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Morris PJ, Burke RD, Sharma AK, Lynch DC, Lemke-Boutcher LE, Mathew S, Elayan I, Rao DB, Gould TD, Zarate CA, Zanos P, Moaddel R, Thomas CJ. A comparison of the pharmacokinetics and NMDAR antagonism-associated neurotoxicity of ketamine, (2R,6R)-hydroxynorketamine and MK-801. Neurotoxicol Teratol 2021; 87:106993. [PMID: 33945878 PMCID: PMC8440345 DOI: 10.1016/j.ntt.2021.106993] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/20/2022]
Abstract
With the increasing use of ketamine as an off-label treatment for depression and the recent FDA approval of (S)-ketamine for treatment-resistant depression, there is an increased need to understand the long-term safety profile of chronic ketamine administration. Of particular concern is the neurotoxicity previously observed in rat models following acute exposure to high doses of ketamine, broadly referred to as 'Olney's lesions'. This type of toxicity presents as abnormal neuronal cellular vacuolization, followed by neuronal death and has been associated with ketamine's inhibition of the N-methyl-d-aspartate receptor (NMDAR). In this study, a pharmacological and neuropathological analysis of ketamine, the potent NMDAR antagonist MK-801, and the ketamine metabolite (2R,6R)-hydroxynorketamine [(2R,6R)-HNK)] in rats is described following both single dose and repeat dose drug exposures. Ketamine dosing was studied up to 20 mg/kg intravenously for the single-dose neuropathology study and up to 60 mg/kg intraperitoneally for the multiple-dose neuropathology study. MK-801 dosing was studied up to 0.8 mg/kg subcutaneously for both the single and multiple-dose neuropathology studies, while (2R,6R)-HNK dosing was studied up to 160 mg/kg intravenously in both studies. These studies confirm dose-dependent induction of 'Olney's lesions' following both single dose and repeat dosing of MK-801. Ketamine exposure, while showing common behavioral effects, did not induce wide-spread Olney's lesions. Treatment with (2R,6R)-HNK did not produce behavioral effects, toxicity or any evidence of Olney's lesion formation. Based on these results, future NMDAR-antagonist neurotoxicity studies should strongly consider taking pharmacokinetics more thoroughly into account.
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Affiliation(s)
- Patrick J Morris
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA.
| | | | | | | | | | - Shiny Mathew
- Division of Pharmacology/Toxicology Neuroscience, Office of New Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Ikram Elayan
- Division of Pharmacology/Toxicology Neuroscience, Office of New Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Deepa B Rao
- Division of Pharmacology/Toxicology Neuroscience, Office of New Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Todd D Gould
- Departments of Psychiatry, Pharmacology, and Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Veterans Affairs Maryland Health Care System, Baltimore, MD, USA
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Panos Zanos
- Department of Psychiatry, Pharmacology, and Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Ruin Moaddel
- Biomedical Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Craig J Thomas
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD 20850, USA
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Schwenk ES, Pradhan B, Nalamasu R, Stolle L, Wainer IW, Cirullo M, Olsen A, Pergolizzi JV, Torjman MC, Viscusi ER. Ketamine in the Past, Present, and Future: Mechanisms, Metabolites, and Toxicity. Curr Pain Headache Rep 2021; 25:57. [PMID: 34269883 DOI: 10.1007/s11916-021-00977-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2021] [Indexed: 12/01/2022]
Abstract
PURPOSE OF REVIEW While ketamine's analgesia has mostly been attributed to antagonism of N-methyl-D-aspartate receptors, evidence suggests multiple other pathways are involved in its antidepressant and possibly analgesic activity. These mechanisms and ketamine's role in the nociplastic pain paradigm are discussed. Animal studies demonstrating ketamine's neurotoxicity have unclear human translatability and findings from key rodent and human studies are presented. RECENT FINDINGS Ketamine's metabolites, and (2R,6R)-hydroxynorketamine in particular, may play a greater role in its clinical activity than previously believed. The activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and the mammalian target of rapamycin by ketamine are mechanisms that are still being elucidated. Ketamine might work best in nociplastic pain, which involves altered pain processing. While much is known about ketamine, new studies will continue to define its role in clinical medicine. Evidence supporting ketamine's neurotoxicity in humans is lacking and should not impede future ketamine clinical trials.
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Affiliation(s)
- Eric S Schwenk
- Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, 111 South 11th Street, Gibbon Building, 8290, Philadelphia, PA, 19107, USA.
| | - Basant Pradhan
- Psychiatry & Pediatrics, Cooper Medical School of Rowan University, Camden, NJ, USA
| | - Rohit Nalamasu
- Department of Physical Medicine and Rehabilitation, University of Nebraska Medical Center, Omaha, NE, USA
| | | | | | - Michael Cirullo
- Department of Anesthesiology, Thomas Jefferson University Hospital, Philadelphia, PA, USA
| | - Alexander Olsen
- Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, 111 South 11th Street, Gibbon Building, 8290, Philadelphia, PA, 19107, USA
| | | | - Marc C Torjman
- Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, 111 South 11th Street, Gibbon Building, 8290, Philadelphia, PA, 19107, USA
| | - Eugene R Viscusi
- Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, 111 South 11th Street, Gibbon Building, 8290, Philadelphia, PA, 19107, USA
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Dubovyk V, Manahan-Vaughan D. Distinct Time-Course of Alterations of Groups I and II Metabotropic Glutamate Receptor and GABAergic Receptor Expression Along the Dorsoventral Hippocampal Axis in an Animal Model of Psychosis. Front Behav Neurosci 2019; 13:98. [PMID: 31139061 PMCID: PMC6519509 DOI: 10.3389/fnbeh.2019.00098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/23/2019] [Indexed: 01/13/2023] Open
Abstract
Psychosis is a clinical state that encompasses a range of abnormal conditions, including distortions in sensory information processing and the resultant delusional thinking, emotional discordance and cognitive impairments. Upon developing this condition, the rate at which cognitive and behavioral deteriorations progress steadily increases suggesting an active contribution of the first psychotic event to the progression of structural and functional abnormalities and disease establishment in diagnosed patients. Changes in GABAergic and glutamatergic function, or expression, in the hippocampus have been proposed as a key factor in the pathophysiology of psychosis. However, little is known as to the time-point of onset of putative changes, to what extent they are progressive, and their relation to disease stabilization. Here, we characterized the expression and distribution patterns of groups I and II metabotropic glutamate (mGlu) receptors and GABA receptors 1 week and 3 months after systemic treatment with an N-methyl-D-aspartate receptor (NMDAR) antagonist (MK801) that is used to model a psychosis-like state in adult rats. We found an early alteration in the expression of mGlu1, mGlu2/3, and GABAB receptors across the hippocampal dorsoventral and transverse axes. This expanded to include an up-regulation of mGlu5 levels across the entire CA1 region and a reduction in GABAB expression, as well as GAD67-positive interneurons particularly in the dorsal hippocampus that appeared 3 months after treatment. Our findings indicate that a reduction of excitability may occur in the hippocampus soon after first-episode psychosis. This changes, over time, into increased excitability. These hippocampus-specific alterations are likely to contribute to the pathophysiology and stabilization of psychosis.
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Affiliation(s)
- Valentyna Dubovyk
- Department of Neurophysiology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr-University Bochum, Bochum, Germany
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Dubovyk V, Manahan-Vaughan D. Time-Dependent Alterations in the Expression of NMDA Receptor Subunits along the Dorsoventral Hippocampal Axis in an Animal Model of Nascent Psychosis. ACS Chem Neurosci 2018; 9:2241-2251. [PMID: 29634239 DOI: 10.1021/acschemneuro.8b00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Psychosis is a mental condition that is characterized by hallucinations, delusions, disordered thought, as well as socio-emotional and cognitive impairments. Once developed, it tends to progress into a chronic psychotic illness. Here, the duration of untreated psychosis plays a crucial role: the earlier the treatment begins, relative to the first episode of the disease, the better the patient's functional prognosis. To what extent the success of early interventions relate to progressive changes at the neurotransmitter receptor level is as yet unclear. In fact, very little is known as to how molecular changes develop, transform, and become established following the first psychotic event. One neurotransmitter receptor for which a specific role in psychosis has been discussed is the N-methyl-d-aspartate receptor (NMDAR). This receptor is especially important for information encoding in the hippocampus. The hippocampus is one of the loci of functional change in psychosis, to which a role in the pathophysiology of psychosis has been ascribed. Here, we examined whether changes in NMDAR subunit expression occur along the dorsoventral axis of the hippocampus 1 week and 3 months after systemic treatment with an NMDAR antagonist (MK801) that initiates a psychosis-like state in adult rats. We found early (1 week) upregulation of the GluN2B levels in the dorso-intermediate hippocampus and late (3 month) downregulation of GluN2A expression across the entire CA1 region. The ventral hippocampus did not exhibit subunit expression changes. These data suggest that a differing vulnerability of the hippocampal longitudinal axis may occur in response to MK801-treatment and provide a time-resolved view of the putative development of pathological changes of NMDAR subunit expression in the hippocampus that initiate with an emulated first episode and progress through to the chronic stabilization of a psychosis-like state in rodents.
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Hayakawa T, Hata M, Kuwahara-Otani S, Yagi H, Okamura H. Postnatal changes of interleukin-18 receptor immunoreactivity in neurons of the retrosplenial cortex in wild-type and interleukin-18 knock out mice. Okajimas Folia Anat Jpn 2017; 94:93-99. [PMID: 29681594 DOI: 10.2535/ofaj.94.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Interleukin-18 (IL-18), which is involved in the inflammatory response, is also found in the cerebral cortex. IL-18 receptor-immunoreactive (IL-18R-ir) neurons are present in layer V of the retrosplenial cortex (RSC). In the adult IL-18 knock out (KO) mice, no IL-18R-ir neurons but many degenerated neurons are present in layer V of the RSC, suggesting that any changes in the neurons of layer V have occurred during postnatal development. We examined changes of IL-18R expression during postnatal development. In the wild-type mice, many IL-18R-ir neurons were present in layers II, III and VI of the RSC in 2-week-old mice, whereas they were sparsely observed in only layer III in 3-week-old mice. No IL-18R-ir neurons were present in 4- and 5-week-old mice. In older than 6-week-old mice, many IL-18R-ir neurons were present in layers V and VI. The IL-18KO mice showed IL-18R-ir neurons in layers II, III and VI at 2-weeks-old, and a few in layer III at 3-week-old mice, similar to that in the wild-type mice. No IL-18R-ir neurons were found in mice older than 4 weeks of age. Thus, IL-18 or IL-18R seem to be involved in the construction of neural circuits corresponding to events after 3-weeks of age.
