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Ahn YJ, Shin HJ, Jeong EA, An HS, Lee JY, Jang HM, Kim KE, Lee J, Shin MC, Roh GS. Exendin-4 Pretreatment Attenuates Kainic Acid-Induced Hippocampal Neuronal Death. Cells 2021; 10:cells10102527. [PMID: 34685508 PMCID: PMC8534217 DOI: 10.3390/cells10102527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 12/15/2022] Open
Abstract
Exendin-4 (Ex-4) is a glucagon-like peptide-1 receptor (GLP-1R) agonist that protects against brain injury. However, little is known about the effect of Ex-4 on kainic acid (KA)-induced seizures and hippocampal cell death. Therefore, this study evaluated the neuroprotective effects of Ex-4 pretreatment in a mouse model of KA-induced seizures. Three days before KA treatment, mice were intraperitoneally injected with Ex-4. We found that Ex-4 pretreatment reversed KA-induced reduction of GLP-1R expression in the hippocampus and attenuated KA-induced seizure score, hippocampal neuronal death, and neuroinflammation. Ex-4 pretreatment also dramatically reduced hippocampal lipocalin-2 protein in KA-treated mice. Furthermore, immunohistochemical studies showed that Ex-4 pretreatment significantly alleviated blood–brain barrier leakage. Finally, Ex-4 pretreatment stimulated hippocampal expression of phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB), a known target of GLP-1/GLP-1R signaling. These findings indicate that Ex-4 pretreatment may protect against KA-induced neuronal damage by regulating GLP-1R/CREB-mediated signaling pathways.
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Affiliation(s)
- Yu-Jeong Ahn
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Hyun-Joo Shin
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Eun-Ae Jeong
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Hyeong-Seok An
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Jong-Youl Lee
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Hye-Min Jang
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Kyung-Eun Kim
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Jaewoong Lee
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
| | - Meong-Cheol Shin
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Gyeongsang National University, Jinju 52828, Korea;
| | - Gu-Seob Roh
- Bio Anti-Aging Medical Research Center, Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea; (Y.-J.A.); (H.-J.S.); (E.-A.J.); (H.-S.A.); (J.-Y.L.); (H.-M.J.); (K.-E.K.); (J.L.)
- Correspondence: ; Tel.: +82-55-772-8035; Fax: +82-55-772-8039
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2
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de Melo IS, Dos Santos YMO, Pacheco ALD, Costa MA, de Oliveira Silva V, Freitas-Santos J, de Melo Bastos Cavalcante C, Silva-Filho RC, Leite ACR, Gitaí DGL, Duzzioni M, Sabino-Silva R, Borbely AU, de Castro OW. Role of Modulation of Hippocampal Glucose Following Pilocarpine-Induced Status Epilepticus. Mol Neurobiol 2021; 58:1217-1236. [PMID: 33123979 DOI: 10.1007/s12035-020-02173-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 10/14/2020] [Indexed: 02/08/2023]
Abstract
Status epilepticus (SE) is defined as continuous and self-sustaining seizures, which trigger hippocampal neurodegeneration, mitochondrial dysfunction, oxidative stress, and energy failure. During SE, the neurons become overexcited, increasing energy consumption. Glucose uptake is increased via the sodium glucose cotransporter 1 (SGLT1) in the hippocampus under epileptic conditions. In addition, modulation of glucose can prevent neuronal damage caused by SE. Here, we evaluated the effect of increased glucose availability in behavior of limbic seizures, memory dysfunction, neurodegeneration process, neuronal activity, and SGLT1 expression. Vehicle (VEH, saline 0.9%, 1 μL) or glucose (GLU; 1, 2 or 3 mM, 1 μL) were administered into hippocampus of male Wistar rats (Rattus norvegicus) before or after pilocarpine to induce SE. Behavioral analysis of seizures was performed for 90 min during SE. The memory and learning processes were analyzed by the inhibitory avoidance test. After 24 h of SE, neurodegeneration process, neuronal activity, and SGLT1 expression were evaluated in hippocampal and extrahippocampal regions. Modulation of hippocampal glucose did not protect memory dysfunction followed by SE. Our results showed that the administration of glucose after pilocarpine reduced the severity of seizures, as well as the number of limbic seizures. Similarly, glucose after SE reduced cell death and neuronal activity in hippocampus, subiculum, thalamus, amygdala, and cortical areas. Finally, glucose infusion elevated the SGLT1 expression in hippocampus. Taken together our data suggest that possibly the administration of intrahippocampal glucose protects brain in the earlier stage of epileptogenic processes via an important support of SGLT1.
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Affiliation(s)
- Igor Santana de Melo
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | | | - Amanda Larissa Dias Pacheco
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Maisa Araújo Costa
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Vanessa de Oliveira Silva
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Jucilene Freitas-Santos
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | | | - Reginaldo Correia Silva-Filho
- Bioenergetics Laboratory, Institute of Chemistry and Biotechnology, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Ana Catarina Rezende Leite
- Bioenergetics Laboratory, Institute of Chemistry and Biotechnology, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Daniel Góes Leite Gitaí
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Marcelo Duzzioni
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Robinson Sabino-Silva
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), Uberlândia, MG, Brazil
| | - Alexandre Urban Borbely
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil
| | - Olagide Wagner de Castro
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceió, AL, Brazil.
