dizocilpine-maleate and Brain-Injuries

Topics: Animals; Benzazepines; Body Temperature; Brain; Brain Injuries; Brain Ischemia; Calcium Channel Blockers; Dextromethorphan; Dizocilpine Maleate; Drug Therapy, Combination; Humans; Ischemic Attack, Transient; N-Methylaspartate

Excitotoxic mechanisms due to overactivity of the amino acid neurotransmitters glutamate and aspartate maybe responsible for brain damage after injury. In this review we examine ischaemia and shear injury, which are relevant to human head injury. The opportunities for treatment using glutamate antagonist drugs are discussed.

Topics: Animals; Brain Damage, Chronic; Brain Injuries; Brain Ischemia; Central Nervous System Agents; Dizocilpine Maleate; Drug Evaluation, Preclinical; Excitatory Amino Acid Antagonists; Glutamates; Glutamic Acid; Humans; Receptors, N-Methyl-D-Aspartate; Retrograde Degeneration

Ischemic damage, chiefly of the focal type, and axonal disruption (diffuse axonal injury) are the major factors causing brain damage after human head injury. About one third of this damage may be delayed hours or days after the injury. Evidence from four animal models, each relevant to different aspects of human head injury, has shown that excitatory amino acid-induced changes are responsible for a proportion of the posttraumatic sequelae and that these effects can be blocked by EAA antagonists. This evidence is reviewed, and the implications for the conduct of human trials with EAA antagonists are discussed.

Topics: Animals; Brain Damage, Chronic; Brain Injuries; Brain Ischemia; Central Nervous System Depressants; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Humans; Ischemic Attack, Transient; Spinal Cord Injuries

The studies reported here represent a continuing search for mechanisms which may play a role in neurological disturbances resulting from brain injury. In particular, they are part of an effort to elucidate the involvement of both the serotonergic and noradrenergic neurotransmitter systems in the wide-spread decrease in cortical glucose utilization, interpreted as reflecting a functional depression, associated with a focal cortical lesion in the rat. Quinolinic acid, an endogenous metabolite of L-tryptophan, a neurotoxin and an N-methyl-D-aspartate (NMDA) receptor agonist was found to accumulate in cortical areas of a traumatized rat hemisphere in parallel with a previously demonstrated increase of 5-hydroxyindoleacetic acid. Ketanserin (20 mg/kg/day), a 5-HT2 receptor blocker ameliorated the depression of glucose utilization in traumatized brain while MK-801 (3 mg/kg, before and after lesion), an NMDA receptor blocker, had no effect. Alpha 1-adrenergic receptors, quantitated in vivo with [125I]-HEAT (iodo-2-[beta-(4-hydroxyphenyl)-ethyl-aminomethyl]tetralone), were found to be elevated in cortical areas of the lesioned hemisphere, but not in other structures.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Brain Injuries; Deoxyglucose; Dibenzocycloheptenes; Dizocilpine Maleate; Hydroxyindoleacetic Acid; Indomethacin; Ketanserin; Male; Prazosin; Rats; Rats, Inbred Strains; Receptors, Adrenergic, alpha; Serotonin

Traumatic brain injury (TBI) is a leading cause of death and morbidity with no effective therapeutic treatments for secondary injury. Preclinical drug evaluation in rodent models of TBI is a lengthy process. In this regard, the zebrafish has numerous advantages to address the technical and time-dependent obstacles associated with drug evaluation. We developed a reproducible brain injury using glutamate excitoxicity in zebrafish larvae, a known initiator of delayed cell death in TBI. Glutamate challenge resulted in dose-dependent lethality over an 84-h observation period. We report significant decrease in locomotion (p < 0.0001) and mean velocity (p < 0.001) with 10 μM glutamate application as measured through automated 96-well plate behavioral analysis. Application of the NMDA receptor antagonist MK-801 (400 nM) or the calpain inhibitor, MDL-28170 (20 μM), resulted in significant recovery of locomotor function. A secA5-YFP transgenic line was used to visualize the localization of cell death due to glutamate exposure in vivo using confocal fluorescence microscopy. Our results indicate that zebrafish larvae exhibit responses to excitotoxic injury and pharmacotherapeutic intervention with pathophysiological relevance to mammalian excitotoxic brain injury. This system has potential to be applied as a high-throughput drug screening model to quickly identify candidate lead compounds for further evaluation.

Topics: Animals; Brain Injuries; Dipeptides; Dizocilpine Maleate; High-Throughput Screening Assays; Larva; Motor Activity; Neuroprotective Agents; Zebrafish

Traumatic brain injury (TBI) is a major health problem in pediatric ages and also has major social, economic, and emotional outcomes, with diverse sequelae in many spheres of everyday life. We aimed to investigate the effect of MK-801, a competitive NMDA receptor antagonist, on hippocampal damage and behavioral deficits on 10-day-old rat pups subjected to contusion injury. The aims of the present study were to determine: (i) the short term effects of MK-801 on hippocampal BDNF, NGF and NMDA receptor immunoreactivity and neuron density in hippocampus (ii) long term effects of MK-801 on cognitive dysfunction following TBI in the immature rats. MK-801, was injected intraperitoneally at the doses of 1mg/kg of body weight immediately after induction of traumatic injury. Hippocampal damage was examined by cresyl violet staining, BDNF, NGF and NMDAR receptor immunohistochemistry on P10 day and behavioral alterations were evaluated using elevated plus maze and novel object recognition tests two months after the trauma. Histopathological and immunohistochemical evaluations showed that treatment with a single dose of 1mg/kg MK-801 (i.p.) significantly ameliorated the trauma induced hippocampal neuron loss and decreased BDNF, NGF and NMDAR expressions in CA1, CA3 and DG hippocampal brain regions. Additionally, treatment with MK-801 ameliorated anxiety and hippocampus dependent memory of animals subjected to trauma. These results show that acute treatment of MK-801 has a neuroprotective role against trauma induced hippocampal neuron loss and associated cognitive impairment in immature rats.

Topics: Animals; Brain Injuries; Brain-Derived Neurotrophic Factor; Cognition Disorders; Dizocilpine Maleate; Hippocampus; Memory; N-Methylaspartate; Nerve Growth Factor; Neurons; Neuroprotective Agents; Rats, Wistar

Traumatic brain injury (TBI) is one of the leading causes of neurological disability and death in the USA across all age groups, ethnicities, and incomes. In addition to the short-term morbidity and mortality, TBI leads to epilepsy and severe neurocognitive symptoms, both of which are referenced to post-traumatic hippocampal dysfunction, although the mechanisms of such hippocampal dysfunction are incompletely understood. Here, we study the temporal profile of the transcription of three select immediate early gene (IEG) markers of neuronal hyperactivation, plasticity, and injury, c-fos, brain-derived neurotrophic factor (BDNF), and Bax, in the acute period following the epileptogenic lateral fluid percussion injury in a rodent TBI model. We found that lateral fluid percussion injury leads to enhanced expression of the selected IEGs within 24 h of TBI. Specifically, BDNF and c-fos increase maximally 1-6 h after TBI in the ipsilesional hippocampus, whereas Bax increases in the hippocampus bilaterally in this time window. Antagonism of the N-methyl-D-aspartate-type glutamate receptor by MK801 attenuates the increase in BDNF and Bax, which underscores a therapeutic role for N-methyl-D-aspartate-type glutamate receptor antagonism in the acute post-traumatic time period and suggests a value to a hippocampal IEG readout as an outcome after injury or acute therapeutic intervention.

Topics: Acute Disease; Animals; bcl-2-Associated X Protein; Brain Injuries; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Functional Laterality; Hippocampus; Male; Proto-Oncogene Proteins c-fos; Rats, Long-Evans; Real-Time Polymerase Chain Reaction; Receptors, N-Methyl-D-Aspartate; RNA, Messenger; Time Factors; Transcription, Genetic

Overstimulation of NMDA-type glutamate receptors is believed to be responsible for neuronal death of the CNS in various disorders, including cerebral and spinal cord ischemia. However, the intrinsic and physiological mechanisms of modulation of these receptors are essentially unknown. Here we report that cholestane-3β,5α,6β-triol (triol), a major metabolite of cholesterol, is an endogenous neuroprotectant and protects against neuronal injury both in vitro and in vivo via negative modulation of NMDA receptors. Treatment of cultured neurons with triol protects against glutamate-induced neurotoxicity, and administration of triol significantly decreases neuronal injury after spinal cord ischemia in rabbits and transient focal cerebral ischemia in rats. An inducible elevation of triol is associated with ischemic preconditioning and subsequent neuroprotection in the spinal cord of rabbits. This neuroprotection is effectively abolished by preadministration of a specific inhibitor of triol synthesis. Physiological concentrations of triol attenuate [Ca(2+)]i induced by glutamate and decrease inward NMDA-mediated currents in cultured cortical neurons and HEK-293 cells transiently transfected with NR1/NR2B NMDA receptors. Saturable binding of [(3)H]triol to cerebellar granule neurons and displacement of [(3)H]MK-801 binding to NMDA receptors by triol suggest that direct blockade of NMDA receptors may underlie the neuroprotective properties. Our findings suggest that the naturally occurring oxysterol, the major cholesterol metabolite triol, functions as an endogenous neuroprotectant in vivo, which may provide novel insights into understanding and developing potential therapeutics for disorders in the CNS.

Topics: Adult; Animals; Brain Injuries; Cells, Cultured; Central Nervous System; Cholestanols; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Glutamic Acid; Humans; Infarction, Middle Cerebral Artery; Male; Neurons; Neuroprotective Agents; Protein Binding; Rabbits; Rats; Rats, Sprague-Dawley; Spinal Cord Ischemia; Time Factors; Tissue Distribution; Young Adult

Neural plasticity following brain injury illustrates the potential for regeneration in the central nervous system. Lesioning of the perforant path, which innervates the outer two-thirds of the molecular layer of the dentate gyrus, was one of the first models to demonstrate structural plasticity of mature granule cells (Parnavelas et al., 1974; Caceres and Steward, 1983; Diekmann et al., 1996). The dentate gyrus also harbors a continuously proliferating population of neuronal precursors that can integrate into functional circuits and show enhanced short-term plasticity (Schmidt-Hieber et al., 2004; Abrous et al., 2005). To examine the response of adult-generated granule cells to unilateral complete transection of the perforant path in vivo, we tracked these cells using transgenic POMC-EGFP mice or by retroviral expression of GFP. Lesioning triggered a marked proliferation of newborn neurons. Subsequently, the dendrites of newborn neurons showed reduced complexity within the denervated zone, but dendritic spines still formed in the absence of glutamatergic nerve terminals. Electron micrographs confirmed the lack of intact presynaptic terminals apposing spines on mature cells and on newborn neurons. Newborn neurons, but not mature granule cells, had a higher density of dendritic spines in the inner molecular layer postlesion accompanied by an increase in miniature EPSC amplitudes and rise times. Our results indicate that injury causes an increase in newborn neurons and lamina-specific synaptic reorganization indicative of enhanced plasticity. The presence of de novo dendritic spines in the denervated zone suggests that the postlesion environment provides the necessary signals for spine formation.

Topics: Animals; Animals, Newborn; Brain Injuries; Bromodeoxyuridine; Cell Movement; Cell Proliferation; Dendritic Spines; Dentate Gyrus; Dizocilpine Maleate; Evoked Potentials; Excitatory Amino Acid Antagonists; Excitatory Postsynaptic Potentials; Genetic Vectors; Green Fluorescent Proteins; In Vitro Techniques; Linear Models; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Electron, Transmission; Neurons; Patch-Clamp Techniques; Perforant Pathway; Pro-Opiomelanocortin; Proto-Oncogene Proteins c-fos; Silver Staining; Statistics, Nonparametric; Synapses; Time Factors; Vesicular Glutamate Transport Protein 2

Alterations in neuronal cytosolic calcium is a key mediator of the traumatic brain injury (TBI) pathobiology, but less is known of the role and source of calcium in shaping early changes in synaptic receptors and neural circuits after TBI. In this study, we examined the calcium source and potential phosphorylation events leading to insertion of calcium-permeable AMPARs (CP-AMPARs) after in vitro traumatic brain injury, a receptor subtype that influences neural circuit dynamics for hours to days following injury. We found that both synaptic and NR2B-containing NMDARs contribute significantly to the calcium influx following stretch injury. Moreover, an early and sustained phosphorylation of the S-831 site of the GluR1 subunit appeared after mechanical injury, and this phosphorylation was blocked with the inhibition of either synaptic NMDARs or NR2B-containing NMDARs. In comparison, mechanical injury led to no significant change in the S-845 phosphorylation of the GluR1 subunit. Although no change in S-845 phosphorylation appeared in injured cultures, we observed that inhibition of NR2B-containing NMDARs significantly increased S-845 phosphorylation 1h after injury while blockade of synaptic NMDARs did not change S-845 phosphorylation at any time point following injury. These findings show that a broad class of NMDARs are activated in parallel and that targeting either subpopulation will reverse some of the consequences of mechanical injury, providing distinct paths to treat the effects of mechanical injury on neural circuits after TBI.

Topics: Animals; Bicuculline; Blotting, Western; Brain Injuries; Calcium; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Cell Death; Cells, Cultured; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; GABA Antagonists; Phenols; Phosphorylation; Piperidines; Rats; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate

It has been long thought that hyperactivation of N-methyl-D-aspartate (NMDA) receptors underlies neurological decline after traumatic brain injury. However, all clinical trials with NMDA receptor antagonists failed. Since NMDA receptors are down-regulated from 4h to 2weeks after brain injury, activation at 24h, rather than inhibition, of these receptors, was previously shown to be beneficial in mice. Here, we tested the therapeutic window, dose regimen and mechanism of action of the NMDA receptor partial agonist D-cycloserine (DCS) in traumatic brain injury. Male mice were subjected to trauma using a weight-drop model, and administered 10mg/kg (i.p.) DCS or vehicle once (8, 16, 24, or 72h) twice (24 and 48h) or three times (24, 48 and 72h). Functional recovery was assessed for up to 60days, using a Neurological Severity Score that measures neurobehavioral parameters. In all groups in which treatment was begun at 24 or 72h neurobehavioral function was significantly better than in the vehicle-treated groups. Additional doses, on days 2 and 3 did not further improve recovery. Mice treated at 8h or 16h post injury did not differ from the vehicle-treated controls. Co-administration of the NMDA receptor antagonist MK-801 completely blocked the protective effect of DCS given at 24h. Infarct volume measured by 2,3,5-triphenyltetrazolium chloride staining at 48h or by cresyl violet at 28days was not affected by DCS treatment. Since DCS is used clinically for other indications, the present study offers a novel approach for treating human traumatic brain injury with a therapeutic window of at least 24h.

Topics: Animals; Brain Injuries; Cycloserine; Dizocilpine Maleate; Drug Administration Schedule; Male; Mice; Receptors, N-Methyl-D-Aspartate; Recovery of Function; Time Factors; Treatment Outcome

Traumatic axonal injury (TAI) is the most common and important pathology of traumatic brain injury (TBI). However, little is known about potential indirect effects of TAI on dendrites. In this study, we used a well-established in vitro model of axonal stretch injury to investigate TAI-induced changes in dendrite morphology. Axons bridging two separated rat cortical neuron populations plated on a deformable substrate were used to create a zone of isolated stretch injury to axons. Following injury, we observed the formation of dendritic alterations or beading along the dendrite shaft. Dendritic beading formed within minutes after stretch then subsided over time. Pharmacological experiments revealed a sodium-dependent mechanism, while removing extracellular calcium exacerbated TAI's effect on dendrites. In addition, blocking ionotropic glutamate receptors with the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 prevented dendritic beading. These results demonstrate that axon mechanical injury directly affects dendrite morphology, highlighting an important bystander effect of TAI. The data also imply that TAI may alter dendrite structure and plasticity in vivo. An understanding of TAI's effect on dendrites is important since proper dendrite function is crucial for normal brain function and recovery after injury.