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Affiliation(s)
- Tetsu Hayakawa
- Laboratory of Tumor Immunology and Cell Therapy Hyogo College of Medicine Mukogawa
| | - Masaki Hata
- Laboratory of Tumor Immunology and Cell Therapy Hyogo College of Medicine Mukogawa
| | | | - Hideshi Yagi
- Department of Anatomy Hyogo College of Medicine Mukogawa
| | - Haruki Okamura
- Laboratory of Tumor Immunology and Cell Therapy Hyogo College of Medicine Mukogawa
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Hayakawa T, Hata M, Kuwahara-Otani S, Yamanishi K, Yagi H, Okamura H. Fine structure of interleukin 18 (IL-18) receptor-immunoreactive neurons in the retrosplenial cortex and its changes in IL18 knockout mice. J Chem Neuroanat 2016; 78:96-101. [PMID: 27593389 DOI: 10.1016/j.jchemneu.2016.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 08/31/2016] [Accepted: 08/31/2016] [Indexed: 11/28/2022]
Abstract
Interleukin 18 (IL-18) participates in the inflammatory immune response of lymphocytes. Delay in learning or memory are common in the IL-18 knockout mouse. Many IL-18-immunoreactive neurons are found in the retrosplenial cortex (RSC) and the subiculum. These neurons also contain the IL-18 receptor. We determined the location and the ultrastructure of the IL-18 receptor-immunoreactive neurons in the RSC and observed changes in the IL-18 receptor-immunoreactive neurons of the IL-18 knockout mouse. The IL-18 receptor-immunoreactive neurons were found specifically in layer V of the granular RSC. They were medium-sized neurons with a light oval nucleus and had little cytoplasm with many free ribosomes, rough endoplasmic reticulum and many mitochondria, but no Nissl bodies. The number of axosomatic terminals was about six per section. The IL-18 receptor-immunoreactive neurons were not found in the RSC in the IL-18 knockout mouse at 5 or 9 weeks of age. However, many small electron-dense neurons were found in layer V. Both the nucleus and cytoplasm were electron-dense, but not necrotic. The mitochondria and rough endoplasmic reticulum were swollen. The IL-18 receptor-immunoreactive neurons were presumed to be degenerating. The degeneration of the IL18-receptor-immunoreactive neurons in the RSC may cause the abnormal behaviors of the IL-18 knockout mice.
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Affiliation(s)
- Tetsu Hayakawa
- Laboratory of Tumor Immunology and Cell Therapy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan.
| | - Masaki Hata
- Laboratory of Tumor Immunology and Cell Therapy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Sachi Kuwahara-Otani
- Department of Anatomy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Kyosuke Yamanishi
- Department of Neuropsychiatry, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Hideshi Yagi
- Department of Anatomy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Haruki Okamura
- Laboratory of Tumor Immunology and Cell Therapy, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
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Gomes FV, Llorente R, Del Bel EA, Viveros MP, López-Gallardo M, Guimarães FS. Decreased glial reactivity could be involved in the antipsychotic-like effect of cannabidiol. Schizophr Res 2015; 164:155-63. [PMID: 25680767 DOI: 10.1016/j.schres.2015.01.015] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 01/06/2015] [Accepted: 01/08/2015] [Indexed: 11/16/2022]
Abstract
NMDA receptor hypofunction could be involved, in addition to the positive, also to the negative symptoms and cognitive deficits found in schizophrenia patients. An increasing number of data has linked schizophrenia with neuroinflammatory conditions and glial cells, such as microglia and astrocytes, have been related to the pathogenesis of schizophrenia. Cannabidiol (CBD), a major non-psychotomimetic constituent of Cannabis sativa with anti-inflammatory and neuroprotective properties induces antipsychotic-like effects. The present study evaluated if repeated treatment with CBD (30 and 60 mg/kg) would attenuate the behavioral and glial changes observed in an animal model of schizophrenia based on the NMDA receptor hypofunction (chronic administration of MK-801, an NMDA receptor antagonist, for 28 days). The behavioral alterations were evaluated in the social interaction and novel object recognition (NOR) tests. These tests have been widely used to study changes related to negative symptoms and cognitive deficits of schizophrenia, respectively. We also evaluated changes in NeuN (a neuronal marker), Iba-1 (a microglia marker) and GFAP (an astrocyte marker) expression in the medial prefrontal cortex (mPFC), dorsal striatum, nucleus accumbens core and shell, and dorsal hippocampus by immunohistochemistry. CBD effects were compared to those induced by the atypical antipsychotic clozapine. Repeated MK-801 administration impaired performance in the social interaction and NOR tests. It also increased the number of GFAP-positive astrocytes in the mPFC and the percentage of Iba-1-positive microglia cells with a reactive phenotype in the mPFC and dorsal hippocampus without changing the number of Iba-1-positive cells. No change in the number of NeuN-positive cells was observed. Both the behavioral disruptions and the changes in expression of glial markers induced by MK-801 treatment were attenuated by repeated treatment with CBD or clozapine. These data reinforces the proposal that CBD may induce antipsychotic-like effects. Although the possible mechanism of action of these effects is still unknown, it may involve CBD anti-inflammatory and neuroprotective properties. Furthermore, our data support the view that inhibition of microglial activation may improve schizophrenia symptoms.
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Affiliation(s)
- Felipe V Gomes
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo, Brazil; Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, Brazil.
| | - Ricardo Llorente
- Department of Physiology, Faculty of Medicine, Complutense University of Madrid, Spain
| | - Elaine A Del Bel
- Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, Brazil; Department of Physiology, Faculty of Odontology of Ribeirão Preto, University of São Paulo, Brazil
| | - Maria-Paz Viveros
- Department of Physiology (Animal Physiology II), Faculty of Biology, Complutense University of Madrid, Spain
| | | | - Francisco S Guimarães
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo, Brazil; Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, Brazil.
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Enhanced dopamine-dependent hippocampal plasticity after single MK-801 application. Neuropsychopharmacology 2015; 40:987-95. [PMID: 25315194 PMCID: PMC4330513 DOI: 10.1038/npp.2014.276] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 09/17/2014] [Accepted: 09/25/2014] [Indexed: 11/09/2022]
Abstract
Dopaminergic hyperfunction and N-methyl-D-aspartate receptor (NMDAR) hypofunction have both been implicated in psychosis. Dopamine-releasing drugs and NMDAR antagonists replicate symptoms associated with psychosis in healthy humans and exacerbate symptoms in patients with schizophrenia. Though hippocampal dysfunction contributes to psychosis, the impact of NMDAR hypofunction on hippocampal plasticity remains poorly understood. Here, we used an NMDAR antagonist rodent model of psychosis to investigate hippocampal long-term potentiation (LTP). We found that single systemic NMDAR antagonism results in a region-specific, presynaptic LTP at hippocampal CA1-subiculum synapses that is induced by activation of D1/D5 dopamine receptors and modulated by L-type voltage-gated Ca(2+) channels. Thereby, our findings may provide a cellular mechanism how NMDAR antagonism can lead to an enhanced hippocampal output causing activation of the hippocampus-ventral tegmental area-loop and overdrive of the dopamine system.
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Lobellová V, Brichtová E, Petrásek T, Valeš K, Stuchlík A. Higher doses of (+)MK-801 (dizocilpine) induced mortality and procedural but not cognitive deficits in delayed testing in the active place avoidance with reversal on the Carousel. Physiol Res 2014; 64:269-75. [PMID: 25317686 DOI: 10.33549/physiolres.932832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Schizophrenia is a devastating disorder affecting 1 % of the world's population. An important role in the study of this disease is played by animal models. Since there is evidence that acute psychotic episodes can have consequences on later cognitive functioning, the present study has investigated the effects of a single systemic application of higher doses of (+)MK-801 (3 mg/kg and 5 mg/kg) to adult male Long-Evans rats from the Institute's breeding colony on delayed testing in the active place avoidance task with reversal on the Carousel (a rotating arena). Besides significant mortality due to the injections, a disruption of procedural functions in active place avoidance, after the dose 5 mg/kg was observed. It was concluded that Long-Evans rats from our breeding colony do not represent a suitable biomodel for studying the effects of single high-dose NMDA antagonists.
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Affiliation(s)
- V Lobellová
- Institute of Physiology CAS, Prague, Czech Republic.
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Wiescholleck V, Manahan-Vaughan D. Long-lasting changes in hippocampal synaptic plasticity and cognition in an animal model of NMDA receptor dysfunction in psychosis. Neuropharmacology 2013; 74:48-58. [DOI: 10.1016/j.neuropharm.2013.01.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/21/2012] [Accepted: 01/04/2013] [Indexed: 12/29/2022]
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Wiescholleck V, Manahan-Vaughan D. Persistent deficits in hippocampal synaptic plasticity accompany losses of hippocampus-dependent memory in a rodent model of psychosis. Front Integr Neurosci 2013; 7:12. [PMID: 23508474 PMCID: PMC3597980 DOI: 10.3389/fnint.2013.00012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/22/2013] [Indexed: 12/24/2022] Open
Abstract
Irreversible N-methyl-D-aspartate receptor (NMDAR) antagonism is known to provoke symptoms of psychosis and schizophrenia in healthy humans. NMDAR hypofunction is believed to play a central role in the pathophysiology of both disorders and in an animal model of psychosis, that is based on irreversible antagonism of NMDARs, pronounced deficits in hippocampal synaptic plasticity have been reported shortly after antagonist treatment. Here, we examined the long-term consequences for long-term potentiation (LTP) of a single acute treatment with an irreversible antagonist and investigated whether deficits are associated with memory impairments. The ability to express LTP at the perforant pathway – dentate gyrus synapse, as well as object recognition memory was assessed 1, 2, 3, and 4 weeks after a single treatment of the antagonist, MK801. Here, LTP in freely behaving rats was significantly impaired at all time-points compared to control LTP before treatment. Object recognition memory was also significantly poorer in MK801-treated compared to vehicle-treated animals for several weeks after treatment. Histological analysis revealed no changes in brain tissue. Taken together, these data support that acute treatment with an irreversible NMDAR-antagonist persistently impairs hippocampal functioning on behavioral, as well as synaptic levels. The long-term deficits in synaptic plasticity may underlie the cognitive impairments that are associated with schizophrenia-spectrum disorders.
