dizocilpine-maleate has been researched along with Reperfusion-Injury* in 49 studies
1 review(s) available for dizocilpine-maleate and Reperfusion-Injury
1 trial(s) available for dizocilpine-maleate and Reperfusion-Injury
48 other study(ies) available for dizocilpine-maleate and Reperfusion-Injury
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Protective effects of remote ischemic preconditioning against spinal cord ischemia-reperfusion injury in rats.
We aimed to investigate the protective effect of remote ischemic preconditioning against spinal cord ischemia and find a clue to its mechanism by measuring glutamate concentrations in the spinal ventral horn.. Male Sprague-Dawley rats were divided into 5 groups (n = 6 in each group) as follows: sham; SCI (only spinal cord ischemia); RIPC/SCI (perform remote ischemic preconditioning before spinal cord ischemia); MK-801/RIPC/SCI (administer MK-801, N-methyl-D-aspartate receptor antagonist, before remote ischemic preconditioning); and MK-801/SCI (administer MK-801 without remote ischemic preconditioning). Remote ischemic preconditioning was achieved by brief limb ischemia 80 minutes before spinal cord ischemia. MK-801 (1 mg/kg, intravenous) was administered 60 minutes before remote ischemic preconditioning. The glutamate concentration in the ventral horn was measured by microdialysis for 130 minutes after spinal cord ischemia. Immunofluorescence was also performed to evaluate the expression of N-methyl-D-aspartate receptor 2B subunit in the ventral horn 130 minutes after spinal cord ischemia.. The glutamate concentrations in the spinal cord ischemia group were significantly higher than in the sham group at all time points (P < .01). Remote ischemic preconditioning attenuated the spinal cord ischemia-induced glutamate increase. When MK-801 was preadministered before remote ischemic preconditioning, glutamate concentration was increased after spinal cord ischemia (P < .01). Immunofluorescence showed that remote ischemic preconditioning prevented the increase in the expression of N-methyl-D-aspartate receptor 2B subunit on the surface of motor neurons (P = .047).. Our results showed that remote ischemic preconditioning prevented spinal cord ischemia-induced extracellular glutamate increase in ventral horn and suppressed N-methyl-D-aspartate receptor 2B subunit expression. Topics: Animals; Anterior Horn Cells; Dizocilpine Maleate; Glutamic Acid; Ischemic Preconditioning; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Spinal Cord; Spinal Cord Ischemia; Treatment Outcome | 2022 |
MK-801 Treatment of Oligodendrocytes as a Cellular Model of Aging.
Cardiovascular-related accidents such as stroke are currently ranked as the second leading cause of death worldwide, and the risk of stroke increases dramatically with age. Aging results in structural and functional alterations of the oligodendrocytes which lead to loss of neuronal connectivity, cognitive deficits, and increased susceptibility to ischemic damage. Here, we have carried out proteomic profiling of MO3.13 oligodendrocyte cells following treatment with NMDA channel blocker MK-801 to increase our understanding of the mechanisms involved in brain aging, as well as those which render it more susceptible to ischemic damage. The main objective was to identify potential biomarkers which could be used to track disease or therapeutic effects. Topics: Adult; Aged; Aged, 80 and over; Aging; Biomarkers; Brain; Cognitive Dysfunction; Dizocilpine Maleate; Female; Humans; Male; Middle Aged; Neurons; Oligodendroglia; Proteomics; Reperfusion Injury; Young Adult | 2020 |
NMDA receptor-mediated CaMKII/ERK activation contributes to renal fibrosis.
This study aimed to understand the mechanistic role of N-methyl-D-aspartate receptor (NMDAR) in acute fibrogenesis using models of in vivo ureter obstruction and in vitro TGF-β administration.. The expression of NR1 was upregulated in obstructed kidneys, while NR1 knockdown significantly reduced both interstitial volume expansion and the changes in the expression of α-smooth muscle actin, S100A4, fibronectin, COL1A1, Snail, and E-cadherin in acute RF. TGF-β1 treatment increased the elongation phenotype of HK-2 cells and the expression of membrane-located NR1 and phosphorylated CaMKII and extracellular signal-regulated kinase (ERK). MK801 and KN93 reduced CaMKII and ERK phosphorylation levels, while MK801, but not KN93, reduced the membrane NR1 signal. The levels of phosphorylated CaMKII and ERK also increased in kidneys with obstruction but were decreased by NR1 knockdown. The 4-week administration of DXM preserved renal cortex volume in kidneys with moderate ischemic-reperfusion injury.. NMDAR participates in both acute and chronic renal fibrogenesis potentially via CaMKII-induced ERK activation. Topics: Animals; Benzylamines; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Dextromethorphan; Dizocilpine Maleate; Epithelial-Mesenchymal Transition; Excitatory Amino Acid Antagonists; Fibrosis; Gene Knockdown Techniques; Humans; In Vitro Techniques; Kidney; Kidney Tubules, Proximal; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Protein Kinase Inhibitors; Receptors, N-Methyl-D-Aspartate; Renal Insufficiency, Chronic; Reperfusion Injury; Sulfonamides; Transforming Growth Factor beta; Ureteral Obstruction | 2020 |
Denitrosylation of nNOS induced by cerebral ischemia-reperfusion contributes to nitrosylation of CaMKII and its inhibition of autophosphorylation in hippocampal CA1.
The aim of this study is to investigate the relation between CaMKII S-nitrosylation and its activation, as well as the underlying mechanism, after global cerebral ischemia-reperfusion.. The rat model of cerebral ischemia-reperfusion was established by four-vessel occlusion of 15 min and reperfusion of different times. nNOS inhibitor 7-nitroindazole (7-NI), exogenous nitric oxide donor GSNO (nitrosoglutathione), or N-methyl-D-aspartate receptor (NMDAR) antagonist MK-801 were administered before ischemia. The expressions of S-nitrosylation and phosphorylation of CaMKII and nNOS were detected by biotin switch assay, immunoblotting, and immunohistochemical staining after cerebral ischemia-reperfusion. The survival of hippocampal CA1 pyramidal cells after administration of the three drugs was examined by cresyl violet staining.. Following cerebral ischemia-reperfusion, the S-nitrosylation of CaMKII was increased, accompanied by a decrease of phosphorylation, suggesting a decrease of activity (p<0.05). Meanwhile, the phosphorylation and S-nitrosylation of nNOS were notably decreased at the same time point (p<0.05). The administration of 7-NI, GSNO, and MK-801 increased the S-nitrosylation and phosphorylation of nNOS, leading to the attenuation of increased S-nitrosylation and decreased autophosphorylation of CaMKII after cerebral ischemia-reperfusion (p<0.05). Administration of MK-801, GSNO, and 7-NI significantly decreased the neuronal damage in rat hippocampal CA1 caused by cerebral ischemia-reperfusion (p<0.05).. After cerebral ischemia-reperfusion, the decrease of autophosphorylation of CaMKII regulated by its S-nitrosylation may be due to the denitrosylation of nNOS and subsequent NO production. Increasing the phosphorylation of CaMKII by nNOS inhibitor, exogenous NO donor or NMDA receptor antagonist exerted neuroprotective effects against cerebral ischemia-reperfusion injury. Topics: Animals; CA1 Region, Hippocampal; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Disease Models, Animal; Dizocilpine Maleate; Indazoles; Male; Nitric Oxide; Nitric Oxide Synthase Type I; Phosphorylation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; S-Nitrosoglutathione | 2019 |
Neuroprotective Effects of Inhibiting Fyn S-Nitrosylation on Cerebral Ischemia/Reperfusion-Induced Damage to CA1 Hippocampal Neurons.
Nitric oxide (NO) can regulate signaling pathways via S-nitrosylation. Fyn can be post-translationally modified in many biological processes. In the present study, using a rat four-vessel-occlusion ischemic model, we aimed to assess whether Fyn could be S-nitrosylated and to evaluate the effects of Fyn S-nitrosylation on brain damage. In vitro, Fyn could be S-nitrosylated by S-nitrosoglutathione (GSNO, an exogenous NO donor), and in vivo, endogenous NO synthesized by NO synthases (NOS) could enhance Fyn S-nitrosylation. Application of GSNO, 7-nitroindazole (7-NI, an inhibitor of neuronal NOS) and hydrogen maleate (MK-801, the N-methyl-d-aspartate receptor (NMDAR) antagonist) could decrease the S-nitrosylation and phosphorylation of Fyn induced by cerebral ischemia/reperfusion (I/R). Cresyl violet staining validated that these compounds exerted neuroprotective effects against the cerebral I/R-induced damage to hippocampal CA1 neurons. Taken together, in this study, we demonstrated that Fyn can be S-nitrosylated both in vitro and in vivo and that inhibiting S-nitrosylation can exert neuroprotective effects against cerebral I/R injury, potentially via NMDAR-mediated mechanisms. These findings may lead to a new field of inquiry to investigate the underlying pathogenesis of stroke and the development of novel treatment strategies. Topics: Animals; Disease Models, Animal; Dizocilpine Maleate; HEK293 Cells; Hippocampus; Humans; Male; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type I; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-fyn; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; S-Nitrosoglutathione; Signal Transduction | 2016 |
Effects of MK-801 concentration on cell proliferation in rats with focal cerebral ischemia-reperfusion.
We explored the relationship between MK-801 concentration and neural stem cell proliferation in rats with focal cerebral ischemia-reperfusion (FCIR). A total of 60 male Sprague Dawley rats were randomized into control (six rats), sham-operation (six rats), operation (12 rats), and MK-801 groups. The MK-801 group comprised 36 rats that were subjected to different doses of MK-801 (0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mg/kg). Suture occlusion was used to establish an ischemia reperfusion model of middle cerebral artery occlusion (MCAO); 30 min before establishing the FCIR model, the MK-801 group rats were intraperitoneally injected with different doses of MK-801, while the sham-operation and control groups were injected with normal saline. Seven days after model establishment, bromodeoxyuridine-positive cerebral cortex cells adjacent to the focus of infarction were labeled for immunohistochemistry. MK-801 at a concentration of 0.4 mg/kg prevented endogenous neural stem cell proliferation, and this inhibitory effect was strengthened with increasing MK-801 concentration, especially at concentrations greater than 0.8 mg/kg. MK-801 inhibits endogenous neural stem cell proliferation in rats with FCIR, and the inhibitory effect is strengthened with increasing MK-801 concentration. Topics: Animals; Brain Ischemia; Cell Proliferation; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Male; Neural Stem Cells; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 2015 |
Combination of mild hypothermia with neuroprotectants has greater neuroprotective effects during oxygen-glucose deprivation and reoxygenation-mediated neuronal injury.
