild oxidative stress may have similar therapeutic value for suppressing stroke-mediated damage in brain.

Vanillin, 4-hydroxybenzyl aldehyde and 4-hydroxybenzyl alcohol prevent hippocampal CA1 cell death following global ischemia

Mongolian gerbils subjected to transient global ischemia exhibit neuroprotection against ischemic neuronal cell death in the hippocampal CA1 region when treated with vanillin, 4-hydroxybenzyl aldehyde (4-HBAL) and 4-hydroxybenzyl alcohol (4-HBA), which are active components of Gastrodia elata Blume. Pre- and post-insult vanillin, 4-HBAL and 4-HBA treated-animals showed a significant increase in neuronal survival (66.32%, 43.21% and 64.58%, respectively) compared to vehicle-treated animals. Animals exhibited a gender difference in this neuroprotective effect. To study the neuroprotective mechanism of 4-HBA, we investigated N-methyl-d-aspartate (NMDA) receptor 1 (NR1), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and gamma-aminobutyric acid transaminase (GABA-T) immunoreactivity at various times after ischemic insults. Treatment with 4-HBA did not affect NR1 expression levels, down-regulated 8-OHdG immunoreactivity, and increased GABA-T expression levels after global ischemia, suggesting that 4-HBA inhibited NR1 stimulation. Moreover, GABA-T was rapidly increased in the early stage after ischemia, which might enhance the survival of cells by supplying energy to the CA1 region. These results suggest that 4-HBA inhibits oxidative stress and excitotoxicity for at least 12 h and suppresses neuronal death in CA1 region. Diethyl ether fractions of GE scavenged hydroxyl radical (OH.) and showed antioxidant activity on lipid peroxidation. Vanillin and 4-HBA treatment blocked oxidative damage in PC12 cells. The neuroprotective effect has therapeutic significance and these compounds need to be evaluated for potential use in protecting against neuronal cell damage during stroke.

Shortage of lipid-radical cycles in membranes as a possible prime cause of energetic failure in aging and Alzheimer disease

Polyunsaturated fatty acids (PUFA) and alpha-tocopherol (alpha-TOH) are the most oxygen-sensitive constituents of cells. alpha-TOH is a member of the vitamin E family that is considered the most important lipophilic antioxidant in cell membranes. Its importance is emphasized by the involvement of oxidative stress in injury to the central nervous system and neurodegenerative diseases. Currently, alpha-TOH transfer protein (TTP), is believed to play a significant role in maintaining the vitamin status but the presence of alpha-TOH in membranes is required but not sufficient to protect the membranes against lipid hydroperoxides (LOOH) formation. The lipid-radical theory presented in this review considers the role of two membrane factors--alpha-tocopherol and cytochrome b5; these factors secure the functioning of lipid-radical cycles and the participation of lipid-radical reactions in the key membrane processes. The prominent intermembrane reaction realized via a protein-lipid interaction, during which electron transport from cytochrome b5--located in the outer membrane--to peroxyl radical (LOO*)--located in inner membrane--causes reduction of the peroxyl radical: cyt.b5red + LOO* --> cyt.b5ox + LOO(-). This secures an interaction of alpha-TOH with other intermediate, LOO(- )excepting the LOOH formation. The discussion will be focused on the consequences of ineffective electron transfer to LOO* and excessive oxidative pathway of metabolism of the PUFA (LOO* --> LOOH). Assuming the operation of cytochrome b5/alpha-tocopherol-controlled lipid-radical cycles and considering the role of the cycles in membrane bioenergetics we arrive at a model for effective function of adenine nucleotide translocator and ATP synthesis in mitochondria. This paper summarizes our experimental evidence that the oxidative and non-oxidative pathways of metabolism of PUFA via their respective intermediates occur in the cells. While this fact is not widely appreciated it may be relevant to elucidation of new mechanisms of neurodegenerative diseases.

DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.

Effects of rosiglitazone on global ischemia-induced hippocampal injury and expression of mitochondrial uncoupling protein 2

We investigate the effect of rosiglitazone, a ligand for peroxisome proliferator-activated receptor-gamma (PPARgamma) with anti-inflammatory and anti-oxidative actions, on hippocampal injury and its roles in mitochondrial uncoupling protein 2 (UCP2) expression caused by transient global ischemia (TGI) in rats. Increased UCP2 expression was observed in mitochondria of hippocampal CA1 2-24h after TGI/reperfusion, with maximal expression levels at 6-18h. Administration of rosiglitazone to hippocampus 30min prior to the onset of TGI further enhanced mitochondrial UCP2 expression 2-6h following TGI/reperfusion. Rats subjected to TGI/reperfusion displayed a significant increase in lipid peroxidation, based on increased malondialdehyde (MDA) levels, in hippocampal CA1 mitochondria 2-6 h after reperfusion. Rosiglitazone significantly attenuated TGI/reperfusion-induced lipid peroxidation and suppressed hippocampal CA1 neuronal death based on the surviving neuronal counts. In conclusion, our results provide correlative evidence for the "PPARgamma-->UCP2-->neuroprotection" cascade in ischemic brain injury.

The co-treatments of vigabatrin and P2X receptor antagonists protect ischemic neuronal cell death in the gerbil hippocampus

During transient global ischemia, the excessive accumulation of intracellular Ca2+ induced by several episodes triggers delayed neuronal death within the vulnerable CA1 region of the hippocampus after ischemia-reperfusion insults. Although P2X receptors provide an additional source of Ca2+ entry, little data are available that these receptors could modulate the performance of the ischemic neuronal death. Therefore, we investigated the roles of the P2X receptor in the ischemic neuronal damage associated with various sequelae of transient ischemia, and the effects of their antagonist on the ischemic insults. As the results, ischemic insults increased P2X receptor expression in the gerbil hippocampus. Neither vigabatrin (VGB) nor P2X receptor antagonists (suramin, pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid) protected against the delayed neuronal death in the CA1 region of the hippocampus after ischemia. However, the co-treatments of VGB and P2X receptor antagonists effectively prevent ischemia-induced neurodegeneration. Therefore, these findings suggest that blockade of the P2X receptor accompanied by activation of GABAergic inhibition may play an important role in the neuroprotection against ischemic insults.

Immunohistochemical Studies of Human Ribosomal Protein S3 (rpS3)

The human ribosomal protein S3 (rpS3) was expressed in E. coli using the pET-15b vector and the monoclonal antibodies (mAbs) were produced and characterized. A total of five hybridoma cell lines were established and the antibodies recognized a single band of molecular weight of 33 kDa on immunoblot with purified rpS3. When the purified rpS3 was incubated with the mAbs, the UV endonuclease activity of rpS3 was inhibited up to a maximum of 49%. The binding affinity of mAbs to rpS3 determined by using a biosensor technology showed that they have similar binding affinities. Using the anti-rpS3 antibodies as probes, we investigated the cross-reactivities of various other mammalian brain tissues and cell lines, including human. The immunoreactive bands on Western blots appeared to be the same molecular mass of 33 kDa in all animal species tested. They also appear to be extensively cross-reactive among different organs in rat. These results demonstrated that only one type of immunologically similar rpS3 protein is present in all of the mammalian brain tissues including human. Furthermore, these antibodies were successfully applied in immunohistochemistry in order to detect rpS3 in the gerbil brain tissues. Among the various regions in the brain tissues, the rpS3 positive neurons were predominantly observed in the ependymal cells, hippocampus and stantia nigra pars compacta. The different distributions of rpS3 in brain tissues reply that rpS3 protein may play an important second function in the neuronal cells.