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Affiliation(s)
- Valentina Wiescholleck
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum Bochum, Germany ; International Graduate School of Neuroscience, Ruhr University Bochum Bochum, Germany
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van der Staay FJ, Gieling ET, Pinzón NE, Nordquist RE, Ohl F. The appetitively motivated “cognitive” holeboard: A family of complex spatial discrimination tasks for assessing learning and memory. Neurosci Biobehav Rev 2012; 36:379-403. [DOI: 10.1016/j.neubiorev.2011.07.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 06/30/2011] [Accepted: 07/04/2011] [Indexed: 12/27/2022]
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Noh SJ, Lee JM, Lee KS, Hong HS, Lee CK, Cho IH, Kim HS, Suh YH. SP-8203 shows neuroprotective effects and improves cognitive impairment in ischemic brain injury through NMDA receptor. Pharmacol Biochem Behav 2011; 100:73-80. [PMID: 21835192 DOI: 10.1016/j.pbb.2011.07.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 07/20/2011] [Accepted: 07/26/2011] [Indexed: 11/15/2022]
Abstract
The extracts of earth worms, Eisenia andrei, have been used as a therapeutic agent for stroke in the traditional medicine. It is also reported that the protease fraction separated from the extracts has strong anti-thrombotic activity. Besides anti-thrombotic actions, we found that SP-8203, N-[3-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)propyl]-N-{4-[3-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)propylamino]butyl}acetamide, derived from the extracts of earth worms blocked N-methyl-(D)-aspartate (NMDA) receptor-mediated excitotoxicity in a competitive manner. The neuroprotective effects of SP-8203 were attributable to prevention of Ca(2+) influx through NMDA receptors. The systemic administration of SP-8203 markedly reduced neuronal death following middle cerebral artery occlusion in rats. SP-8203 significantly improved spatial learning and memory in the water maze test. These results provided strong pharmacological basis for its potential therapeutic roles in cerebral ischemia.
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Affiliation(s)
- Su-Jin Noh
- Department of Pharmacology, College of Medicine, National Creative Research Initiative Center for Alzheimer's Dementia and Neuroscience Research Institute, MRC, Seoul National University, Seoul, Republic of Korea
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Proctor DT, Coulson EJ, Dodd PR. Post-synaptic scaffolding protein interactions with glutamate receptors in synaptic dysfunction and Alzheimer's disease. Prog Neurobiol 2011; 93:509-21. [PMID: 21382433 DOI: 10.1016/j.pneurobio.2011.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 02/18/2011] [Accepted: 02/24/2011] [Indexed: 11/19/2022]
Abstract
Alzheimer's disease (AD) is characterized clinically by an insidious decline in cognition. Much attention has been focused on proposed pathogenic mechanisms that relate Aβ plaque and neurofibrillary tangle pathology to cognitive symptoms, but compelling evidence now identifies early synaptic loss and dysfunction, which precede plaque and tangle formation, as the more probable initiators of cognitive impairment. Glutamate-mediated transmission is severely altered in AD. Glutamate receptor expression is most markedly altered in regions of the AD brain that show the greatest pathological changes. Signaling via glutamate receptors controls synaptic strength and plasticity, and changes in these parameters are likely to contribute to memory and cognitive deficits in AD. Glutamate receptor expression and activity are modulated by interactions with post-synaptic scaffolding proteins that augment the strength and direction of signal cascades initiated by glutamate receptor activity. Scaffold proteins offer promising targets for more focused and effective drug therapy. In consequence, interest is developing into the roles these proteins play in neurological disease. In this review we discuss disruptions to excitatory neurotransmission at the level of glutamate receptor-post-synaptic scaffolding protein interactions that may contribute to synaptic dysfunction in AD.
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Affiliation(s)
- Dustin T Proctor
- School of Chemistry and Molecular Biosciences, Molecular Biosciences Building #76, Coopers Road, St Lucia campus, University of Queensland, Brisbane 4072, Australia
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Bender C, de Olmos S, Bueno A, de Olmos J, Lorenzo A. Comparative analyses of the neurodegeneration induced by the non-competitive NMDA-receptor-antagonist drug MK801 in mice and rats. Neurotoxicol Teratol 2010; 32:542-50. [DOI: 10.1016/j.ntt.2010.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 05/03/2010] [Accepted: 05/05/2010] [Indexed: 10/19/2022]
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Yamada D, Wada E, Amano T, Wada K, Sekiguchi M. Lack of neurotensin type 1 receptor facilitates contextual fear memory depending on the memory strength. Pharmacol Biochem Behav 2010; 96:363-9. [PMID: 20600248 DOI: 10.1016/j.pbb.2010.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 05/26/2010] [Accepted: 06/11/2010] [Indexed: 12/18/2022]
Abstract
Neurotensin is known to have antipsychotic-like behavioral and neurochemical effects, but its participation in fear memory has not been fully elucidated. Here, we report that a lack of type 1 neurotensin receptor (Ntsr1) increases the behavioral fear response elicited by weak fear memory. Adult Ntsr1-knockout (KO) mice and their wild-type (WT) littermates were compared in contextual fear conditioning. The mice were exposed twice for 3min to the context 24 and 48h after conditioning (first and second exposure, respectively), and freezing response of mice at the exposure was measured to evaluate fear memory. Ntsr1-KO mice showed a higher freezing rate than WT mice at both first and second exposures under the condition where a relatively weak unconditioned stimulus (footshock) was applied and thus elicited a relatively lower freezing rate. The difference in the first exposure between Ntsr1-KO and WT mice disappeared under the condition where a more intense unconditioned stimulus was used. The enhancement of freezing response in Ntsr1-KO mice at second exposure was abolished by propranolol, a beta-adrenergic blocker that suppresses fear memory reconsolidation, and suppressed by MK-801, an NMDA receptor antagonist. These results suggest that Ntsr1 plays inhibitory roles in weak fear memory.
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Affiliation(s)
- Daisuke Yamada
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan
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Loss of tau elicits axonal degeneration in a mouse model of Alzheimer's disease. Neuroscience 2010; 169:516-31. [PMID: 20434528 DOI: 10.1016/j.neuroscience.2010.04.037] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/01/2010] [Accepted: 04/16/2010] [Indexed: 01/20/2023]
Abstract
A central issue in the pathogenesis of tauopathy is the question of how tau protein dysfunction leads to neurodegeneration. We have previously demonstrated that the absence of tau protein is associated with destabilization of microtubules and impaired neurite outgrowth (Dawson et al., 2001; Rapoport et al., 2002). We now hypothesize that the absence of functional tau protein may render the central nervous system more vulnerable to secondary insults such as the overexpression of mutated beta amyloid precursor protein (APP) and traumatic brain injury. We therefore crossed tau knockout mice (Dawson et al., 2001) to mice overexpressing a mutated human APP (APP(670,671), A(sw)) (Hsiao et al., 1996) and created a mouse model (A(sw)/mTau(-/-)) that provides evidence that the loss of tau function causes degeneration of neuronal processes. The overexpression of APP(670,671) in tau knockout mice, elicits the extensive formation of axonal spheroids. While spheroids are only found associated with Abeta plaques in mice expressing APP(670,671) on an endogenous mouse tau background (Irizarry et al., 1997), A(sw)/mTau(-/-) mice have spheroids not only surrounding Abeta plaques but also in white matter tracks and in the neuropil. Plaque associated and neuropil dystrophic neurites and spheroids are prominent features of Alzheimer's disease (Masliah et al., 1993; Terry, 1996; Stokin et al., 2005), and our current data suggests that loss of tau function may lead to neurodegeneration.
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Kim JS, Jung J, Lee HJ, Kim JC, Wang H, Kim SH, Shin T, Moon C. Differences in immunoreactivities of Ki-67 and doublecortin in the adult hippocampus in three strains of mice. Acta Histochem 2009; 111:150-6. [PMID: 18649926 DOI: 10.1016/j.acthis.2008.05.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 04/18/2008] [Accepted: 05/07/2008] [Indexed: 11/25/2022]
Abstract
Neurogenesis in the adult hippocampus is differentially influenced by the genetic background. We examined the differences in Ki-67 (a proliferating cell marker) and doublecortin (DCX; an immature progenitor cell marker) immunolabelling in the dentate gyrus (DG) of the adult hippocampus in three strains of mice (ICR, C57BL/6, and BALB/c) to evaluate the effect of genetic background on adult hippocampal neurogenesis. All strains showed constitutive immunoreactivity of either Ki-67 or DCX in the DG of the adult hippocampus. C57BL/6 mice showed significantly higher levels of Ki-67-immunopositive cells in the subgranular zone (SGZ) of the DG (approximately 2.2-fold) compared to ICR and BALB/c mice. The greatest number of DCX-immunopositive cells was found in C57BL/6 (approximately 1.6-fold), which differed significantly from ICR and BALB/c mice. However, there was no significant difference in the number of Ki-67- and DCX-immunopositive cells between BALB/c and ICR mice. Genetic differences with respect to certain aspects of hippocampal neurogenesis in adult mice may influence hippocampal functions, including learning and memory.
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Zavitsanou K, Nguyen V, Newell K, Ballantyne P, Huang XF. Rapid cortico-limbic alterations in AMPA receptor densities after administration of PCP: Implications for schizophrenia. J Chem Neuroanat 2008; 36:71-6. [DOI: 10.1016/j.jchemneu.2008.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 06/24/2008] [Accepted: 06/24/2008] [Indexed: 11/17/2022]
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Kim JS, Yang M, Son Y, Kim SH, Kim JC, Kim S, Lee Y, Shin T, Moon C. Strain-dependent Differences of Locomotor Activity and Hippocampus-dependent Learning and Memory in Mice. Toxicol Res 2008; 24:183-188. [PMID: 32038793 PMCID: PMC7006272 DOI: 10.5487/tr.2008.24.3.183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 08/13/2008] [Accepted: 08/16/2008] [Indexed: 12/29/2022] Open
Abstract
The behavioral phenotypes of out-bred ICR mice were compared with those of in-bred C57BL/6 and BALB/c mice. In particular, this study examined the locomotor activity and two forms of hippocampus-dependent learning paradigms, passive avoidance and object recognition memory. The basal open-field activity of the ICR strain was greater than that of the C57BL/6 and BALB/c strains. In the passive avoidance task, all the mice showed a significant increase in the cross-over latency when tested 24 hours after training. The strength of memory retention in the ICR mice was relatively weak and measurable, as indicated by the shorter cross-over latency than the C57BL/6 and BALB/c mice. In the object recognition memory test, all strains had a significant preference for the novel object during testing. The index for the preference of a novel object was lower for the ICR and BALB/c mice. Nevertheless, the variance and the standard deviation in these strains were comparable. Overall, these results confirm the strain differences on locomotor activity and hippocampus-dependent learning and memory in mice.