Co-treatment of neuroprotective reagents may improve the therapeutic efficacy of hypothermia in protecting neurons during ischemic stroke. This study aimed to find promising drugs that enhance the neuroprotective effect of mild hypothermia (MH). 26 candidate drugs were selected based on different targets. Primary cultured cortical neurons were exposed to oxygen-glucose deprivation and reoxygenation (OGD/R) to induce neuronal damage, followed by either single treatment (a drug or MH) or a combination of a drug and MH. Results showed that, compared with single treatment, combination of MH with brain derived neurotrophic factor, glibenclamide, dizocilpine, human urinary kallidinogenase or neuroglobin displayed higher proportion of neuronal cell viability. The latter three drugs also caused less apoptosis rate in combined treatment. Furthermore, co-treatment of those three drugs and MH decreased the level of reactive oxygen species (ROS) and intracellular calcium accumulation, as well as stabilized mitochondrial membrane potential (MMP), indicating the combined neuroprotective effects are probably via inhibiting mitochondrial apoptosis pathway. Taken together, the study suggests that combined treatment with hypothermia and certain neuroprotective reagents provide a better protection against OGD/R-induced neuronal injury. Topics: Animals; Animals, Newborn; Apoptosis; Calcium; Cell Survival; Cerebral Cortex; Cold Temperature; Combined Modality Therapy; Culture Media; Dizocilpine Maleate; Globins; Glucose; Kallikreins; Membrane Potential, Mitochondrial; Mitochondria; Nerve Tissue Proteins; Neuroglobin; Neurons; Neuroprotective Agents; Oxygen; Primary Cell Culture; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury | 2014 |
S-nitrosylation of mixed lineage kinase 3 contributes to its activation after cerebral ischemia.
Previous studies in our laboratory have shown that mixed lineage kinase 3 (MLK3) can be activated following global ischemia. In addition, other laboratories have reported that the activation of MLK3 may be linked to the accumulation of free radicals. However, the mechanism of MLK3 activation remains incompletely understood. We report here that MLK3, overexpressed in HEK293 cells, is S-nitrosylated (forming SNO-MLK3) via a reaction with S-nitrosoglutathione, an exogenous nitric oxide (NO) donor, at one critical cysteine residue (Cys-688). We further show that the S-nitrosylation of MLK3 contributes to its dimerization and activation. We also investigated whether the activation of MLK3 is associated with S-nitrosylation following rat brain ischemia/reperfusion. Our results show that the administration of 7-nitroindazole, an inhibitor of neuronal NO synthase (nNOS), or nNOS antisense oligodeoxynucleotides diminished the S-nitrosylation of MLK3 and inhibited its activation induced by cerebral ischemia/reperfusion. In contrast, 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (an inhibitor of inducible NO synthase) or nNOS missense oligodeoxynucleotides did not affect the S-nitrosylation of MLK3. In addition, treatment with sodium nitroprusside (an exogenous NO donor) and S-nitrosoglutathione or MK801, an antagonist of the N-methyl-D-aspartate receptor, also diminished the S-nitrosylation and activation of MLK3 induced by cerebral ischemia/reperfusion. The activation of MLK3 facilitated its downstream protein kinase kinase 4/7 (MKK4/7)-JNK signaling module and both nuclear and non-nuclear apoptosis pathways. These data suggest that the activation of MLK3 during the early stages of ischemia/reperfusion is modulated by S-nitrosylation and provides a potential new approach for stroke therapy whereby the post-translational modification machinery is targeted. Topics: Animals; Brain Ischemia; Dizocilpine Maleate; Enzyme Activation; Enzyme Inhibitors; HEK293 Cells; Humans; Male; MAP Kinase Kinase Kinases; Mitogen-Activated Protein Kinase Kinase Kinase 11; Neuroprotective Agents; Nitric Oxide Synthase Type I; Oligodeoxyribonucleotides, Antisense; Protein Multimerization; Protein Processing, Post-Translational; Rats; Rats, Sprague-Dawley; Reperfusion Injury; S-Nitrosoglutathione; Thiazines | 2012 |
S-nitrosylation of c-Src via NMDAR-nNOS module promotes c-Src activation and NR2A phosphorylation in cerebral ischemia/reperfusion.
Previous studies suggested that activated c-Src promote the tyrosine phosphorylation of NMDA receptor subunit NR2A, and thus aggravate the injury induced by transient cerebral ischemia/reperfusion (I/R) in rat hippocampus CA1 region. In this study, we examined the effect of nitric oxide (NO) on the activation of c-Src and the tyrosine phosphorylation of NMDA receptor NR2A subunit. The results show that S-nitrosylation and the phosphorylation of c-Src were induced after cerebral I/R in rats, and administration of nNOS inhibitor 7-NI, nNOS antisense oligonucleotides and exogenous NO donor sodium nitroprusside diminished the increased S-nitrosylation and phosphorylation of c-Src during cerebral I/R. The cysteine residues of c-Src modified by S-nitrosylation are Cys489, Cys498, and Cys500. On the other hand, NMDAR antagonist MK-801 could attenuate the S-nitrosylation and activation of c-Src. Taken together, the S-nitrosylation of c-Src is provoked by NO derived from endogenous nNOS, which is activated by Ca(2+) influx from NMDA receptors, and promotes the auto-phosphorylation at tyrosines and further phosphorylates NR2A. The molecular mechanism we outlined here is a novel postsynaptic NMDAR-nNOS/c-Src-mediated signaling amplification, the 'NMDAR-nNOS → NO → SNO-c-Src → p-c-Src → NMDAR-nNOS' cycle, which presents the possibility as a potential therapeutic target for stroke treatment. Topics: Amino Acid Motifs; Animals; Apoptosis; Brain Ischemia; Cysteine; Dizocilpine Maleate; Enzyme Activation; HEK293 Cells; Hippocampus; Humans; Indazoles; Male; Neuroprotective Agents; Nitric Oxide Donors; Nitric Oxide Synthase Type I; Nitroprusside; Phosphorylation; Protein Processing, Post-Translational; Protein Structure, Tertiary; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; S-Nitrosoglutathione; src-Family Kinases | 2012 |
Cerebral ischemia-reperfusion induces GAPDH S-nitrosylation and nuclear translocation.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a glycolytic enzyme, plays an important role in glycolysis. It was reported that GAPDH undergoes S-nitrosylation, which facilitated its binding to Siah1 and resulted in nuclear translocation and cell apoptosis. The results of this study show that GAPDH S-nitrosylation, Siah1 binding, translocation to nucleus, and concomitant neuron death occur during the early stages of reperfusion in the rat four-vessel occlusion ischemic model. N-Methyl-D-aspartate receptor antagonist MK801, neuronal nitric oxide synthase inhibitor 7-nitroindazole, or monoamine oxidase-B inhibitor (R)-(-)-deprenyl hydrochloride could inhibit GAPDH S-nitrosylation and translocation and exert neuroprotective effects. Topics: Active Transport, Cell Nucleus; Analysis of Variance; Animals; Apoptosis; Brain Ischemia; CA1 Region, Hippocampal; Cell Nucleus; Dizocilpine Maleate; Enzyme Inhibitors; Glyceraldehyde-3-Phosphate Dehydrogenases; Humans; Indazoles; Male; Monoamine Oxidase; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Synthase Type I; Nitroso Compounds; Nuclear Proteins; Pyramidal Cells; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Selegiline; Ubiquitin-Protein Ligases; Vitamin B 12 | 2012 |
Glutamate excitotoxicity mediates neuronal apoptosis after hypothermic circulatory arrest.
Prolonged hypothermic circulatory arrest results in neuronal cell death and neurologic injury. We have previously shown that hypothermic circulatory arrest causes both neuronal apoptosis and necrosis in a canine model. Inhibition of neuronal nitric oxide synthase reduced neuronal apoptosis, while glutamate receptor antagonism reduced necrosis in our model. This study was undertaken to determine whether glutamate receptor antagonism reduces nitric oxide formation and neuronal apoptosis after hypothermic circulatory arrest.. Sixteen hound dogs underwent 2 hours of circulatory arrest at 18 degrees C and were sacrificed after 8 hours. Group 1 (n = 8) was treated with MK-801, 0.75 mg/kg intravenously prior to arrest followed by 75 microg/kg/hour infusion. Group 2 dogs (n = 8) received vehicle only. Intracerebral levels of excitatory amino acids and citrulline, an equal coproduct of nitric oxide, were measured. Apoptosis, identified by hematoxylin and eosin staining and confirmed by electron microscopy, was blindly scored from 0 (normal) to 100 (severe injury), while nick-end labeling demonstrated DNA fragmentation.. Dogs in groups 1 and 2 had similar intracerebral levels of glutamate. However, MK-801 significantly reduced intracerebral glycine and citrulline levels compared with hypothermic circulatory arrest controls. The MK-801 significantly inhibited apoptosis (7.92 +/- 7.85 vs 62.08 +/- 6.28, group 1 vs group 2, p < 0.001).. Our results showed that glutamate receptor antagonism significantly reduced nitric oxide formation and neuronal apoptosis. We provide evidence that glutamate excitotoxicity mediates neuronal apoptosis in addition to necrosis after hypothermic circulatory arrest. Clinical glutamate receptor antagonists may have therapeutic benefits in ameliorating both types of neurologic injury after hypothermic circulatory arrest. Topics: Animals; Apoptosis; Brain; Circulatory Arrest, Deep Hypothermia Induced; Citrulline; Dizocilpine Maleate; DNA Fragmentation; Dogs; Excitatory Amino Acid Antagonists; Excitatory Amino Acids; Glutamic Acid; Glycine; In Situ Nick-End Labeling; Microdialysis; Microscopy, Electron; Necrosis; Neurons; Nitric Oxide; Reperfusion Injury | 2010 |
Lack of protection with a novel, selective melanocortin receptor subtype-4 agonist RY767 in a rat transient middle cerebral artery occlusion stroke model.
Previous studies utilizing alpha-melanocyte-stimulating hormone (alpha-MSH) or the synthetic analog [Nle(4), D-Phe(7)] alpha-MSH have reported beneficial effects in animal models of ischemic stroke, with the latter studies suggesting melanocortin receptor subtype-4 (MC4R) activation as a protective mechanism. The present study directly addresses the hypothesis that MC4R activation may ameliorate ischemic brain injury by assessing the efficacy of a novel small molecule MC4R agonist RY767, administered in a pharmacokinetically guided and pharmacologically validated dosing regimen, in a rat stroke model of transient middle cerebral artery occlusion (tMCAO). Male Wistar rats were subjected to 90-min tMCAO followed by 72 h of reperfusion. Treatments were i.p. pretreatment with MK-801 (15 min prior to occlusion, positive control), or combined i.v. and p.o. daily administrations of vehicle, dextrose (negative control) or RY767 in blinded fashion initiated 2 h after occlusion. Infarct volume in MK-801-treated rats (158.7 +/- 22.3 mm(3)) was reduced significantly compared to vehicle infarct volume (243.4 +/- 12.5 mm(3)), whereas infarct volumes in dextrose- (224.3 +/- 16.5 mm(3)) and RY767- (262.1 +/- 19.2 mm(3)) treated rats did not differ from vehicle infarct volume. These results indicate that selective MC4R activation provides no significant neuroprotection, as reflected by infarct volume, in a rat stroke model utilizing a 90-min ischemic insult. Topics: Administration, Oral; Animals; CHO Cells; Cricetinae; Cricetulus; Disease Models, Animal; Dizocilpine Maleate; Humans; Infarction, Middle Cerebral Artery; Injections, Intravenous; Male; Neuroprotective Agents; Piperazines; Piperidines; Rats; Rats, Wistar; Receptor, Melanocortin, Type 4; Reperfusion Injury | 2009 |
Neuroprotective effects of mebudipine and dibudipine on cerebral oxygen-glucose deprivation/reperfusion injury.