Topics: Animals; Axons; Brain Injuries; Calcium; Cell Survival; Cells, Cultured; Dendrites; Dizocilpine Maleate; Extracellular Space; Neocortex; Neurons; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Sodium; Stress, Mechanical

Excitatory amino acid release and subsequent biochemical cascades following traumatic brain injury (TBI) have been well documented, especially glutamate-related excitotoxicity. The effects of TBI on the essential functions of inhibitory GABA-A receptors, however, are poorly understood.. We used Western blot procedures to test whether in vivo TBI in rat altered the protein expression of hippocampal GABA-A receptor subunits alpha1, alpha2, alpha3, alpha5, beta3, and gamma2 at 3 h, 6 h, 24 h, and 7 days post-injury. We then used pre-injury injections of MK-801 to block calcium influx through the NMDA receptor, diltiazem to block L-type voltage-gated calcium influx, or diazepam to enhance chloride conductance, and re-examined the protein expressions of alpha1, alpha2, alpha3, and gamma2, all of which were altered by TBI in the first study and all of which are important constituents in benzodiazepine-sensitive GABA-A receptors.. Western blot analysis revealed no injury-induced alterations in protein expression for GABA-A receptor alpha2 or alpha5 subunits at any time point post-injury. Significant time-dependent changes in alpha1, alpha3, beta3, and gamma2 protein expression. The pattern of alterations to GABA-A subunits was nearly identical after diltiazem and diazepam treatment, and MK-801 normalized expression of all subunits 24 hours post-TBI.. These studies are the first to demonstrate that GABA-A receptor subunit expression is altered by TBI in vivo, and these alterations may be driven by calcium-mediated cascades in hippocampal neurons. Changes in GABA-A receptors in the hippocampus after TBI may have far-reaching consequences considering their essential importance in maintaining inhibitory balance and their extensive impact on neuronal function.

Topics: Animals; Blotting, Western; Brain Injuries; Calcium Channel Blockers; Calcium Signaling; Chlorides; Diazepam; Diltiazem; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Hippocampus; Male; Neurons; Protein Subunits; Rats; Rats, Sprague-Dawley; Receptors, GABA-A; Receptors, N-Methyl-D-Aspartate

Glutamate antagonists are very attractive drugs in laboratory works to protect neural tissue against ischemia. In this work, the effects of magnesium, MK-801 and combination of magnesium and MK-801 on blood-brain barrier (BBB) and brain edema after experimentally induced traumatic brain injury are evaluated.. A standard closed head injury was induced on the rats by a controlled impact device using a 450-g free falling mass from a height of 2 m onto a metallic disc fixed to the intact skull. One of the following was injected to animals intraperitoneally 30 minutes after injury: saline, magnesium, MK-801 and magnesium plus MK-801. To quantify the brain edema, the specific gravity of the brain tissue was determined. To demonstrate the alteration of the BBB permeability, Evans blue dye was used as a tracer.. In all treatment groups, the specific gravity of brain tissue values was significantly higher compared with the control group. Evans blue dye content in the brain tissue was significantly reduced in all three treatment groups with respect to the control group. There was no significant difference of effect between the groups of magnesium alone and MK-801 alone when compared with each other and when compared with their combination.. The present data demonstrate that treatment with magnesium, MK-801 and combination of magnesium and MK-801 can reduce formation of brain edema and can help restore BBB permeability after experimental diffuse brain injury.

Topics: Animals; Blood-Brain Barrier; Body Water; Brain Edema; Brain Injuries; Diffuse Axonal Injury; Disease Models, Animal; Dizocilpine Maleate; Drug Combinations; Drug Synergism; Evans Blue; Head Injuries, Closed; Indicators and Reagents; Magnesium Compounds; Male; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Specific Gravity; Treatment Outcome

Protease-activated receptor 1 (PAR1) is a G-protein coupled receptor that is expressed throughout the central nervous system. PAR1 activation by brain-derived as well as blood-derived proteases has been shown to have variable and complex effects in a variety of animal models of neuronal injury and inflammation. In this study, we have evaluated the effects of PAR1 on lesion volume in wild-type or PAR1-/- C57Bl/6 mice subjected to transient occlusion of the middle cerebral artery or injected with NMDA in the striatum. We found that removal of PAR1 reduced infarct volume following transient focal ischemia to 57% of control. Removal of PAR1 or application of a PAR1 antagonist also reduced the neuronal injury associated with intrastriatal injection of NMDA to 60% of control. To explore whether NMDA receptor potentiation by PAR1 activation contributes to the harmful effects of PAR1, we investigated the effect of NMDA receptor antagonists on the neuroprotective phenotype of PAR1-/- mice. We found that MK801 reduced penumbral but not core neuronal injury in mice subjected to transient middle cerebral artery occlusion or intrastriatal NMDA injection. Lesion volumes in both models were not significantly different between PAR1-/- mice treated with and without MK801. Use of the NMDA receptor antagonist and dissociative anesthetic ketamine also renders NMDA-induced lesion volumes identical in PAR1-/- mice and wild-type mice. These data suggest that the ability of PAR1 activation to potentiate NMDA receptor function may underlie its harmful actions during injury.

Topics: Analysis of Variance; Animals; Brain Injuries; Cells, Cultured; Corpus Striatum; Disease Models, Animal; Dizocilpine Maleate; Embryo, Mammalian; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Female; Guanidines; Injections, Intraventricular; Ischemic Attack, Transient; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; N-Methylaspartate; Neurons; Oligopeptides; Pregnancy; Rats; Receptor, PAR-1; Receptors, N-Methyl-D-Aspartate

Neural-cadherin (N-cadherin), a member of the classical cadherin family of transmembrane glycoproteins, mediates cellular recognition and cell-cell adhesion through calcium-dependent homophilic interactions and plays important roles in the development and maintenance of the nervous system. Metalloproteinase is known to cleave N-cadherin, which is further cleaved by gamma-secretase. The intracellular domain of N-cadherin interacts with beta-catenin, and beta-catenin stability is critical for cell-cell adhesion and cell survival. In the present study, we showed that N-cadherin is cleaved specifically by calpain, resulting in the generation of a novel 110 kDa fragment. The cleavage occurred in ischemic brain lesions and in vitro neural cells in the presence of NMDA and ionomycin, and was restored by calpain inhibitors but not matrix metalloproteinase or gamma-secretase inhibitors. Calpain directly cleaved N-cadherin in in vitro calpain assays, and calpain inhibitors prevented its cleavage in a dose-dependent manner. Using N-cadherin deletion mutants, we found that calpain cleavage sites exist in at least four regions of the cytoplasmic domain. Treatment with NMDA induced neuronal death, and it suppressed the expression of surface N-cadherin and the N-cadherin/beta-catenin interaction, effects that were prevented by calpain inhibitor. Furthermore, calpain-mediated N-cadherin cleavage significantly affected cell-cell adhesion, AKT signaling, the N-cadherin/beta-catenin interaction and the Wnt target gene expressions through the accumulation of nuclear beta-catenin.

Topics: Animals; Animals, Newborn; beta Catenin; Biotinylation; Brain Injuries; Cadherins; Calcium; Calpain; Cells, Cultured; Disease Models, Animal; Dizocilpine Maleate; Embryo, Mammalian; Endocytosis; Enzyme Inhibitors; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Gene Expression Regulation; Green Fluorescent Proteins; In Vitro Techniques; Ionomycin; Ionophores; Mice; Models, Biological; Mutation; N-Methylaspartate; Neurons; Protein Structure, Tertiary; Proto-Oncogene Proteins c-akt; Signal Transduction; Subcellular Fractions; Transfection; Wnt Proteins

NMDA receptor channel plays an important role in the pathophysiological process of traumatic brain injury (TBI). The present study aims to study the pathological mechanism of TBI and the impairment of learning and memory after TBI, and to investigate the mechanism of the protective effect of NMDA receptor antagonist MK-801 on learning and memory disorder after TBI.. Forty Sprague-Dawley rats (weighing approximately 200 g) were randomized into 5 groups (n = 8 in each group): control group, model group, low-dose group (MK-801 0.5 mg/kg), middle-dose group (MK-801 2 mg/kg), and high-dose group (MK-801 10 mg/kg). TBI model was established using a weight-drop head injury mode. After 2-month drug treatment, learning and memory ability was evaluated by using Morris water maze test. Then the animals were sacrificed, and brain tissues were taken out for morphological and immunohistochemical assays.. The ability of learning and memory was significantly impaired in the TBI model animals. Besides, the neuronal caspase-3 expression, neuronal nitric oxide synthase (nNOS)-positive neurons and OX-42-positive microglia were all increased in TBI animals. Meanwhile, the number of neuron synapses was decreased, and vacuoles degeneration could be observed in mitochondria. After MK-801 treatment at 3 different dosages, the ability of learning and memory was markedly improved, as compared to that of the TBI model animals. Moreover, neuronal caspase-3 expression, OX-42-positive microglia and nNOS-positive neurons were all significantly decreased. Meanwhile, the mitochondria degeneration was greatly inhibited.. MK-801 could significantly inhibit the degeneration and apoptosis of neurons in damaged brain areas. It could also inhibit TBI-induced increase in nNOS-positive neurons and OX-42-positive microglia. Impairment in learning and memory in TBI animals could be repaired by treatment with MK-801.

Topics: Animals; Brain; Brain Injuries; Caspase 3; Disease Models, Animal; Dizocilpine Maleate; Learning; Male; Maze Learning; Memory; Microglia; Mitochondria; Neurons; Neuroprotective Agents; Neuropsychological Tests; Nitric Oxide Synthase Type I; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Synapses

Interaction between extracellular matrix proteins and regulatory proteinases can mediate synaptic integrity. Previously, we documented that matrix metalloproteinase 3 (MMP-3) expression and activity increase following traumatic brain injury (TBI). We now report protein and mRNA analysis of agrin, a MMP-3 substrate, over the time course of trauma-induced synaptogenesis. Agrin expression during the successful synaptic reorganization of unilateral entorhinal cortical lesion (UEC) was compared with expression when normal synaptogenesis fails (combined fluid percussion TBI and bilateral entorhinal lesion [BEC]). We observed that agrin protein was increased in both models at 2 and 7 days postinjury, and immuohistochemical (IHC) co-localization suggested reactive astrocytes contribute to that increase. Agrin formed defined boundaries for sprouting axons along deafferented dendrites in the UEC, but failed to do so after combined insult. Similarly, Western blot analysis revealed greater increase in UEC agrin protein relative to the combined TBI+BEC model. Both models showed increased agrin transcription at 7 days postinjury and mRNA normalization by 15 days. Attenuation of synaptic pathology with the NMDA antagonist MK-801 reduced 7-day UEC agrin transcript to a level not different from unlesioned controls. By contrast, MK-801 in the combined insult failed to significantly change 7-day agrin transcript, mRNA levels remaining elevated over uninjured sham cases. Together, these results suggest that agrin plays an important role in the sprouting phase of reactive synaptogenesis, and that both its expression and distribution are correlated with extent of successful recovery after TBI. Further, when pathogenic conditions which induce synaptic plasticity are reduced, increase in agrin mRNA is attenuated.

Topics: Agrin; Animals; Brain Injuries; Denervation; Disease Models, Animal; Dizocilpine Maleate; Entorhinal Cortex; Excitatory Amino Acid Antagonists; Extracellular Matrix; Gene Expression Regulation; Male; Matrix Metalloproteinase 3; Nerve Regeneration; Neuronal Plasticity; Neuroprotective Agents; Presynaptic Terminals; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; RNA, Messenger; Up-Regulation

Disturbed cortical development is implicated in some psychiatric diseases, e.g. in schizophrenia. Additionally, N-methyl-d-aspartate (NMDA) receptor antagonists like ketamine or phencyclidine have been reported to exacerbate schizophrenic symptoms. We here investigated the effects of neonatal entorhinal cortex (EC) lesions on adult rat behavior before and after repeated high-dose treatment with the NMDA antagonist dizocilpine, in order to combine these etiopathogenetical factors in an animal model. Bilateral neonatal (postnatal day 7) lesions were induced by microinjection of ibotenic acid (1.3 microg/0.2 microl PBS) into the EC. Naive and sham-lesioned rats served as controls. Adult rats were tested for behavioral flexibility on a cross maze, for locomotor activity in the open field and for sensorimotor gating using prepulse inhibition (PPI) of startle. Rats were then treated with dizocilpine (0.5 mg/kg b.i.d. for 7 days) and retested 1 week after withdrawal using the same behavioral tests as before. PPI was additionally measured after acute low-dose challenge with dizocilpine (0.15 mg/kg). EC lesions reduced behavioral flexibility as shown by impaired switching between spatial (allocentric) and non-spatial (egocentric) maze strategies. High-dose dizocilpine treatment disturbed switching to the egocentric strategy in all groups, which added to the effect of EC lesions. Neonatal EC lesions did not alter locomotor activity or PPI, but high-dose dizocilpine treatment reduced motor activity of all groups without changing PPI. The combination of neonatal EC lesions and adult dizocilpine treatment does not lead to super-additive effects on behavior. However, both treatments may serve to model certain aspects of psychiatric symptoms.

Topics: Acoustic Stimulation; Analysis of Variance; Animals; Animals, Newborn; Behavior, Animal; Brain Injuries; Disease Models, Animal; Dizocilpine Maleate; Drug Administration Schedule; Entorhinal Cortex; Exploratory Behavior; Ibotenic Acid; Inhibition, Psychological; Male; Maze Learning; Neuroprotective Agents; Rats; Rats, Wistar

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

Age-dependent, MK801-induced, activated caspase-3 expression in the postnatal brain is generally not observed in neurons expressing calcium-binding proteins (CaBPs), suggesting that apoptosis and calcium buffering are inversely related. In regions such as the cingulate and retrosplenial cortex, injury peaks at postnatal Day 7 (P7) and rapidly diminishes thereafter, whereas expression of calbindin (CB) and calretinin (CR) was relatively low from P0 to P7 and steadily increased from P7 to P14. At ages thereafter, CB and CR expression either remained stable then declined or rapidly declined. Parvalbumin (PV) was generally low-absent prior to P7 but expression dramatically increased from P10 onwards, peaking at P21. These studies suggest calcium entry (through N-methyl-D-aspartate receptor (NMDARs)) and buffering (by CaBPs) are integral to normal CNS maturation. Because schizophrenia is associated with glutamate hypo-function, developmental injury, and aberrant CaBP expression, our data indicate that this postnatal brain injury model may offer important insights into the nature of this disorder.

Topics: Age Factors; Animals; Brain Injuries; Calbindin 2; Calcium; Caspase 3; Cell Count; Cerebral Cortex; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Glutamic Acid; Gyrus Cinguli; Immunohistochemistry; Parvalbumins; Rats; Receptors, N-Methyl-D-Aspartate; S100 Calcium Binding Protein G

Noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine, ketamine, and MK-801 produce schizophrenia-like psychosis in humans. The same NMDA antagonists injure retrosplenial cortical neurons in adult rats. We examined the effects of atypical antipsychotics and an inhibitor of nonreceptor tyrosine kinase pp60 (Src) on the cortical injury produced by MK-801. An atypical antipsychotic (either clozapine, ziprasidone, olanzapine, quetiapine, or risperidone) or vehicle was administered to adult female Sprague-Dawley rats. PP1 (Src inhibitor), PP3 (nonfunctional analog of PP1) or vehicle (DMSO) was administered to another group of animals. After pretreatment, animals were injected with MK-801, killed 24 h after the MK-801, and injury to retrosplenial cortex assessed by neuronal Hsp70 protein expression. All atypical antipsychotics examined significantly attenuated MK-801-induced cortical damage. PP1 protected compared to vehicle, whereas PP3 did not protect. The ED50s (decrease injury by 50%) were as follows: PP1 <0.1 mg/kg; olanzapine 0.8 mg/kg; risperdal 1 mg/kg; clozapine 3 mg/kg; ziprasidone 32 mg/kg; and quetiapine 45 mg/kg. The data show that the atypical antipsychotics tested as well as a Src kinase inhibitor prevent the injury produced by the psychomimetic MK-801, and the potency of the atypical antipsychotics for preventing cortical injury was roughly similar to the potency of these drugs for treating psychosis in patients.

Topics: Analysis of Variance; Animals; Antipsychotic Agents; Behavior, Animal; Brain Injuries; Cerebral Cortex; Dizocilpine Maleate; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; HSP70 Heat-Shock Proteins; Immunohistochemistry; Pyrazoles; Pyrimidines; Rats; Rats, Sprague-Dawley

We observed recently that elevated plasma cysteine levels are associated with poor clinical outcome in acute stroke patients. In a rat stroke model, cysteine administration increased the infarct volume apparently via its conversion to hydrogen sulfide (H2S). We therefore investigated the effects of H2S and the inhibition of its formation on stroke.. Cerebral ischemia was studied in a rat stroke model created by permanent occlusion of the middle cerebral artery (MCAO). The resultant infarct volume was measured 24 hours after occlusion.. Administration of sodium hydrosulfide (NaHS, an H2S donor) significantly increased the infarct volume after MCAO. The NaHS-induced increase in infarct volume was abolished by the administration of dizolcilpine maleate (an N-methyl-d-aspartate receptor channel blocker). MCAO caused an increase in H2S level in the lesioned cortex as well as an increase in the H2S synthesizing activity. Administration of 4 different inhibitors of H2S synthesis reduced MCAO-induced infarct volume dose dependently. The potency of these inhibitors in effecting neuroprotection in vivo appeared to parallel their potency as inhibitors of H2S synthesis in vitro. It also appeared that most of the H2S synthesizing activity in the cortex results from the action of cystathionine beta-synthase.. The present results strongly suggest that H2S plays a part in cerebral ischemic damage after stroke. Inhibition of H2S synthesis should be investigated for its potential as a novel neuroprotective stroke therapy.