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Affiliation(s)
- Joong-Sun Kim
- 14Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757 Korea
| | - Miyoung Yang
- 14Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757 Korea
| | - Yeonghoon Son
- 14Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757 Korea
| | - Sung-Ho Kim
- 14Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757 Korea
| | - Jong-Choon Kim
- 24Department of Veterinary Toxicology, College of Veterinary Medicine and Veterinary Medical Research Center, Chonnam National University, Gwangju, 500-757 Korea
| | - Seungjoon Kim
- 34Department of Veterinary Obstetrics, College of Veterinary Medicine, Kyungpook National University, Daegu, 702-701 Korea
| | - Yongduk Lee
- 44Department of Veterinary Anatomy, College of Veterinary Medicine, Cheju National University, Jeju, 690-756 Korea
| | - Taekyun Shin
- 44Department of Veterinary Anatomy, College of Veterinary Medicine, Cheju National University, Jeju, 690-756 Korea
| | - Changjong Moon
- 14Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757 Korea
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de Olmos S, Bueno A, Bender C, Lorenzo A, de Olmos J. Sex differences and influence of gonadal hormones on MK801-induced neuronal degeneration in the granular retrosplenial cortex of the rat. Brain Struct Funct 2008; 213:229-38. [DOI: 10.1007/s00429-008-0186-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2007] [Accepted: 05/16/2008] [Indexed: 10/22/2022]
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Majewski-Tiedeken CR, Rabin CR, Siegel SJ. Ketamine exposure in adult mice leads to increased cell death in C3H, DBA2 and FVB inbred mouse strains. Drug Alcohol Depend 2008; 92:217-27. [PMID: 17920787 PMCID: PMC2234578 DOI: 10.1016/j.drugalcdep.2007.08.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 07/30/2007] [Accepted: 08/07/2007] [Indexed: 12/01/2022]
Abstract
BACKGROUND Drug abuse is common among adolescents and young adults. Although the consequences of intoxication are known, sequelae of drugs emerging on campuses and in clubs nationwide are not. We previously demonstrated that ketamine exposure results in lasting physiological abnormalities in mice. However, the extent to which these deficits reflect neuropathologic changes is not known. METHODS The current study examines neuropathologic changes following sub-anesthetic ketamine administration (5mg/kg i.p. x 5) to three inbred mouse strains. Stereologic quantification of silver stained nuclear and linear profiles as well as activated caspase-3 labeling was used to address: (1) whether or not ketamine increases excitotoxic and apoptotic cell death in hippocampal CA3 and (2) whether or not ketamine-induced cell death varies by genetic background. RESULTS Ketamine increased cell death in hippocampal CA3 of adult C3H, DBA2 and FVB mice. Neither silver staining nor activated caspase-3 labeling varied by strain, nor was there an interaction between ketamine-induced cell death and strain. CONCLUSIONS Ketamine exposure among young adults, even in limited amounts, may lead to irreversible changes in both brain function and structure. Loss of CA3 hippocampal cells may underlie persistent ERP changes previously shown in mice and possibly contribute to lasting cognitive deficits among ketamine abusers.
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Affiliation(s)
- Chalon R. Majewski-Tiedeken
- Division of Neuropsychiatry, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cara R. Rabin
- Division of Neuropsychiatry, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Steven J. Siegel
- Division of Neuropsychiatry, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania,* - Communicating Author Steven J. Siegel, MD, PhD, Assistant Professor, Division of Neuropsychiatry, Director, Laboratory for Experimental Therapeutics in Psychiatry, Department of Psychiatry, University of Pennsylvania, Translational Research Laboratories, Rm. 2223, 125 S. 31st Street, Philadelphia PA 19104, Office: 215 573-0278, Clinical: 215 662-2826, Lab: 215 573 4749, fax: 215 573-2041, http://www.Stanley.med.upenn.edu
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Culley DJ, Raghavan SV, Waly M, Baxter MG, Yukhananov R, Deth RC, Crosby G. Nitrous oxide decreases cortical methionine synthase transiently but produces lasting memory impairment in aged rats. Anesth Analg 2007; 105:83-8. [PMID: 17578961 DOI: 10.1213/01.ane.0000266491.53318.20] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Nitrous oxide is a commonly used anesthetic that inhibits the activity of methionine synthase, an enzyme involved in methylation reactions and DNA synthesis and repair. This inhibition triggers vacuole formation and degeneration of neurons in areas of the developing and mature brain that are important for spatial memory, raising the possibility that nitrous oxide might have sustained effects on learning. METHODS To test this possibility, we randomized 18-month-old Fischer 344 rats (n = 13 per group) to 4 h of 70% nitrous oxide + 30% oxygen or 70% nitrogen + 30% oxygen (control) and assessed memory using a 12-arm radial maze for 14 days beginning 2 days after nitrous oxide inhalation. In separate, identically treated groups of rats, we measured methionine synthase activity in the cortex and liver at the end of nitrous oxide exposure and 2 days later (n = 3 rats per group per time point) using a standard assay. RESULTS Liver and cortical methionine synthase was inhibited during nitrous oxide inhalation (6% and 23% of control in liver and cortex, respectively; P < 0.01). Liver enzyme activity remained depressed 2 days later, whereas cortical enzyme activity recovered. There was no difference in error rate between control and nitrous oxide treated rats. However, those exposed to nitrous oxide took more time to complete the maze and made fewer correct choices before first error (P < 0.05). CONCLUSIONS Sedation with 70% nitrous oxide profoundly, but transiently, reduces the activity of cortical methionine synthase but produces lasting impairment in spatial working memory in aged rats.
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Affiliation(s)
- Deborah J Culley
- Department of Anesthesiology Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA
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Yan X, Benson JM, Gomez AP, Baden DG, Murray TF. Brevetoxin-induced neural insult in the retrosplenial cortex of mouse brain. Inhal Toxicol 2007; 18:1109-16. [PMID: 17043031 PMCID: PMC2613569 DOI: 10.1080/08958370600945804] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Brevetoxins (polyether breve toxins; PbTx) are polyether neurotoxins produced by the marine dinoflagellate Karenia brevis, an organism associated with red tide blooms in the Gulf of Mexico and along the Atlantic coast from Florida to North Carolina. Brevetoxin-3 (PbTx-3) is a major component of the array of brevetoxins found in marine aerosols measured along red tide affected beaches. Humans exposed to aerosolized brevetoxins for short periods of time often suffer a variety of adverse health effects. It was consequently of interest to assess the potential for aerosolized brevetoxin to produce a neurotoxic response. Female BALB/c mice were exposed nose-only for 2 consecutive days to PbTx-3 aerosol, with a 2-h exposure on the first day and a 4-h exposure on the second day. The average PbTx-3 exposure concentrations on days 1 and 2 were 312 +/- 113 mug brevetoxin 3/m3 and 278 +/- 24 mug brevetoxin 3/m3, respectively. The brevetoxin-containing aerosol had a mass median aerodynamic diameter of 0.92 mum with a geometric standard deviation of 1.38. Coronal sections of mouse brains were evaluated for neuronal damage using both silver and Fluoro-Jade B staining to identify degenerating neuronal elements. PbTx-3 inhalation exposure produced neuronal degeneration in the posterior cingulate/retrosplenial cortex of mice as evidenced by silver-positive degenerating neurons in this region. No staining was found in other regions of the PBTx-3-exposed mouse brains or in brains of control, sham-exposed mice. The existence of a neurotoxic insult in PbTx-3-exposed mice was confirmed using Fluoro-Jade B to label degenerating neurons. Fluro-Jade-positive neurons were observed in the retrosplenial cortex of PBTx-3 exposed, but not control, mice. These results suggest that subacute exposure to PbTx-3 for 2 days is sufficient to induce neuronal degeneration in a discrete region of the mouse cerebral cortex.
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Affiliation(s)
- Xiuzhen Yan
- Department of Physiology and Pharmacology, University of Georgia Athens, Georgia, USA
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Kondziella D, Brenner E, Eyjolfsson EM, Markinhuhta KR, Carlsson ML, Sonnewald U. Glial-neuronal interactions are impaired in the schizophrenia model of repeated MK801 exposure. Neuropsychopharmacology 2006; 31:1880-7. [PMID: 16395297 DOI: 10.1038/sj.npp.1300993] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Schizophrenia-mimicking compounds such as phencyclidine (PCP) and MK801 are antagonists at the N-methyl-D-aspartate (NMDA) receptor and produce the whole spectrum of positive, negative, and cognitive symptoms. This is one of the most important pillars of the hypoglutamatergic hypothesis of schizophrenia. Since the synthesis of glutamate and GABA in neurons is closely connected to astrocyte metabolism, the study of astrocytic function is essential in this context. Dizocilpine-maleate (MK801) (0.5 mg/kg) was injected into rats every day for 6 days. The last dose was given together with [1-(13)C]glucose and [1,2-(13)C]acetate. Extracts from frontal, retrosplenial, and cingulate cortices (CRFC) and temporal lobes were examined by (13)C nuclear magnetic resonance spectroscopy, high pressure liquid chromatography, and light microscopy. In CRFC, significant increases in the levels of glutamate, glutathione, and taurine were seen, whereas amounts and turnover of noradrenaline, dopamine, and serotonin were unchanged. Glutamate and glutamine, derived from [1,2-(13)C]acetate and thus astrocytes, were significantly decreased in CRFC as compared to controls. Labeling from [1-(13)C]glucose and thus mostly neuronal metabolism was affected in the same brain region with decreased labeling of glutamate and GABA. The present model mimics the increased glutamate/glutamine activity found in drug-naive patients with first episode schizophrenia. Moreover, the decreased labeling indicates the transition to lower glutamatergic function seen in chronic schizophrenia patients. The disturbance in astrocytic function and the glutamine-glutamate-GABA cycle are of significant importance and might add to the malfunction of the cortico-striato-thalamo-cortical loop caused by NDMA receptor blockade.
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Affiliation(s)
- Daniel Kondziella
- Department of Neuroscience, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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Bordi F, Mugnaini M, Terron A, Barnaby R, Reggiani A. GV150526: A Neuroprotective Agent. CNS DRUG REVIEWS 2006. [DOI: 10.1111/j.1527-3458.2000.tb00142.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Creeley C, Wozniak DF, Labruyere J, Taylor GT, Olney JW. Low doses of memantine disrupt memory in adult rats. J Neurosci 2006; 26:3923-32. [PMID: 16611808 PMCID: PMC6673894 DOI: 10.1523/jneurosci.4883-05.2006] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Memantine, a drug recently approved for treatment of Alzheimer's disease, has been characterized as a unique NMDA antagonist that confers protection against excitotoxic neurodegeneration without the serious side effects that other NMDA antagonists are known to cause. In the present study, we determined what dose of memantine is required to protect the adult rat brain against an NMDA receptor-mediated excitotoxic process and then tested that dose and a range of lower doses to determine whether the drug in this dose range is associated with significant side effects. Consistent with previous research, we found that memantine confers a neuroprotective effect beginning at an intraperitoneal dose of 20 mg/kg, a dose that we found, contrary to previous reports, produces locomotor disturbances severe enough to preclude testing for learning and memory effects. We then determined that, at intraperitoneal doses of 10 and 5 mg/kg, memantine disrupts both memory and locomotor behaviors. Rats treated with these doses performed at control-like levels in learning a hole-board task but were significantly impaired in demonstrating what they had learned when tested 24 h later. This impairment of memory retention was not state dependent in that it was demonstrable regardless of whether the rats were or were not exposed to memantine on the day of retention testing. We conclude that, in the adult rat, memantine behaves like other NMDA antagonists in that it is neuroprotective only at doses that produce intolerable side effects, including memory impairment.