In the present study, we investigated the effects of mebudipine and dibudipine, two new Ca(2+) channel blockers, on primary murine cortical neurons exposed to oxygen-glucose deprivation/reperfusion. The experiments were performed on cells after 11-16 days of culture. To initiate oxygen-glucose deprivation /reperfusion, the culture medium was replaced by glucose-free medium, and the cells were transferred to a humidified incubation chamber in a mixture of 95% N(2) and 5% CO(2) at 37 degrees C for 30 min. The cultures were pretreated with mebudipine and dibudipine 3 h prior to oxygen-glucose deprivation/reperfusion, in order to explore their effects on neurons under oxygen-glucose deprivation conditions. Cell viability and nitric oxide (NO) production were assessed by MTT assay and the modified Griess method, respectively. Exposure of murine cortical neuronal cells to 30 min oxygen-glucose deprivation significantly decreased cell viability and increased NO production. Pretreatment of the cultures with mebudipine and dibudipine significantly increased cell viability and decreased NO generation in a dose-dependent manner. However, the drugs had no protective effect in cells subjected to oxygen-glucose deprivation for 60 min. Pretreatment of cultures with MK-801 (10 microM), a non-competitive NMDA antagonist, decreased neuronal death after 30-min oxygen-glucose deprivation, while application of NBQX (30 microM), a selective AMPA-kainate receptor antagonist, partially attenuated the cell injury. oxygen-glucose deprivation -induced cytotoxicity and NO production were also inhibited by N-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor and MK-801. We conclude that mebudipine and dibudipine could protect cortical neurons against oxygen-glucose deprivation /reperfusion-induced cell injury in a dose-dependent manner, and that this could be mediated partially by decreased NO production. Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Cell Death; Cell Survival; Cells, Cultured; Cerebral Cortex; Dizocilpine Maleate; Dose-Response Relationship, Drug; Embryo, Mammalian; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Formazans; Glucose; Hypoxia; Mice; N-Methylaspartate; Neurons; Neuroprotective Agents; NG-Nitroarginine Methyl Ester; Nifedipine; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Quinoxalines; Receptors, Kainic Acid; Reperfusion Injury; Tetrazolium Salts; Time Factors | 2009 |
Modulation of pro-survival and death-associated pathways under retinal ischemia/reperfusion: effects of NMDA receptor blockade.
Loss of retinal ganglion cells occurs in a variety of pathological conditions, including central retinal artery occlusion, diabetes and glaucoma. Using an experimental model of retinal ischemia induced by transiently raise the intraocular pressure (IOP), In this study, we report the original observation that ischemic retinal ganglion cells death is associated with the transient deactivation of the pro-survival kinase Akt and activation of GSK-3beta followed, during reperfusion, by a longer lasting, PI3K-dependent, activation of Akt and phosphorylation of GSK-3beta. Under these experimental conditions, retinal ischemia induced the expression of Bad, a pro-apoptotic protein, member of the Bcl-2 family. The detrimental effects yielded by the ischemic stimulus were minimized by intravitreal administration of the NMDA receptor antagonist, MK801, that reduced the expression of Bad and significantly increased Akt phosphorylation. In conclusion, our present results contribute to unravel the mechanisms underlying retinal damage by high IOP-induced transient ischemia in rat. In addition, these data implicate the pro-survival PI3K/Akt pathway and the observed reduced expression of Bad in the neuroprotection afforded by MK801. Topics: Analysis of Variance; Androstadienes; Animals; bcl-Associated Death Protein; Cell Death; Chromones; Dizocilpine Maleate; Enzyme Inhibitors; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Intraocular Pressure; Ischemia; Male; Morpholines; Oncogene Protein v-akt; Proto-Oncogene Proteins c-bcl-2; PTEN Phosphohydrolase; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Retinal Diseases; Serine; Signal Transduction; Time Factors; Wortmannin | 2008 |
Tyrosine phosphorylation of HPK1 by activated Src promotes ischemic brain injury in rat hippocampal CA1 region.
Hematopoietic progenitor kinase 1 (HPK1) is a hematopoietic cell-restricted member of the Ste20 serine/threonine kinase super family. We recently reported that HPK1 is involved in c-Jun NH2-terminal kinase (JNK) signaling pathway by sequential activation of MLK3-MKK7-JNK3 after cerebral ischemia. Here, we used 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3,4-d] pyrimidine (PP2) and MK801 to investigate the events upstream of HPK1 in ischemic brain injury. Immunoprecipitation and immunoblot results showed that PP2 and MK801 significantly decreased the activation of Src, HPK1, MLK3, JNK3 and c-Jun, respectively, during ischemia/reperfusion. Histology and TUNEL staining showed PP2 or MK801 protects against neuron death after brain ischemia. We speculate that this unique signaling pathway through the tyrosine phosphorylation of HPK1 promotes ischemic brain injury by activated Src via N-methyl-d-aspartate receptor and, ultimately, the activation of the MLK3-MKK7-JNK3 pathway after cerebral ischemia. Topics: Animals; Brain Ischemia; Cytoprotection; Dizocilpine Maleate; Hippocampus; Male; MAP Kinase Kinase Kinases; Mitogen-Activated Protein Kinase 10; Mitogen-Activated Protein Kinase Kinase Kinase 11; Neuroprotective Agents; Phosphorylation; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Pyrimidines; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; src-Family Kinases; Tyrosine | 2008 |
[Effect of MK801 on apoptosis in the development of brain injury after hind limbs ischemia/reperfusion in rats].
To evaluate development of brain injury after hind limbs ischemia/reperfusion (LI/R) in rats, and the effect of MK801 on the brain injury following LI/R.. The limbs ischemia/reperfusion model was established in rats. The MDA contents were evaluated in each group, apoptotic cells were detected with TUNEL, the expression of apoptosis-associated protein, such as bcl-2, cytoC and caspase-3 were determined with immunohistochemistry and Western-blot.. The contents of MDA in brain tissue increased significantly following LI/R. The expression of bcl-2, cytoC, Caspase-3 was increased than those in the control group (P < 0.01) following LI/R significantly. The expression of Caspase-3 was increased 24 h after the onset of reperfusion. The expression of Caspase-3, bcl-2 gene was quite obvious in the midbrain red nucleus region. MK801 inhibited the expression of bcl-2, cytoC, Caspase-3 obviously.. The excessive apoptosis and apoptosis-associated factors could play an important role in the brain injury following LI/R in rat, MK801 might decrease the production of free radical and the excite toxicity of glutamate, inhibit the expression of apoptosis associated protein and reduce the occurrence of apoptosis. Topics: Animals; Apoptosis; Brain Injuries; Caspase 3; Cytochromes c; Dizocilpine Maleate; Extremities; Ischemia; Male; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 2007 |
Adenosine A2A receptor mediated protective effect of 2-(6-cyano-1-hexyn-1-yl)adenosine on retinal ischaemia/reperfusion damage in rats.
To determine the effect of 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado), an adenosine A2A receptor agonist, on retinal ischaemia/reperfusion damage in rats.. Retinal ischaemia/reperfusion damage was induced by elevating the intraocular pressure of one eye to 130 mm Hg for 60 minutes and returning it to normal. 7 days later, retinal ischaemia/reperfusion damage was histologically quantified by measuring the thickness of retinal layers. Intraocular pressure was measured by pressure transducer.. Retinal ischaemia/reperfusion caused cell loss in the ganglion cell layer and thinning of the inner plexiform and nuclear layer. Both ocular topical and intravenous administration of 2-CN-Ado caused a reduction of retinal ischaemia/reperfusion damage. A selective A2A receptor antagonist, 1,3,7-trimethyl-8-(3-chlorostyryl) xanthine (CSC), but not a selective A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), or a selective A2B receptor antagonist, alloxazine, reduced the protective effect of 2-CN-Ado. While ocular topical administration of 2-CN-Ado caused a sustained reduction of intraocular pressure, intravenous administration of 2-CN-Ado showed a transient ocular hypotensive effect.. These results suggest that 2-CN-Ado attenuates retinal ischaemia/reperfusion damage, and at least some of this protective effect of 2-CN-Ado might be mediated via activation of the adenosine A2A receptor. Topics: Adenosine; Adenosine A2 Receptor Agonists; Administration, Topical; Animals; Antihypertensive Agents; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Intraocular Pressure; Ischemic Preconditioning; Male; Phenethylamines; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Retinal Vessels | 2006 |
[Effects of Ginkgo biloba extract against excitotoxicity induced by NMDA receptors and mechanism thereof].