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3
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de Melo IS, Pacheco ALD, Dos Santos YMO, Figueiredo LM, Nicacio DCSP, Cardoso-Sousa L, Duzzioni M, Gitaí DLG, Tilelli CQ, Sabino-Silva R, de Castro OW. Modulation of Glucose Availability and Effects of Hypo- and Hyperglycemia on Status Epilepticus: What We Do Not Know Yet? Mol Neurobiol 2020; 58:505-519. [PMID: 32975651 DOI: 10.1007/s12035-020-02133-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/14/2020] [Indexed: 12/22/2022]
Abstract
Status epilepticus (SE) can lead to serious neuronal damage and act as an initial trigger for epileptogenic processes that may lead to temporal lobe epilepsy (TLE). Besides promoting neurodegeneration, neuroinflammation, and abnormal neurogenesis, SE can generate an extensive hypometabolism in several brain areas and, consequently, reduce intracellular energy supply, such as adenosine triphosphate (ATP) molecules. Although some antiepileptic drugs show efficiency to terminate or reduce epileptic seizures, approximately 30% of TLE patients are refractory to regular antiepileptic drugs (AEDs). Modulation of glucose availability may provide a novel and robust alternative for treating seizures and neuronal damage that occurs during epileptogenesis; however, more detailed information remains unknown, especially under hypo- and hyperglycemic conditions. Here, we review several pathways of glucose metabolism activated during and after SE, as well as the effects of hypo- and hyperglycemia in the generation of self-sustained limbic seizures. Furthermore, this study suggests the control of glucose availability as a potential therapeutic tool for SE.
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Affiliation(s)
- Igor Santana de Melo
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Amanda Larissa Dias Pacheco
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Yngrid Mickaelli Oliveira Dos Santos
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Laura Mello Figueiredo
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Dannyele Cynthia Santos Pimentel Nicacio
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Leia Cardoso-Sousa
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), ARFIS, Av. Pará, 1720, Campus Umuruama, Uberlandia, MG, CEP 38400-902, Brazil
| | - Marcelo Duzzioni
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Daniel Leite Góes Gitaí
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil
| | - Cristiane Queixa Tilelli
- Physiology Laboratory, Federal University of Sao Joao del Rei (UFSJ), Central-West Campus, Divinopolis, MG, Brazil
| | - Robinson Sabino-Silva
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), ARFIS, Av. Pará, 1720, Campus Umuruama, Uberlandia, MG, CEP 38400-902, Brazil.
| | - Olagide Wagner de Castro
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Av. Lourival de Melo Mota, km 14, Campus A. C. Simões, Cidade Universitária, Maceió, AL, CEP 57072-970, Brazil.
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Wulsin AC, Herman JP, Danzer SC. RU486 Mitigates Hippocampal Pathology Following Status Epilepticus. Front Neurol 2016; 7:214. [PMID: 27965624 PMCID: PMC5124765 DOI: 10.3389/fneur.2016.00214] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/14/2016] [Indexed: 11/13/2022] Open
Abstract
Status epilepticus (SE) induces rapid hyper-activation of the hypothalamo-pituitary-adrenocortical (HPA) axis. HPA axis hyperactivity results in excess exposure to high levels of circulating glucocorticoids, which are associated with neurotoxicity and depression-like behavior. These observations have led to the hypothesis that HPA axis dysfunction may exacerbate SE-induced brain injury. To test this hypothesis, we used the mouse pilocarpine model of epilepsy to determine whether use of the glucocorticoid receptor antagonist RU486 can attenuate hippocampal pathology following SE. Excess glucocorticoid secretion was evident 1 day after SE in the mice, preceding the development of spontaneous seizures (which can take weeks to develop). RU486 treatment blocked the SE-associated elevation of glucocorticoid levels in pilocarpine-treated mice. RU486 treatment also mitigated the development of hippocampal pathologies induced by SE, reducing loss of hilar mossy cells and limiting pathological cell proliferation in the dentate hilus. Mossy cell loss and accumulation of ectopic hilar cells are positively correlated with epilepsy severity, suggesting that early treatment with glucocorticoid antagonists could have anti-epileptogenic effects.