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Eyjolfsson EM, Brenner E, Kondziella D, Sonnewald U. Repeated injection of MK801: An animal model of schizophrenia? Neurochem Int 2006; 48:541-6. [PMID: 16517016 DOI: 10.1016/j.neuint.2005.11.019] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Accepted: 11/02/2005] [Indexed: 12/20/2022]
Abstract
Glutamate-induced neurotoxicity plays an important role in neurological and psychiatric diseases. Thus, much attention has been given to the potential neuroprotective role of glutamate receptor antagonists, especially to those acting on the N-methyl-d-aspartate (NMDA) subtype. However, in addition to their neuroprotective potential, these compounds have also neurotoxic and psychotogenic properties. In the present study we used repeated injections of MK801 to examine if this non-competitive NMDA receptor antagonist could be used to produce schizophrenia-like alterations in behavior and brain metabolism in animals. Rats were given injections of MK801 (0.1 mg/kg) on six consecutive days, the last dose together with [1-(13)C]glucose and [1,2-(13)C]acetate, to probe neuronal and astrocytic metabolism, respectively. Analyses of extracts from parts of the frontal cortex plus cingulate and retrosplenial cortices and temporal lobes were performed using (13)C and (1)H magnetic resonance spectroscopy. Changes in glutamate and glutamine were restricted to the temporal lobe, in which amounts and labeling from [1-(13)C]glucose and [1,2-(13)C]acetate were increased compared to control. Locomotor activity was slightly higher in rats treated with MK801 compared to untreated animals. Metabolic changes did not resemble the alterations occurring in schizophrenia and those after repeated high dose (0.5 mg/kg) [Kondziella, D., Brenner, E., Eyjolfsson, E.M., Markinhuhta, K.R., Carlsson, M., Sonnewald, U., 2005. Glial-neuronal interactions are impaired in the schizophrenia model of repeated MK801 exposure. Neuropsychopharmacology, Epub ahead of print] but rather those caused by MK801 seen after a single high dose (0.5 mg/kg) [Brenner, E., Kondziella, D., Haberg, A., Sonnewald, U., 2005. Impaired glutamine metabolism in NMDA receptor hypofunction induced by MK801. J. Neurochem. 94, 1594-1603.].
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Affiliation(s)
- Elvar M Eyjolfsson
- Department of Neuroscience, Norwegian University of Science and Technology, NTNU, N-7489 Trondheim, Norway
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Hunt PS. Neonatal treatment with a competitive NMDA antagonist results in response-specific disruption of conditioned fear in preweanling rats. Psychopharmacology (Berl) 2006; 185:179-87. [PMID: 16416331 DOI: 10.1007/s00213-005-0291-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Accepted: 12/02/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE The N-methyl-D-aspartate (NMDA) receptor has been implicated in processes of neurodevelopment, including cell proliferation, synaptogenesis, and apoptosis. Several studies have reported that administration of NMDA antagonists early in development can cause long-lasting changes in behavior. For example, Gould and Cameron [Behav Neurosci 111:49-56 (1997a)] have shown that a single injection of the competitive NMDA antagonist CGP 43487 on postnatal day (PD) 5 affected behavioral immobility in young rats exposed to the odor of a natural predator. OBJECTIVES This experiment was undertaken to determine whether the behavioral effects previously reported would also be seen with conditioned cues. Both stimulus-elicited behavioral immobility (freezing) and changes in heart rate were recorded to examine impairments in responding across multiple measures. METHODS Animals were given a single injection of 0, 2.5, or 5.0 mg/kg CGP 43487 on PD 5. On PD 20 subjects were given paired or unpaired presentations of either an olfactory or auditory conditioned stimulus (CS) with a 110-dB-white-noise unconditioned stimulus. CS-elicited freezing and changes in heart rate were measured. RESULTS Pups treated with CGP exhibited impairments in conditioned freezing, but were unaffected in their expression of conditioned changes in heart rate, to both olfactory and auditory stimuli. CONCLUSIONS These results indicate that neonatal treatment with an NMDA antagonist affects the expression of fear in a response-specific manner. The data suggest that antagonist-induced alterations in neural systems involved in the expression of freezing are affected by NMDA receptor blockade early in life.
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Affiliation(s)
- Pamela S Hunt
- Department of Psychology, College of William and Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA.
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Nair A, Bonneau RH. Stress-induced elevation of glucocorticoids increases microglia proliferation through NMDA receptor activation. J Neuroimmunol 2005; 171:72-85. [PMID: 16278020 DOI: 10.1016/j.jneuroim.2005.09.012] [Citation(s) in RCA: 278] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 09/21/2005] [Indexed: 11/28/2022]
Abstract
The immunosuppressive nature of glucocorticoids has been well documented both in vitro and in vivo. This glucocorticoid-mediated immunosuppression has also been observed in immune cells within the central nervous system (CNS). For example, microglia have previously been shown to exhibit decreased proliferation, cytokine production, and antigen presentation upon treatment with glucocorticoids in vitro. Despite these in vitro findings, the impact of glucocorticoids on microglia function in vivo has not been fully investigated. To determine the interaction between glucocorticoids and microglia within the CNS, we used a restraint model of psychological stress to elevate corticosterone levels in mice. Quantification of microglia from stressed mice indicated that four sessions of stress induced the proliferation of microglia. This proliferation was a function of corticosterone-induced activation of the N-methyl-D-aspartate (NMDA) receptor within the CNS since blockade of corticosterone synthesis, the glucocorticoid receptor, or the NMDA receptor each prevented stress-induced increases in microglia number. In addition, the NMDA receptor antagonist MK-801 prevented increases in microglia following exogenous corticosterone administration to non-stressed mice. We conclude that activation of the NMDA receptor and subsequent microglia proliferation is a downstream effect of elevated corticosterone levels. These findings demonstrate that elevated levels of glucocorticoids are able to activate microglia in vivo and suggest that stress is able to induce a pro-inflammatory response within the CNS. A pro-inflammatory microglia response may be a contributing factor in the development of various stress-induced inflammatory conditions in the CNS.
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Affiliation(s)
- Aji Nair
- Graduate Program in Neuroscience, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
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Hirai T, Taniura H, Goto Y, Tamaki K, Oikawa H, Kambe Y, Ogura M, Ohno Y, Takarada T, Yoneda Y. Counteraction by repetitive daily exposure to static magnetism against sustained blockade of N-methyl-D-aspartate receptor channels in cultured rat hippocampal neurons. J Neurosci Res 2005; 80:491-500. [PMID: 15846781 DOI: 10.1002/jnr.20497] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In rat hippocampal neurons cultured with the antagonist for N-methyl-D-aspartate (NMDA) receptors dizocilpine (MK-801) for 8 days in vitro (DIV), a significant decrease was seen in the expression of microtubule-associated protein-2 (MAP-2) as well as mRNA for both brain-derived neurotrophic factor (BDNF) and growth-associated protein-43 (GAP-43), in addition to decreased viability. MK-801 not only decreased the expression of the NR1 subunit of NMDA receptors but also increased NR2A expression, without affecting NR2B expression. Repetitive daily exposure to static magnetic fields at 100 mT for 15 min led to a decrease in the expression of MAP-2, without significantly affecting cell viability or the expression of neuronal nuclei (NeuN) and GAP-43. However, the repetitive magnetism prevented decreases in both BDNF mRNA and MAP-2 and additionally increased the expression of NR2A subunit, without altering NR1 expression in neurons cultured in the presence of MK-801. Repetitive magnetism was also effective in preventing the decrease by MK-801 in the ability of NMDA to increase intracellular free Ca2+ ions, without affecting the decrease in the maximal response. These results suggest that repetitive magnetism may at least in part counteract the neurotoxicity of MK-801 through modulation of the expression of particular NMDA receptor subunits in cultured rat hippocampal neurons.
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Affiliation(s)
- Takao Hirai
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kakuma-machi, Kanazawa, Ishikawa, Japan
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Jevtovic-Todorovic V, Carter LB. The anesthetics nitrous oxide and ketamine are more neurotoxic to old than to young rat brain. Neurobiol Aging 2005; 26:947-56. [PMID: 15718054 DOI: 10.1016/j.neurobiolaging.2004.07.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Revised: 06/08/2004] [Accepted: 07/30/2004] [Indexed: 11/19/2022]
Abstract
Nitrous oxide (N2O) and ketamine are common general anesthetics and antagonists of N-methyl-D-aspartate (NMDA) glutamate receptors. In clinically relevant concentrations, they induce a psychotomimetic reaction in humans and pathomorphological changes in the rat brain. We have previously shown that ketamine and N2O in combination cause the neurotoxic reaction in young adult rat brain that is apparently synergistic. Ketamine and N2O are occasionally used in geriatric anesthesia since they do not suppress cardiorespiratory function and thus are beneficial for frail elderly patients. However, in view of the evidence that N2O and ketamine have potentially serious neurotoxic effects, and that they potentiate one another's neurotoxicity, their neurotoxic potential in the aging brain needs to be evaluated. In this study we compared the neurotoxicity of ketamine and N2O, alone or in combination, in aging (18- and 24-month-old) rats and in young adult (6-month-old) rats and found that the aging brain is substantially more sensitive than the young adult brain to the neurotoxic reaction induced by either ketamine alone or the ketamine + N2O combination, but equally sensitive to the neurotoxicity induced by N2O alone.
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Affiliation(s)
- Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Virginia Health System, P.O. Box 800710, Charlottesville, VA 22908, USA.