Topics: Air Pollutants; Animals; Brain Injuries; Brain Ischemia; Cerebral Cortex; Cysteine; Dizocilpine Maleate; Dose-Response Relationship, Drug; Humans; Hydrogen Sulfide; Infarction, Middle Cerebral Artery; Male; Models, Statistical; Neuroprotective Agents; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Stroke; Time Factors; Treatment Outcome

Glutamate antagonists have recently been shown to limit tumor growth, providing potential new therapeutic targets and strategies against brain tumors. Here, we demonstrate that the glutamate NMDA receptor antagonist MK801, after a delay, adversely reverses functional recovery in rats with compressive mass lesions of the sensorimotor cortex. Our data suggest that the controlled focal cortical compression model may be a valuable pre-clinical tool to screen compounds for the treatment of brain tumors. It may be possible to use this model to develop interventions that maintain anti-cancer effects but with diminished harm to bystander tissue and brain plasticity.

Topics: Animals; Brain Injuries; Brain Neoplasms; Dizocilpine Maleate; Drug Evaluation, Preclinical; Excitatory Amino Acid Antagonists; Male; Motor Cortex; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Recovery of Function; Somatosensory Cortex

The interaction between extracellular matrix (ECM) and regulatory matrix metalloproteinases (MMPs) is important in establishing and maintaining synaptic connectivity. By using fluid percussion traumatic brain injury (TBI) and combined TBI and bilateral entorhinal cortical lesion (TBI + BEC), we previously demonstrated that hippocampal stromelysin-1 (MMP-3) expression and activity increased during synaptic plasticity. We now report a temporal analysis of MMP-3 protein and mRNA response to TBI during both degenerative (2 day) and regenerative (7, 15 day) phases of reactive synaptogenesis. MMP-3 expression during successful synaptic reorganization (following unilateral entorhinal cortical lesion; UEC) was compared with MMP-3 expression when normal synaptogenesis fails (after combined TBI + BEC insult). Increased expression of MMP-3 protein and message was observed in both models at 2 days postinjury, and immuohistochemical (IHC) colocalization suggested that reactive astrocytes contribute to that increase. By 7 days postinjury, model differences in MMP-3 were observed. UEC MMP-3 mRNA was equivalent to control, and MMP-3 protein was reduced within the deafferented region. In contrast, enzyme mRNA remained elevated in the maladaptive TBI + BEC model, accompanied by persistent cellular labeling of MMP-3 protein. At 15 days survival, MMP-3 mRNA was normalized in each model, but enzyme protein remained higher than paired controls. When TBI + BEC recovery was enhanced by the N-methyl-D-aspartate antagonist MK-801, 7-day MMP-3 mRNA was significantly reduced. Similarly, MMP inhibition with FN-439 reduced the persistent spatial learning deficits associated with TBI + BEC insult. These results suggest that MMP-3 might differentially affect the sequential phases of reactive synaptogenesis and exhibit an altered pattern when recovery is perturbed.

Topics: Adaptation, Physiological; Analysis of Variance; Animals; Brain Injuries; Disease Models, Animal; Dizocilpine Maleate; Entorhinal Cortex; Functional Laterality; Gene Expression; Gene Expression Regulation; Hydroxamic Acids; Immunohistochemistry; Male; Matrix Metalloproteinase 3; Maze Learning; Microscopy, Electron, Transmission; Neuronal Plasticity; Neuroprotective Agents; Oligopeptides; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Synapses

This study was undertaken to evaluate the therapeutic effect of hypothermia and dizocilpine maleate in traumatic brain injury (TBI) on newborn rats. After induction of TBI, physiologic and histopathological assessments were performed on both the control and therapeutic groups to evaluate the effects of both agents. Rats were assigned into four groups as follows: normothermic (n = 23), hypothermic (n = 18), normothermia plus dizocilpine maleate (n = 18) and hypothermia plus dizocilpine maleate (n = 18). All the rats were injured using a weight-drop head injury model, artificially ventilated with a 33% O(2) and 66% NO(2) mixture, and physiological parameters, intracranial pressure, and brain and rectal temperatures were recorded. Mortality, physiological, neurological parameters, and histopathological changes were assessed after 24 h. As a result, intracranial pressure, cerebral perfusion pressure, morbidity, weight loss, and microscopic changes were significantly worse in the normothermic group (p <0.05). There was no statistical difference between other groups (p > 0.05). Hypothermia and dizocilpine maleate displayed similar neuroprotective effects in TBI on newborn rats, but no additive effect was observed.

Topics: Animals; Animals, Newborn; Brain Injuries; Cerebrovascular Circulation; Combined Modality Therapy; Dizocilpine Maleate; Hypothermia, Induced; Intracranial Pressure; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Time Factors

The matrix metalloproteinase (MMP) enzyme family contributes to the regulation of a variety of brain extracellular matrix molecules. In order to assess their role in synaptic plasticity following traumatic brain injury (TBI), we compared expression of stromelysin-1 (MMP-3) protein and mRNA in two rodent models of TBI exhibiting different levels of recovery: adaptive synaptic plasticity following central fluid percussion injury and maladaptive synaptic plasticity generated by combined TBI and bilateral entorhinal cortical lesion (TBI + BEC). We sampled the hippocampus at 7 days postinjury, targeting a selectively vulnerable brain region and a survival interval exhibiting rapid synaptogenesis. We report elevated expression of hippocampal MMP-3 mRNA and protein after TBI. MMP-3 immunohistochemical staining showed increased protein levels relative to sham-injured controls, primarily localized to cell bodies within the deafferented dendritic laminae. Injury-related differences in MMP-3 protein were also observed. TBI alone elevated MMP-3 immunobinding over the stratum lacunosum moleculare (SLM), inner molecular layer and hilus, while TBI + BEC generated more robust increases in MMP-3 reactivity within the deafferented SLM and dentate molecular layer (DML). Double labeling with GFAP confirmed the presence of MMP-3 within reactive astrocytes induced by each injury model. Semi-quantitative RT-PCR revealed that MMP-3 mRNA also increased after each injury, however, the combined insult induced a much greater elevation than fluid percussion alone: 1.9-fold vs. 79%, respectively. In the TBI + BEC model, MMP-3 up-regulation was spatio-temporally correlated with increased enzyme activity, an effect which was attenuated with the neuroprotective compound MK-801. These results show that distinct pathological conditions elicited by TBI can differentially affect MMP-3 expression during reactive synaptic plasticity. Notably, these effects are both transcriptional and translational and are correlated with functionally active enzyme.

Topics: Animals; Astrocytes; Brain Injuries; Denervation; Disease Models, Animal; Dizocilpine Maleate; Entorhinal Cortex; Gene Expression Regulation, Enzymologic; Glial Fibrillary Acidic Protein; Gliosis; Hippocampus; Immunohistochemistry; Male; Matrix Metalloproteinase 3; Neural Pathways; Neuronal Plasticity; Neuroprotective Agents; Presynaptic Terminals; Rats; Rats, Sprague-Dawley; RNA, Messenger; Up-Regulation

Spreading depression (SD)-like depolarizations may augment neuronal damage in neurovascular disorders such as stroke and traumatic brain injury. Spreading ischemia (SI), a particularly malignant variant of SD-like depolarization, is characterized by inverse coupling between the spreading depolarization wave and cerebral blood flow. SI has been implicated in particular in the pathophysiology of subarachnoid hemorrhage. Under physiological conditions, SD is blocked by N-methyl-D-aspartate receptor (NMDAR) antagonists. However, because both SD-like depolarizations and SI occur in presence of an increased extracellular K+ concentration ([K+]o), we tested whether this increase in baseline [K+]o would reduce the efficacy of NMDAR antagonists.. Cranial window preparations, laser Doppler flowmetry, and K+-sensitive/reference microelectrodes were used to record SD, SD-like depolarizations, and SI in rats in vivo; microelectrodes and intrinsic optical signal measurements were used to record SD and SD-like depolarizations in human and rat brain slices.. In vivo, the noncompetitive NMDAR antagonist dizocilpine (MK-801) blocked SD propagation under physiological conditions, but did not block SD-like depolarizations or SI under high baseline [K+]o. Similar results were found in human and rat neocortical slices with both MK-801 and the competitive NMDAR antagonist D-2-amino-5-phosphonovaleric acid.. Our data suggest that elevated baseline [K+]o reduces the efficacy of NMDAR antagonists on SD-like depolarizations and SI. In conditions of moderate energy depletion, as in the ischemic penumbra, or after subarachnoid hemorrhage, NMDAR inhibition may not be sufficient to block these depolarizations.

Topics: 2-Amino-5-phosphonovalerate; Animals; Body Temperature; Brain; Brain Injuries; Cortical Spreading Depression; Dizocilpine Maleate; Electrodes; Excitatory Amino Acid Antagonists; Humans; Ions; Ischemia; Laser-Doppler Flowmetry; Male; Neuroprotective Agents; Potassium; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Subarachnoid Hemorrhage

To determine whether hippocampal pyramidal neurons retain authentic functional properties in mature organotypic culture, hippocampal slice cultures were established from young adult rats (P20-21). Cultures maintained 7 days in vitro retained tight organization of neuronal layers, as opposed to the widening restructure of pyramidal neurons often observed in perinatal slices. CA3 and CA1 pyramidal neurons fired action potentials in response to current injection and exhibited spontaneous and evoked synaptic currents, indicating intact neuronal function and normal hippocampal neural circuitry. We also tested neuronal sensitivity of slice cultures to ischemic injury. Acute ischemic paradigm resulted in selective death of pyramidal neurons in the CA1 region, which was prevented by treatment with an NMDA-antagonist, MK-801. Robust efflux of excitatory and inhibitory amino acid neurotransmitters was detected during ischemia, consistent with changes shown in acute slices. In summary, hippocampal organotypic cultures prepared from young adult rats maintained neuronal architecture and synaptic activity in vitro and can be used in parallel with an acute slice system to model mature brain tissue to examine ischemic pathophysiology and neuroprotective treatment.

Topics: Action Potentials; Animals; Animals, Newborn; Azides; Brain Injuries; Cell Death; Disease Models, Animal; Dizocilpine Maleate; Electric Stimulation; Evaluation Studies as Topic; Excitatory Amino Acid Antagonists; Glial Fibrillary Acidic Protein; Glucose; Hippocampus; Hypoxia; Immunohistochemistry; Male; Models, Biological; Neurons; Neurotransmitter Agents; Organ Culture Techniques; Oxygen; Patch-Clamp Techniques; Phenothiazines; Phosphopyruvate Hydratase; Rats; Rats, Wistar; Synaptic Transmission

Methylphenidate (MPH), a dopamine reuptake inhibitor, is used increasingly to treat attention deficit and hyperactivity disorders in children. Given that dopaminergic mechanisms, contribute to the structural and functional maturation of brain circuitry, consideration of the potential influence of MPH in disrupting such processes seems warranted. Following a similar logic regarding the relevance of glutamate neurotransmission in mediating aspects of brain maturation, we and others have previously utilized in vivo and in vitro studies of the developing rodent brain to establish that MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist has both neuroprotective and pro-apoptotic actions. In this study we used a neonatal murine model of excitotoxin-induced cortical injury to compare such actions between MPH and MK-801, and found that MPH shared some biological properties with MK-801. Specifically, both drugs were neuroprotective against excitotoxic challenge resulting in neonatal brain lesions and in vitro neuronal death, but both drugs also exacerbated programmed neural cell death. However, this profile of action was not shared by the dopamine reuptake blocker GBR-12783, a molecule which like MPH binds to and blocks the dopamine transporter, but which is structurally dissimilar to MPH, suggesting that inhibition of dopamine reuptake alone cannot explain the results from our MPH studies. The implications of our findings are that when studied in our developmental mouse model both drugs demonstrate similar capacities to be either neuroprotective or pro-apoptotic, depending on the specific biologic setting in which they act. Additional studies to identify some potential positive as well as negative consequences of exposure to these drugs during brain development in clinical settings are warranted.

Topics: Animals; Animals, Newborn; Apoptosis; Brain; Brain Injuries; Dizocilpine Maleate; Dopamine Uptake Inhibitors; Ibotenic Acid; In Situ Nick-End Labeling; Methylphenidate; Mice; Neurons; Neuroprotective Agents; Piperazines; Receptors, N-Methyl-D-Aspartate

Transplanting fetal striatal tissue is currently considered to be an important alternative strategy in the treatment of Huntington's disease. Although grafted striatal tissue differentiates and shows certain structural and neurochemical features of the normal striatum and receives host afferents, it is not clear whether host-derived afferent inputs can modulate the activity of neurotransmitter receptors and their signaling in the graft. An intricate interaction between dopaminergic and glutamatergic systems is pivotal for striatal function. In the present study, the modulation of D(2) receptors in the graft by host-derived glutamatergic afferents via NMDA receptors was investigated using haloperidol-induced c-Fos expression. The results indicate that haloperidol induces c-Fos in a large number of neurons in the P-zones of the graft and this induction is significantly suppressed by pretreatment with the NMDA receptor antagonist, MK-801. Therefore, the NMDA receptor-mediated modulation of D(2) receptor function seen in the normal striatum is established in the striatostriatal grafts.

Topics: Animals; Brain Injuries; Brain Tissue Transplantation; Corpus Striatum; Disease Models, Animal; Dizocilpine Maleate; Dopamine Antagonists; Excitatory Amino Acid Antagonists; Fetal Tissue Transplantation; Fluorescent Antibody Technique; Glutamine; Haloperidol; Huntington Disease; Immunohistochemistry; Male; Neurons, Afferent; Proto-Oncogene Proteins c-fos; Quinolinic Acid; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D2; Receptors, N-Methyl-D-Aspartate

Volatile anesthetics reduce neuronal excitation and cerebral metabolism but can also increase intracellular water accumulation in normal and injured brains. While attenuation of neuronal excitation and glutamate release are beneficial under pathological conditions, any increase in edema formation should be avoided. In the present study we investigated duration-dependent effects of the commonly used isoflurane/nitrous oxide (N2O) anesthesia on EEG activity, specific NMDA receptor binding, extracellular, CSF, and plasma glutamate, and cerebral water content in brain-injured rats subjected to short (30 minutes) or prolonged (4 hours) anesthesia.. Before controlled cortical impact injury (CCI), during prolonged (4-8 hours) or short anesthesia (7.5-8 hours after CCI), and before brain removal, changes in neuronal activity were determined by quantitative EEG analysis and glutamate was measured in arterial plasma. Brains were processed to determine acute and persisting changes in cerebral water content and 125I-Mk801 NMDA receptor binding at 8 and 32 hours after CCI, i.e., immediately or 24 hours after short or prolonged anesthesia. During prolonged anesthesia glutamate was measured via microdialysis within the cortical contusion. CSF was sampled before brain removal.. Prolonged isoflurane (1.8 vol%) anesthesia significantly increased EEG activity, plasma, cortical extracellular, and CSF glutamate, cortical and hippocampal 125I-Mk801 NMDA receptor binding, and cerebral water content in brain-injured rats. These changes were partially reversible within 24 hours after prolonged anesthesia. At 24 hours, CSF glutamate was significantly reduced following long isoflurane anesthesia compared to rats previously subjected to short anesthesia despite an earlier significant increase. Conclusions. The partially reversible increases in EEG activity, 125I-Mk801 NMDA receptor binding, cerebral water content, plasma and CSF glutamate appear important for physiological, pathophysiological, and pharmacological studies requiring prolonged anesthesia with isoflurane. Increases in extracellular cortical and plasma glutamate could contribute to acute aggravation of underlying tissue damage.