To observe the effects of Ginkgo biloba extract (GBE) on N-methyl-D-aspartate (NMDA) excitotoxicity and focal cerebral ischemia, and further explore the neuroprotective mechanisms of GBE.. Neonatal SD rat hippocampus was taken out to make into cell suspension. immunohistochemistry with neuron nucleoprotein monoclonal antibody (NeuN) was used to calculate the percentage of NeuN positive cells. Twelve days after incubation the suspension of neurons were randomly divided into 4 groups: normal control group (exposed to normal saline for 15 min and then to DMEM without NMDA and glycine for 24 h), NMDA group (exposed to culture fluid with NMDA of the terminal concentration of 100 micromol/L and glycine of the terminal concentration of 10 micromol/L for 15 min and then to DMEM without NMDA and glycine for 24 h), MK-801 group (exposed to MK-801, an NMDAR antagonist, for 2 min, to culture fluid with NMDA for 15 min, and then to DMEM without NMDA and glycine for 24 h), and GBE pretreatment group (exposed to GBE of the terminal concentration of 150 microg/ml for 3 d, culture fluid with NMDS for 15 min, and then to DMEM without NMDA and glycine foe 24 h). Trypan blue staining was used to calculate the survival rate of the neurons. The lactic dehydrogenase (LDH) level in the supernatant of cultured cell suspension was detected. Whole-cell patch clamp recording was carried out to evaluate the modulatory effects of GBE on NMDA-activated currents in the rat hippocampal neurons. 108 SD rats were randomly divided into 5 groups: sham operation group (n = 12), standard middle cerebral artery occlusion (MCAO) group (n = 24, undergoing MCAO and then reperfusion), MK-801 acute administration group (n = 24, undergoing MCAO and immediate peritoneal administration of MK-801 1 mg/kg), GBE acute administration group (n = 24, undergoing peritoneal injection of GBE 100 mg/kg immediately after the MCAO), and GBE pretreatment group (n = 24, undergoing peritoneal administration of GBE every day for 7 days before the MCAO). The 4 groups were re-divided into 4 subgroups with 3 approximately 4 rats: 0.5 h ischemia, and 3 h, 1 d, and 7 d ischemia-reperfusion (IR) subgroups. The neurological symptoms were evaluated by Longa's scoring after the rats became conscious. The rats were killed at different time-points, their brains were taken out to undergo 2, 3, 5-triphenyl-tetrazolium chloride staining, the areas of cerebral infarction were calculated, and immunohistochemistry was used to evaluate the contents of NeuN and microtubule-associated protein (MAP-2).. The cell viability of the GBE group was 85% +/- 5%, significantly higher than that of the NMDA group (39.8% +/- 2.1%, P < 0.01), and significantly lower than that of the MK-801 group (93.8% +/- 2.7%, P < 0.05). The LDH efflux of the GBE group was 87 U/L +/- 8 U/L, significantly lower than that of the NMDA group (138 U/L +/- 12 U/L, P < 0.01) and significantly higher than that of the MK-801 group (47 U/L +/- 7 U/L, P < 0.05). The inward current (I(NMDA)) of the NMDA group was significantly activated, The inhibitory rate of the NMDA-activated I(NMDA) of the GBE group was 40% +/- 17%, significantly lower than that of the MK-801 group (78% +/- 18%, P < 0.05); After washing out with standard extracellular solution, the I(NMDA) could recover to 91% +/- 8% in the GBE group, but not in the MK-801 group (P < 0.05), which indicated that GBE had lower affinity to NMDA receptor than MK-801. The Longa's scores of the 3 h and 24 h IR subgroups of the GBS pretreatment group were all significantly lower than those of the corresponding subgroups of the standard MCAO and GBE acute administration groups. The symptoms of the MK-801 were the most severe. Cerebral infarction began to appear in the 1-day subgroups. The cerebral infarction areas of the 1 d subgroups of the GBF pretreatment and MK-801 groups were 11.5% +/- 1.3% and 6.5% +/- 0.9% respectively, both significantly smaller than those of the MCAO and GBE acute administration groups (24.5% +/- % and 22.9% +/- 1.3% respectively, both P < 0.01), however, there was no significant difference in the cerebral infarction area between the GBE acute administration and MCAO group. It was true too for the cerebral infarction areas of the 7 d subgroups. Except in the control group, loss of NeuN positive neuron was seen in all groups, especially the MCAO and GBE acute administration groups. Except in the control group, the MAP-2 positive neurons were decreased in all groups, especially the MCAO and GBE acute administration groups, and 1 day and 7 days after the IR MAP-2 positive neurons were almost unseen in the MCAO and GBE acute administration groups, however, could be seen in small amounts in the GBE and MK-801 groups (all P < 0.01).. GBE pretreatment protects the neurons from excitotoxicity induced by over-activated NMDA receptor and focal cerebral ischemia, which can be explained by the mild blocking effect of GBE on NMDA receptor with low affinity, comparing with MK-801, and GBE is expected to interfere in excitotoxicity in clinic without neurotoxic behaviors. Topics: Animals; Animals, Newborn; Brain Ischemia; Cell Survival; Cells, Cultured; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Ginkgo biloba; Glycine; Hippocampus; Immunohistochemistry; Male; Membrane Potentials; Microtubule-Associated Proteins; N-Methylaspartate; Nerve Tissue Proteins; Neurons; Nuclear Proteins; Plant Extracts; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury | 2006 |
Effect of N-methyl-d-aspartate receptor blockade on neuronal plasticity and gastrointestinal transit delay induced by ischemia/reperfusion in rats.
Intestinal ischemia impairs gastrointestinal motility. The aims of this study were to investigate the effect of intestinal ischemia on gastrointestinal transit and on the expression of enteric transmitters in the rat, and whether the glutamate N-methyl-d-aspartate receptors influence these effects. Ischemia (1 h), induced by occluding the superior mesenteric artery, was followed by 0 or 24 h of reperfusion. Normal and sham-operated rats served as controls. Serosal blood flow was measured with laser Doppler flow meter. Gastrointestinal transit was measured as time of appearance of a marker in fecal pellets. Immunohistochemistry was used to evaluate the number of neurons immunoreactive for neuronal nitric oxide synthase (NOS) or vasoactive intestinal polypeptide and the density of substance P immunoreactive fibers in the myenteric plexus. The N-methyl-d-aspartate receptors antagonist, (+)-5-methyl-10,11-dihydro-5HT-[a,b] cyclohepten-5,10-imine (MK-801) (1 mg/kg i.v.) or the NOS inhibitor, N-nitro-l-arginine (10 mg/kg i.v.) was administered prior to ischemia. Serosal blood flow was decreased by 70% during ischemia, but it was not altered in sham-operated rats. Gastrointestinal transit was significantly prolonged in ischemic/reperfused rats compared with controls. There was a significant increase in the number of vasoactive intestinal polypeptide and neuronal nitric oxide synthase immunoreactive neurons, and a marked decrease of substance P immunoreactive fibers in ischemia followed by 24 h of reperfusion animals compared with controls. These alterations were not observed in ischemia without reperfusion. A significant delay of gastrointestinal transit and increase of vasoactive intestinal polypeptide neurons were also observed in sham-operated rats. The changes in transmitter expression and gastrointestinal transit in ischemic/reperfused rats were prevented by pre-treatment with the NOS inhibitor, N-nitro-l-arginine or the N-methyl-d-aspartate receptors antagonist, MK-801. This study suggests an involvement of the glutamatergic system and its interaction with nitric oxide in intestinal ischemia/reperfusion. Ischemia/reperfusion might induce local release of glutamate that activates N-methyl-d-aspartate receptors leading to increased production of nitric oxide and adaptive changes in enteric transmitters that might contribute to gastrointestinal dysmotility. Topics: Analysis of Variance; Animals; Arginine; Dizocilpine Maleate; Drug Interactions; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Gastrointestinal Motility; Gastrointestinal Transit; Immunohistochemistry; Ischemia; Laser-Doppler Flowmetry; Male; Neural Inhibition; Neuronal Plasticity; NG-Nitroarginine Methyl Ester; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Regional Blood Flow; Reperfusion Injury; Time Factors; Vasoactive Intestinal Peptide | 2005 |
Endobain E, a brain endogenous factor, is present and modulates NMDA receptor in ischemic conditions.
We have isolated from rat cerebral cortex an endogenous Na(+), K(+)-ATPase inhibitor, termed endobain E, which modulates glutamatergic N-methyl-d-aspartate (NMDA) receptor. This endogenous factor allosterically decreases [(3)H]dizocilpine binding to NMDA receptor, most likely acting as a weak channel blocker. In the present study we investigated whether endobain E is present in the cerebral cortex of rats subjected to ischemia and modulates NMDA receptor exposed to the same conditions. Ischemia-reperfusion was carried out by bilateral occlusion of common carotid arteries followed by a 15-min reperfusion period. Elution profile of brain soluble fraction showed that endobain E is present in cerebral cortex of ischemia-reperfusion rats. On assaying its effect on synaptosomal membrane Na(+), K(+)-ATPase activity and [(3)H]dizocilpine binding to cerebral cortex membranes prepared from animals without treatment, it was found that the endogenous modulator isolated from ischemia-reperfusion rats was able to inhibit both enzyme activity and ligand binding. On the other hand, endobain E prepared from rats without treatment also decreased binding to cerebral cortex or hippocampal membranes obtained from animals exposed to ischemia-reperfusion. Since ischemia decreases tissue pH and NMDA receptor activity varies according to proton concentration, pH influence on endobain E effect was tested. Endobain E ( approximately 80 mg original tissue) decreased [(3)H]dizocilpine binding 25% at pH 7.4 or 8.0 but 90% at pH 6.5. These results demonstrate that endobain E is present and also able to modulate NMDA receptor in the short-term period that follows cerebral ischemia and that its effect depends on proton concentration, suggesting greater NMDA receptor modulation by endobain E at low pH, typical of ischemic tissues. Topics: Animals; Brain Ischemia; Cerebral Cortex; Disease Models, Animal; Dizocilpine Maleate; Hydrogen-Ion Concentration; Intracellular Membranes; Male; Ouabain; Protein Binding; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Sodium-Potassium-Exchanging ATPase; Subcellular Fractions | 2005 |
Non-NMDA mechanism in the inhibition of cellular apoptosis and memory impairment induced by repeated ischemia in rats.
The spatial memory impairment and expression of apoptotic cells in hippocampal CA1 cells were investigated in rats using single and repeated ischemia models. The neuroprotective and memory-improving effect of YM-90K, an alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor antagonist, was compared to MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist. Twice-repeated ischemia, but not single ischemia, impaired the spatial memory and increased expression of apoptotic cells. YM-90K, given before and 6 h after the second reperfusion, significantly improved the memory and reduced the apoptotic cells 7 days after the second reperfusion in repeated ischemia. MK-801 neither improved the spatial memory nor reduced apoptotic cells. The present study showed that delayed expression of apoptotic cells is mediated by mechanisms involving AMPA receptors, but not by NMDA receptor, during the late phase after reperfusion. YM-90K could provide neuroprotective activity and improve the spatial memory impaired by repeated ischemia. Topics: Animals; Apoptosis; Brain Ischemia; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Hippocampus; Male; Maze Learning; Memory Disorders; Nerve Degeneration; Neurons; Neuroprotective Agents; Quinoxalines; Rats; Rats, Wistar; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate; Recovery of Function; Reperfusion Injury | 2004 |
Neuroprotective synergy of N-methyl-D-aspartate receptor antagonist (MK801) and protein synthesis inhibitor (cycloheximide) on spinal cord ischemia-reperfusion injury in rats.
Thoraco-abdominal aortic surgery requiring temporal cross clamping of the aorta results in a high incidence of paraplegia due to temporary ischemia of the spinal cord. Both excitotoxicity and apoptosis are implicated in the pathogenesis of spinal cord ischemia-reperfusion injury. We propose that the N-methyl-D-aspartate receptor antagonist dizocilpine maleate (MK801) and the protein synthesis inhibitor cycloheximide produce a synergic effect in a rodent model of spinal cord ischemia-reperfusion injury. Injury was induced by 20 min of temporal thoracic aorta occlusion and distal blood volume reduction. After injury, the animals were treated with vehicle, MK801, cycloheximide or MK801 and cycloheximide. Hind limb motor function recovery was better in the MK801 and combined therapy groups than in the control and cycloheximide groups. The mean neuronal survival rate of the control group was 45.3 +/- 3.2% on the 7(th) day after injury. In the MK801 and cycloheximide treatment groups, neuronal survival increased to 62.4 +/- 3.6% and 54.1 +/- 2.4%, respectively. For the combined therapy group, neuronal survival increased to 75.6 +/- 2.5%. The number of apoptotic cells in the control group was 211.4 +/- 8.8 per section on the 7th day after ischemic insult, while apoptosis was significantly reduced in the cycloheximide (96.8 +/- 6.7 cells) and combined (84.8 +/- 8.5 cells) groups. It was unchanged in the MK801 group (209.8 +/- 5.4 cells). These results suggest that combined treatments directed at blocking both N-methyl-D-aspartate receptor-mediated excitotoxic necrosis and caspase-mediated apoptosis might have synergic therapeutic potential in reducing spinal cord ischemia-reperfusion injury. Topics: Animals; Apoptosis; Cycloheximide; Dizocilpine Maleate; Drug Synergism; Excitatory Amino Acid Antagonists; Male; Necrosis; Neuroprotective Agents; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Spinal Cord | 2003 |
Effects of intraocular injection of a low concentration of zinc on the rat retina.