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Affiliation(s)
- Aynara C Wulsin
- Department of Psychiatry and Behavioral Neuroscience, College of Medicine, University of Cincinnati, Cincinnati, OH, USA; Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - James P Herman
- Department of Psychiatry and Behavioral Neuroscience, College of Medicine, University of Cincinnati, Cincinnati, OH, USA; Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Steve C Danzer
- Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, USA; Department of Anesthesia and Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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5
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Schauwecker PE. The effects of glycemic control on seizures and seizure-induced excitotoxic cell death. BMC Neurosci 2012; 13:94. [PMID: 22867059 PMCID: PMC3465215 DOI: 10.1186/1471-2202-13-94] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/24/2012] [Indexed: 12/20/2022] Open
Abstract
Background Epilepsy is the most common neurological disorder after stroke, affecting more than 50 million persons worldwide. Metabolic disturbances are often associated with epileptic seizures, but the pathogenesis of this relationship is poorly understood. It is known that seizures result in altered glucose metabolism, the reduction of intracellular energy metabolites such as ATP, ADP and phosphocreatine and the accumulation of metabolic intermediates, such as lactate and adenosine. In particular, it has been suggested that the duration and extent of glucose dysregulation may be a predictor of the pathological outcome of status. However, little is known about neither the effects of glycemic control on brain metabolism nor the effects of managing systemic glucose concentrations in epilepsy. Results In this study, we examined glycemic modulation of kainate-induced seizure sensitivity and its neuropathological consequences. To investigate the relationship between glycemic modulation, seizure susceptibility and its neuropathological consequences, C57BL/6 mice (excitotoxin cell death resistant) were subjected to hypoglycemia or hyperglycemia, followed by systemic administration of kainic acid to induce seizures. Glycemic modulation resulted in minimal consequences with regard to seizure severity but increased hippocampal pathology, irrespective of whether mice were hypoglycemic or hyperglycemic prior to kainate administration. Moreover, we found that exogenous administration of glucose following kainic acid seizures significantly reduced the extent of hippocampal pathology in FVB/N mice (excitotoxin cell death susceptible) following systemic administration of kainic acid. Conclusion These findings demonstrate that modulation of the glycemic index can modify the outcome of brain injury in the kainate model of seizure induction. Moreover, modulation of the glycemic index through glucose rescue greatly diminishes the extent of seizure-induced cell death following kainate administration. Our data support the hypothesis that deficient insulin signaling may represent a critical contributing factor in the susceptibility to seizure-induced cell death and this may be an important therapeutic target.
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Affiliation(s)
- Paula Elyse Schauwecker
- Department of Cell and Neurobiology, USC Keck School of Medicine, 1333 San Pablo Street, BMT 403, Los Angeles, CA 90089-9112, USA.
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Greenberg DA, Subaran R. Blinders, phenotype, and fashionable genetic analysis: a critical examination of the current state of epilepsy genetic studies. Epilepsia 2011; 52:1-9. [PMID: 21219301 PMCID: PMC3021750 DOI: 10.1111/j.1528-1167.2010.02734.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Although it is accepted that idiopathic generalized epilepsy (IGE) is strongly, if not exclusively, influenced by genetic factors, there is little consensus on what those genetic influences may be, except for one point of agreement: epilepsy is a "channelopathy." This point of agreement has continued despite the failure of studies investigating channel genes to demonstrate the primacy of their influence on IGE expression. The belief is sufficiently entrenched that the more important issues involving phenotype definition, data collection, methods of analysis, and the interpretation of results have become subordinate to it. The goal of this article is to spark discussion of where the study of epilepsy genetics has been and where it is going, suggesting we may never get there if we continue on the current road. We use the long history of psychiatric genetic studies as a mirror and starting point to illustrate that only when we expand our outlook on how to study the genetics of the epilepsies, consider other mechanisms that could lead to epilepsy susceptibility, and, especially, focus on the critical problem of phenotype definition, will the major influences on common epilepsy begin to be understood.
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Affiliation(s)
- David A Greenberg
- Division of Statistical Genetics, Department of Biostatistics, Mailman School of Public Health, New York State Psychiatric Institute, Columbia University Medical Center, New York, New York, USA.
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Zemlyak I, Manley N, Vulih-Shultzman I, Cutler AB, Graber K, Sapolsky RM, Gozes I. The microtubule interacting drug candidate NAP protects against kainic acid toxicity in a rat model of epilepsy. J Neurochem 2009; 111:1252-63. [PMID: 19799711 DOI: 10.1111/j.1471-4159.2009.06415.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
NAP (NAPVSIPQ, generic name, davunetide), a neuroprotective peptide in clinical development for neuroprotection against Alzheimer's disease and other neurodegenerative indications, has been recently shown to provide protection against kainic acid excitotoxicity in hippocampal neuronal cultures. In vivo, kainic acid toxicity models status epilepticus that is associated with hippocampal cell death. Kainic acid toxicity has been previously suggested to involve the microtubule cytoskeleton and NAP is a microtubule-interacting drug candidate. In the current study, kainic acid-treated rats showed epileptic seizures and neuronal death. Injection of NAP into the dentate gyrus partially protected against kainic acid-induced CA3 neuron death. Microarray analysis (composed of > 31 000 probe sets, analyzing over 30 000 transcripts and variants from over 25 000 well-substantiated rat genes) in the kainic acid-injured rat brain revealed multiple changes in gene expression, which were prevented, in part, by NAP treatment. Selected transcripts were further verified by reverse transcription coupled with quantitative real-time polymerase chain reaction. Importantly, among the transcripts regulated by NAP were key genes associated with proconvulsant properties and with long-lasting changes that underlie the epileptic state, including activin A receptor (associated with apoptosis), neurotensin (associated with proper neurotransmission) and the Wolfram syndrome 1 homolog (human, associated with neurodegeneration). These data suggest that NAP may provide neuroprotection in one of the most serious neurological conditions, epilepsy.