Topics: Anesthetics, Inhalation; Animals; Body Water; Brain; Brain Injuries; Dizocilpine Maleate; Drug Administration Schedule; Electroencephalography; Excitatory Amino Acid Antagonists; Glutamic Acid; Isoflurane; Rats; Receptors, N-Methyl-D-Aspartate

Recent experimental evidence indicates that erythropoietin (Epo), in addition to its hormonal role in regulating red cell production, operates as a neuroprotective agent. So far, the neuroprotective effect of human recombinant Epo (rhEpo) has been mainly demonstrated in models of cerebral ischemia/hypoxia and in selected in vivo studies of traumatic neuronal injury. To further investigate the potential role of this multifunctional trophic factor in post-traumatic cell death, we examined the protective effects of rhEpo in a newly developed model of mechanical trauma in organotypic hippocampal slices. Organotypic rat hippocampal slices were subjected to traumatic injury by allowing a stylus to impact on the CA1 area with an energy of 6 microJ. Hippocampal damage was identified and measured 24 and 48 h later with the fluorescent dye propidium iodide (PI). In untreated slices, the impact induced a significant increase in the mean hippocampal PI fluorescence, co-localized with the area of impact at 24 h (primary post-traumatic injury) and progressively spread to the whole slice between 24 and 48 h (secondary post-traumatic injury). Addition of rhEpo (1-100 UI/mL) or of the NMDA antagonist MK-801 (30 microM) immediately after the traumatic injury reduced hippocampal damage by approximately 30% when observed 24 h later. At 48 h after trauma, the protective effect of rhEpo was greater (by about 47%) and significantly more pronounced than that of MK-801 (28%). Our results suggest that the neuroprotective activity of rhEpo is particularly effective against delayed, secondary post-traumatic damage. This well tolerated agent could provide a therapeutic benefit in pathologies involving post-traumatic neurodegeneration.

Topics: Animals; Animals, Newborn; Brain Injuries; Dizocilpine Maleate; Down-Regulation; Erythropoietin; Excitatory Amino Acid Antagonists; Hippocampus; In Vitro Techniques; Models, Biological; Nerve Degeneration; Neurons; Neuroprotective Agents; Propidium; Rats; Rats, Wistar; Recombinant Fusion Proteins; Recombinant Proteins; Treatment Outcome

Cells that survive traumatic brain injury are exposed to changes in their neurochemical environment. One of these changes is a prolonged (48 h) uptake of calcium which, by itself, is not lethal. The N-methyl-D-aspartate receptor (NMDAR) is responsible for the acute membrane flux of calcium following trauma; however, it is unclear if it is involved in a flux lasting 2 days. We proposed that traumatic brain injury induced a molecular change in the NMDAR by modifying the concentrations of its corresponding subunits (NR1 and NR2). Changing these subunits could result in a receptor being more sensitive to glutamate and prolong its opening, thereby exposing cells to a sustained flux of calcium. To test this hypothesis, adult rats were subjected to a lateral fluid percussion brain injury and the NR1, NR2A and NR2B subunits measured within different regions. Although little change was seen in NR1, both NR2 subunits decreased nearly 50% compared with controls, particularly within the ipsilateral cerebral cortex. This decrease was sustained for 4 days with levels returning to control values by 2 weeks. However, this decrease was not the same for both subunits, resulting in a decrease (over 30%) in the NR2A:NR2B ratio indicating that the NMDAR had temporarily become more sensitive to glutamate and would remain open longer once activated. Combining these regional and temporal findings with 45calcium autoradiographic studies revealed that the degree of change in the subunit ratio corresponded to the extent of calcium accumulation. Finally, utilizing a combination of NMDAR and NR2B-specific antagonists it was determined that as much at 85% of the long term NMDAR-mediated calcium flux occurs through receptors whose subunits favor the NR2B subunit. These data indicate that TBI induces molecular changes within the NMDAR, contributing to the cells' post-injury vulnerability to glutamatergic stimulation.

Topics: Animals; Autoradiography; Behavior, Animal; Blotting, Western; Brain Injuries; Calcium; Calcium Radioisotopes; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Fluoresceins; Fluorescent Dyes; Male; Occipital Lobe; Organic Chemicals; Parietal Lobe; Piperidines; Protein Isoforms; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Time Factors; Trauma Severity Indices; Wounds, Nonpenetrating

Antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors have been shown not only to have neuroprotective effects but also to exhibit neurotoxic properties. In this study, we used c-Fos, a protein product of an immediate early gene, as a marker of neuronal injury to compare the neuroprotective effects of xenon and the neurotoxic properties of xenon, nitrous oxide, and ketamine, three anaesthetics with NMDA receptor antagonist properties.. We used an in vivo rat model of brain injury in which N-methyl-DL-aspartic acid (NMA) is injected subcutaneously (s.c.) and c-Fos expression in the arcuate nucleus is used as a measure of injury. To examine the neurotoxic potential of each of the three anaesthetics with NMDA receptor antagonist properties, c-Fos expression in the posterior cingulate and retrosplenial (PC/RS) cortices was measured.. Xenon dose-dependently suppressed NMA-induced c-Fos expression in the arcuate nucleus with an IC(50) of 47 (2)% atm. At the highest concentration tested (75% atm) NMA-induced neuronal injury was decreased by as much as that observed with the prototypical NMDA antagonist MK801 (0.5 mg kg(-1) s.c.). Both nitrous oxide and ketamine dose-dependently increased c-Fos expression in PC/RS cortices; in contrast, xenon produced no significant effect. If the dopamine receptor antagonist haloperidol was given before either nitrous oxide or ketamine, their neurotoxic effects were eliminated.. Uniquely amongst anaesthetics with known NMDA receptor antagonist action, xenon exhibits neuroprotective properties without co-existing neurotoxicity. The reason why ketamine and nitrous oxide, but not xenon, produce neurotoxicity may involve their actions on dopaminergic pathways.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Biomarkers; Brain; Brain Injuries; Dizocilpine Maleate; Female; Gene Expression; Haloperidol; Ketamine; Models, Animal; N-Methylaspartate; Neuroprotective Agents; Nitrous Oxide; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Xenon

Previous studies have observed that fluid percussion brain injury (FPI) impaired NMDA induced pial artery dilation (PAD) in an age dependent manner. Unrelated studies observed a similar age dependent impairment of hypotensive cerebral autoregulation after FPI. This study was designed to test the hypothesis that NMDA receptor activation contributes to impairment of cerebral autoregulation during hypotension after FPI in an age dependent manner. Therefore, the role of NMDA in impaired hypotensive cerebrovascular regulation after FPI was compared in newborn and juvenile pigs equipped with a closed cranial window. Ten minutes of hypotension (10-15 ml blood/kg) decreased mean arterial blood pressure uniformly in both groups (approximately 44%). In the newborn, hypotensive PAD was blunted within 1 h of FPI but partially protected by pretreatment with the NMDA antagonist MK801 (1 mg/kg i.v.) (34+/-1 vs. 8+/-1 vs. 25+/-2% for sham control, FPI, and FPI-MK801, respectively). Cerebral blood flow (CBF) was reduced during normotension by FPI, further reduced by hypotension, but both were partially protected by MK801 in the newborn (56+/-5, 35+/-2, and 16+/-1 vs. 62+/-6, 45+/-3, and 30+/-2 ml/min 100 g for normotension, normotension-FPI, and hypotension-FPI in the absence and presence of MK801, respectively). In contrast, blunted hypotensive PAD was protected significantly less by MK801 in the juvenile (32+/-2 vs. 7+/-2 vs. 16+/-2% for sham control, FPI, and FPI-MK801, respectively). Similarly, MK801 had less protective effect on normotensive and hypotensive CBF values post FPI in the juvenile. These data indicate that NMDA receptor activation contributes to impaired hypotensive cerebral hemodynamics following brain injury in an age dependent manner.

Topics: Aging; Animals; Animals, Newborn; Blood Chemical Analysis; Brain Injuries; Cerebral Arteries; Cerebrovascular Circulation; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Homeostasis; Hypotension; Male; Microspheres; N-Methylaspartate; Receptors, N-Methyl-D-Aspartate; Swine

To understand the pathogenesis of diffuse axonal injury, we investigated the temporal and spatial profiles of neuronal degeneration in impact-acceleration injury in rats using Fluoro-Jade (FJ) staining. Impact-acceleration injury was produced in Wistar rats by the method described by Marmarou et al. with some modifications. Animals were sacrificed 1, 2, 7, 14, or 28 days after injury. Paraffin-embedded coronal sections were stained with HE or FJ, or analyzed immunohistochemically for GFAP or amyloid precursor protein (APP). FJ-positive degenerative neurons were found primarily in the dorsal brainstem and thalamus from 1 to 2 days following injury and these were associated with GFAP expression. However, FJ-positive cells were rarely found after 7 days. In all rats, significant expression of APP was observed primarily in the cingulum, cerebral peduncle and pontomedullary junction. FJ also stained these injured axons. Intrathecal administration of both NMDA and AMPA/kinate glutamate receptor antagonists MK-801 and NBQX, respectively, reduced the neuronal injury. NBQX showed more significant effects on axonal injury than MK-801. These observations indicate that not only axonal damage, but also primary neuronal damage occurs in this impact-acceleration injury model. It is also suggested that NBQX can act both directly on neuronal cells and white matter and that NMDA could have a significant protective effect against not only neuronal, but also axonal injury.

Topics: Amyloid beta-Protein Precursor; Animals; Brain Injuries; Brain Stem; Dizocilpine Maleate; Glial Fibrillary Acidic Protein; Male; Neurons; Quinoxalines; Rats; Rats, Wistar; Thalamus

It has been demonstrated that the endogenous cannabinoid receptor ligand, anandamide, and other N-acylethanolamines (NAEs), accumulate during neuronal injury in vitro, a process that may be linked to the neuroprotective effects of NAEs. The crucial step for generation of NAEs is the synthesis of the corresponding precursors, N-acylethanolamine phospholipids (NAPEs). However, it is unknown whether this key event for NAE formation is regulated differently in the context of insults causing necrotic or apoptotic neuronal death. To address this question, we monitored a range of cortical NAPE species in three infant rat models of in vivo neurodegeneration: (i) necrosis caused by intrastriatal injection of NMDA (25 nmol); (ii) apoptosis induced by systemic administration of the NMDA-receptor antagonist (+)MK-801 (3 x 0.5 mg/kg, i.p.); and (iii) apoptosis following focal necrosis triggered by concussive head trauma. A marked increase of all NAPE species was observed in both hemispheres 4 and 24 h after NMDA-induced injury, with a relatively larger increase in N-stearoyl-containing NAPE species. Thus, the percentage of the anandamide precursor fell from 1.1 to 0.5 mol %. In contrast, administration of (+)MK-801 did not alter cortical NAPE levels. Concussion head trauma resulted in a similar but less pronounced upregulation of NAPE levels at both 4 and 24 h as compared to NMDA injections. Increased levels of NAPE 24 h post-trauma possibly reflect that necrosis is still ongoing at this time point. Consequently, our data suggest that excitotoxic necrotic mechanisms of neurodegeneration, as opposed to apoptotic neurodegeneration, have a profound effect on in vivo NAE precursor homeostasis.

Topics: Animals; Apoptosis; Arachidonic Acids; Brain Injuries; Cerebral Cortex; Corpus Striatum; Disease Models, Animal; Dizocilpine Maleate; Endocannabinoids; Ethanolamines; Male; N-Methylaspartate; Necrosis; Neurodegenerative Diseases; Neurons; Phospholipids; Polyunsaturated Alkamides; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Species Specificity; Wounds, Nonpenetrating

The effects of selective blockade of group I metabotropic glutamate receptor subtype 1 (mGluR1) on neuronal cell survival and post-traumatic recovery was examined using rat in vitro and in vivo trauma models. The selective mGluR1 antagonists (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA), 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt), and (S)-(+)-alpha-amino-4-carboxy-2-methylbezeneacetic acid (LY367385) provided significant neuroprotection in rat cortical neuronal cultures subjected to mechanical injury, in both pretreatment or posttreatment paradigms. Administration of the antagonists also attenuated glutamate-induced neuronal cell death in the cultures. Coapplication of these antagonists with the N-methyl-d-aspartate (NMDA) receptor antagonist (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) had additive neuroprotective effects in glutamate injured cultures. Intracerebroventricular administration of AIDA to rats markedly improved recovery from motor dysfunction after lateral fluid percussion induced traumatic brain injury (TBI). Treatment with mGluR1 antagonists also significantly reduced lesion volumes in rats after TBI, as evaluated by MRI. It appears that these compounds mediate their neuroprotective effect through an mGluR1 antagonist action, as demonstrated by inhibition of agonist induced phosphoinositide hydrolysis in our in vitro system. Moreover, AIDA, CPCCOEt, and LY367385, at concentrations shown to be neuroprotective, had no significant effects on the steady state NMDA evoked whole cell current. Taken together, these data suggest that modulation of mGluR1 activity may have substantial therapeutic potential in brain injury.

Topics: Animals; Benzoates; Brain Injuries; Cell Death; Cells, Cultured; Chromones; Disease Models, Animal; Dizocilpine Maleate; Drug Synergism; Evoked Potentials; Excitatory Amino Acid Antagonists; Glycine; In Vitro Techniques; Indans; Injections, Intraventricular; Male; Models, Biological; Neuroprotective Agents; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Receptors, N-Methyl-D-Aspartate; Wounds, Nonpenetrating

The effects of three glutamate receptor antagonists, (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801) for the N-methyl-D-aspartate receptor, 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f] quinoxaline-7-sulfonamide (NBQX) for the alpha-amino-3-hydroxy-5methyl-4-isoxazole propionate /kinate receptor and (S)-alpha-methyl-4-carboxyphenylglycine (MCPG) for the metabotropic receptor, on c-fos and c-jun mRNA expression were investigated in cultured cortical glial cells following traumatic scratch injury. Expression of the two genes along the edges of wounds detected by in situ hybridization was not affected by MK-801 and NBQX. However, 100 and 500 microM of MCPG remarkably reduced the hybridization signals for both c-fos and c-jun mRNAs. The present results suggest that group I metabotropic glutamate receptors might have some association with immediate early gene induction after in vitro traumatic injury in glial cells.

Topics: Animals; Benzoates; Brain Injuries; Cells, Cultured; Cerebral Cortex; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Fetus; Gene Expression Regulation; Genes, Immediate-Early; Gliosis; Glycine; Nerve Regeneration; Neuroglia; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; Quinoxalines; Rats; Rats, Wistar; Receptors, AMPA; Receptors, Metabotropic Glutamate; Receptors, N-Methyl-D-Aspartate; RNA, Messenger; Transcriptional Activation

Adult rats were subjected to a moderate lateral fluid percussion injury (FPI), followed by survival periods of 2 and 12 h. Regional NMDA subtype glutamate, muscarinic acetylcholine and GABA(A) receptor binding in various brain regions was analysed by quantitative in vitro autoradiography and short-lived positron emission tomography tracers [11C]cyano-dizocilpine, 4-N-[11C]methylpiperidylbenzilate (4-N-[11C]MPB), and [11C]flumazenil, respectively. The binding potential (BP, Bmax/KD) was calculated. The data with [11C]cyano-dizocilpine showed a significant decrease in BP bilaterally for the frontoparietal cortex and hippocampus at both time points, in comparison with that of the sham-operated controls. At 12 h the decrease was significantly more prominent for the ipsilateral cortex and hippocampus than for the contralateral side. The BP of 4-N-[11C]MPB was significantly decreased after 2 h for the trauma-side hippocampus, and after 12 h it had decreased for the trauma-site cortex and the bilateral hippocampus. The [11C]flumazenil exhibited a significant decrease in BP for the trauma-site cortex and the underlying hippocampus by 2 h after the traumatic brain injury. After 12 h a significantly decreased BP was observed only for the trauma-site cortex. The finding of a decreased BP demonstrates the involvement of these receptor systems in the development of cellular dysfunction, which is widespread and not limited to the site of lateral FPI.