The main aim of this study was to investigate whether intraocular injection of low concentrations of zinc (no greater than 10 microM) aid the survival of ganglion cells in the rat retina after excitotoxic (NMDA) and ischemia/reperfusion injuries. We also determined whether low amounts of zinc cause any detectable retinal toxicity. Intraocular injection of NMDA caused substantial reductions in the mRNA levels of the ganglion cell-specific markers Thy-1 and neurofilament light (NF-L). Co-injection of 0.1 or 1 nmol zinc neither diminished nor exacerbated the effect of NMDA on the levels of these mRNAs. Likewise, ischemia/reperfusion caused significant decreases in the levels of Thy-1 and NF-L mRNAs and in the b-wave amplitude of the electroretinogram. These effects were not counteracted by injection of zinc. Intraocular injection of NMDA caused marked toxicological effects in retinal glial cells, including upregulations of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), glial fibrial acidic protein (GFAP), basic fibroblast growth factor (FGF-2) and ciliary neurotrophic factor (CNTF). Interestingly, injection of 1 nmol zinc caused no changes in the levels of COX-2 and iNOS, yet produced similar, although quantitatively less pronounced, changes in FGF-2, GFAP and CNTF. The upregulations of FGF-2 and CNTF suggest that increasing zinc intake may benefit injured retinal neurons. However, this was not found to be the case in the present studies, perhaps due to the acute nature of the injury paradigms utilised. Topics: Animals; Astringents; Cell Death; Cell Survival; Ciliary Neurotrophic Factor; Cyclooxygenase 2; Dizocilpine Maleate; Dose-Response Relationship, Drug; Drug Interactions; Electroretinography; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Eye; Fibroblast Growth Factor 2; Glial Fibrillary Acidic Protein; Immunoblotting; Immunohistochemistry; Isoenzymes; N-Methylaspartate; Neuroglia; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Reperfusion Injury; Retina; Retinal Ganglion Cells; Reverse Transcriptase Polymerase Chain Reaction; Rhodopsin; RNA, Messenger; Thy-1 Antigens; Time Factors; Zinc Sulfate | 2003 |
Alpha-lipoic acid protects the retina against ischemia-reperfusion.
The aim of this study was to examine whether the antioxidant alpha-lipoic acid protects retinal neurons from ischemia-reperfusion injury. Rats were injected intraperitoneally with either vehicle or alpha-lipoic acid (100 mg/kg) once daily for 11 days. On the third day, ischemia was delivered to the rat retina by raising the intraocular pressure above systolic blood pressure for 45 min. The electroretinogram was measured prior to ischemia and 5 days after reperfusion. Rats were killed 5 or 8 days after reperfusion and the retinas were processed for immunohistochemistry and for determination of mRNA levels by RT-PCR. Ischemia-reperfusion caused a significant reduction of the a- and b-wave amplitudes of the electroretinogram, a decrease in nitric oxide synthase and Thy-1 immunoreactivities, a decrease of retinal ganglion cell-specific mRNAs and an increase in bFGF and CNTF mRNA levels. All of these changes were clearly counteracted by alpha-lipoic acid. Moreover, in mixed rat retinal cultures, alpha-lipoic acid partially counteracted the loss of GABA-immunoreactive neurons induced by anoxia. The results of the study demonstrate that alpha-lipoic acid provides protection to the retina as a whole, and to ganglion cells in particular, from ischemia-reperfusion injuries. alpha-Lipoic acid also displayed negligible affinity for voltage-dependent sodium and calcium channels. Topics: Anesthetics, Local; Animals; Antioxidants; Binding, Competitive; Brain-Derived Neurotrophic Factor; Calcium; Calcium Channel Blockers; Cells, Cultured; Ciliary Neurotrophic Factor; Diltiazem; Dizocilpine Maleate; DNA Primers; Dose-Response Relationship, Drug; Drug Interactions; Electroretinography; Fibroblast Growth Factors; Glial Fibrillary Acidic Protein; Glyceraldehyde-3-Phosphate Dehydrogenases; N-Methylaspartate; Nifedipine; Rats; Reperfusion Injury; Retinal Diseases; Reverse Transcriptase Polymerase Chain Reaction; Rhodopsin; RNA, Messenger; Sodium; Tetrodotoxin; Thioctic Acid; Thy-1 Antigens; Veratridine | 2002 |
Neuroprotective MK801 is associated with nitric oxide synthase during hypoxia/reoxygenation in rat cortical cell cultures.
The neuroprotective effect of MK801 against hypoxia and/or reoxygenation-induced neuronal cell injury and its relationship to neuronal nitric oxide synthetase (nNOS) expression were examined in cultured rat cortical cells. Treatment of cortical neuronal cells with hypoxia (95% N(2)/5% CO(2)) for 2 h followed by reoxygenation for 24 h induced a release of lactate dehydrogenase (LDH) into the medium, and reduced the protein level of MAP-2 as well. MK801 attenuated the release of LDH and the reduction of the MAP-2 protein by hypoxia, suggesting a neuroprotective role of MK801. MK801 also diminished the number of nuclear condensation by hypoxia/reoxygenation. The NOS inhibitors 7-nitroindazole (7-NI) and N (G)-nitro-L-arginine methyl ester (L-NAME), as well as the Ca(2+) channel blocker nimodipine, reduced hypoxia-induced LDH, suggesting that nitric oxide (NO) and calcium homeostasis contribute to hypoxia and/or the reoxygenation-induced cell injury. The levels of nNOS immunoactivities and mRNA by RT-PCR were enhanced by hypoxia with time and, down regulated following 24 h reoxygenation after hypoxia, and were attenuated by MK801. In addition, the reduction of nNOS mRNA levels by hypoxia/reoxygenation was also diminished by MK801. Further delineation of the mechanisms of NO production and nNOS regulation are needed and may lead to additional strategies to protect neuronal cells against hypoxic/reoxygenation insults. Topics: Animals; Apoptosis; Base Sequence; Cells, Cultured; Cerebral Cortex; Dizocilpine Maleate; DNA Primers; Hypoxia; Neuroprotective Agents; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 2002 |
Effect of ketamine, dextromethorphan, and MK-801 on cochlear dysfunction induced by transient ischemia.
Overstimulation of the N-methyl-D-aspartate (NMDA) glutamate receptor has been implicated as a factor in the pathogenesis of hypoxic-ischemic injury in the central nervous system. To evaluate the role played by NMDA antagonists in ischemia-reperfusion injury of the cochlea, 3 noncompetitive NMDA antagonists--ketamine, dextromethorphan, and MK-801--were administered to 53 albino guinea pigs subjected to transient ischemia of 30 minutes' duration, and the threshold shifts of the compound action potential were compared with those of nontreated animals 4 hours after the onset of recirculation. Ketamine and dextromethorphan moderately ameliorated the compound action potential threshold shifts, whereas MK-801, the most potent NMDA receptor antagonist among these 3 agents, did not show any protective effect. These results indicate that the action antagonizing the NMDA receptor has no protective effect against ischemia-reperfusion injury of the cochlea, and that ketamine and dextromethorphan act as protective agents for the cochlea via other pathways. Topics: Action Potentials; Animals; Cochlea; Dextromethorphan; Dizocilpine Maleate; Guinea Pigs; Ketamine; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury | 2002 |
Hypoxia/reoxygenation induces cell injury via different mechanisms in cultured rat cortical neurons and glial cells.
Hypoxia/reoxygenation (H/R) causes cell injury/death. We examined the protection by drugs intervening at various stages of the injury cascade in cultured neurons and glia. Primary cultures of rat cortical neurons and mixed glia were subjected to H/R. Measurements of cell death (by lactate dehydrogenase release into the medium) and viability (by MTT reduction) indicated that H/R led to time-dependent injury in both neuronal and mixed glial cultures. The extent of cell injury in neurons was significantly greater than in glia cells. Pretreatment with (+)-MK-801 hydrogen maleate (MK-801) (an N-methyl-D-aspartate antagonist), N(omega)-nitro-L-arginine methyl ester (L-NAME) (an inhibitor of nitric oxide synthase) or free radical scavengers reduced the extent of the H/R-elicited neuronal damage. MK-801, in contrast, was without effect on glial cells while L-NAME was effective. Our results suggest differential mechanism(s) and susceptibility to injury caused by H/R for neurons and mixed glia. Topics: Animals; Antioxidants; Astrocytes; Cell Death; Cells, Cultured; Dizocilpine Maleate; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Female; Free Radicals; Hypoxia-Ischemia, Brain; L-Lactate Dehydrogenase; Neuroglia; Neurons; Neuroprotective Agents; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Pregnancy; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Tetrazolium Salts; Thiazoles | 2002 |
Alteration of phosphatidylinositol transfer protein during global brain ischemia-reperfusion in gerbils.
Phosphatidylinositol transfer proteins (PI-TPs) are responsible for the transport of phosphatidylinositol and other phospholipids. Moreover, these proteins are involved in vesicle transport and in the function of cytoskeleton. Our previous data indicated that brain ischemia affected phosphoinositides metabolism and the level of lipid derived second messengers. In this study, the effect of ischemia-reperfusion injury on the level of PI-TPs and of the role of NMDA receptor stimulation on the alteration of these proteins was investigated during reperfusion after 5 min of forebrain ischemia in gerbils. Some groups of animals were injected intraperitoneally with MK-801, an antagonist of NMDA receptor 30 min before ischemia. The levels of both PI-TP isoforms alpha+beta and separately the alpha-isoform were determined in cytosol and membrane fraction from brain cortex and hippocampus using Western blot analysis. In the cytosolic fractions, the concentration of both isoforms of PI-TP was 2 times higher when compared to the membrane fraction. In brain cortex, PI-TP alpha isoform consist about 32-44% but in hippocampus 72-82% of both isoforms (PI-TP alpha+beta) in cytosolic and membrane fraction respectively. Ischemia-reperfusion had no effect on PI-TPs in brain cortex. However, in hippocampus after 5 min ischemia and during whole reperfusion time up till 7 days the level of PI-TP alpha+beta and PI-TP alpha was significantly higher by about 20-55%, respectively when compared to control. MK-801 eliminated ischemia-reperfusion evoked alteration of PI-TPs. To confirm the role of NMDA receptor in PI-TP alteration additional experiments were carried out on PC-12 cells in culture. The results indicated that activation of NMDA receptor enhances significantly the level of PI-TP alpha. The competitive antagonist of NMDA receptor inhibited this effect. These results indicated that activation of NMDA receptor is connected with PI-TPs alteration and plays an important role in modulation of PI-TPs during ischemia-reperfusion injury that may have important physiopathological consequence. Topics: Animals; Blotting, Western; Brain; Carrier Proteins; Dizocilpine Maleate; Excitatory Amino Acid Agonists; Male; Membrane Proteins; PC12 Cells; Phospholipid Transfer Proteins; Rats; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury | 2002 |
N-methyl-D-aspartate receptor antagonist reduces nitrotyrosine formation in caudate-putamen in rat focal cerebral ischemia-reperfusion.