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Fagan AM, Christopher E, Taylor JW, Parsadanian M, Spinner M, Watson M, Fryer JD, Wahrle S, Bales KR, Paul SM, Holtzman DM. ApoAI deficiency results in marked reductions in plasma cholesterol but no alterations in amyloid-beta pathology in a mouse model of Alzheimer's disease-like cerebral amyloidosis. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:1413-22. [PMID: 15466405 PMCID: PMC1618648 DOI: 10.1016/s0002-9440(10)63399-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/10/2004] [Indexed: 11/24/2022]
Abstract
Epidemiological studies suggest links between cholesterol metabolism and Alzheimer's disease (AD), with hypercholesterolemia associated with increased AD risk, and use of cholesterol-lowering drugs associated with decreased risk. Animal models using cholesterol-modifying dietary or pharmacological interventions demonstrate similar findings. Proposed mechanisms include effects of cholesterol on the metabolism of amyloid-beta (Abeta), the protein that deposits in AD brain. To investigate the effect of genetic alterations in plasma cholesterol on Abeta pathology, we crossed the PDAPP transgenic mouse model of AD-like cerebral amyloidosis to apolipoprotein AI-null mice that have markedly reduced plasma cholesterol levels due to a virtual absence of high density lipoproteins, the primary lipoprotein in mice. Interestingly and in contrast to models using non-physiological high fat diets or cholesterol-lowering drugs to modify plasma cholesterol, we observed no differences in Abeta pathology in PDAPP mice of the various apoAI genotypes despite robust differences in plasma cholesterol levels between the groups. Absence of apoAI also resulted in reductions in brain but not cerebrospinal fluid cholesterol, but had no effect on brain apolipoprotein E levels. These and other data suggest that it is perhaps the level of brain apolipoprotein E, not cholesterol per se, that plays a primary role in brain Abeta metabolism.
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Affiliation(s)
- Anne M Fagan
- Department of Neurology and Center for the Study of Nervous System Injury, Alzheimer's Disease Research Center, Washington University School of Medicine, 660 S. Euclid Ave., Box 8111, St. Louis, MO 63110, USA.
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Rogawski MA, Wenk GL. The neuropharmacological basis for the use of memantine in the treatment of Alzheimer's disease. CNS DRUG REVIEWS 2003; 9:275-308. [PMID: 14530799 PMCID: PMC6741669 DOI: 10.1111/j.1527-3458.2003.tb00254.x] [Citation(s) in RCA: 266] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Memantine has been demonstrated to be safe and effective in the symptomatic treatment of Alzheimer's disease (AD). While the neurobiological basis for the therapeutic activity of memantine is not fully understood, the drug is not a cholinesterase inhibitor and, therefore, acts differently from current AD therapies. Memantine can interact with a variety of ligand-gated ion channels. However, NMDA receptors appear to be a key target of memantine at therapeutic concentrations. Memantine is an uncompetitive (channel blocking) NMDA receptor antagonist. Like other NMDA receptor antagonists, memantine at high concentrations can inhibit mechanisms of synaptic plasticity that are believed to underlie learning and memory. However, at lower, clinically relevant concentrations memantine can under some circumstances promote synaptic plasticity and preserve or enhance memory in animal models of AD. In addition, memantine can protect against the excitotoxic destruction of cholinergic neurons. Blockade of NMDA receptors by memantine could theoretically confer disease-modifying activity in AD by inhibiting the "weak" NMDA receptor-dependent excitotoxicity that has been hypothesized to play a role in the progressive neuronal loss that underlies the evolving dementia. Moreover, recent in vitro studies suggest that memantine abrogates beta-amyloid (Abeta) toxicity and possibly inhibits Abeta production. Considerable attention has focused on the investigation of theories to explain the better tolerability of memantine over other NMDA receptor antagonists, particularly those that act by a similar channel blocking mechanism such as dissociative anesthetic-like agents (phencyclidine, ketamine, MK-801). A variety of channel-level factors could be relevant, including fast channel-blocking kinetics and strong voltage-dependence (allowing rapid relief of block during synaptic activity), as well as reduced trapping (permitting egress from closed channels). These factors may allow memantine to block channel activity induced by low, tonic levels of glutamate--an action that might contribute to symptomatic improvement and could theoretically protect against weak excitotoxicity--while sparing synaptic responses required for normal behavioral functioning, cognition and memory.
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Affiliation(s)
- Michael A Rogawski
- Epilepsy Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-4457, USA.
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35
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Li Z, Kim CH, Ichikawa J, Meltzer HY. Effect of repeated administration of phencyclidine on spatial performance in an eight-arm radial maze with delay in rats and mice. Pharmacol Biochem Behav 2003; 75:335-40. [PMID: 12873624 DOI: 10.1016/s0091-3057(03)00085-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Phencyclidine (PCP) is an N-methyl-D-aspartate (NMDA) glutamate receptor channel noncompetitive antagonist that produces some of the symptoms of schizophrenia, including delusions, hallucinations, and negative symptoms as well as cognitive impairment. Thus, administration of PCP to rodents and nonhuman primates has been suggested to provide a potential animal model for schizophrenia. There have been some reports that 7-14 days of PCP administration can bring about enduring impairments in working memory in rodents but not all studies have been consistent in this regard. The present study determined whether repeated PCP administration impaired spatial performance in rats or mice trained to make minimal errors in an eight-arm radial maze task with a delay. Male Sprague-Dawley rats and C57BL/6J mice received 14 daily injection of vehicle or PCP (10 mg/kg, s.c.) followed by a withdrawal period of 1 week. The number of arm reentry errors and the distance traveled to complete the task were not significantly different between PCP-treated and vehicle-treated rats on 2, 8, and 14 days of PCP administration or 8 days following withdrawal of PCP. Mice treated with PCP for up to 2 weeks also had no significant differences in the number of arm reentry errors, travel distances, the numbers of visits to different arms during the first eight choices, or latencies to take all eight pellets compared to the vehicle-treated group. Thus, the present study failed to demonstrate that repeated administration of PCP to rats or mice produces enduring memory impairment. Factors potentially contributing to the discrepancies between various studies are discussed.
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Affiliation(s)
- Zhu Li
- Division of Psychopharmacology, Departments of Psychiatry and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
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Bardgett ME, Boeckman R, Krochmal D, Fernando H, Ahrens R, Csernansky JG. NMDA receptor blockade and hippocampal neuronal loss impair fear conditioning and position habit reversal in C57Bl/6 mice. Brain Res Bull 2003; 60:131-42. [PMID: 12725901 DOI: 10.1016/s0361-9230(03)00023-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The interpretation of learning and memory deficits in transgenic mice has largely involved theories of NMDA receptor and/or hippocampal function. However, there is little empirical data that describes what NMDA receptors or the hippocampus do in mice. This research assessed the effects of different doses of the NMDA receptor antagonist, MK-801, or different-sized hippocampal lesions on several behavioral parameters in adult male C57Bl/6 mice. In the first set of experiments, different doses of MK-801 (0.05-0.3mg/kg, s.c.) were assayed in fear conditioning, shock sensitivity, locomotion, anxiety, and position habit reversal tests. Contextual and cued fear conditioning, and position habit reversal were impaired in a dose-dependent manner. Locomotor activity was increased immediately after injection of the highest dose of MK-801. A second set of experiments determined the behavioral effects of a moderate and large excitotoxic hippocampal lesion. Both lesions impaired contextual conditioning, while the larger lesion interfered with cued conditioning. Reversal learning was significantly diminished by the large lesion, while the moderate lesion had a detrimental effect at a trend level (P<0.10). These results provide important reference data for studies involving genetic manipulations of NMDA receptor or hippocampal function in mice. Furthermore, they serve as a basis for a non-transgenic mouse model of the NMDA receptor or hippocampal dysfunction hypothesized to occur in human cognitive disorders.
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Affiliation(s)
- Mark E Bardgett
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
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Brendza RP, O'Brien C, Simmons K, McKeel DW, Bales KR, Paul SM, Olney JW, Sanes JR, Holtzman DM. PDAPP; YFP double transgenic mice: a tool to study amyloid-beta associated changes in axonal, dendritic, and synaptic structures. J Comp Neurol 2003; 456:375-83. [PMID: 12532409 DOI: 10.1002/cne.10536] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neuritic plaques are one of the stereotypical hallmarks of Alzheimer's disease (AD) pathology. These structures are composed of extracellular accumulations of fibrillar forms of the amyloid-beta peptide (Abeta), a variety of other plaque-associated proteins, activated glial cells, and degenerating nerve processes. To study the neuritic toxicity of different structural forms of Abeta in the context of regional connectivity and the entire cell, we crossed PDAPP transgenic (Tg) mice, a model with AD-like pathology, to Tg mice that stably express yellow fluorescent protein (YFP) in a subset of neurons in the brain. In PDAPP; YFP double Tg mice, markedly enlarged YFP-labeled axonal and dendritic varicosities were associated with fibrillar Abeta deposits. These varicosities were absent in areas where there were nonfibrillar Abeta deposits. Interestingly, YFP-labeled varicosities revealed changes that corresponded with changes seen with electron microscopy and the de Olmos silver staining technique. Other silver staining methods and immunohistochemical localization of phosphorylated neurofilaments or phosphorylated tau were unable to detect the majority of these dystrophic neurites. Some but not all synaptic vesicle markers accumulated abnormally in YFP-labeled varicosities associated with neuritic plaques. In addition to the characterization of the effects of Abeta on axonal and dendritic structure, YFP-labeled neurons in Tg mice should prove to be a valuable tool to interpret the localization patterns of other markers and for future studies examining the dynamics of axons and dendrites in a variety of disease conditions in living tissue both in vitro and in vivo.
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Affiliation(s)
- Robert P Brendza
- Center for the Study of Nervous System Injury, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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DeMattos RB, O'dell MA, Parsadanian M, Taylor JW, Harmony JAK, Bales KR, Paul SM, Aronow BJ, Holtzman DM. Clusterin promotes amyloid plaque formation and is critical for neuritic toxicity in a mouse model of Alzheimer's disease. Proc Natl Acad Sci U S A 2002; 99:10843-8. [PMID: 12145324 PMCID: PMC125060 DOI: 10.1073/pnas.162228299] [Citation(s) in RCA: 258] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Studies have shown that clusterin (also called apolipoprotein J) can influence the structure and toxicity of amyloid-beta (Abeta) in vitro. To determine whether endogenous clusterin plays a role in influencing Abeta deposition, structure, and toxicity in vivo, we bred PDAPP mice, a transgenic mouse model of Alzheimer's disease, to clusterin(-/-) mice. By 12 months of age, PDAPP, clusterin(-/-) mice had similar levels of brain Abeta deposition as did PDAPP, clusterin(+/+) mice. Although Abeta deposition was similar, PDAPP, clusterin(-/-) mice had significantly fewer fibrillar Abeta (amyloid) deposits than PDAPP mice expressing clusterin. In the absence of clusterin, neuritic dystrophy associated with the deposited amyloid was markedly reduced, resulting in a dissociation between fibrillar amyloid formation and neuritic dystrophy. These findings demonstrate that clusterin markedly influences Abeta structure and neuritic toxicity in vivo and is likely to play an important role in Alzheimer's disease pathogenesis.
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Affiliation(s)
- Ronald B DeMattos
- Center for the Study of Nervous System Injury, Alzheimer's Disease Research Center, and Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, MO 63110, USA
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Wang Q, Bardgett ME, Wong M, Wozniak DF, Lou J, McNeil BD, Chen C, Nardi A, Reid DC, Yamada K, Ornitz DM. Ataxia and paroxysmal dyskinesia in mice lacking axonally transported FGF14. Neuron 2002; 35:25-38. [PMID: 12123606 DOI: 10.1016/s0896-6273(02)00744-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Fibroblast growth factor 14 (FGF14) belongs to a distinct subclass of FGFs that is expressed in the developing and adult CNS. We disrupted the Fgf14 gene and introduced an Fgf14(N-beta-Gal) allele that abolished Fgf14 expression and generated a fusion protein (FGF14N-beta-gal) containing the first exon of FGF14 and beta-galactosidase. Fgf14-deficient mice were viable, fertile, and anatomically normal, but developed ataxia and a paroxysmal hyperkinetic movement disorder. Neuropharmacological studies showed that Fgf14-deficient mice have reduced responses to dopamine agonists. The paroxysmal hyperkinetic movement disorder phenocopies a form of dystonia, a disease often associated with dysfunction of the putamen. Strikingly, the FGF14N-beta-gal chimeric protein was efficiently transported into neuronal processes in the basal ganglia and cerebellum. Together, these studies identify a novel function for FGF14 in neuronal signaling and implicate FGF14 in axonal trafficking and synaptosomal function.
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Affiliation(s)
- Qing Wang
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis 63110, USA
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NMDA receptor antagonists disinhibit rat posterior cingulate and retrosplenial cortices: a potential mechanism of neurotoxicity. J Neurosci 2002. [PMID: 11943810 DOI: 10.1523/jneurosci.22-08-03070.2002] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
NMDA receptor antagonists produce region-specific neurodegeneration by an undetermined mechanism, but one proposed mechanism involves disinhibition. In certain areas of the brain, NMDA receptors mediate excitatory drive onto inhibitory interneurons. Thus, NMDA receptor/channel antagonists may reduce inhibition (i.e., produce "disinhibition"). If a sufficient level of disinhibition is produced, enhanced vulnerability to excitotoxicity may result. Furthermore, if there are region-specific differences in NMDA antagonist-induced disinhibition, this could underlie region-specific NMDA antagonist-induced neurotoxicity. In the present study, we tested this hypothesis by exposing rat brain slices to the NMDA receptor antagonist dizocilpine maleate (MK-801) and measuring MK-801-induced disinhibition in areas of higher and lower vulnerability to neurodegeneration [posterior cingulate/retrosplenial cortices (PCC/RSC) and parietal cortex, respectively]. Using whole-cell patch-clamp techniques, bicuculline-sensitive GABA(A) receptor-mediated IPSCs were measured in biocytin-labeled pyramidal neurons in the PCC/RSC and parietal cortex. In the PCC/RSC, bath-applied MK-801 (10-40 microm) produced disinhibition, shown as a concentration-dependent decrease in spontaneous IPSC frequency and amplitude; MK-801 (40 microm) also reduced evoked IPSC amplitudes. In parietal cortex, MK-801 produced significantly less disinhibition. To determine whether disinhibition is caused by presynaptic or postsynaptic mechanisms, we tested the effects of MK-801 (40 microm) against miniature IPSC (mIPSC) frequency and amplitude in tetrodotoxin (TTX; 0.5 microm)-treated slices and found that MK-801 did not alter mIPSC frequency or amplitude. Taken together, these results suggest that NMDA receptors regulate activity of inhibitory interneurons and, consequently, GABA release in certain cortical areas. This region-specific reduction in inhibitory input to pyramidal cells could underlie the region-specific neurotoxicity of NMDA antagonists.
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Impaired spatial performance in rats with retrosplenial lesions: importance of the spatial problem and the rat strain in identifying lesion effects in a swimming pool. J Neurosci 2002. [PMID: 11826144 DOI: 10.1523/jneurosci.22-03-01155.2002] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Behavioral, electrophysiological, and anatomical evidence suggests that retrosplenial (RS) cortex (areas RSA and RSG) plays a role in spatial navigation. This conclusion has been questioned in recent work, suggesting that it is damage to the underlying cingulum bundle (CG) (areas CG and IG), and not RS, that disrupts spatial place learning (Aggleton et al., 2000). We revisited this issue by comparing Long-Evans rats, the strain used in studies that report RS deficits, to Dark Agouti rats, the strain in which no RS deficit has been reported. Rat groups with RS, RS + CG, or no lesion were tested on a place task in a swimming pool, a test of nonspatial and spatial learning, and a matching-to-place task, a relatively selective test of spatial learning. Long-Evans rats given RS and RS + CG lesions, either before or after training on the two tasks, were impaired on both tasks, a deficit not attributable to impaired visual acuity. Control Dark Agouti rats and RS Dark Agouti rats, although not different on the place task, were both significantly impaired relative to Long-Evans rats. The RS Dark Agouti group, however, was also impaired on the matching-to-place task. Thus, we show that RS cortex is part of an extended neural circuit involved in spatial behavior in both Long-Evans and Dark Agouti rats, but its role in the place task may be masked by an innate nonspatial deficit in Dark Agouti rats. The results are discussed in relation to the importance of assessing spatial learning with appropriate spatial tests, the problems of interpretation posed by rat strain differences, and the role of retrosplenial cortex in spatial behavior.
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Sebban C, Tesolin-Decros B, Ciprian-Ollivier J, Perret L, Spedding M. Effects of phencyclidine (PCP) and MK 801 on the EEGq in the prefrontal cortex of conscious rats; antagonism by clozapine, and antagonists of AMPA-, alpha(1)- and 5-HT(2A)-receptors. Br J Pharmacol 2002; 135:65-78. [PMID: 11786481 PMCID: PMC1573114 DOI: 10.1038/sj.bjp.0704451] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2001] [Revised: 10/22/2001] [Accepted: 10/22/2001] [Indexed: 11/09/2022] Open
Abstract
1. The electroencephalographic (EEG) effects of the propsychotic agent phencyclidine (PCP), were studied in conscious rats using power spectra (0 - 30 Hz), from the prefrontal cortex or sensorimotor cortex. PCP (0.1 - 3 mg kg(-1) s.c.) caused a marked dose-dependent increase in EEG power in the frontal cortex at 1 - 3 Hz with decreases in power at higher frequencies (9 - 30 Hz). At high doses (3 mg kg(-1) s.c.) the entire spectrum shifted to more positive values, indicating an increase in cortical synchronization. MK 801 (0.05 - 0.1 mg kg(-1) i.p.) caused similar effects but with lesser changes in power. 2. In contrast, the non-competitive AMPA antagonists GYKI 52466 and GYKI 53655 increased EEG power over the whole power spectrum (1 - 10 mg kg(-1) i.p.). The atypical antipsychotic clozapine (0.2 mg kg(-1) s.c.) synchronized the EEG (peak 8 Hz). The 5-HT(2A)-antagonist, M100907, specifically increased EEG power at 2 - 3 Hz at low doses (10 and 50 microg kg(-1) s.c.), whereas at higher doses (0.1 mg kg(-1) s.c.) the profile resembled that of clozapine. 3. Clozapine (0.2 mg kg(-1) s.c. ), GYKI 53655 (5 mg kg(-1) i.p.), prazosin (0.05 and 0.1 mg kg(-1) i.p.), and M100907 (0.01 and 0.05 mg kg(-1) s.c.) antagonized the decrease in power between 5 and 30 Hz caused by PCP (1 mg kg(-1) s.c.), but not the increase in power at 1 - 3 Hz in prefrontal cortex.
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Affiliation(s)
- Claude Sebban
- Laboratoire de Biologie du Vieillissement - Hopital Charles Foix - 7 avenue de la République, 94205 Ivry sur Seine cedex - France
| | - Brigitte Tesolin-Decros
- Laboratoire de Biologie du Vieillissement - Hopital Charles Foix - 7 avenue de la République, 94205 Ivry sur Seine cedex - France
| | - Jorge Ciprian-Ollivier
- Moyana Hospital, Academic Unit, University of Buenos Aires, Francisco de Vittoria 2324, 1425 Buenos Aires, Argentina
| | - Laurent Perret
- Institut de Recherches Internationales SERVIER, 192 Av. Charles de Gaulle, 92200 Neuilly sur Seine, France
| | - Michael Spedding
- Institut de Recherches Internationales SERVIER, 192 Av. Charles de Gaulle, 92200 Neuilly sur Seine, France
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Lukoyanov NV, Paula-Barbosa MM. Memantine, but not dizocilpine, ameliorates cognitive deficits in adult rats withdrawn from chronic ingestion of alcohol. Neurosci Lett 2001; 309:45-8. [PMID: 11489543 DOI: 10.1016/s0304-3940(01)02037-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adult rats were given a 20% ethanol solution as their only source of fluid for 6 months and then withdrawn from alcohol. During the first 4 weeks of the withdrawal period, animals were intraperitoneally injected with either memantine (20 mg/kg bolus followed by 1 mg/kg every 12 h) or dizocilpine (MK-801; 0.1 mg/kg every 12 h), both of which are antagonists of N-methyl-D-aspartate receptors. Ten weeks after initiation of the withdrawal procedure, cognitive status of animals was assessed using the Morris water maze. Withdrawal from alcohol produced robust deficits in the performance of rats on the acquisition task and on the probe trial. Treatment with memantine resulted in a complete reversal of these behavioral impairments. In contrast, treatment with MK-801 was found to be ineffective in preventing cognitive alterations associated with chronic alcohol consumption and withdrawal.
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Affiliation(s)
- N V Lukoyanov
- Department of Anatomy, Porto Medical School, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.
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44
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Hartman RE, Wozniak DF, Nardi A, Olney JW, Sartorius L, Holtzman DM. Behavioral phenotyping of GFAP-apoE3 and -apoE4 transgenic mice: apoE4 mice show profound working memory impairments in the absence of Alzheimer's-like neuropathology. Exp Neurol 2001; 170:326-44. [PMID: 11476599 DOI: 10.1006/exnr.2001.7715] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
For the purpose of studying the potential neurobehavioral effects of different human apolipoprotein E (apoE) isoforms produced within the brain, transgenic (TG) mice were generated in which human apoE3 or apoE4 isoforms were under control of an astrocyte-specific, glial fibrillary acidic protein promoter and these TG mice were bred back to apoE knockout (KO) mice. Behavioral phenotypes of apoE3 and apoE4 TG mice were derived by conducting a longitudinal study in which apoE3 and apoE4 TG mice were compared with apoE KO and wild-type (WT) mice (all male) on several behavioral measures. Analysis of locomotor activity, "open-field" behaviors, acoustic startle/prepulse inhibition, and elevated plus maze data suggested that the apoE TG/KO groups were more "emotionally reactive" than WT mice, with apoE4 mice typically being the most reactive. The absence of performance differences among groups on the rotating holeboard and water navigation tasks suggested intact reference memory processing in apoE TG/KO mice. However, apoE4 mice were profoundly impaired on a working memory-based protocol in the radial arm maze (11-14 months). Nonassociative factors (sensorimotor capacities or emotionality differences) did not appear to confound interpretation of the learning/memory results. Western blot analysis revealed no alterations in the level of synaptic, neuronal, or glial markers in neocortex or hippocampus and histologic analysis revealed no evidence of Abeta deposition or neuritic plaques in the apoE KO/TG mice. Our findings suggest that apoE4 expression in the brain may have selective deleterious effects on memory function in the absence of typical Alzheimer's-like neuropathology.
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Affiliation(s)
- R E Hartman
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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45
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Holtzman DM, Fagan AM, Mackey B, Tenkova T, Sartorius L, Paul SM, Bales K, Hsiao Ashe K, Irizarry MC, Hyman BT. Apolipoprotein E facilitates neuritic and cerebrovascular plaque formation in an Alzheimer's disease model. Ann Neurol 2001. [DOI: 10.1002/1531-8249(200006)47:6<739::aid-ana6>3.0.co;2-8] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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46
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El-Nabawi A, Quesenberry M, Saito K, Silbergeld E, Vasta G, Eldefrawi A. The N-methyl-D-aspartate neurotransmitter receptor is a mammalian brain target for the dinoflagellate Pfiesteria piscicida toxin. Toxicol Appl Pharmacol 2000; 169:84-93. [PMID: 11076700 DOI: 10.1006/taap.2000.9042] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Blooms of Pfiesteria piscicida, a dinoflagellate in eastern U.S. coastal rivers, are believed to secrete toxins that kill fish and produce short-term memory loss in humans. Only one or two of Pfiesteria's multiple stages secrete the toxin, and only under certain environmental conditions. Thus, neither the presence of Pfiesteria nor fish kill alone can be indicative of toxin presence. The objective of this study was to identify the mammalian molecular brain target for the toxin that is associated with decrements in memory. Seven rat brain neurotransmitter receptors were selected to study because of their reported roles in cognitive function: receptors for nicotine, muscarine, AMPA/kainate, N-methyl-D-aspartate (NMDA), gamma-aminobutyric acid, and dopamine 1 and 2. The effects of 17 environmental and laboratory samples on radioactive ligand binding to these receptors were studied. Of the seven receptors, binding only to the NMDA receptor was inhibited by only the two Pfiesteria-containing waters (identified by PCR) that also killed fish, and not by any of the other 15 samples tested. It is suggested that inhibition of NMDA-receptor binding is the cause of memory loss in exposed humans. Thus, it could be a useful biomarker for the toxin's presence in rivers for decisions on closures and for identification of the fractions containing the toxin during its purification. Knowledge of the toxin's molecular target, and how it affects its function, also leads to suggestions for therapeutics to use in animal models.
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Affiliation(s)
- A El-Nabawi
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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47
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Rejdak K, Rejdak R, Stelmasiak Z, Czuczwar SJ, Kleinrok Z, Sieklucka-Dziuba M. The effect of CGP-40116 on pilocarpine evoked seizures in mice exposed to transient episode of brain ischemia. Epilepsy Res 2000; 41:213-22. [PMID: 10962212 DOI: 10.1016/s0920-1211(00)00143-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The objective of the study was to examine the role of N-methyl-D-aspartate (NMDA) receptors in the modulation of a brain tolerance after a transient cerebral ischemia. Adult mice were exposed for 30 min to bilateral clamping of common carotid arteries (BCCA) under anaesthesia. The competitive NMDA antagonist CGP-40116 was administered intraperitoneally (i.p.) in two experimental paradigms, (a) acute treatment: twice, 4.0 mg/kg; 1.5 h before the clamping of vessels and 6 h after re-circulation and (b) chronic treatment in a dose of 1.0 mg/kg; started 24 h after re-circulation and continued once daily for 13 days with the last injection 24 h before the induction of convulsions. Seizures were evoked with pilocarpine (400 mg/kg, i.p.) 14 days after BCCA. The preliminary study showed that BCCA induced protection against pilocarpine toxicity. The acute treatment with CGP-40116 partially diminished the anticonvulsant phenomenon. In contrast, the chronic treatment with the drug led to a marked potentiation of the effect. The whole brain gamma-aminobutyric acid (GABA) analysis performed 14 days after BCCA showed a moderate increase in vehicle-treated mice and a significant elevation after chronic treatment with CGP-40116. It can be concluded that NMDA antagonists may exert the opposite effects on the brain tolerance against pilocarpine toxicity after BCCA. The acute treatment with CGP-40116 diminished its induction while the chronic low-dose treatment enhanced a brain tolerance, possibly through the mechanism of chemical preconditioning.
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Affiliation(s)
- K Rejdak
- Department of Hygiene, Medical University, 11 Radziwillowska Str., 20-080, Lublin, Poland
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48
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Brosnan-Watters G, Ogimi T, Ford D, Tatekawa L, Gilliam D, Bilsky EJ, Nash D. Differential effects of MK-801 on cerebrocortical neuronal injury in C57BL/6J, NSA, and ICR mice. Prog Neuropsychopharmacol Biol Psychiatry 2000; 24:925-38. [PMID: 11041535 DOI: 10.1016/s0278-5846(00)00111-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1. Antagonists of the N-methyl-D-aspartate (NMDA) glutamate (Glu) receptor, including [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate], dizocilpine maleate (MK-801), injure pyramidal neurons in the posterior cingulate/retrosplenial (PC/RS) cortex when administered systemically to adult rats and mice. 2. These results have, to our knowledge, only been reported previously in Harlan Sprague Dawley albino rats and International Cancer Research (ICR) mice, an outbred albino strain. 3. Male Non-Swiss Albino (NSA) mice, an albino outbred strain, and male C57BL/6J (B6) mice, a pigmented inbred strain, were injected systemically with 1 mg/kg of MK-801 in the first experiment. This dose of MK-801 reliably produces cytoplasmic vacuoles in neurons in layers III and IV of the PC/RS cortex in 100% of ICR mice treated 4. There was a significant difference in the number of vacuolated neurons in B6 and NSA mice, as assessed by ANOVA. The NSA were not significantly different than previously examined ICR mice, but the B6 had fewer vacuolated neurons than either of the two outbred strains. 5. In the second experiment, male NSA, ICR, and B6 mice were injected systemically with a high dose, 10 mg/kg, of MK-801. This dose has been demonstrated to result in necrosis in the same population of neurons injured by lower doses of MK-801. 6. An ANOVA indicated that there was a significant difference among the three strains of mice, and a Fisher's protected t revealed that the B6 mice were significantly different from both the NSA and ICR, but that, with our test, those two strains were indistinguishable. 7. Male ICR, NSA, and B6 mice were tested in the holeboard food search task 5 hours after 1 mg/kg of MK-801. There were significant differences between the strains in performance both pre and posttreatment. The effect of the drug was not statistically significant. 8. These results suggest that there may be a genetically mediated difference in the reaction to NMDA receptor antagonists, a finding which may be important given the NMDA receptor hypofunction hypothesis for the etiology of schizophrenic symptoms.
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Affiliation(s)
- G Brosnan-Watters
- Psychology Department, Vanguard University of Southern California, Costa Mesa 92626, USA.
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49
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Lukoyanov NV, Paula-Barbosa MM. A single high dose of dizocilpine produces long-lasting impairment of the water maze performance in adult rats. Neurosci Lett 2000; 285:139-42. [PMID: 10793246 DOI: 10.1016/s0304-3940(00)01053-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The long-lasting effects of a single high dose treatment with the non-competitive N-methyl-D-aspartate (NMDA) antagonist dizocilpine (MK-801; 10 mg/kg, i.p.) on the water maze performance of rats were investigated. MK-801-treated rats learned to find the escape platform at a slower rate than control animals, and showed increased thigmotaxis during acquisition of the task. However, no differences were found between MK-801 and control groups on the probe trial, during repeated acquisition and on the visible platform task. These findings further support the idea that NMDA antagonists can be used in animal research to model persisting symptomatology of cognitive and psychotic disorders.
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Affiliation(s)
- N V Lukoyanov
- Department of Anatomy, Porto Medical School, 4200-319, Porto,
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50
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Schroeder U, Schroeder H, Schwegler H, Sabel BA. Neuroleptics ameliorate phencyclidine-induced impairments of short-term memory. Br J Pharmacol 2000; 130:33-40. [PMID: 10780995 PMCID: PMC1572029 DOI: 10.1038/sj.bjp.0703171] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Phencyclidine (PCP), a non-competitive NMDA-receptor antagonist, is able to induce schizophrenia-like symptoms in animals and in humans. It is known that schizophrenic patients have deficits in memory processes. 2. Therefore, it was investigated whether subchronic pulsatile or continuous application of 5.0 mg kg(-1) PCP over 5 days induce short-term memory deficits in holeboard learning and the action of two different neuroleptics on this behavioural test. 3. First, an impairment in the holeboard task was described when the animals were tested 24 h after the last application but not after 15 min or 1 h after the last injection. Secondly, the influence of haloperidol and risperidone on the PCP-induced short-term memory changes was tested. 4. The combined application of PCP and risperidone led to a complete antagonism of the short-term deficits, but the combined treatment with haloperidol was accompanied by a partial abolishment of the PCP-induced deficits. 5. PCP led to an upregulation of the glutamate binding sites in striatum and nucleus accumbens whereas the D(2) binding sites were reduced in striatum. The D(1) binding sites seem to be unchanged. The receptor protein expression of glutamate receptors mGluR1, GluR2, GluR5/7 and NMDAR1 were not modified in response to PCP treatment. 6. The determination of a subpopulation of GABAergic interneurons shows a decrease of the cells within the CA3 of the hippocampal formation. 7. These findings indicate that PCP induced impairments in short term memory can be detected by holeboard learning and may provide an interesting tool for the search of new neuroleptics.
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Affiliation(s)
- U Schroeder
- Institute of Medical Psychology, Medical Faculty, Leipziger Str. 44, 39 120 Magdeburg, Germany.
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