Topics: Animals; Autoradiography; Binding Sites; Brain; Brain Injuries; Cerebral Cortex; Dizocilpine Maleate; Flumazenil; Frozen Sections; Hippocampus; Humans; Kinetics; Male; Nitriles; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, GABA-A; Receptors, Muscarinic; Receptors, N-Methyl-D-Aspartate; Tomography, Emission-Computed

Trauma is the leading cause of death in individuals between the ages of 1 and 44 years. And, in the case of severe head injury mortality can reach as high as 35-70%. Despite this fact, there has been little progress in the development of effective pharmacological agents to protect brain injured patients. To date, there is little data on the mechanisms involved in neuronal cellular insult after severe head injury, especially in humans. Glutamate acts both as a primary excitatory neurotransmitter and a potential neurotoxin within the mammalian brain. Evidence indicates that hyperactivity of the glutamate system contributes to neuronal death in brain trauma. Also, in animal models of neurotrauma, this neural injury is followed by gliosis which has been linked to the severity of brain injury. To investigate the glutamate system in brain trauma, we carried out [3H]glutamate and [3H]MK801 (a noncompetitive NMDA-receptor antagonist) binding and [3H]glutamate uptake assays in human cerebral cortex preparations obtained from severely brain injured and control victims. Additionally, to investigate gliosis following brain injury, we performed GFAP immunohistochemistry. There were no significant differences in [3H]glutamate binding (affinity or density of sites) between the control and head injured groups. In contrast, cerebral cortical [3H]MK801 binding revealed both a significant increase in the density of sites (Bmax) and a decrease in the dissociation constant (Kd) in the head injured group when compared to controls. There were no significant differences in [3H]glutamate uptake between groups. The injured brains presented an increased number of GFAP-positive astrocytes and more intense GFAP reaction in comparison to control brains. In the context of traumatic brain injury, our results encourage further investigation into compounds capable of selective modulation of NMDA receptor subtype in humans while also therapeutically manipulating glial cell responses following brain trauma.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Brain Chemistry; Brain Injuries; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Glial Fibrillary Acidic Protein; Gliosis; Glutamic Acid; Humans; Male; Middle Aged; Radioligand Assay; Synaptosomes; Tritium

The selective 5-HT(1A) receptor agonist Repinotan HCl (BAY x3702) has been reported to attenuate cortical damage and improve functional performance in experimental models of cerebral ischemia and acute subdural hematoma. Using a clinically relevant contusion model of traumatic brain injury, we tested the hypothesis that a 4-h continuous infusion of Repinotan HCl (10 microg/kg/h i.v.) commencing 5 min post-injury would ameliorate functional outcome and attenuate histopathology. Forty isoflurane-anesthetized male adult rats were randomly assigned to receive either a controlled cortical impact (2.7 mm tissue deformation, 4 m/s) or sham injury (Injury/Vehicle=10, Injury/MK-801=10, Injury/Repinotan HCl=10, Sham/Vehicle=10), then tested for vestibulomotor function on post-operative days 1-5 and for spatial learning on days 14-18. Neither Repinotan HCl nor the non-competitive N-methyl-D-aspartate receptor antagonist MK-801, which served as a positive control, improved vestibulomotor function on beam balance and beam walk tasks relative to the Injury/Vehicle group, but both did significantly attenuate spatial learning and memory deficits on a water maze task. Repinotan HCl also reduced hippocampal CA(1) and CA(3) neuronal loss, as well as cortical tissue damage, compared to the Injury/Vehicle group at 4 weeks post-trauma. No significant difference in histological outcome was revealed between the Repinotan HCl- and MK-801-treated groups.These findings extend the therapeutic efficacy of Repinotan HCl to a contusion model of experimental brain injury and demonstrate for the first time that 5-HT(1A) receptor agonists confer neuroprotection and attenuate spatial learning deficits following controlled cortical impact injury. This treatment strategy may be beneficial in a clinical context where memory impairments are common following human traumatic brain injury.

Topics: Animals; Benzopyrans; Body Temperature; Brain; Brain Injuries; Cognition; Cognition Disorders; Dizocilpine Maleate; Drug Administration Schedule; Excitatory Amino Acid Antagonists; Hippocampus; Male; Maze Learning; Nerve Degeneration; Neurons; Neuroprotective Agents; Postural Balance; Rats; Rats, Sprague-Dawley; Receptors, Serotonin; Receptors, Serotonin, 5-HT1; Serotonin Receptor Agonists; Thiazoles; Vestibular Nuclei

(1S, 2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606) is a noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors containing the NR2B subunit. This compound was used to investigate the role of NR2B containing receptors in three responses to NMDA receptor activation in vivo. In mouse, CP-101,606 completely inhibited increases in fos-like immunoreactivity in dentate gyrus caused by a subconvulsant intraperitoneal dose of NMDA. In rat, the compound completely blocked cortical c-fos mRNA induction following focal injury in parietal cortex and the initiation and propagation of electrically induced cortical spreading depression. Inhibition of these responses by CP-101,606 indicates that c-fos induction and cortical spreading depression are dependent on activation of NMDA receptors containing the NR2B subunit. Since NMDA receptor dependent c-fos induction and cortical spreading depression may contribute to neuron loss after focal CNS injury, inhibition of these responses by CP-101,606 may contribute to the neuroprotective efficacy of the compound.

Topics: Animals; Blotting, Northern; Brain Injuries; Cortical Spreading Depression; Dizocilpine Maleate; Electric Stimulation; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Gene Expression; Genes, fos; Hippocampus; Immunohistochemistry; Male; Mice; N-Methylaspartate; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; RNA, Messenger

Previous studies have utilized a lesion model of cortical injury that produces transient behavioral impairments to investigate the recovery of function process. To better understand the recovery process, it would be beneficial to use a lesion model that produces more severe, enduring, behavioral impairments. The purpose of experiment 1 was to validate whether large lesions of the sensorimotor cortex (SMC), which included the rostral forelimb and caudal forelimb regions, produced enduring behavioral deficits. Rats were given large unilateral electrolytic lesions of the SMC, administered either the N-methyl-D-aspartate (NMDA) antagonist, MK-801 or saline 16 h after injury, and tested on a battery of behavioral tests. Enduring behavioral deficits were observed, for at least 6 months, on two tests of forelimb placing while transient deficits were observed on the foot-fault and somatosensory neutralization tests. Administration of MK-801 facilitated recovery on the somatosensory neutralization test; however, it did not induce recovery on either forelimb placing test. A second experiment was performed to determine if earlier administration of MK-801, the NMDA antagonist magnesium chloride (MgCl(2)), or the anti-oxidant N-tert-butyl-alpha-phenylnitrone (PBN) could induce behavioral recovery in this chronic model. Treatment with these drugs induced behavioral recovery on the forelimb placing tests, whereas, the saline-treated rats did not show any signs of behavioral recovery for at least 3 months. Anatomical analysis of the striatum showed that MK-801 and MgCl(2) but not PBN reduced the extent of lesion-induced striatal atrophy. These results suggest that administration of MK-801, MgCl(2), or PBN shortly after cortical injury can induce recovery of function when recovery is otherwise not expected in un-treated rats.

Topics: Animals; Antioxidants; Brain Injuries; Cyclic N-Oxides; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Forelimb; Lameness, Animal; Magnesium Chloride; Male; Motor Activity; Motor Cortex; Nerve Degeneration; Neuroprotective Agents; Nitrogen Oxides; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Touch; Vibrissae

Glutamate promotes neuronal survival during brain development and destroys neurons after injuries in the mature brain. Glutamate antagonists are in human clinical trials aiming to demonstrate limitation of neuronal injury after head trauma, which consists of both rapid and slowly progressing neurodegeneration. Furthermore, glutamate antagonists are considered for neuroprotection in chronic neurodegenerative disorders with slowly progressing cell death only. Therefore, humans suffering from Huntington's disease, characterized by slowly progressing neurodegeneration of the basal ganglia, are subjected to trials with glutamate antagonists. Here we demonstrate that progressive neurodegeneration in the basal ganglia induced by the mitochondrial toxin 3-nitropropionate or in the hippocampus by traumatic brain injury is enhanced by N-methyl-d-aspartate antagonists but ameliorated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate antagonists. These observations reveal that N-methyl-d-aspartate antagonists may increase neurodestruction in mature brain undergoing slowly progressing neurodegeneration, whereas blockade of the action of glutamate at alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors may be neuroprotective.

Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Brain Injuries; Cell Death; Dizocilpine Maleate; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Memantine; N-Methylaspartate; Neurons; Neuroprotective Agents; Neurotoxins; Nitro Compounds; Piperazines; Propionates; Quinoxalines; Rats; Rats, Wistar; Wounds and Injuries

This study was undertaken in order to investigate the role of insulin-like growth factor (IGF)-II, c-fos, N-methyl-D-aspartate (NMDA) receptors, and nNOS in the cellular processes following a penetrating brain injury. IGF-II mRNA levels, as determined by Northern analysis, were decreased at 4, 8, and 24 h after brain injury, in the lesioned, compared to the contralateral intact hemisphere. Forty-eight and 72 h after the injury, there was no difference between the lesioned and the contralateral intact hemisphere in IGF-II mRNA levels. c-fos mRNA levels followed a parallel, but opposite course: They were increased at 4, 8 and 24 h after the injury, while at 48 and 72 h c-fos mRNA levels in the lesioned hemisphere did not differ from those in the intact. Administration of MK-801 reversed the injury-induced decrease in IGF-II mRNA levels. Administration of MK-801 resulted in an increase in IGF-II mRNA in both the intact and the lesioned hemispheres. Brain injury resulted in an increase in nNOS immunopositive cells in the hippocampal formation, which was detectable at 4 and 12, but not 48 h after the injury. These results suggest that IGF-II, c-fos, NMDA receptors and nNOS are involved in the cellular responses to brain injury.

Topics: Animals; Brain Injuries; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Gene Expression; Hippocampus; Immunohistochemistry; Insulin-Like Growth Factor II; Male; Neurons; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; RNA, Messenger; Time Factors

Muscarinic and NMDA receptors contribute to post-traumatic hypersensitivity to secondary ischemia. However, the effect of these receptor antagonists on behavior and CA1 neuronal death after traumatic brain injury (TBI) with acute (1 h after TBI) forebrain ischemia has not been systematically assessed. We examined cognitive and motor dysfunction and the relationship of behavior deficits to neuronal death in this model using muscarinic and NMDA antagonists. Three behavioral groups (n=10/group) of Wistar rats were subjected to mild TBI and 6 min of forebrain ischemia imposed 1 h after TBI with 45 days survival. Motor and spatial memory performance were assessed using the rotarod task and Morris water maze. Seven additional groups (n=6/group) were evaluated only for CA1 death after 7 days survival following sham, individual or combined injury with and without drug treatments. Rats were given 0.3 mg/kg MK-801 (M) and 1.0 mg/kg scopolamine (S) alone or combined (M-S) before or 45 min after TBI. Rotarod performance was tested at days 1-5 and maze performance on days 11-15 and 40-44 after M-S treatment. The 7-day studies showed M-S treatment (p<0.01) reduced CA1 neuronal death better than either S or M alone. Behavioral groups had inadvertent post-ischemic hypothermia that decreased CA1 death and likely influenced behavioral morbidity. M-S given before TBI (p<0.01) decreased memory deficits on day 15, while M-S treatment given after TBI was ineffective. Unexpectedly, M-S treatment before or after TBI produced transient motor deficits (p<0. 01). Memory improvement occurred independent of CA1 death.

Topics: Animals; Body Weight; Brain Injuries; Combined Modality Therapy; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Ischemic Attack, Transient; Male; Maze Learning; Muscarinic Antagonists; Psychomotor Performance; Rats; Rats, Wistar; Scopolamine; Treatment Outcome

Morbidity and mortality from head trauma is highest among children. No animal model mimicking traumatic brain injury in children has yet been established, and the mechanisms of neuronal degeneration after traumatic injury to the developing brain are not understood. In infant rats subjected to percussion head trauma, two types of brain damage could be characterized. The first type or primary damage evolved within 4 hr and occurred by an excitotoxic mechanism. The second type or secondary damage evolved within 6-24 hr and occurred by an apoptotic mechanism. Primary damage remained localized to the parietal cortex at the site of impact. Secondary damage affected distant sites such as the cingulate/retrosplenial cortex, subiculum, frontal cortex, thalamus and striatum. Secondary apoptotic damage was more severe than primary excitotoxic damage. Morphometric analysis demonstrated that the N-methyl-D-aspartate receptor antagonists 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonate and dizocilpine protected against primary excitotoxic damage but increased severity of secondary apoptotic damage. 2-Sulfo-alpha-phenyl-N-tert-butyl-nitrone, a free radical scavenger, did not affect primary excitotoxic damage but mitigated apoptotic damage. These observations demonstrate that apoptosis and not excitotoxicity determine neuropathologic outcome after traumatic injury to the developing brain. Whereas free radical scavengers may prove useful in therapy of head trauma in children, N-methyl-D-aspartate antagonists should be avoided because of their propensity to increase severity of apoptotic damage.

Topics: Animals; Apoptosis; Brain; Brain Injuries; Caudate Nucleus; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Frontal Lobe; Gyrus Cinguli; In Situ Nick-End Labeling; N-Methylaspartate; Nerve Degeneration; Parietal Lobe; Piperazines; Rats; Rats, Wistar; Thalamus; Time Factors

Immunotoxic lesions of the diagonal band of Broca (VDB) in monkeys disrupted cholinergic input to the hippocampus, producing impaired learning of visuospatial conditional discriminations but not simple visual discriminations. Immunotoxic lesions of the basal nucleus of Meynert (NBM) deprived the cortex of most of its cholinergic input, producing impaired learning of simple visual discriminations but not visuospatial conditional discriminations. Combined lesions of the NBM + VDB resulted in impaired learning of both types of task. The impairment after NBM lesions ameliorated with time but could be reinstated by a low dose of the glutamate blocking drug MK801, which, at this dose, did not impair simple visual discrimination learning in normal monkeys. The cholinergic projections from the NBM and VDB may sustain the function of the glutamatergic pyramidal cell pathways within the cortex and hippocampus, respectively.

Topics: Analysis of Variance; Animals; Antibodies, Monoclonal; Brain Injuries; Callithrix; Cholinergic Agents; Cognition; Discrimination Learning; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Frontal Lobe; Immunotoxins; Male; N-Glycosyl Hydrolases; Recovery of Function; Ribosome Inactivating Proteins, Type 1; Saporins; Visual Perception

Extreme overreliance on the impaired forelimb following unilateral lesions of the forelimb representation area of the rat sensorimotor cortex (FL-SMC) leads to exaggeration of the initial cortical injury. Glutamate has repeatedly been implicated in the secondary processes leading to neuronal death following traumatic insult, chiefly because of the neuroprotective properties of excitatory amino acid antagonists in a variety of animal models of brain injury. The present study investigated the possibility that NMDA receptor-mediated processes are involved in use-dependent exaggeration of neuronal injury. Rats were fitted with one-sleeved casts that immobilized the intact forelimb for the first 7 days following FL-SMC lesion, a procedure previously shown to result in use-dependent exaggeration of injury and more severe and persistent limb-use deficits. In the present investigation, administration of MK-801 (1 mg/kg ip once daily on alternate days) during the casting period spared neural tissue surrounding the lesion and enhanced functional recovery of the impaired forelimb. These results suggest a role for NMDA receptor-mediated processes in use-dependent exaggeration of injury.

Topics: Analysis of Variance; Animals; Brain Injuries; Dizocilpine Maleate; Forelimb; Functional Laterality; Glutamic Acid; Male; Microdialysis; Motor Activity; Rats; Rats, Long-Evans; Receptors, N-Methyl-D-Aspartate; Somatosensory Cortex; Time Factors

Neuronal necrosis and apoptosis occur after traumatic brain injury (TBI) in animals and contribute to subsequent neurological deficits. In contrast, relatively little apoptosis is found after mechanical injury in vitro. Because in vivo trauma models and clinical head injury have associated cerebral ischemia and/or metabolic impairment, we transiently impaired cellular metabolism after mechanical trauma of neuronal-glial cultures by combining 3-nitropropionic acid treatment with concurrent glucose deprivation. This produced greater neuronal cell death than mechanical trauma alone. Such injury was attenuated by the NMDA receptor antagonist dizocilpine (MK801). In addition, this injury significantly increased the number of apoptotic cells over that accruing from mechanical injury alone. This apoptotic cell death was accompanied by DNA fragmentation, attenuated by cycloheximide, and associated with an increase in caspase-3-like but not caspase-1-like activity. Cell death was reduced by the pan-caspase inhibitor BAF or the caspase-3 selective inhibitor z-DEVD-fmk, whereas the caspase-1 selective inhibitor z-YVAD-fmk had no effect; z-DEVD-fmk also reduced the number of apoptotic cells after combined injury. Moreover, cotreatment with MK801 and BAF resulted in greater neuroprotection than either drug alone. Thus, in vitro trauma with concurrent metabolic inhibition parallels in vivo TBI, showing both NMDA-sensitive necrosis and caspase-3-dependent apoptosis.