The aim of this study is to determine experimentally whether N-methyl-D-aspartate (NMDA) receptor is involved in nitrotyrosine formation in rat brain subjected to focal ischemia-reperfusion, by using the NMDA receptor antagonist MK-801. Halothane-anesthetized and artificially ventilated rats were given MK-801 (5 mg/kg, i.p.) or vehicle prior to 2 h of focal cerebral ischemia followed by 0.5 h of reperfusion. The brain was then removed and divided into four sections, cortical ischemic core, peri-ischemic cortex, lateral caudate-putamen and non-ischemic cortex. Tissue nitrotyrosine was measured by means of hydrolysis/HPLC. MK-801 significantly attenuated nitrotyrosine formation in the lateral caudate-putamen. We conclude that nitrotyrosine formation required activation of NMDA receptors, at least in part. Topics: Animals; Brain Ischemia; Calcium Channels; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Male; Neostriatum; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Tyrosine | 2001 |
Interleukin-1beta mediates ischemic injury in the rat retina.
Two types of experiment were performed to examine the role of interleukin-1beta in ischemia-induced damage in the rat retina. In the in vivo study, enzyme-linked immunosorbent assay was used to investigate the expression of immunoreactive interleukin-1beta in the rat retina following a hypertension-induced ischemia/reperfusion, while the effect of a recombinant human interleukin-1 receptor antagonist or an anti-interleukin-1beta neutralizing antibody on the ischemia-induced damage was examined histologically. A transient increase in the expression of immunoreactive interleukin-1beta was observed in the retina 3-12 hr after reperfusion, and morphometric evaluation at 7 days after the ischemia showed a decrease in cell numbers in the ganglion cell layer and a decreased thickness of the inner plexiform layer with no change in the other retinal layers. Intravitreal injection of interleukin-1 receptor antagonist (1 or 10 ng per eye) or anti-interleukin-1beta antibody (50 or 500 ng per eye) 5 min before the onset of the ischemia reduced the damage. In the in vitro study, interleukin-1 receptor antagonist (500 ng ml(-1)) significantly reduced glutamate-induced neurotoxicity in rat cultured retinal neurons. These results suggest that interleukin-1 plays an important role in mediating ischemic and excitotoxic damage in the retina, and that interleukin-1 inhibitors may be therapeutically useful against neuronal injury caused by optic nerve or retinal diseases such as glaucoma and central retinal artery or vein occlusion. Topics: Analysis of Variance; Animals; Cell Count; Cell Survival; Cells, Cultured; Choroid Plexus; Dizocilpine Maleate; Enzyme-Linked Immunosorbent Assay; Ganglia, Sensory; Glutamic Acid; Interleukin-1; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Retina; Retinal Diseases | 2001 |
Hypoxic but not ischemic neurotoxicity of free radicals revealed by dynamic changes in glucose metabolism of fresh rat brain slices on positron autoradiography.
Dynamic changes in the regional cerebral glucose metabolic rate induced by hypoxia/reoxygenation or ischemia/reperfusion were investigated with a positron autoradiography technique. Fresh rat brain slices were incubated with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [18F]FDG uptake in the slices were obtained. In the case of loading hypoxia (oxygen deprivation)/pseudoischemia (oxygen and glucose deprivation) for various periods of time, the net influx constant (K) of [18F]FDG at preloading and after reoxygenation/pseudoreperfusion (post-loading) was quantitatively evaluated by applying the Patlak graphical method to the image data. Regardless of the brain region, with hypoxia lasting > or =20 minutes, the postloading K value was decreased compared with the unloaded control, whereas with pseudoischemia of < or =40 minutes, approximately the same level as the unloaded control was maintained. Next, the neuroprotective effect against hypoxia/pseudoischemia loading induced by the addition of a free radical scavenger or an N-methyl-D-aspartate (NMDA) antagonist was assessed by determining whether a decrease in the postloading K value was prevented. Whereas with 20-minute hypoxia, both agents exhibited a neuroprotective effect, in the case of 50-minute pseudoischemia, only the NMDA antagonist did so, with the free radical scavenger being ineffective. These results demonstrate that hypoxia causes irreversible neuronal damage within a shorter period than ischemia, with both free radicals and glutamate suggested to be involved in tandem in the neurotoxicity induced by hypoxia, whereas glutamate alone is involved in ischemic neurotoxicity. Topics: Animals; Autoradiography; Brain; Cerebrovascular Circulation; Cyclic N-Oxides; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Fluorodeoxyglucose F18; Free Radicals; Glucose; Glutamic Acid; Hypoxia, Brain; In Vitro Techniques; Ischemic Attack, Transient; Male; Neurotoxins; Nitrogen Oxides; Oxygen; Radionuclide Imaging; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Spin Labels | 2000 |
Lomerizine, a Ca2+ channel blocker, reduces glutamate-induced neurotoxicity and ischemia/reperfusion damage in rat retina.
We examined the effects of a new Ca2+ channel blocker, lomerizine, on the intraocular hypertension-induced ischemia/reperfusion injury in rat retina and on the glutamate-induced neurotoxicity in rat cultured retinal neurons, and compared its effects with those of a Ca2+ channel blocker (flunarizine) and an N-methyl-D-aspartate receptor antagonist (MK-801). Morphometric evaluation at 7 days after ischemia/reperfusion showed that treatment with lomerizine (0.1 and 1 mg kg(-1), i.v.) prior to ischemia and again immediately after reperfusion dose-dependently reduced the retinal damage. Treatment with MK-801 (1 mg kg(-1), i.v.) before ischemia significantly reduced the resulting retinal damage. Flunarizine (0.1 and 1 mg kg(-1), i.v.) tended to reduce the retinal damage, but its effect did not reach statistical significance. In an in vitro study, pretreatment with lomerizine (0.1 and 1 microM) or flunarizine (1 microM) significantly reduced glutamate-induced neurotoxicity, the effects being concentration dependent. Lomerizine (1 microM) also exhibited protective effects against both the N-methyl-D-aspartate and kainate induced types of neurotoxicity. However, lomerizine (1 microM) had little effect on the neurotoxicity induced by ionomycin (1 microM) application. Glutamate-induced neurotoxicity was abolished by removing Ca2+ from the medium. These results indicate that lomerizine protects neuronal cells against retinal neurotoxicity both in vivo and in vitro, and that this Ca2+ channel blocker may be useful as a therapeutic drug against retinal diseases that cause neuronal injury, such as normal tension glaucoma (NTG). Topics: Animals; Calcium Channel Blockers; Cells, Cultured; Dizocilpine Maleate; Dose-Response Relationship, Drug; Flunarizine; Glutamic Acid; Male; Neuroprotective Agents; Neurotoxicity Syndromes; Piperazines; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 2000 |
Posthypoxic reoxygenation-induced neurotoxicity prevented by free radical scavenger and NMDA/non-NMDA antagonist in tandem as revealed by dynamic changes in glucose metabolism with positron autoradiography.
Using a positron autoradiography technique, dynamic changes in the cerebral glucose metabolic rate (CMRglc) induced by hypoxia/reoxygenation were investigated in living brain slices. After incubating fresh rat brain slices (300 microm thick) with [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, serial two-dimensional time-resolved images of [(18)F]FDG uptake in the slices were obtained on imaging plates. As compared to the unloaded control values, with hypoxia-loading [(18)F]FDG uptake increased markedly, suggesting enhanced glycolysis. The net influx constant (K) of [(18)F]FDG at pre-hypoxia-loading and after reoxygenation with loading hypoxia for various periods of time was quantitatively evaluated by applying the Patlak graphical method to the image data. Regardless of the brain region, with hypoxia of /=20 min duration only partial or no recovery was seen, indicating irreversible neuronal damage. The 30-min administration of either N-methyl-D-aspartate (NMDA)/non-NMDA antagonist or a free radical scavenger at the same time as reoxygenation after 20 min hypoxia showed a neuroprotective effect inhibiting the decrease in the post-hypoxia-loading K value. In contrast, no such neuroprotective effect was evident with administration of either of these agents only during hypoxia loading, possibly indicating that immediately after reoxygenation neuronal damage was induced mediated by excitatory amino acids and free radicals in tandem. These results demonstrate that serial quantitative evaluation of CMRglc using this technique may be of use in investigating the brain tissue injury associated with hypoxia/reoxygenation as well as clarifying the underlying mechanisms and protective effect of various drugs against such injury. Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Animals; Autoradiography; Cell Hypoxia; Cell Survival; Coloring Agents; Cyclic N-Oxides; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Fluorodeoxyglucose F18; Free Radical Scavengers; Glucose; Glycolysis; Hypoxia, Brain; In Vitro Techniques; Lactic Acid; Male; Neurons; Neuroprotective Agents; Nitrogen Oxides; Oxazines; Rats; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Xanthenes | 2000 |
Hypothermia prevents biphasic glutamate release and corresponding neuronal degeneration after transient spinal cord ischemia in the rat.
1. Spinal cord ischemia evoked a biphasic increase in CSF-Glu during 20 min of ischemia (40%) and at 2 hr after reperfusion (70%) in the nontreated group that was attenuated by all treated groups. But MK-801 (15 micrograms i.t.) did not affect the increased Glu at 2 hr (80%). 2. The argyrophilia observed in laminae II-V at 8 hr after reperfusion was attenuated by hypothermia (33 degrees C) and combination with MK-801, but the attenuation was less with MK-801. 3. Mild hypothermia attenuated the biphasic increase in CSF-Glu and corresponding development of neuronal damage after spinal cord ischemia. 4. Mild hypothermia with NMDA antagonism did not yield any further effects, suggesting that hypothermia itself plays a pivotal role in the protection. Topics: Animals; Combined Modality Therapy; Denervation; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Glutamic Acid; Hypothermia, Induced; Injections, Spinal; Male; Microdialysis; Nerve Degeneration; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Spinal Cord | 1999 |
Use of brain slices in the study of pathogenic role of inducible nitric oxide synthase in cerebral ischemia-reperfusion.
We have recently demonstrated that inducible nitric oxide synthase (iNOS) is expressed in rat forebrain slices exposed to oxygen and glucose deprivation (OGD). Now, we have found that the expression of iNOS after OGD is time-dependent since 20 min of OGD produces the appearance of iNOS at earlier times than 10 min of OGD. OGD also causes neurotoxicity in this model, as revealed by the increase in excitatory amino acid, neuron specific enolase and lactate dehydrogenase (LDH) efflux to the incubation solution. Finally, the administration of the NMDA receptor antagonist MK-801 (100 nM) inhibits both the expression of iNOS and the release of LDH. Our findings demonstrate that this method may be considered an useful in vitro model of ischemia-reperfusion to determine the therapeutic role of neuroprotective tools. Topics: Animals; Brain Ischemia; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Excitatory Amino Acids; Glucose; Hypoxia; In Vitro Techniques; L-Lactate Dehydrogenase; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Phosphopyruvate Hydratase; Prosencephalon; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 1999 |
The effects of MK-801 and U-83836E on post-ischemic reperfusion injury in rat brain.