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Affiliation(s)
- Ilona Zemlyak
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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8
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Palacios Bote R, Blázquez-Llorca L, Fernández-Gil MÁ, Alonso-Nanclares L, Muñoz A, De Felipe J. Hippocampal Sclerosis: Histopathology Substrate and Magnetic Resonance Imaging. Semin Ultrasound CT MR 2008; 29:2-14. [DOI: 10.1053/j.sult.2007.11.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Kaufer D, Ogle WO, Pincus ZS, Clark KL, Nicholas AC, Dinkel KM, Dumas TC, Ferguson D, Lee AL, Winters MA, Sapolsky RM. Restructuring the neuronal stress response with anti-glucocorticoid gene delivery. Nat Neurosci 2004; 7:947-53. [PMID: 15300253 DOI: 10.1038/nn1296] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 07/07/2004] [Indexed: 11/09/2022]
Abstract
Glucocorticoids, the adrenal steroids released during stress, compromise the ability of neurons to survive neurological injury. In contrast, estrogen protects neurons against such injuries. We designed three genetic interventions to manipulate the actions of glucocorticoids, which reduced their deleterious effects in both in vitro and in vivo rat models. The most effective of these interventions created a chimeric receptor combining the ligand-binding domain of the glucocorticoid receptor and the DNA-binding domain of the estrogen receptor. Expression of this chimeric receptor reduced hippocampal lesion size after neurological damage by 63% and reversed the outcome of the stress response by rendering glucocorticoids protective rather than destructive. Our findings elucidate three principal steps in the neuronal stress-response pathway, all of which are amenable to therapeutic intervention.
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MESH Headings
- 11-beta-Hydroxysteroid Dehydrogenase Type 2/genetics
- 11-beta-Hydroxysteroid Dehydrogenase Type 2/metabolism
- Animals
- Blotting, Western/methods
- Cell Count/methods
- Cell Death/drug effects
- Cell Death/genetics
- Culture Techniques
- Estrogen Receptor alpha
- Fibroblast Growth Factors/genetics
- Fibroblast Growth Factors/metabolism
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/genetics
- Glucocorticoids/antagonists & inhibitors
- Hippocampus/drug effects
- Hippocampus/physiology
- Humans
- Immediate-Early Proteins
- Immunohistochemistry/methods
- Indoles
- Kainic Acid/toxicity
- Male
- Microtubule-Associated Proteins/metabolism
- Models, Molecular
- Neurons/drug effects
- Neurons/physiology
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Protein Structure, Tertiary/physiology
- RNA, Messenger/metabolism
- Rats
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Glucocorticoid/genetics
- Receptors, Glucocorticoid/metabolism
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Recombinant Fusion Proteins/pharmacology
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Stress, Physiological/genetics
- Stress, Physiological/metabolism
- Transgenes
- Translocation, Genetic/physiology
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Affiliation(s)
- D Kaufer
- Department of Biological Sciences, Stanford University, Stanford, California, USA.
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10
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Dinkel K, Dhabhar FS, Sapolsky RM. Neurotoxic effects of polymorphonuclear granulocytes on hippocampal primary cultures. Proc Natl Acad Sci U S A 2003; 101:331-6. [PMID: 14684829 PMCID: PMC314185 DOI: 10.1073/pnas.0303510101] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Many neurological insults and neurodegenerative disorders are accompanied by an acute inflammatory reaction that can contribute to neuronal damage. This inflammation involves infiltration of bloodborne polymorphonuclear leukocytes (PMNs) into the injured brain area. The role of inflammation in brain injury, however, is controversial, because recent studies suggest that inflammation may actually be beneficial in the recovery from brain damage. Therefore, we investigated the effects of pathophysiologically relevant concentrations of PMNs in vitro on mixed hippocampal primary cultures. Rat PMNs and peripheral blood lymphocytes were isolated by density centrifugation and cocultured with hippocampal cells for 24-72 h plus or minus an excitotoxic insult (50 microM kainic acid) or 6-h oxygen glucose deprivation. Cell death was analyzed by immunocytochemistry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and neuron-specific [2,2'-azino-bis(ethylbenzothiazoline-6-sulfonic acid)] assay. After 3 days of coculture in the absence of insult, PMNs caused massive neuron loss and dramatic morphological changes in glial cells (astrocyte detachment, aggregation). Furthermore PMNs exacerbated kainic acid- and oxygen glucose deprivation-induced neuron death by 20-30%. The cytotoxic effect of PMNs required heterocellular contact and were ameliorated by protease inhibitors. Lymphocytes, on the other hand, were not neurotoxic, but, instead, increased astrocyte proliferation. These findings suggest that PMN might represent a harmful part of inflammation after brain injury that can contribute to secondary damage.
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Affiliation(s)
- Klaus Dinkel
- Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA
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Abstract
The CNS can mount an inflammatory reaction to excitotoxic insults that contributes to the emerging brain damage. Therefore, anti-inflammatory drugs should be beneficial in neurological insults. In contrast, glucocorticoids (GCs), while known for their anti-inflammatory effects, can exacerbate neurotoxicity in the hippocampus after excitotoxic insults. We investigated the effect of GCs on the inflammatory response after a neurological insult. Intact control (INT; intact stress response GC profile), adrenalectomized/GC-supplemented (ADX; low basal GC profile) and GC-treated (COR; chronically high GC profile) rats were injected with kainic acid into the hippocampal CA3 region. Lesion size was determined 8-72 h later. The inflammatory response was characterized using immunohistochemistry, RNAse protection assay and ELISA. The INT and COR rats developed larger CA3 lesions than ADX rats. We found that GCs surprisingly caused an increase in relative numbers of inflammatory cells (granulocytes, monocytes/macrophages and microglia). Additionally, mRNA and protein (IL-1beta and TNF-alpha) levels of the pro-inflammatory cytokines IL-1alpha, IL-1beta and TNF-alpha were elevated in COR rats compared with INT and ADX rats. These data strongly question the traditional view of GCs being uniformly anti-inflammatory and could further explain how GCs worsen the outcome of neurological insults.