Topics: Animals; Apoptosis; Brain Injuries; Caspase 3; Caspase Inhibitors; Caspases; Cell Death; Cells, Cultured; Cerebral Cortex; Coculture Techniques; Dizocilpine Maleate; Hypoglycemia; Necrosis; Neuroglia; Neurons; Nitro Compounds; Oligopeptides; Propionates; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Succinate Dehydrogenase

We have previously demonstrated that traumatic injury of the lateral aspect of the right parietal cortex results in reduced acquisition of the passive avoidance task but enhanced learning in an active avoidance procedure. In order to try to explain the apparent dichotomy between these findings a series of experiments examined the effect of fluid percussion-induced traumatic brain injury (FP-TBI) on the conditioned freezing response to a context previously paired with an aversive stimulus. Rats subjected to FP-TBI displayed less conditioned freezing than the sham-operated controls. This effect was particularly marked when the delay between context exposure and footshock was short (< or = 30 s) and was no longer significant when this delay was 3 min, indicating that the injured animals did not have an impaired freezing response per se. This phenomenon was enduring such that it could still be observed 2 months following the surgery. There was no significant freezing deficit after FP-TBI of the motor cortex, demonstrating that the site of injury is important and that the freezing deficit is not a general response to CNS trauma. The NMDA receptor antagonist dizocilpine (MK-801, 1 mg/kg i.v.) significantly reduced the trauma-induced freezing deficit when administered as a single bolus 15 min prior to the surgery, or as three repeated treatments (3 x 0.33 mg/kg) 15 min, and 6 and 24 h following lesion. The trauma-induced deficit in conditioned freezing can explain the differences in active and passive avoidance behaviours and appears to be specific to lesion of the lateral parietal cortex. In addition, the behavioural deficit can be attenuated using the neuroprotective agent dizocilpine, suggesting that it may prove useful as a sensitive and specific measure of cortical damage following traumatic injury.

Topics: Animals; Brain Injuries; Conditioning, Classical; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Immobilization; Male; Motor Cortex; Parietal Lobe; Rats; Rats, Sprague-Dawley; Time Factors

The combination of central fluid percussion traumatic brain injury (TBI) followed 24 h later by a bilateral entorhinal cortical deafferentation (BEC) produces profound cognitive morbidity. We recently showed that MK-801 given prior to TBI in this insult improved spatial memory for up to 15 days. In the present study we examine whether MK-801 treatment of the BEC component in the combined insult model affects cognitive recovery. Two strategies for drug treatment were tested. Fifteen minutes prior to the BEC lesion in the combined insult, rats were given i.p. doses of either 3 mg/kg (acute group) or 1 mg/kg (chronic group) MK-801. The acute group received no further injections, whereas the chronic group received 1 mg/kg MK-801 i.p. twice a day for 2 days post-BEC lesion. Two additional groups of animals received BEC lesion alone and either acute or chronic MK-801 treatment identical with the combined insult cases. Each group was then assessed for spatial memory deficits with the Morris water maze at days 11-15 and 60-64 postinjury. Both acute and chronic MK-801 treatment in the combined insult group significantly reduced spatial memory deficits at 15 days postinjury relative to untreated injured cases (P < .01). This reduction appeared more robust at 15 days and persisted for up to 64 days in the chronically treated group (P < .05). By contrast, neither acute nor chronic MK-801 treatment affected memory performance with the BEC insult alone. Immunocytochemical localization of parvalbumin showed that chronic administration of MK-801 in the combined insult cases attenuated the injury-induced dendritic atrophy of inhibitory neurons in the dentate gyrus and area CA1. Synaptophysin immunobinding revealed that chronic MK-801 treatment of the BEC component of the combined insult normalized the distribution of presynaptic terminals within the dentate gyrus. These results suggest that cognitive deficits produced by head trauma involving both neuroexcitation and deafferentation can be attenuated with chronic application of glutamatergic antagonists during the period of deafferentation injury and that this attenuation is correlated with axo-dendritic integrity.

Topics: Afferent Pathways; Animals; Axons; Brain Injuries; Cognition; Dendrites; Denervation; Dizocilpine Maleate; Entorhinal Cortex; Excitatory Amino Acid Antagonists; Immunohistochemistry; Male; Parvalbumins; Rats; Rats, Sprague-Dawley; Synaptophysin

1. The aim of this study was to assess whether an excitotoxic insult induced by NMDA may induce an iNOS activity which contributes to the lesion in the rat striatum. 2. For this purpose, rats were perfused with 10 mM NMDA through a microdialysis probe implanted in the left striatum. Microdialysate nitrite content, striatal Ca-independent nitric oxide synthase activity and lesion volume were measured 48 h after NMDA exposure in rats treated with dexamethasone (DXM) (3 mg kg(-1) x 4) or aminoguanidine (AG) (100 mg kg(-1) x 4). 3. A significant increase in microdialysate nitrite content and in the Ca-independent NOS activity was observed 48 h after NMDA infusion. Both these increases were reduced by DXM and AG. The NMDA-induced striatal lesion was also reduced by both treatments. 4. Our results demonstrate that NMDA excitotoxic injury induces a delayed, sustained activation of a Ca-independent NOS activity. This activity is blocked by DXM and AG, strongly suggesting the involvement of iNOS. The fact that AG and DXM reduce the NMDA-elicited lesion suggests that iNOS contributes to the brain damage induced by excitotoxic insult.

Topics: Animals; Brain Injuries; Corpus Striatum; Dexamethasone; Dizocilpine Maleate; Guanidines; Male; N-Methylaspartate; Neurotoxins; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Rats; Rats, Sprague-Dawley

The postsynaptic neuronal dendrite is selectively vulnerable to hypoxic-ischemic brain injury and glutamate receptor overactivation. We explored the glutamate receptor pharmacology and ionic basis of rapid, reversible alterations in dendritic shape which occur in cultured neurons exposed to glutamate. Dendrite morphology was assessed with the fluorescent membrane tracer, DiI, or immunofluorescence labeling of the somatodendritic protein, MAP2. Cortical cultures derived from 15-day-old mouse embryos underwent segmental dendritic beading when exposed to NMDA, AMPA, or kainate, but not to metabotropic glutamate receptor agonists. Varicosity formation in response to NMDA or kainate application was substantially attenuated in reduced sodium buffer (substituted with N-methyl-D-glucamine). Furthermore, veratridine-induced sodium entry mimicked excitotoxic alterations in dendrites and additionally caused varicosity formation in axons. Solutions deficient in chloride (substituted with Na methylsulfate) and antagonists of chloride-permeable GABA/glycine receptors reduced NMDA- or kainate-induced varicosity formation. An increase in dendrite volume was observed as varicosities formed, and varicosity formation was attenuated in sucrose-supplemented hypertonic media. Despite marked structural changes affecting virtually all neurons, dendrite shape returned to normal within 2 h of terminating glutamate receptor agonist application. Neurons exposed to kainate recovered more rapidly than those exposed to NMDA, and neurons exposed to NMDA in calcium-free buffer recovered more rapidly than cells treated with NMDA in normal buffer. While sodium, chloride, and water entry contribute to excitotoxic dendritic injury acutely, calcium entry through NMDA receptors results in lasting structural changes in damaged dendrites.

Topics: Animals; Brain Injuries; Bridged Bicyclo Compounds; Calcium; Cells, Cultured; Chlorides; Coculture Techniques; Cytosol; Dendrites; Dizocilpine Maleate; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Kainic Acid; Mice; Microscopy, Fluorescence; N-Methylaspartate; Quinoxalines; Receptors, Glutamate; Sodium; Veratridine

Cerebral contusions increase cortical expression of insulin-like growth factor 1 (IGF-1), IGF binding protein-2 (IGFBP-2) and IGFBP-4, mRNA levels increase at the contusion site (IGF-1, IGFBP-2 and -4) and along the ipsilateral cortex (IGFBP-2 and -4). Here we explore whether this upregulation is glutamate dependent. Rats were treated with the non-competitive N-methyl-D-aspartate (NMDA) antagonist MK-801 or the non-NMDA antagonist CNQX before and after trauma, and analysed using quantitative in situ hybridization. The induction of IGF-1 expression was completely blocked by MK-801 or CNQX. IGFBP-2 mRNA levels remained high at the contusion site in the presence of either drug, but the increase was blocked in the cortex temporal to the impact by MK-801. The increase in IGFBP-4 mRNA was blocked by MK-801 but not by CNQX.

Topics: Animals; Brain Injuries; Dizocilpine Maleate; In Situ Hybridization; Insulin-Like Growth Factor Binding Protein 2; Insulin-Like Growth Factor Binding Protein 4; Insulin-Like Growth Factor I; Male; Rats; Rats, Sprague-Dawley

Increased neuronal vulnerability to ischemia or hypoxia has been demonstrated following traumatic brain injury but not explained. Animal data suggest that neuronal damage after traumatic brain injury is caused mainly by massive glutamate release that activates N-methyl-D-aspartate (NMDA) receptors. Using rat models with controlled closed head injury (CHI) followed by hypoxia, we investigated extracellular concentrations of neuroactive amino acids in the hippocampus by in vivo microdialysis. CHI alone produced an immediate increase of glutamate and taurine; hypoxia alone did not alter amino acid concentrations. CHI followed by hypoxia produced a biphasic increase in extracellular glutamate and taurine, with an immediate peak after CHI and a prolonged plateau after hypoxia. Though changes in gamma-aminobutylic acid (GABA) concentration is also prolonged by combined traumatic and hypoxic insults, it showed less alteration than glutamate. Pre-treatment with dizocilpine maleate (MK-801), a non-competitive NMDA antagonist, did not affect the immediate peak of glutamate after CHI but significantly diminished the prolonged plateau after hypoxia. These findings suggest that traumatic brain injury may increase hypoxic release of glutamate, contributing to increased vulnerability to hypoxia. Our data suggest that MK-801 may be beneficial in preventing secondary neuronal damages by hypoxia.

Topics: Amino Acids; Animals; Brain Injuries; Dizocilpine Maleate; Hippocampus; Hypoxia; Male; Microdialysis; Rats; Rats, Sprague-Dawley

The potential interaction between group I metabotropic glutamate receptors (mGluR) and NMDA receptors in mediating of post-traumatic neuronal death was studied using an in vitro trauma model. Treatment with group I mGluR antagonists provided significant neuroprotection either in the presence or absence of an NMDA receptor antagonist. In contrast, treatment with a group I mGluR agonist alone significantly exacerbated injury; this exacerbation was significantly, but incompletely, reduced in the presence of an NMDA receptor antagonist. These findings are consistent with the conclusion that the effects of group I mGluR activation on post-traumatic cell death are mediated only in part through NMDA receptor modulation and suggest that group I mGluR antagonists may have important therapeutic potential.

Topics: Animals; Animals, Newborn; Brain Injuries; Cell Death; Cells, Cultured; Cerebral Cortex; Coculture Techniques; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Glycine; Indans; L-Lactate Dehydrogenase; Models, Neurological; Neuroglia; Neurons; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Receptors, N-Methyl-D-Aspartate; Resorcinols

We have used an animal model of traumatic brain injury (TBI) that incorporates both the neurotransmitter toxicity of fluid percussion TBI and deafferentation of bilateral entorhinal cortical (BEC) lesion to explore whether administration of muscarinic cholinergic or N-methyl-D-aspartate glutamatergic antagonists prior to injury ameliorates cognitive morbidity. Fifteen minutes prior to moderate central fluid percussion TBI, rats were given intraperitoneal injections of either scopolamine (1.0 mg/kg) or MK-801 (0.3 mg/kg) and 24 hr later underwent BEC lesion. Body weight was followed for 5 days postinjury, as was beam balance and beam walk performance to assure motor recovery prior to spatial memory testing. Each group was assessed for spatial memory deficits with the Morris water maze at short term (days 11-15) and long-term (60-64 days) postinjury intervals and then compared with untreated combined insult and sham-injured controls. Results showed that each drug significantly elevated body weight relative to untreated injured cases. Both scopolamine and MK-801 reduced beam balance deficits, whereas neither drug had a significant effect on beam walk deficits. Interestingly, short-term cognitive deficits assessed on days 11-15 were differentially affected by the two drugs: MK-801 pretreatment enhanced the recovery of spatial memory performance, whereas scopolamine pretreatment did not. Long-term (days 60-64) deficits in spatial memory were not altered by pretreatment with either drug. Our results suggest that, unlike fluid percussion TBI alone, behavioral impairment may require more select intervention when deafferentation is part of the head trauma pathology.

Topics: Animals; Body Temperature Regulation; Body Weight; Brain Injuries; Dizocilpine Maleate; Entorhinal Cortex; Excitatory Amino Acid Antagonists; Male; Maze Learning; Muscarinic Antagonists; Neuroprotective Agents; Psychomotor Performance; Rats; Rats, Sprague-Dawley; Scopolamine

Damage resulting from a partial acute lesion of white matter in the central nervous system (CNS) gradually spreads also to neurons that escaped the primary injury, resulting in their degeneration. Such spreading has been referred to as secondary degeneration. In order to demonstrate that this degeneration is indeed secondary to that caused by the acute insult, as well as to investigate the mechanism underlying the spread of damage and ways in which to protect neurons from such damage, we have proposed the use of partial lesion of the rodent optic nerve as a model. In this model we examined whether an antagonist of a receptor-mediated channel, shown to be beneficial in gray matter lesions, can protect neurons from undergoing secondary degeneration following white matter lesion. A well-calibrated partial crush lesion inflicted on the optic nerve of adult rats was immediately followed by a single intraperitoneal injection of the N-methyl-D-aspartate receptor antagonist, MK-801 (1 mg/kg). Protection of neurons from secondary degeneration was assessed by retrograde labeling and by measurement of the visual evoked potential (VEP) response to light. Two weeks after the injury, the mean number of neurons that were still intact was about threefold higher in the MK-801-treated group than in the saline-treated control group, indicating a treatment-induced protection of neurons that had escaped primary injury. A positive VEP response to light was obtained in 90% of the MK-801 treated animals and in only 50% of injured controls. The questions regarding whether the secondary degeneration of initially spared neurons starts in their cell bodies or in their axons, and consequently the identity of the primary site of their protection by MK-801, are discussed in relation to the absence of N-methyl-D-aspartate receptors on nerve fibers. The present findings may have implications for both acute and chronic injuries of the CNS.

Topics: Analysis of Variance; Animals; Body Temperature; Brain Injuries; Case-Control Studies; Disease Models, Animal; Dizocilpine Maleate; Evoked Potentials, Visual; Excitatory Amino Acid Antagonists; Male; Nerve Degeneration; Neural Pathways; Neuroprotective Agents; Optic Nerve; Optic Nerve Injuries; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate

Ion-selective microelectrodes were used to study acute effects of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy- 5-methyl-4-isoxazole (AMPA) receptor blockade on posttraumatic calcium disturbances. An autoradiographic technique with 45 Ca2+ was used to study calcium disturbances at 8, 24, and 72 h. Compression contusion trauma of the cerebral cortex was produced by a 21-g weight dropped from a height of 35 cm onto a piston that compressed the brain 2 mm. Pre- and posttrauma interstitial [Ca2+] ([Ca2+]e) concentrations were measured in the perimeter, i.e., the shear stress zone (SSZ) and in the central region (CR) of the trauma site. For the [Ca2+]e studies the animals were divided into controls and groups pretreated with dizocilipine maleate (MK-801) or with 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[F]quinoxaline (NBQX). In all groups, [Ca2+]e decreased from pretrauma values of approximately 1 mM to posttraumatic values of 0.1 mM in both the CR and the SSZ. This was followed by a slow restitution toward pretraumatic levels during the 2-h observation period. There was no significant difference in recovery pattern between controls and pretreated animals. Accumulation of 45Ca2+ and serum proteins was seen in the entire SSZ, while neuronal necrosis was confined to a narrow band within the SSZ. The CR was unaffected apart from occasional eosinophilic neurons and showed no accumulation of 45Ca2+. Posttraumatic treatment with MK-801 or NBQX had no obvious effect on neuronal injury in the SSZ. We conclude that (a) acute [Ca2+]e disturbances in compression contusion brain trauma are not affected by blockade of NMDA or AMPA receptors, (b) 45Ca2+ accumulation in the SSZ reflects mainly protein accumulation due to blood-brain barrier breakdown rather than cell death, and (c) acute cellular Ca2+ over-load per se does not seem to be a major determinant of cell death after cerebral trauma in our model.