Rats were subjected to incomplete cerebral ischemia induced by occlusion of common carotid arteries for 30 min, and subsequent reperfusion for 15 min. The concentrations of reduced glutathione (GSH), malondialdehyde (MDA) and superoxide dismutase (SOD) activity were determined in the dorsal hippocampus in order to evaluate their changes during ischemia and reperfusion following ischemia. The depletion of GSH was observed during ischemia with a further depletion during post-ischemic reperfusion (P < 0.001), while a significant increase in SOD activity and MDA levels was found only after reperfusion following ischemia (P < 0.001). Animals in which ischemia was followed by reperfusion were treated with a non-competitive NMDA receptor antagonist, MK-801 (1 mg/kg, i.v.), and a radical scavenger, U-83836E (5 mg/kg, i.v.), prior to ischemia. Although a full recovery of GSH levels was not observed following MK-801 and U-83836E pretreatment as compared to control (P < 0.05), MK-801 was more potent than U-83836E in the partial protection of the GSH pool (P < 0.05 and P < 0.01, respectively). The rise in SOD activity and MDA level were brought close to those of control due to the effects of both MK-801 and U-83836E (P > 0.05). In conclusion, the tissue changes in GSH concentrations evoked by ischemia and reperfusion were partially prevented by the effects of both drugs, MK-801 having the greater effect. This suggests that the NMDA receptor activation may play a role in the generation of reactive oxygen species. On the other hand, the inhibition of lipid peroxidation brought about by both MK-801 or U-83836E suggests the therapeutic efficiency of these agents in ischemia/reperfusion injury. Topics: Animals; Antioxidants; Chromans; Dizocilpine Maleate; Glutathione; Hippocampus; Ischemic Attack, Transient; Male; Malondialdehyde; Neuroprotective Agents; Piperazines; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase | 1999 |
Involvement of platelet-activating factor in cell death induced under ischemia/postischemia-like conditions in an immortalized hippocampal cell line.
The involvement of platelet-activating factor (PAF) in cell damage induced by ischemia/postischemia-like conditions was studied in a hippocampus-derived cell line, HN33.11. Cells exposed to N2-saturated glucose-free HEPES-buffered saline (ischemia) for 5 h followed by 18 h of incubation in serum-free control medium (postischemia reincubation) remained 67.4 +/- 2.4% viable in comparison with sham-treated cells. Analysis of DNA fragmentation in combination with Hoechst 33258 staining indicates that apoptosis is the dominant mode of cell death in the present model. PAF level during 10 h of ischemia was unchanged. However, an increase in PAF accumulation was found early during the reincubation period that followed 5 h of ischemia. Peak PAF concentrations were noted at 2 h after initiation of reincubation and rapidly declined to control level after 7 h of reincubation. Consistent with a role of PAF in mediating cell death under ischemia/postischemia reincubation in this model, the PAF antagonist BN 50739 exerted a dose-dependent protective effect. Maximal protection (85.7 +/- 5.4%) of the cells from ischemia/reincubation-induced cell damage was achieved at 0.1 microM BN 50739. The PAF antagonist lacked any protective effect against ischemia-induced cell death. On the other hand, the addition of the stable PAF analogue 1-O-hexadecyl-2-N-methylcarbamyl-sn-glycero-3-phosphocholine (MC-PAF) at the onset of ischemia potentiated ischemia/reincubation-induced apoptosis--an effect that was blocked by BN 50739. Pretreatment of HN33.11 cells with the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester (BAPTA-AM) also provided a protective effect against ischemia/reincubation-induced cell damage. BAPTA-AM increased cell viability by 50%. Pretreatment with BAPTA-AM also decreased ischemia/reincubation-induced PAF accumulation in HN33.11 cells. The results suggest that PAF, acting via a PAF receptor, is at least in part mediating apoptosis under ischemia/postischemia-like conditions in HN33.11 cells. Topics: Azepines; Calcium; Cell Death; Cell Line, Transformed; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Hippocampus; Ischemia; Platelet Activating Factor; Platelet Membrane Glycoproteins; Pyridinium Compounds; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Reperfusion Injury; Signal Transduction; Triazoles | 1998 |
Prolonged enhancement and depression of synaptic transmission in CA1 pyramidal neurons induced by transient forebrain ischemia in vivo.
Evoked postsynaptic potentials of CA1 pyramidal neurons in rat hippocampus were studied during 48 h after severe ischemic insult using in vivo intracellular recording and staining techniques. Postischemic CA1 neurons displayed one of three distinct response patterns following contralateral commissural stimulation. At early recirculation times (0-12 h) approximately 50% of neurons exhibited, in addition to the initial excitatory postsynaptic potential, a late depolarizing postsynaptic potential lasting for more than 100 ms. Application of dizocilpine maleate reduced the amplitude of late depolarizing postsynaptic potential by 60%. Other CA1 neurons recorded in this interval failed to develop late depolarizing postsynaptic potentials but showed a modest blunting of initial excitatory postsynaptic potentials (non-late depolarizing postsynaptic potential neuron). The proportion of recorded neurons with late depolarizing postsynaptic potential characteristics increased to more than 70% during 13-24 h after reperfusion. Beyond 24 h reperfusion, approximately 20% of CA neurons exhibited very small excitatory postsynaptic potentials even with maximal stimulus intensity. The slope of the initial excitatory postsynaptic potentials in late depolarizing postsynaptic potential neurons increased to approximately 150% of control values up to 12 h after reperfusion indicating a prolonged enhancement of synaptic transmission. In contrast, the slope of the initial excitatory postsynaptic potentials in non-late depolarizing postsynaptic potential neurons decreased to less than 50% of preischemic values up to 24 h after reperfusion indicating a prolonged depression of synaptic transmission. More late depolarizing postsynaptic potential neurons were located in the medial portion of CA1 zone where neurons are more vulnerable to ischemia whereas more non-late depolarizing postsynaptic potential neurons were located in the lateral portion of CA1 zone where neurons are more resistant to ischemia. The result from the present study suggests that late depolarizing postsynaptic potential and small excitatory postsynaptic potential neurons may be irreversibly injured while non-late depolarizing postsynaptic potential neurons may be those that survive the ischemic insult. Alterations of synaptic transmission may be associated with the pathogenesis of postischemic neuronal injury. Topics: Animals; Dizocilpine Maleate; Electric Stimulation; Electrophysiology; Evoked Potentials; Excitatory Amino Acid Agonists; Excitatory Postsynaptic Potentials; Ischemic Attack, Transient; Male; Pyramidal Cells; Rats; Rats, Wistar; Reperfusion Injury; Synaptic Transmission | 1998 |
MK-801, a non-competitive NMDA receptor antagonist, prevents postischemic decrease of inositol 1,4,5-trisphosphate receptor mRNA expression in mongolian gerbil brain.
Changes of inositol 1,4,5-trisphosphate receptor (IP3R) mRNA expression after transient brain ischemia and the effect of MK-801, a non-competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, on the IP3R mRNA expression was studied in mongolian gerbil brain by in situ hybridization. Transient ischemia was induced by ligating left common carotid artery for 10 min, and the animals were allowed recovery from 15 min to 24 h. MK-801 was introduced intraperitoneally 30 min before ischemia. IP3R mRNA expression was decreased in dentate gyrus and hippocampus from 90 min until 24 h after ischemia. MK-801 pretreatment prevented the change of IP3R mRNA expression after ischemia. These results suggest that IP3R mRNA expression in ischemia may be related with NMDA receptor. Topics: Animals; Brain; Calcium Channels; Dentate Gyrus; Dizocilpine Maleate; Gerbillinae; Hippocampus; In Situ Hybridization; Inositol 1,4,5-Trisphosphate Receptors; Ischemic Attack, Transient; Male; Receptors, Cytoplasmic and Nuclear; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; RNA, Messenger; Time Factors; Tissue Distribution | 1998 |
NMDA receptor-dependent nitric oxide and cGMP synthesis in brain hemispheres and cerebellum during reperfusion after transient forebrain ischemia in gerbils: effect of 7-Nitroindazole.
In this study, the N-Methyl-D-Aspartate (NMDA) receptor-dependent nitric oxide and cyclic GMP (cGMP) synthesis in the course of reperfusion after 5 min of ischemia in gerbil brain hemispheres and cerebellum were investigated. Moreover, the role of the neuronal isoform of nitric oxide (NO) synthase (nNOS) in liberation of NO in postischemic brain and the involvement of NO in membrane lipoperoxidations activated during reperfusion were evaluated. Enhancement of Ca2+/calmodulin-regulated NOS activity and cGMP level in brain hemispheres and in cerebellum during reperfusion was found to be coupled to the activation of the NMDA receptor. cGMP concentration 40% above the control level was observed to persist up to 7 days after ischemia. The amount of conjugated double bounds in membrane lipids and the level of thiobarbituric acid reactive substances were increased exclusively in brain hemispheres, indicating activation of lipid peroxidation. The NMDA receptor antagonist, MK-801, eliminated, and a rather selective nNOS inhibitor, 7-Nitroindazole (7-NI) attenuated, NMDA receptor-evoked enhancement of NOS activity and cGMP level in brain hemispheres and in cerebellum during reperfusion. Moreover, 7-NI decreased significantly membrane lipid peroxidation during the early time of reperfusion. Histological examination demonstrated that 7-NI protects against death a selected population of neuronal cells in CA1 layer of hippocampus. It is suggested that NMDA receptor dependence of NO release during reperfusion is responsible for the degeneration of some populations of neurons and that the effect is mediated by activation of free radical formation and lipid peroxidation. Moreover, in cerebellum, ischemia-evoked activation of glutamatergic system stimulates NO-dependent signal transmission. Our results indicated that 7-NI has a significant ameliorating effect on biochemical alterations evoked by ischemia, suggesting nNOS inhibitors as a potential therapeutic agents in reperfusion injury. Topics: Animals; Brain Ischemia; Cerebellum; Cerebral Cortex; Cyclic GMP; Dizocilpine Maleate; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Gerbillinae; Indazoles; Lipid Peroxidation; Male; Membrane Lipids; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Prosencephalon; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Signal Transduction; Thiobarbituric Acid Reactive Substances | 1998 |
Kainate-induced cerebrovascular dilation is resistant to ischemia in piglets.
Cerebral arteriolar dilation to N-methyl-D-aspartate (NMDA) is drastically reduced by anoxic stress. The effects of anoxic stress on cerebrovascular dilation to activation of other types of glutamate receptors are unknown. The purpose of this study was to examine the effects of ischemia on cerebral arteriolar responses to kainate in anesthetized piglets.. Arteriolar responses to 5 x 10(-5) mol/L and 10(-4) mol/L kainate were evaluated before and 10 minutes after total, global ischemia. Ischemia was induced by increasing intracranial pressure. We measured pial arteriolar diameters (approximately 100 microns) using a cranial window and intravital microscopy.. Before ischemia, kainate dilated arterioles by 16 +/- 2% at 5 x 10% mol/L and 30 +/- 2% at 10(-4) mol/L (mean +/- SEM; n = 6). After ischemia, the diameter of arterioles increased by 17 +/- 3% and 26 +/- 3% to 5 x 10% and 10(-4) mol/L kainate, respectively (P > .05). We also investigated the mechanisms involved in mediating arteriolar dilation to kainate. Intravenous administration of N omega-nitro-L-arginine methyl ester (L-NAME) (15 mg/kg) (n = 7) or indomethacin (10 mg/kg) (n = 6) individually reduced arteriolar dilation to kainate by approximately one half. Coadministration of L-NAME and indomethacin almost completely eliminated arteriolar dilation to kainate (n = 10). Administration of theophylline (20 mg/kg IV) did not affect dilator responses to kainate (n = 7). Blockade of NMDA receptors by MK801 had minimal effects on arteriolar dilation to kainate (n = 6).. There are three main findings from this study: (1) kainate is a potent dilator agent in the neonatal cerebral circulation; (2) nitric oxide and prostaglandins both participate in the vasodilator response to kainate; and (3) in contrast to NMDA, cerebral arteriolar dilator responses to kainate are resistant to ischemic stress. Topics: Animals; Animals, Newborn; Arterioles; Brain Ischemia; Cerebral Arteries; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Indomethacin; Kainic Acid; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Prostaglandins; Reperfusion Injury; Swine; Theophylline; Vasodilator Agents | 1997 |
The sequential change of local cerebral blood flow and local cerebral glucose metabolism after focal cerebral ischaemia and reperfusion in rat and the effect of MK-801 on local cerebral glucose metabolism.