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Affiliation(s)
- Klaus Dinkel
- Department of Biological Sciences, Gilbert Hall, Stanford University, Stanford, CA 94305-5020, USA.
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12
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Abstract
Status epilepticus is a serious medical emergency that requires prompt and appropriate intervention. Maintenance of adequate vital function with attention to airway, breathing, and circulation; prevention of systemic complications; and rapid termination of seizures must be coupled with investigating and treating any underlying cause. In most patients with SE, the use of adequate dosages of first-line antiepileptic agents allows for the successful and rapid termination of SE and avoidance of potential neurologic complications. Refractory SE requires more aggressive treatment, often the use of intravenous anesthetic agents and intense monitoring, and therefore must be managed in a pediatric intensive care unit with a multidisciplinary approach. Large, controlled, multicenter, comparative studies are needed urgently to clarify better the optimal management of these patients.
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Affiliation(s)
- U A Hanhan
- Division of Pediatrics, Department of Critical Care Medicine, University Community Hospital, Tampa, Florida, USA
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13
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McLaughlin J, Roozendaal B, Dumas T, Gupta A, Ajilore O, Hsieh J, Ho D, Lawrence M, McGaugh JL, Sapolsky R. Sparing of neuronal function postseizure with gene therapy. Proc Natl Acad Sci U S A 2000; 97:12804-9. [PMID: 11058147 PMCID: PMC18845 DOI: 10.1073/pnas.210350097] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Numerous studies have demonstrated that gene therapy interventions can protect neurons from death after neurological insults. In nearly all such studies, however, "protection" consists of reduced neurotoxicity, with no demonstrated preservation of neuronal function. We used a herpes simplex virus-1 system to overexpress either the Glut-1 glucose transporter (GT) (to buffer energetics), or the apoptosis inhibitor Bcl-2. Both decreased hippocampal neuron loss to similar extents during excitotoxic insults in vitro and in vivo. However, the mediating mechanisms and consequences of the two interventions differed. GT overexpression attenuated early, energy-dependent facets of cell death, blocking oxygen radical accumulation. Bcl-2 expression, in contrast, blocked components of death downstream from the energetic and oxidative facets. Most importantly, GT- but not Bcl-2-mediated protection preserved hippocampal function as assessed spatial maze performance. Thus, gene therapeutic sparing of neurons from insult-induced death does not necessarily translate into sparing of function.
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Affiliation(s)
- J McLaughlin
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
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14
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Dumas TC, McLaughlin JR, Ho DY, Lawrence MS, Sapolsky RM. Gene therapies that enhance hippocampal neuron survival after an excitotoxic insult are not equivalent in their ability to maintain synaptic transmission. Exp Neurol 2000; 166:180-9. [PMID: 11031094 DOI: 10.1006/exnr.2000.7500] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Research shows that overexpression of cytoprotective genes can spare neurons from necrotic death, but few studies have addressed the functional status of surviving neurons. Overexpression of a brain glucose transporter, Glut-1, or the anti-apoptotic protein, Bcl-2, in rats decreases the size of hippocampal lesions produced by kainic acid (KA) treatment. In animals in which KA-induced lesions are reduced to similar extents by Glut-1 or Bcl-2 overexpression, spatial learning is spared by Glut-1, but not Bcl-2. We postulated that Glut-1 and Bcl-2 act differently to protect hippocampal function and investigated the effects of vector overexpression on synaptic physiology after KA treatment. Three days after KA and vector delivery to the dentate gyrus, mossy fiber-CA3 (MF-CA3) population excitatory postsynaptic potentials (EPSPs) were recorded in vitro. In addition to producing a lesion in area CA3, KA treatment reduced baseline MF-CA3 synaptic strength, posttetanic potentiation (PTP), and long-term potentiation (LTP). A similar reduction in the KA-induced lesion was produced by overexpression of Glut-1 or Bcl-2. Glut-1, but not Bcl-2, attenuated the impairments in synaptic strength and PTP. Overexpression of Glut-1 or Bcl-2 preserved LTP after KA treatment. Results indicate greater protection of MF-CA3 synaptic transmission with overexpression of Glut-1 compared to Bcl-2 and suggest that not all neuroprotective gene therapy techniques are equivalent in their ability to spare function.
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Affiliation(s)
- T C Dumas
- Department of Biological Sciences, Stanford University, Stanford, California 94305, USA
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15
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Maecker H, Desai A, Dash R, Rivier J, Vale W, Sapolsky R. Astressin, a novel and potent CRF antagonist, is neuroprotective in the hippocampus when administered after a seizure. Brain Res 1997; 744:166-70. [PMID: 9030428 DOI: 10.1016/s0006-8993(96)01207-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Corticotropin-releasing factor (CRF), the principle hypothalamic regulator of the adrenocortical axis, also functions as a neurotransmitter. In this latter role, CRF causes electrophysiological activation and epileptiform activity in various brain regions. That finding, coupled with the observation that CRF mRNA is induced in endangered brain regions following necrotic insults, suggests that the peptide might contribute to necrotic neuron loss. Supporting that, a number of studies have shown that CRF antagonists decrease ischemic or excitotoxic damage to neurons. In the present report, we demonstrate the considerable neuroprotective potential of a novel and potent CRF antagonist, astressin, against kainic acid-induced excitotoxic seizures. Intracerebroventricular infusion of the peptide both 30 min before and 10 min after seizures decreased damage in some hippocampal cell fields by as much as 84%, a magnitude of protection greater than reported for other CRF antagonists against other models of necrotic neuronal injury. Administration of astressin was done against both local microinfusion (0.035 microgram) or systemic infusion (10 mg/kg body weight) of the excitotoxin; furthermore, the peptide protected even if administered only 10 min following excitotoxin exposure. This fulfills a critical prerequisite for any eventual therapeutic use of CRF antagonists, namely that they need not be administered in anticipation of a neurological insult.
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Affiliation(s)
- H Maecker
- Department of Biological Sciences, Stanford University, CA 94305, USA
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16
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Smith-Swintosky VL, Pettigrew LC, Sapolsky RM, Phares C, Craddock SD, Brooke SM, Mattson MP. Metyrapone, an inhibitor of glucocorticoid production, reduces brain injury induced by focal and global ischemia and seizures. J Cereb Blood Flow Metab 1996; 16:585-98. [PMID: 8964797 DOI: 10.1097/00004647-199607000-00008] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Increasing evidence indicates that glucocorticoids (GCs), produced in response to physical/emotional stressors, can exacerbate brain damage resulting from cerebral ischemia and severe seizure activity. However, much of the supporting evidence has come from studies employing nonphysiological paradigms in which adrenalectomized rats were compared with those exposed to constant GC concentrations in the upper physiological range. Cerebral ischemia and seizures can induce considerable GC secretion. We now present data from experiments using metyrapone (an 11-beta-hydroxylase inhibitor of GC production), which demonstrate that the GC stress-response worsens subsequent brain damage induced by ischemia and seizures in rats. Three different paradigms of brain injury were employed: middle cerebral artery occlusion (MCAO) model of focal cerebral ischemia; four-vessel occlusion (4VO) model of transient global forebrain ischemia; and kainic acid (KA)-induced (seizure-mediated) excitotoxic damage to hippocampal CA3 and CA1 neurons. Metyrapone (200 mg/kg body wt) was administered systemically in a single i.p. bolus 30 min prior to each insult. In the MCAO model, metyrapone treatment significantly reduced infarct volume and also preserved cells within the infarct. In the 4VO model, neuronal loss in region CA1 of the hippocampus was significantly reduced in rats administered metyrapone. Seizure-induced damage to hippocampal pyramidal neurons (assessed by cell counts and immunochemical analyses of cytoskeletal alterations) was significantly reduced in rats administered metyrapone. Measurement of plasma levels of corticosterone (the species-typical GC of rats) after each insult showed that metyrapone significantly suppressed the injury-induced rise in levels of circulating corticosterone. These findings indicate that endogenous corticosterone contributes to the basal level of brain injury resulting from cerebral ischemia and excitotoxic seizure activity and suggest that drugs that suppress glucocorticoid production may be effective in reducing brain damage in stroke and epilepsy patients.
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Affiliation(s)
- V L Smith-Swintosky
- Sanders-Brown Research Center on Aging, University of Kentucky, Lexington 40536-0230, USA
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17
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Lawrence MS, Ho DY, Dash R, Sapolsky RM. Herpes simplex virus vectors overexpressing the glucose transporter gene protect against seizure-induced neuron loss. Proc Natl Acad Sci U S A 1995; 92:7247-51. [PMID: 7638175 PMCID: PMC41316 DOI: 10.1073/pnas.92.16.7247] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have generated herpes simplex virus (HSV) vectors vIE1GT and v alpha 4GT bearing the GLUT-1 isoform of the rat brain glucose transporter (GT) under the control of the human cytomegalovirus ie1 and HSV alpha 4 promoters, respectively. We previously reported that such vectors enhance glucose uptake in hippocampal cultures and the hippocampus. In this study we demonstrate that such vectors can maintain neuronal metabolism and reduce the extent of neuron loss in cultures after a period of hypoglycemia. Microinfusion of GT vectors into the rat hippocampus also reduces kainic acid-induced seizure damage in the CA3 cell field. Furthermore, delivery of the vector even after onset of the seizure is protective, suggesting that HSV-mediated gene transfer for neuroprotection need not be carried out in anticipation of neurologic crises. Using the bicistronic vector v alpha 22 beta gal alpha 4GT, which coexpresses both GT and the Escherichia coli lacZ marker gene, we further demonstrate an inverse correlation between the extent of vector expression in the dentate and the amount of CA3 damage resulting from the simultaneous delivery of kainic acid.
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Affiliation(s)
- M S Lawrence
- Department of Biological Sciences, Stanford University, CA 94305, USA
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18
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Affiliation(s)
- J L Scully
- Institute of Physiology, University of Basel, Switzerland
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19
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Stittsworth JD, Lanthorn TH. Lactate mimics only some effects of D-glucose on epileptic depolarization and long-term synaptic failure. Brain Res 1993; 630:21-7. [PMID: 8118687 DOI: 10.1016/0006-8993(93)90637-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Lactate supports normal synaptic function and may be neuroprotective following an anoxic insult. The present study investigated the effects of lactate on epileptic depolarization and long-term synaptic failure during a zero-magnesium-induced epileptic insult using the hippocampal slice preparation. In artificial cerebrospinal fluid (aCSF) containing 10 mM D-glucose, no epileptic depolarization was observed. At lower concentrations of D-glucose, epileptic depolarization occurred and often was followed by long-term synaptic failure. Low concentrations of lactate, in place of D-glucose, supported normal synaptic transmission. However, no concentration of lactate tested (up to 30 mM) blocked the occurrence of epileptic depolarization. High concentrations of lactate allowed for partial recovery of synaptic responses following epileptic depolarization. Reinstatement of D-glucose was necessary to observe this recovery. The results confirm that lactate can replace D-glucose in maintaining synaptic responses, but demonstrate that lactate cannot replace D-glucose in blocking an insult-induced depolarization. The inability of lactate to mimic all the effects of D-glucose is consistent with the notion of compartmentation of energy utilization within neurons.
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20
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Abstract
Alcoholism is often associated with brain damage and cognitive deficits. Because drinking patterns can include periods of alcohol consumption followed by abstinence, binge drinking may enhance the possibility of brain damage. Chronic administration of ethanol leads to upregulation of N-methyl-D-aspartate (NMDA) and calcium receptors and increased release of glucocorticoids. NMDA-mediated mechanisms and glucocorticoid actions on the hippocampus are associated with brain damage. Thus, ethanol withdrawal may make the brain more vulnerable to damage from these mechanisms, especially with binge drinking. Therapeutic adjuncts for treating ethanol withdrawal, including NMDA, calcium, and glucocorticoid antagonists, may eventually prove useful in preventing further brain damage in alcoholism.
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Affiliation(s)
- W A Hunt
- Neurosciences and Behavioral Research Branch, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD 20857-0001
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21
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Fox MW, Anderson RE, Meyer FB. Neuroprotection by corticotropin releasing factor during hypoxia in rat brain. Stroke 1993; 24:1072-5; discussion 1075-6. [PMID: 8322382 DOI: 10.1161/01.str.24.7.1072] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND AND PURPOSE Corticotropin releasing factor is an endogenous neuropeptide released by the hypothalamus that activates the pituitary-adrenocortical system in response to stressful stimuli. It has been demonstrated that corticotropin releasing factor increases the excitability of hippocampal neurons in both in vitro and in vivo studies, which may contribute to neurological injury during hypoxia. The purpose of this study was to determine the effects of corticotropin releasing factor and its synthetic competitive antagonist, alpha-CRF, on neuronal synaptic recovery after a hypoxic insult using the hippocampal slice. METHODS Wistar rat hippocampal brain slices (n = 120) were treated with various concentrations (10(-6) to 10(-11)) of corticotropin releasing factor or its synthetic antagonist during a 10-minute hypoxic episode. Extracellular recording of population spikes was used during and after the hypoxic insult to assess neuronal recovery. RESULTS Corticotropin releasing factor provided dose-dependent neuronal protection with maximum recovery (37.95 +/- 8.71%) occurring at 10(-9) concentrations. The competitive antagonist alpha-CRF provided a similar degree of recovery at 10(-6) concentration, whereas 10(-9) molar concentration of competitive antagonist resulted in 16.84 +/- 7.68% recovery. CONCLUSIONS Corticotropin releasing factor provides moderate protection to hypoxic hippocampal neurons in the brain slice preparation. The mechanism of action is unknown but appears to be a direct neuronal effect. These results support the hypothesis that corticotropin releasing factor may act as an endogenous neuroprotective hormone during hypoxia.
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Affiliation(s)
- M W Fox
- Department of Neurosurgery, Mayo Clinic, Rochester, MN 55905
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22
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Abstract
Status epilepticus, particularly the convulsive form, is a medical emergency, warranting prompt and aggressive treatment. To do this, one must have a thorough understanding of the pharmacology of the anticonvulsant agents. Therapy should be directed toward rapid termination of the status epilepticus, prevention of seizure recurrence, and treatment of any underlying cause. Most importantly, one should establish and adhere to a standard treatment protocol for best results.
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Affiliation(s)
- R E Ramsay
- Department of Neurology, University of Miami, Florida
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23
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Tan WK, Williams CE, Gunn AJ, Mallard CE, Gluckman PD. Suppression of postischemic epileptiform activity with MK-801 improves neural outcome in fetal sheep. Ann Neurol 1992; 32:677-82. [PMID: 1449248 DOI: 10.1002/ana.410320511] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To determine the effect of suppression of epileptiform activity that develops after hypoxic-ischemic injury in the immature brain, chronically instrumented near-term fetal sheep (119-133 days) were subjected to 30 minutes of complete cerebral ischemia: 6 were given a 0.3-mg/kg bolus of MK-801 at 6 hours after the insult followed by continuous infusion of 1 mg/kg over the next 36 hours, and were compared to 6 control sheep. Electrocorticographic activity and edema within the parasagittal region of the cortex were quantified with real-time spectral analysis and impedance measurements, respectively. Histological outcome was assessed 72 hours later. The intense epileptiform activity seen from 9 +/- 2 to 30 +/- 3 hours in the control group was completely suppressed in the MK-801-treated group. The onset of secondary cortical edema was delayed from 9.4 +/- 1.1 hours to 14.8 +/- 0.7 hours (p < 0.01). Neuronal damage was reduced, particularly in the lateral cortex and hippocampus (p < 0.05). Infarction of the parasagittal cortex was not prevented. These results suggest that N-methyl-D-aspartate-mediated epileptiform activity that develops after a global hypoxic-ischemic insult worsens neuronal outcome in the immature brain.
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Affiliation(s)
- W K Tan
- Department of Pediatrics, University of Auckland, New Zealand
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24
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Stein-Behrens B, Adams K, Yeh M, Sapolsky R. Failure of beta-amyloid protein fragment 25-35 to cause hippocampal damage in the rat. Neurobiol Aging 1992; 13:577-9. [PMID: 1461345 DOI: 10.1016/0197-4580(92)90058-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Considerable excitement has been generated as of late over reports that fragments of the amyloid precursor protein can be neurotoxic both in vivo and in vitro. In this brief report we study the neurotoxicity of the fragment corresponding to amino acids 25-35 of the beta-amyloid protein in the hippocampus in vivo. Under the conditions studied, we do not observe any evidence of consistent, dose-related damage above that seen with vehicle alone.
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Affiliation(s)
- B Stein-Behrens
- Department of Biological Sciences, Stanford University, CA 94305
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25
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Armanini MP, Hutchins C, Stein BA, Sapolsky RM. Glucocorticoid endangerment of hippocampal neurons is NMDA-receptor dependent. Brain Res 1990; 532:7-12. [PMID: 2149301 DOI: 10.1016/0006-8993(90)91734-x] [Citation(s) in RCA: 173] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The adrenal stress hormones glucocorticoids (GCs) impair the ability of hippocampal neurons to survive neurological insults, including hypoxia-ischemia and seizure. These insults are thought to be toxic via a cascade of excessive synaptic concentrations of excitatory neurotransmitters (e.g. glutamate), activation of the NMDA receptor, and pathologic mobilization of cytosolic calcium post-synaptically. We tested whether GCs exacerbate these insults by exacerbating this 'NMDA cascade'. We sought a toxin which damaged independently of the NMDA cascade, and whose toxicity was enhanced by GCs. After testing a number of neurotoxins, we found that the antimetabolite 3-acetylpyridine (3AP) fit this requirement. We then tested if blockade of the NMDA receptor blocks the ability of GCs to enhance 3AP toxicity. Hippocampi were microinfused with 160 micrograms of 3AP. Elevating circulating GC concentrations to the range seen during major stressors for a week before and after microinfusion caused a significant increase in 3AP-induced damage (when compared to adrenalectomized rats kept GC-free for the same period). Infusing the NMDA receptor blocker APV with 3AP did not alter the toxicity in adrenalectomized rats. However, APV reduced 3AP-induced damage in GC-treated rats to levels seen in adrenalectomized rats. This suggests that GCs endanger hippocampal neurons by enhancing glutamatergic signals and/or enhancing vulnerability to such signals. As a possible explanation for this observation, GCs inhibit glucose uptake into hippocampal neurons, and numerous steps in the NMDA cascade are exacerbated when neuronal energy stores are diminished.
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Affiliation(s)
- M P Armanini
- Department of Biological Sciences, Stanford University, CA 94305
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26
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Hayes RL, Lyeth BG, Jenkins LW, Zimmerman R, McIntosh TK, Clifton GL, Young HF. Possible protective effect of endogenous opioids in traumatic brain injury. J Neurosurg 1990; 72:252-61. [PMID: 2295922 DOI: 10.3171/jns.1990.72.2.0252] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Naloxone (0.1, 1.0, or 20.0 mg/kg), morphine (1.0 or 10.0 mg/kg), or saline was administered systemically intraperitoneally to rats 15 minutes prior to moderate fluid-percussion brain injury. The effects of the drugs were measured on systemic physiological, neurological, and body-weight responses to injury. The animals were trained prior to injury and were assessed for 10 days after injury on body-weight responses and neurological endpoints. Low doses of naloxone (0.1 or 1.0 mg/kg) significantly exacerbated neurological deficits associated with injury. Morphine (10.0 mg/kg) significantly reduced neurological deficits associated with injury. The drugs had no effect on neurological measures or body weight in sham-injured animals. Drug treatments did not significantly alter systemic physiological responses to injury. Data from these experiments suggest the involvement of endogenous opioids in at least some components of neurological deficits following traumatic brain injury and suggest the possibility that at least some classes of endogenous opioids may protect against long-term neurological deficits produced by fluid-percussion injury to the rat.
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Affiliation(s)
- R L Hayes
- Richard Roland Reynolds Neurosurgical Research Laboratories, Department of Surgery, Medical College of Virginia/Virginia Commonwealth University, Richmond
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27
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Sapolsky RM. Glucocorticoids, hippocampal damage and the glutamatergic synapse. PROGRESS IN BRAIN RESEARCH 1990; 86:13-23. [PMID: 1982366 DOI: 10.1016/s0079-6123(08)63163-5] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- R M Sapolsky
- Department of Biological Sciences, Stanford University, CA 94305
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