Topics: Animals; Autoradiography; Brain Injuries; Calcium; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Ion Channels; Male; Necrosis; Neurons; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, Glutamate; Receptors, N-Methyl-D-Aspartate

Recent evidence implicates the endogenous excitatory neurotransmitters, glutamate (Glu) and aspartate, in the pathophysiology of traumatic injury in the adult CNS, but it is not known whether similar excitotoxic mechanisms mediate traumatic injury in the immature CNS. Therefore, we developed a model of brain contusion injury in infant rats and used this model to study the nature and evolution of the acute cytopathologic changes and to evaluate the ability of Glu receptor antagonists to protect the immature brain against such changes. Seven-day-old rat pups were subjected to contusion injury and were killed 0, 0.5, 1, 2, 4, and 6 h later for histologic evaluation of the brain. Physical tearing of the dura and minor disruption of underlying brain tissue was noted at 0 h. At 30 min a discrete zone of neuronal necrosis began to appear at the border of the trauma site; this zone progressively expanded over a period of 4 h. The cytopathologic changes closely resembled the type of changes Glu is known to cause; these changes consisted of swollen dendrites, degenerating neurons with pyknotic nuclei and markedly swollen cytoplasm, and dark cells with vacuolated cytoplasm. The noncompetitive N-methyl-D-aspartate (NMDA) antagonist, dizocilpine maleate, when administered 30 min before or 1 h after trauma, significantly attenuated the lesion. The competitive NMDA antagonist, 3-((-2)-carboxypiperazine-4-yl)-propyl-1-phosphonate, was also neuroprotective. The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate/kainate receptor antagonist 2,3-dihydro-6-nitro-7-sulfamoyl-benzo(f)quinoxaline did not significantly suppress the lesion when given as three treatments (30 mg/kg each) 30 min before plus 15 and 75 min after the insult. These findings suggest that traumatic injury in the infant rat brain is mediated by endogenous excitotoxins (Glu and aspartate) acting at NMDA receptors and can be substantially mitigated by timely treatment with NMDA receptor antagonists.

Topics: Animals; Brain Injuries; Dendrites; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Piperazines; Quinoxalines; Rats; Rats, Sprague-Dawley; Time Factors; Wounds and Injuries

The mechanisms of neuronal degeneration following traumatic head injury are not well understood and no adequate treatment is currently available for the prevention of traumatic brain damage in humans. Seven day old rat pups were subjected to mechanical percussion of the head. Cortical damage in infant rats was reduced by pre-treatment with the N-methyl-D-aspartate (NMDA) antagonists dizocilpine (MK-801) or 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-I-phosphonate (CPP). The AMPA antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo (f) quinoxaline (NBQX) did not significantly suppress cortical damage in infant rats. In adult rats, traumatic head injury leads to primary (at impact-cortex) and secondary (distant-hippocampus) damage to the brain. Morphometric analysis demonstrated that both cortical and hippocampal damage was mitigated by pre-treatment with either the NMDA antagonist CPP or the non-NMDA antagonist NBQX. Neither treatment prevented primary damage in the cortex when therapy was started after trauma. Delayed treatment of rats with NBQX, but not with CPP, beginning between 1 and 7 h after trauma prevented the hippocampal damage. No protection was seen when therapy with NBQX was started 10 h after trauma. These data indicate that NMDA antagonists may possess better neuroprotective properties against excitotoxic processes triggered by traumatic brain injury in young individuals whereas AMPA antagonists may be more beneficial in adults.

Topics: Animals; Animals, Newborn; Brain Injuries; Cerebral Cortex; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Hippocampus; Nerve Degeneration; Parietal Lobe; Rats

We investigated by immunohistochemistry dendritic and axonal changes occurring in the rat brain after mild focal cortical trauma produced by the weight drop technique. One and 3 days after injury, nerve cell bodies and dendrites in the perimeter of the impact site displayed decreased microtubule-associated protein 2 (MAP2) immunoreactivity. Some dendrites in the immediate adjacent region were more intensely stained and distorted. The dentate hilar region of the hippocampus showed a reduction of immunoreactive nerve cell bodies and dendrites. Twenty-one days after injury the strongly stained cortical dendrites and the reduction of immunoreactivity in the hippocampus remained, whereas the reduced staining in the perimeter of the lesion had normalised. These results indicate that there is a long-lasting disturbed dendritic organisation implicating impaired neurotransmission after this type of mild brain trauma. beta-Amyloid precursor protein (APP) immunohistochemistry revealed numerous stained axons in the ipsilateral subcortical white matter and thalamus indicating local and remote axonal injuries with disturbed axonal transport. Twenty-one days after injury, numerous small immunostained profiles appeared in the neuropil of the cortical impact site and in the ipsilateral thalamus. The axonal changes indicate disturbed connectivity between the site of the impact and other brain regions, chiefly the thalamus. The presence of beta-amyloid was investigated 21 days after trauma. There were no signs of beta-amyloid depositions in the brain after injury. Finally, we tested if the non-competitive NMDA receptor antagonist dizocilpine maleate (MK-801) could influence the observed MAP2 and APP changes. Pretreatment with this compound did not affect the early MAP2 and APP alterations. Instead, an increased expression of the APP antigen in the thalamus was observed 21 days after trauma in the MK-801-treated animals. The cause of this phenomenon is not known but may be related to a delayed neurotoxic action of MK-801 treatment.

Topics: Amyloid beta-Protein Precursor; Animals; Brain Injuries; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Immunohistochemistry; Male; Microtubule-Associated Proteins; Nerve Tissue Proteins; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate

Activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors is implicated in the pathophysiology of traumatic brain injury. Here, the effects of mechanical injury on the voltage-dependent magnesium (Mg2+) block of NMDA currents in cultured rat cortical neurons were examined. Stretch-induced injury was found to reduce the Mg2+ blockade, resulting in significantly larger ionic currents and increases in intracellular free calcium (Ca2+) concentration after NMDA stimulation of injured neurons. The Mg2+ blockade was partially restored by increased extracellular Mg2+ concentration or by pretreatment with the protein kinase C inhibitor calphostin C. These findings could account for the secondary pathological changes associated with traumatic brain injury.

Topics: Animals; Brain Injuries; Calcium; Cells, Cultured; Cerebral Cortex; Dizocilpine Maleate; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Magnesium; Membrane Potentials; N-Methylaspartate; Naphthalenes; Neurons; Patch-Clamp Techniques; Protein Kinase C; Rats; Receptors, N-Methyl-D-Aspartate

Four hours following cryo-injury rat cerebral pericapillary astrocytes from the perilesional area were markedly swollen occupying 17% of the pericapillary space as compared to 11% in sham operated controls. Ornithine decarboxylase activity and polyamine levels were increased over sham controls. The astrocytic swelling, the percentage of the pericapillary space occupied by astrocytic processes, and polyamine levels were reduced to near control levels by the following: (1) alpha-difluoromethylornithine; (2) Ifenprodil; and (3) MK-801. alpha-Difluoromethylornithine is a specific inhibitor of ornithine decarboxylase, Ifenprodil is an inhibitor of the polyamine binding site on the n-methyl-d-aspartate receptor, and MK-801 is an antagonist to n-methyl-d-aspartate binding to the n-methyl-d-aspartate receptor. Addition of putrescine, the product of ornithine decarboxylase activity, reversed the effect of alpha-difluoromethylornithine and restored the pericapillary swelling. Putrescine did not affect the MK-801-induced reduction in pericapillary astrocytic swelling. Therefore, polyamines and the n-methyl-d-aspartate receptor modulate excitotoxic responses to cryo-injury in pericapillary cerebral astrocytes.

Topics: Animals; Astrocytes; Biogenic Polyamines; Brain; Brain Injuries; Capillaries; Cold Temperature; Dizocilpine Maleate; Eflornithine; Ornithine Decarboxylase; Piperidines; Rats; Receptors, N-Methyl-D-Aspartate; Statistics as Topic

In a rat hippocampal cell culture, we studied the mechanism of adenosine-mediated neuroprotection in traumatic injury to neurons. When the processes and bodies of cells in culture were mechanically disrupted, neurons that were located at a distance from the damage site died. This secondary neuronal death is at least partially mediated by glutamate, because MK801, a specific N-methyl-D-aspartate glutamate channel blocker, diminished the toxic effect. Furthermore, cyclopentyl adenosine, a specific A1 adenosine receptor agonist that specifically attenuates synaptic release at the excitatory terminal, also blocked this trauma-mediated cell death. The dissemination of neurotoxicity from cell injury implies a release of a toxin by the dying cells. Consistent with this hypothesis, we found that neurotoxicity could be transferred to an uninjured neuronal culture by applying extracellular solution of the damaged culture to the healthy undamaged culture, as long as the fluid was transferred within 5 minutes. However, the glutamate concentrations in this medium were never higher than 20 nmol/L, suggesting that glutamate is not mediating the soluble and transferable toxicity. Consistent with this observation, the transferable neurotoxicity was not blocked by MK801 but was effectively blocked by cyclopentyl adenosine. Our observations suggest that traumatic cell death in culture is mediated by multiple mechanisms, including glutamate excitotoxicity.

Topics: Adenosine; Animals; Brain Injuries; Cell Death; Cells, Cultured; Culture Media; Dizocilpine Maleate; Extracellular Space; Hippocampus; Rats; Rats, Sprague-Dawley; Theophylline

Topics: Amnesia; Animals; Brain Injuries; Dizocilpine Maleate; Rats; Reaction Time

Male Sprague-Dawley rats were subjected to traumatic brain injury (TBI) using a lateral fluid percussion-induced injury model. Effects of varying severities of TBI (mild = 1.1 +/- 0.1 atm; moderate = 2.2 +/- 0.2 atm; severe = 2.9 +/- 0.1 atm) on the levels of protein kinase C in rat cerebral cortex and hippocampus were investigated by quantitative autoradiography using [3H]phorboldibutyrate ester ([3H]PDBu) binding as a marker. Binding of [3H]PDBu in the cerebral cortex and hippocampus was increased bilaterally following TBI, with changes related to injury severity. Significant increases were observed in hippocampus of injured animals, as compared to sham-operated controls, at 1 h after trauma. Maximum levels of binding in both cerebral cortex and hippocampus were reached by 3 h, with a return to control levels at 6 h and 72 h, respectively. Treatment with MK-801 (1 mg/kg, i.v.) administered 15 min before trauma prevented the injury-induced increase of [3H]PDBu binding in hippocampus and cerebral cortex. These results demonstrate that TBI induces bilateral, time-dependent increases of protein kinase C in the hippocampus and cerebral cortex that are related to injury severity. Changes are mediated by actions at NMDA receptors, probably reflecting post-traumatic release of glutamate.

Topics: Animals; Autoradiography; Brain Injuries; Carbon Dioxide; Cerebral Cortex; Dizocilpine Maleate; Functional Laterality; Hippocampus; Kinetics; Male; Oxygen; Partial Pressure; Phorbol 12,13-Dibutyrate; Protein Binding; Protein Kinase C; Pyramidal Cells; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reference Values; Time Factors; Tritium

We explored the therapeutic potentials of two N-methyl-D-aspartate (NMDA) receptor antagonists in vivo using different techniques. NMDA injected into the striatum of neonatal rats (20 nmol/0.5 microliters) induced a rapid increase in the diffusion-weighted (DW) image intensity, spreading over a large part of the ipsilateral hemisphere. Subcutaneous injection of the NMDA receptor antagonist MK-801 (1 mg/kg) or D-(E)-4-(3-phosphono-2-prop-enyl)-2-piperazine-carboxylic acid (D-CPPene; 1.5 mg/kg) reversed both the volume and the grading of the NMDA-induced hyperintensity of DW images, the reversal by MK-801 being more rapid than that by D-CPPene. In the cerebral cortex, there was an inverse relationship between changes in DW image intensity and the size of the extracellular space, assessed by electrical impedance measurements. The reduction of the hyperintense volume in DW images 1 or 2 h after MK-801 or D-CPPene treatment of NMDA-injected animals depended on the type of antagonist used and on the interval between intrastriatal NMDA injection and antagonist treatment. The reduction was 95% when MK-801 was given with a delay of 90 min and decreased to 20% when it was given at 360 min. With D-CPPene, the reduction was 80% after a delay of 30 min and virtually absent when it was administered at 360 min. Quantitative analysis showed significant correlations between the residual hyperintense volume 1 or 2 h after MK-801 or D-CPPene treatment and the final lesion volume, assessed from either T2-weighted images (R = 0.89, p < 0.001) or histology (R = 0.80, p < 0.001) 5 days after the insult. This study illustrates the sensitivity of DW magnetic resonance imaging to monitor in vivo early events after an excitotoxic insult and the effect of putative protective drugs that may counteract the resulting damage.

Topics: Animals; Animals, Newborn; Brain; Brain Injuries; Dizocilpine Maleate; Electric Conductivity; Magnetic Resonance Imaging; N-Methylaspartate; Neurotoxins; Piperazines; Rats; Wound Healing

The ability of lactation and progesterone administration to inhibit the induction of Fos protein in the piriform cortex after brain injury in pentobarbital-anaesthetized rats was assessed in three studies. Consistent with previous reports we found that brain injury-induced Fos expression in the piriform cortex could be eliminated by the administration of the non-competitive NMDA receptor antagonist MK 801 (4 mg/kg i.p.). Fos induction was not reduced, however, in lactating dams (days 7-9) post-partum or in progesterone-treated males. These results are not consistent with the hypothesis that suckling stimulation and progesterone have a direct effect at the NMDA receptor complex.

Topics: Anesthesia; Animals; Brain Injuries; Cerebral Cortex; Dizocilpine Maleate; Female; Lactation; Male; Pentobarbital; Progesterone; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate

The authors have examined the effect of experimental traumatic brain injury on the amnesia produced by the N-methyl-D-aspartate (NMDA) antagonist MK-801. Rats were either subjected to a moderate level of fluid-percussion injury or prepared for injury but not injured ("sham injury"). Nine days following injury or sham injury, the rats were injected either with saline (sham/saline group, nine rats; injured/saline group, nine rats) or with 0.1 mg/kg of MK-801 (sham/MK-801 group, nine rats; injured/MK-801 group, eight rats) 30 minutes before being trained on a passive-avoidance task. Twenty-four hours later, the rats were tested for retention of the passive-avoidance task. Results revealed that the low dose of MK-801 did not significantly affect retention of the passive-avoidance task in the sham-injured group. In injured animals, administration of MK-801 produced a profound amnesia in contrast to the sham-injured animals treated with MK-801 and the injured animals treated with saline. To further investigate this enhanced sensitivity to the amnesic effects of MK-801 exhibited by the injured animals, nine injured and eight sham-injured rats were injected with 0.3 mg/kg of MK-801 15 minutes before injury. Results indicated that the animals treated with MK-801 before injury did not significantly differ from the sham-injured animals in retention of the passive-avoidance task. In addition, test results in the animals treated with MK-801 before injury and reinjected with MK-801 before passive-avoidance testing did not differ from those in untreated injured animals reinjected with saline before passive-avoidance testing. These findings indicate that MK-801 treatment before injury prevented the enhanced sensitivity to MK-801-induced amnesia that follows traumatic brain injury.

Topics: Amnesia; Animals; Avoidance Learning; Brain Concussion; Brain Injuries; Dizocilpine Maleate; Male; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, N-Methyl-D-Aspartate

The precise mechanisms that underlie acute changes in tissue water diffusion following cerebral ischemia or related insults such as glutamate exposure remain unexplained, but it has been suggested that these may be caused by cell swelling due to water uptake. This study was undertaken to compare the changes observed in diffusion-weighted MR images with changes in the cellular volume measured by electrical impedance in a model of N-methyl-D-aspartate-induced brain injury in perinatal rats. The results show that the temporal course of the intensity changes in the diffusion-weighted images parallelled the progressive shrinkage of the extracellular space measured from the electrical impedance. After administration of the N-methyl-D-aspartate antagonist MK-801 the signal enhancement in the images was reversed, which paralleled the normalization of the extracellular space observed by the impedance measurements. It was estimated that the extracellular space decreased from 24 to 12% while the apparent diffusion coefficient of water decreased from 0.89 x 10(-9) in normal tissue to 0.42 x 10(-9) m2/s in tissue exposed to N-methyl-D-aspartate. These data indicate that changes in tissue water diffusion are related to changes in cell volume.