In order to investigate the time course change of local cerebral blood flow (1CBF) and local cerebral glucose metabolism (ICGM) and the effect of MK-801 (dizocilpine), an NMDA receptor antagonist on glucose metabolism in a middle cerebral artery occlusion-reperfusion model, 14C-Iodo-antipyrine and 14C-Deoxyglucose autoradiographic method have been used. The 1CBF was reduced to 0-10% of the control level in the ischaemic core and to 12-40% in the ischaemic penumbra between 60 and 120 min after the onset of the ischaemia. In the ischaemic core, the marked hyperfusion appeared at 15 min and maintained about 30 to 45 min following reperfusion. In the ischaemic penumbra, the hyperfusion during reperfusion was not found. Hypermetabolism occurred at 30 min and reached to the peak at 60 min after the middle cerebral artery (MCA) occlusion both in the ischaemic core and in the penumbra. The shift from hyper- to hypometabolism was observed during the ischaemia. The reperfusion following 2 hours of MCA occlusion facilitated the decrease of cerebral glucose metabolism in the ischaemic region. The pretreatment of MK-801 (0.4 mg/kg) inhibited both increased glucose metabolism during the ischaemia and decreased glucose metabolism during the reperfusion. The effect of limiting decreased glucose metabolism during the reperfusion by MK-801 was remarkable in the ischaemic penumbra. These findings support the hypothesis that excitation-induced hypermetabolism play a major role in the ischaemic insult following focal cerebral vascular occlusion. Topics: Animals; Autoradiography; Blood Glucose; Brain; Brain Ischemia; Dizocilpine Maleate; Energy Metabolism; Male; Neuroprotective Agents; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Regional Blood Flow; Reperfusion Injury | 1997 |
The time course of glucose metabolism in rat cerebral ischemia with middle cerebral artery occlusion-reperfusion model and the effect of MK-801.
Following cerebral ischemia, the extracellular concentration of excitatory amino acids increases, and the excitatory cell death may play an important role contributing to ischemic neuronal damage. Although sequential metabolic changes in permanent local cerebral ischemia have been reported, the effect of reperfusion in local cerebral ischemia on glucose metabolism is less clear. In order to investigate the time course change of glucose metabolism in a middle cerebral artery occlusion-reperfusion model and the effect of dizocilpin (MK-801) on glucose metabolism, the 14C-Deoxyglucose method was used. Hypermetabolism occurred at 30 min after the middle cerebral artery (MCA) occlusion, and reached a peak at 60 min after ischemia in both ischemic core and penumbra. The shift from hyper- to hypometabolism was observed after the ischemia. The reperfusion facilitated the decrease of cerebral glucose metabolism in the ischemic region following 2 h of MCA occlusion. The pretreatment of MK-801 (0.4 mg kg-1) inhibited both increased glucose metabolism during ischemia and decreased glucose metabolism during reperfusion. These findings support the hypothesis that excitation-induced hyper-metabolism plays a major role in the ischemic insult following focal cerebral vascular occlusion. Topics: Animals; Arterial Occlusive Diseases; Blood Gas Analysis; Blood Glucose; Body Temperature; Brain Chemistry; Brain Ischemia; Cerebral Arteries; Disease Models, Animal; Dizocilpine Maleate; Glucose; Male; Neuroprotective Agents; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Time Factors | 1996 |
Protective role of excitatory amino acid antagonists in experimental retinal ischemia.
Excitatory amino acids and their analogues (NMDA, kainate and AMPA) are implicated in the pathogenesis of ischemic brain injury. In order to fully understand their involvement in the pathogenesis of retinal ischemic injury, we studied the electrophysiological and histopathological effects of two excitatory amino acid antagonists, cis-PDA and MK 801, in an experimental retinal ischemia model.. The two antagonists were injected intravitreously 15 min before ischemia was induced by elevatory intraocular pressure caused by external compression. Electrophysiological and histopathological evaluation was made 48 h after 45 min transient ischemia.. The excitatory amino acid antagonists cis-PDA and MK 801 can partially protect against retinal ischemic injury; whereas the mean post-ischemic b-wave amplitude corresponded to 41% of the pre-ischemic value in the control group, it was 64% (P = 0.003) and 59% (P = 0.005) following administration of cis-PDA and MK 801 respectively. Histopathological study corroborated these data, showing significant differences for morphometric parameters (P = 0.011 and P = 0.007 respectively).. These preliminary results suggest the possibility of limiting excito-toxicity, one of the lesion-forming mechanisms in ischemic retinal injury. Topics: Animals; Disease Models, Animal; Dizocilpine Maleate; Electroretinography; Excitatory Amino Acid Antagonists; Injections; Ischemia; Pipecolic Acids; Rats; Reperfusion Injury; Retina; Retinal Vessels; Vitreous Body | 1995 |
Systemic excitatory amino acid receptor antagonists of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and of the N-methyl-D-aspartate (NMDA) receptor relieve mechanical hypersensitivity after transient spinal cord ischemia in
We have previously reported that transient spinal cord ischemia induced a behavioral hypersensitivity (allodynia) to innocuous cutaneous mechanical stimulation in rats. The spinal ischemia-induced allodynia was not relieved by morphine, but it was relieved by the gamma-aminobutyric acid (GABA)-B receptor agonist baclofen, indicating that the allodynia may be related to dysfunction of the spinal GABA-ergic inhibitory system. In the present study we report that systemic application of 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX), an antagonist of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor for excitatory amino acids, dose-dependently relieved allodynia after spinal cord ischemia. The analgesic effect of NBQX at a low dose (7.5 mg/kg) was not accompanied by motor deficits or sedation. On the other hand, the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) only partially alleviated allodynia, even at doses that produced severe motor deficits. It is suggested that the abnormal, possibly painful, sensations elicited by innocuous mechanical stimulation observed after spinal cord ischemia may be mediated by excitatory amino acids, acting mainly on the AMPA receptor. Antagonists of excitatory amino acid receptors, especially at the AMPA site, may be effective in treating pain conditions where input from low threshold afferents triggers painful sensations. Topics: Animals; Dizocilpine Maleate; Female; Pain; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Skin Physiological Phenomena; Spinal Cord; Vocalization, Animal | 1993 |
Asphyxial brain damage in the newborn: new insights into pathophysiology and possible pharmacologic interventions.
New insights into the pathophysiology of the hypoxic-ischemic insult have opened the possibility of pharmacologic intervention in neonatal hypoxic-ischemic encephalopathy. It is now known that many neurons survive a hypoxic-ischemic insult but remain dysfunctional for hours, with profound alterations in cell function. A cascade of biochemical alterations occurs as a consequence of cellular ionic shifts, energy depletion, degradation of cell membrane phospholipids, and increased release of neurotransmitters. In addition, there are alterations in the metabolism of arachidonic acid and prostanoids and an excessive production of oxygen free radicals. The new therapeutic modalities are aimed at preventing or arresting the biochemical changes that occur in the period after hypoxia-ischemia. This review details the biochemical alterations associated with neonatal hypoxic-ischemic encephalopathy and discusses the possible use in newborns of pharmacologic agents currently undergoing extensive investigations in experimental animals and adult humans. Topics: Asphyxia Neonatorum; Brain Ischemia; Calcium Channel Blockers; Dizocilpine Maleate; Free Radical Scavengers; Humans; Hypoxia, Brain; Infant, Newborn; Lipid Peroxides; Pregnatrienes; Reperfusion Injury | 1993 |
Protective effect of synaptic inhibition during cerebral ischemia in rats and rabbits.
Excitatory neurotransmitters appear to cause cell death during ischemia by inducing depolarization, influx of ions, and metabolic failure in the postsynaptic neuron. If this hypothesis is correct, then postsynaptic membrane hyperpolarization and inhibition of metabolism may be protective. Antagonists of the excitotoxic amino acid glutamate protect neurons in culture and in animal models of stroke but appear to cause unacceptable side effects in humans. We propose an alternative strategy of protection using agonists of the inhibitory neurotransmitter gamma-aminobutyric acid.. We caused multifocal cerebral ischemia in rats and rabbits by injecting microspheres into the carotid circulation. We administered saline, muscimol, or MK-801 within 5 minutes of stroke onset. We used a bioassay to measure outcome. In rats, we also used learning to assess cortical function, and we performed detailed quantitative brain morphometry 3 months after infarction.. Using the bioassay, we found that muscimol exerted a protective effect in rats (p less than 0.01). There was a dose-response effect seen in muscimol-treated rabbits. Rats treated with muscimol or MK-801 exhibited significantly better visual-spatial learning compared with saline-treated subjects (p less than 0.001). Hemisphere volume after ischemia was comparable in all groups.. Agonists of gamma-aminobutyric acid and antagonists of glutamate appear to protect brain during ischemia. Since agonists of gamma-aminobutyric acid are known to have fewer side effects in humans, they may prove more useful in the clinical setting as neuroprotective agents. Topics: Animals; Brain Ischemia; Dizocilpine Maleate; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; Glutamic Acid; Learning; Male; Muscimol; Rabbits; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 1992 |
Effect of dizocilpine maleate on cerebral anoxia and ischemic damage in rodents.
The Protective effects of dizocilpine maleate (DM) against anoxia in mice and ischemic damage in rats of 4-vessel occlusion (4-VO) were studied. DM 0.5 or 1.0 mg.kg-1 ip significantly prolonged the survival time of mice in closed containers. DM 0.5 and 1.0 mg.kg-1 ip 30 min prior to 4-VO obviously accelerated the electroencephalographic recovery, reduced the neuronal loss in the hippocampus, and increased the survival rate after 72-h reperfusion. These effects followed a dose-dependent manner. Our results indicate that selective non-competitive N-methyl-D-aspartate receptor blocker DM protects against anoxic and ischemic cerebral damage. Topics: Animals; Brain Ischemia; Dizocilpine Maleate; Dose-Response Relationship, Drug; Electroencephalography; Hippocampus; Hypoxia; Male; Mice; Rats; Rats, Sprague-Dawley; Reperfusion Injury | 1992 |