Topics: Animals; Brain; Brain Injuries; Cell Size; Cerebral Cortex; Disease Models, Animal; Dizocilpine Maleate; Electric Impedance; Extracellular Space; Magnetic Resonance Imaging; N-Methylaspartate; Rats

In order to examine the effectiveness of pre- and post-injury administration of muscarinic cholinergic and NMDA antagonists in reducing cognitive deficits following traumatic brain injury (TBI), rats were injected with either scopolamine (1 mg/kg) or MK-801 (0.3 mg/kg) 15 min prior to or 15 min after fluid percussion TBI. Cognitive performance was assessed with the Morris water maze procedure on days 11-15 after TBI or sham injury. When scopolamine and MK-801 were injected 15 min before injury, Morris water maze deficits were significantly reduced (P < 0.01 and P < 0.05, respectively). When scopolamine and MK-801 were injected 15 min after TBI, neither drug was effective in attenuating Morris water maze deficits. Consistent with other research, these results suggest that the cognitive deficits produced by TBI are the consequence of a brief period of excessive excitation of cholinergic and NMDA receptor systems. The results of this experiment also suggest that the temporal therapeutic window for the treatment of cognitive dysfunction with receptor antagonist intervention appears to be quite brief (< 15 min) in the rat.

Topics: Animals; Brain Injuries; Cognition Disorders; Dizocilpine Maleate; Learning; Male; Muscarinic Antagonists; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Scopolamine; Space Perception

Recent studies show that focal brain injury, cerebral ischaemia, hypoglycaemia and seizures increase the expression of c-fos and brain-derived neurotrophic factor in brain. Here we report that hippocampal focal brain injury transiently induces the immediate early genes c-fos, jun-B, c-jun and krox-24 (zif-268) messenger RNA and protein and brain-derived neurotrophic factor messenger RNA in rat dentate gyrus neurons, an effect that was blocked by the N-methyl-D-aspartate receptor antagonist MK-801. Prior administration of the protein synthesis inhibitor cycloheximide super-induced immediate early gene messenger RNA, abolished immediate early gene protein induction, but had no effect on injury-mediated induction of brain-derived neurotrophic factor messenger RNA. Thus, while N-methyl-D-aspartate receptor activation results in the induction of both immediate early genes and brain-derived neurotrophic factor messenger RNA, de novo synthesis of immediate early gene proteins is not critical for the increased expression of brain-derived neurotrophic factor messenger RNA seen in brain after focal injury. These results suggest that brain-derived neurotrophic factor is induced after injury as an immediate early gene.

Topics: Animals; Brain Injuries; Brain-Derived Neurotrophic Factor; Cycloheximide; Dizocilpine Maleate; Gene Expression; Genes, Immediate-Early; Hippocampus; Immunohistochemistry; In Situ Hybridization; Male; Nerve Tissue Proteins; Neurons; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate

The neuroprotective potential of eliprodil (SL 82.0715), an N-methyl-D-aspartate (NMDA) receptor antagonist acting at the polyamine modulatory site, in brain trauma was examined in a rat model of lateral fluid-percussion brain injury. The volume of the lesion was assessed histologically by measuring, at 7 days post-injury, the area of brain damage at 10 coronal planes. Eliprodil (10 mg/kg i.p.) when given 15 min, 6 h and 24 h after fluid percussion (1.6 atm) and then b.i.d. for the following 6 days, reduced by 60% the volume of cortical damage. A similar neuroprotection was obtained when the first administration of eliprodil was delayed by up to 12 h after the brain insult. Moreover, when the treatment with this compound was started at 18 h post-injury, cortical damage was still significantly reduced by 33%. Autoradiographic studies showed that eliprodil treatment (10 mg/kg, i.p.), initiated 15 min after the trauma, also caused a marked reduction of the loss of the neuronal marker omega 1-2 (central benzodiazepine) binding sites and of the increase in the glial/macrophage marker peripheral type benzodiazepine binding sites in the cerebral cortex. In contrast, dizocilpine (a blocker of the cationic channel coupled to the NMDA receptor) when administered 6 h and 24 h after fluid percussion and then b.i.d. for the following 6 days induced a non significant reduction of the volume of the lesion at the highest tolerated dose (0.6 mg/kg i.p.). These results demonstrate the neuroprotective activity of eliprodil in experimental brain trauma using neuropathology as an endpoint and indicate that there is a very large time window for therapeutic intervention, consistent with the delayed nature of the neuronal loss, in this condition.

Topics: Animals; Autoradiography; Benzodiazepines; Binding Sites; Brain; Brain Injuries; Dizocilpine Maleate; Drug Administration Schedule; Male; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Time Factors

The role of metabotropic excitatory amino acid receptors in seizures and brain injury was examined using the selective metabotropic agonist 1S,3R-ACPD [(1S,3R)-1-aminocyclopentane-1-3-dicarboxylic acid] in 7-d-old neonatal rats. Systemic administration of 1S,3R-ACPD produced dose-dependent convulsions (ED50 = 16 mg/kg, i.p.) that were stereoselective for the active metabotropic ACPD isomer, since 1R,3S-ACPD was less potent (ED50 = 93 mg/kg, i.p.). 1S,3R-ACPD-induced seizures were antagonized by systemic administration of dantrolene, an inhibitor of intracellular calcium mobilization, but not by the ionotropic glutamate antagonists MK-801 or GYKI-52466. As indexed by hemispheric brain weight differences 5 d postinjection, unilateral intrastriatal injection of 1S,3R-ACPD (0.1-2.0 mumol/microliters), but not 1R,3S-ACPD, produced dose-dependent brain injury (maximal effect of 3.4 +/- 0.5% damage). 1S,3R-ACPD brain injury occurred in the absence of prominent behavioral convulsions. Histologic and ultrastructural examination of 1S,3R-ACPD-injected rat brains revealed swelling and degeneration of select neurons at 4 hr postinjection, but little evidence of injured neurons 5 d later. 1S,3R-ACPD-mediated brain injury was not attenuated by systemic administration of the NMDA antagonist MK-801 or the AMPA antagonist GYKI-52466. However, cointrastriatal injection of dantrolene reduced the severity of 1S,3R-ACPD injury by 88 +/- 7%. These studies indicate that seizures and neuronal injury can be elicited by the selective activation of metabotropic glutamate receptors in perinatal rats, and these effects of 1S,3R-ACPD involve the mobilization of intracellular calcium stores.

Topics: Animals; Animals, Newborn; Anti-Anxiety Agents; Benzodiazepines; Brain Injuries; Cell Nucleus; Corpus Striatum; Cycloleucine; Dantrolene; Dizocilpine Maleate; Female; Hippocampus; Male; Microscopy, Electron; Neurons; Neurotoxins; Rats; Rats, Sprague-Dawley; Receptors, Glutamate; Seizures; Stereotaxic Techniques

Changes in the latency of visual cortical evoked responses (VER) were studied in rats subjected to cryogenic injury of the cerebral cortex. Four hours after cold injury the animals revealed a significant reduction of VER latency, which lasted approximately one week, with maximal reduction in latency occurring after 3 days. A potential role of excitotoxic amino acids in this phenomenon was tested by direct application of glutamate to the exposed cerebral cortex of the control rat and by administration of MK-801, antagonist of the NMDA receptor, in rats subjected previously to cryogenic injury and displaying a significant reduction in the VER latency. The direct application of glutamate to the cortex resulted in a decrease of the VER latency similar in magnitude to that observed after cold injury and this effect could repeatedly be demonstrated after washing out the initial application of the glutamate. The administration of MK-801 in animals subjected previously to cryogenic injury produced, within 5 minutes, reversion of reduced VER latencies. The maximal prolongation of latency occurred 30 min after MK-801 administration and reached in some cases latency values greater than in controls. Reduced latencies, corresponding to those observed originally, reappeared within 2 to 4 hours. Our studies suggest that the described reductions in the VER latencies are related to cortical areas of hyperexcitation due to excessive release of neuroexcitatory transmitters.

Topics: Animals; Brain Injuries; Cerebral Cortex; Dizocilpine Maleate; Electric Stimulation; Electrophysiology; Evoked Potentials, Visual; Female; Freezing; Male; Rats; Rats, Inbred Strains; Reference Values; Time Factors

The excitatory and excitotoxic actions of the endogenous excitatory amino acid (EAA) neurotransmitter, glutamate, are mediated by activation of three common subtypes of EAA receptors: N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/quisqualate and kainate receptors. EAA neurotransmitter systems play a number of physiological roles in the regulation and organization of neural systems during development. However, excessive activation of this neurotransmitter system is also implicated in the pathophysiology of several forms of acute and chronic brain injury. In this study, the susceptibility of the developing rat brain to AMPA/quisqualate receptor mediated injury was examined at eight postnatal ages (1-90 days). The receptor agonists, AMPA (25 nmol) or quisqualate (100 nmol), were stereotaxically microinjected unilaterally into the anterior striatum. The severity of resulting brain injury was assessed 5 days later by comparison of reductions in regional cortical and striatal cross-sectional areas. Microinjection of AMPA (25 nmol) produced widespread unilateral forebrain injury in the intermediate postnatal period (days 5-28). The severity of injury resulting from microinjection of a fixed dose of AMPA (25 nmol) transiently exceeded the severity of injury in adults between PND 5-28 with peak sensitivity occurring near PND 10. At PND 1, microinjection of AMPA produced a 24.5 +/- 1.7% reduction in striatal cross-sectional area, which is similar to the response observed in adult animals, and the lesion was confined to the injection site. Susceptibility to AMPA toxicity increased 2-fold from PND 1 to PND 5. At PND 10, the age of maximal sensitivity, the excitotoxic reaction to AMPA extended throughout the entire cerebral hemisphere and the mean striatal cross-sectional area was reduced by 81.7 +/- 3.9%. With advancing postnatal age, the severity of injury progressively diminished and the lesion became confined to the injection site. The developmental pattern of sensitivity to AMPA toxicity in other brain regions differed although peak sensitivity consistently occurred near PND 10. Microinjection of quisqualate produced a developmental pattern of striatal susceptibility similar to AMPA although quisqualate was a considerable less potent neurotoxin. In additional experiments, the in vivo pharmacology of AMPA and quisqualate mediated brain injury was evaluated in a PND 7 rat model in order to determine the neurotoxic cha

Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Aging; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Analysis of Variance; Animals; Brain; Brain Injuries; Diazepam; Dizocilpine Maleate; Female; Ibotenic Acid; Male; N-Methylaspartate; Neurotoxins; Organ Specificity; Phenytoin; Quinoxalines; Quisqualic Acid; Rats; Rats, Inbred Strains; Seizures

Unilateral lesions of the rat hippocampus produced by needle insertion lead to ipsilateral accumulation of c-fos protein in dentate granule cells and neurons in the piriform cortex, as well as in glial-like cells in the corpus callosum and in ependymal cells lining the lateral ventricle adjacent to the lesion site. C-fos protein was detected immunocytochemically using two different antibodies in formalin-fixed brain sections. The N-methyl-D-aspartate (NMDA) antagonist MK-801 produced a dose- and time-dependent inhibition of c-fos protein accumulation in dentate granule cells and in neurons in the piriform cortex, but did not affect glial or ependymal c-fos protein accumulation. MK-801 at 4 mg/kg injected two hours before lesion inhibited c-fos accumulation. Thus, c-fos protein accumulation in hippocampal neurons and in neurons in the piriform cortex induced after traumatic brain injury involves activation of NMDA receptors.

Topics: Animals; Brain Injuries; Dibenzocycloheptenes; Dizocilpine Maleate; Dose-Response Relationship, Drug; Hippocampus; Immunohistochemistry; Male; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fos; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter

The proto-oncogene c-fos is rapidly and transiently induced in the CNS by a variety of stimuli. Brain injury, disruption of pia-arachnoid in a limited area, is one of the situations that leads to a dramatic increase in c-fos immunoreactivity. This increase is limited to the lesioned hemisphere. Injections of atropine (25 mg/kg, i.p.), naltrexone (5 mg/kg, i.p.), nifedipine (5 mg/kg, i.p.), and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (20 mg/kg, i.p.), prior to the injury, did not affect the activation of c-fos as assessed by immunohistochemistry in adult Sprague-Dawley rats perfused 2 h after the lesion. The non-competitive N-methyl-D-aspartate antagonists ketamine (100 mg/kg, i.p.) and MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate] (1 and 3 mg/kg, i.p.) markedly reduced c-fos activation. Phencyclidine (10 mg/kg, i.p.) produced a slight reduction in damage-induced fos activation. This study suggests that c-fos activation in this particular model is N-methyl-D-aspartate receptor-mediated and supports the idea that the fos proto-oncogene might play a role in plasticity and/or neurotoxic changes following brain damage.

Topics: Animals; Anticonvulsants; Atropine; Brain; Brain Injuries; Dibenzocycloheptenes; Disease Models, Animal; Dizocilpine Maleate; DNA-Binding Proteins; Female; Gene Expression Regulation; Immunohistochemistry; Ketamine; Male; Nifedipine; Phencyclidine; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fos; Proto-Oncogenes; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter

Pharmacological inhibition of excitatory neurotransmission attenuates cell death in models of global and focal ischemia and hypoglycemia, and improves neurological outcome after experimental spinal cord injury. The present study examined the effects of the noncompetitive N-methyl-D-aspartate receptor blocker MK-801 on neurochemical sequelae following experimental fluid-percussion brain injury in the rat. Fifteen minutes after fluid-percussion brain injury (2.8 atmospheres), animals received either MK-801 (1 mg/kg, i.v.) or saline. MK-801 treatment significantly attenuated the development of focal brain edema at the site of injury 48 h after brain injury, significantly reduced the increase in tissue sodium, and prevented the localized decline in total tissue magnesium that was observed in injured tissue of saline-treated animals. Using phosphorus nuclear magnetic resonance spectroscopy, we also observed that MK-801 treatment improved brain metabolic status and promoted a significant recovery of intracellular free magnesium concentrations that fell precipitously after brain injury. These results suggest that excitatory amino acid neurotransmitters may be involved in the pathophysiological sequelae of traumatic brain injury and that noncompetitive N-methyl-D-aspartate receptor antagonists may effectively attenuate some of the potentially deleterious neurochemical sequelae of brain injury.

Topics: Adenosine Triphosphate; Animals; Anticonvulsants; Body Water; Brain; Brain Edema; Brain Injuries; Carbon Dioxide; Cations; Dibenzocycloheptenes; Dizocilpine Maleate; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Male; Oxygen; Phosphates; Phosphocreatine; Rats; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Reference Values

The effect of a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK801, was studied in a model of closed head injury in rats. Head trauma (HT) was induced over the left cerebral hemisphere by a calibrated weight-drop device. One or 3 h later, MK801 in saline was given i.p. in a single bolus of either 1, 3, or 10 mg/kg. The rats were killed at 4, 24, or 48 h after HT. Cortical tissue samples were taken from the injured zone and from the corresponding region of the contralateral hemisphere and analyzed for specific gravity (SG) by linear gradient columns. The neurological status of the traumatized rats was evaluated by a neurological severity score (NSS) 1 h after trauma and just before death. Pathological evaluation, based on size and severity of the lesion, was performed 24 and 48 h after HT on control and MK801-treated rats. A dose of 3 mg/kg MK801 given 1 h after trauma effectively prevented the reduction in tissue SG only at 24 h. The NSS could not be evaluated at 24 h after trauma because of the sedating effect of the drug. At 48 h posttrauma, however, the drug significantly improved the neurological state of the rats. No significant difference was found in the pathological score between treated and untreated rats. The results demonstrate neuroprotective properties of MK801, as expressed in two different variables--reduced edema formation and improved neurological recovery after HT. These findings support existing evidence that pharmacological intervention with NMDA receptor antagonist after head injury may be of clinical value in the management of head-injured patients.

Topics: Animals; Brain Edema; Brain Injuries; Dizocilpine Maleate; Dose-Response Relationship, Drug; Male; Rats

Pharmacologic inhibition of excitatory amino acid (EAA) neurotransmission attenuates cell death in models of global and focal ischemia and hypoglycemia and improves neurologic outcome after experimental traumatic spinal cord injury. The present study examined the effects of the noncompetitive N-methyl-D-aspartate (NMDA) receptor blocker MK-801 on cardiovascular and neurologic function after experimental fluid-percussion (FP) brain injury in the rat. Animals received either an intravenous bolus of MK-801 (1 mg/kg) or saline (equal volume) 15 min prior to FP brain injury or 15 min following FP brain injury. MK-801 pretreatment significantly improved postinjury cardiovascular variables and attenuated postinjury neurologic dysfunction. Postinjury treatment with MK-801 also significantly improved cardiovascular variables, but had little effect on postinjury neurologic scores. These results suggest that EAA neurotransmitters may be involved in the pathophysiological sequelae of traumatic brain injury and that noncompetitive blockade of the NMDA receptor prior to brain injury may reduce EAA-induced damage and limit neurologic dysfunction.

Topics: Amino Acids; Animals; Brain Injuries; Cardiovascular System; Dibenzocycloheptenes; Dizocilpine Maleate; Male; Rats; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter