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Postnikova TY, Griflyuk AV, Zhigulin AS, Soboleva EB, Barygin OI, Amakhin DV, Zaitsev AV. Febrile Seizures Cause a Rapid Depletion of Calcium-Permeable AMPA Receptors at the Synapses of Principal Neurons in the Entorhinal Cortex and Hippocampus of the Rat. Int J Mol Sci 2023; 24:12621. [PMID: 37628802 PMCID: PMC10454714 DOI: 10.3390/ijms241612621] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 08/01/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Febrile seizures (FSs) are a relatively common early-life condition that can cause CNS developmental disorders, but the specific mechanisms of action of FS are poorly understood. In this work, we used hyperthermia-induced FS in 10-day-old rats. We demonstrated that the efficiency of glutamatergic synaptic transmission decreased rapidly after FS by recording local field potentials. This effect was transient, and after two days there were no differences between control and post-FS groups. During early ontogeny, the proportion of calcium-permeable (CP)-AMPA receptors in the synapses of the principal cortical and hippocampal neurons is high. Therefore, rapid internalization of CP-AMPA receptors may be one of the mechanisms underlying this phenomenon. Using the whole-cell patch-clamp method and the selective CP-AMPA receptor blocker IEM-1460, we tested whether the proportion of CP-AMPA receptors changed. We have demonstrated that FS rapidly reduces synaptic CP-AMPA receptors in both the hippocampus and the entorhinal cortex. This process was accompanied by a sharp decrease in the calcium permeability of the membrane of principal neurons, which we revealed in experiments with kainate-induced cobalt uptake. Our experiments show that FSs cause rapid changes in the function of the glutamatergic system, which may have compensatory effects that prevent excessive excitotoxicity and neuronal death.
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Affiliation(s)
| | | | | | | | | | | | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 44, Toreza Prospekt, Saint Petersburg 194223, Russia; (T.Y.P.); (A.V.G.); (A.S.Z.); (E.B.S.); (O.I.B.); (D.V.A.)
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2
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Perversi F, Costa C, Labate A, Lattanzi S, Liguori C, Maschio M, Meletti S, Nobili L, Operto FF, Romigi A, Russo E, Di Bonaventura C. The broad-spectrum activity of perampanel: state of the art and future perspective of AMPA antagonism beyond epilepsy. Front Neurol 2023; 14:1182304. [PMID: 37483446 PMCID: PMC10359664 DOI: 10.3389/fneur.2023.1182304] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 06/07/2023] [Indexed: 07/25/2023] Open
Abstract
Glutamate is the brain's main excitatory neurotransmitter. Glutamatergic neurons primarily compose basic neuronal networks, especially in the cortex. An imbalance of excitatory and inhibitory activities may result in epilepsy or other neurological and psychiatric conditions. Among glutamate receptors, AMPA receptors are the predominant mediator of glutamate-induced excitatory neurotransmission and dictate synaptic efficiency and plasticity by their numbers and/or properties. Therefore, they appear to be a major drug target for modulating several brain functions. Perampanel (PER) is a highly selective, noncompetitive AMPA antagonist approved in several countries worldwide for treating different types of seizures in various epileptic conditions. However, recent data show that PER can potentially address many other conditions within epilepsy and beyond. From this perspective, this review aims to examine the new preclinical and clinical studies-especially those produced from 2017 onwards-on AMPA antagonism and PER in conditions such as mesial temporal lobe epilepsy, idiopathic and genetic generalized epilepsy, brain tumor-related epilepsy, status epilepticus, rare epileptic syndromes, stroke, sleep, epilepsy-related migraine, cognitive impairment, autism, dementia, and other neurodegenerative diseases, as well as provide suggestions on future research agenda aimed at probing the possibility of treating these conditions with PER and/or other AMPA receptor antagonists.
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Affiliation(s)
| | - Cinzia Costa
- Section of Neurology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
- Neurological Clinic, S. Maria Della Misericordia Hospital, Perugia, Italy
| | - Angelo Labate
- Neurophysiopatology and Movement Disorders Clinic, University of Messina, Messina, Italy
| | - Simona Lattanzi
- Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Claudio Liguori
- Department of Systems Medicine, University of Rome ‘Tor Vergata”, Rome, Italy
- Epilepsy Center, Neurology Unit, University Hospital “Tor Vergata”, Rome, Italy
| | - Marta Maschio
- Center for Tumor-Related Epilepsy, UOSD Neuro-Oncology, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - Stefano Meletti
- Neurology Department, University Hospital of Modena, Modena, Italy
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio-Emilia, Modena, Italy
| | - Lino Nobili
- Child Neuropsychiatry Unit, IRCCS Istituto G. Gaslini, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Child and Maternal Health (DINOGMI), University of Genova, Genova, Italy
| | - Francesca Felicia Operto
- Child and Adolescent Neuropsychiatry Unit, Department of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
- Department of Science of Health, School of Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Andrea Romigi
- Sleep Medicine Center, Neurological Mediterranean Institute IRCCS Neuromed, Pozzilli, Italy
- Psychology Faculty, International Telematic University Uninettuno, Rome, Italy
| | - Emilio Russo
- Department of Science of Health, School of Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Carlo Di Bonaventura
- Epilepsy Unit, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
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Jean WH, Huang CT, Hsu JH, Chiu KM, Lee MY, Shieh JS, Lin TY, Wang SJ. Anticonvulsive and Neuroprotective Effects of Eupafolin in Rats Are Associated with the Inhibition of Glutamate Overexcitation and Upregulation of the Wnt/β-Catenin Signaling Pathway. ACS Chem Neurosci 2022; 13:1594-1603. [PMID: 35500294 DOI: 10.1021/acschemneuro.2c00227] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Several plant compounds have been found to possess neuroactive properties. The aim of this study was to investigate the anticonvulsant effect of eupafolin, a major active component extracted from Salvia plebeia, a herb used in traditional medicine for its anti-inflammatory properties. To this end, we assessed the anticonvulsant effects of eupafolin in rats intraperitoneally (i.p.) injected with kainic acid (KA) to elucidate this mechanism. Treatment with eupafolin (i.p.) for 30 min before KA administration significantly reduced behavioral and electrographic seizures induced by KA, similar to carbamazepine (i.p.), a widely used antiepileptic drug. Eupafolin treatment also significantly decreased KA seizure-induced neuronal cell death and glutamate elevation in the hippocampus. In addition, eupafolin notably reversed KA seizure-induced alterations in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit GluR2, glutamate decarboxylase 67 (GAD67, GABAergic enzyme), and Wnt signaling-related proteins, including porcupine, Wnt1, phosphorylated-glycogen synthase kinase-3β, β-catenin, and Bcl-2 in the hippocampus. Furthermore, the increased level of Dickkopf-related protein 1 (Dkk-1, a Wnt signaling antagonist) and the decreased level of Disheveled1 (Dvl-1, a Wnt signaling activator) in the hippocampus of KA-treated rats were reversed by eupafolin. This study provides evidence of the anticonvulsant and neuroprotective properties of eupafolin and of the involvement of regulation of glutamate overexcitation and Wnt signaling in the mechanisms of these properties. These findings support the benefits of eupafolin in treating epilepsy.
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Affiliation(s)
- Wei-Horng Jean
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Chih-Ta Huang
- Department of Neurosurgery, Cathay General Hospital, Taipei City 106, Taiwan
| | - Jung-Hsuan Hsu
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 24205, Taiwan
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Electrical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Department of Medical Research, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
| | - Jiann-Shing Shieh
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 22060, Taiwan
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan
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4
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Amakhin DV, Soboleva EB, Chizhov AV, Zaitsev AV. Insertion of Calcium-Permeable AMPA Receptors during Epileptiform Activity In Vitro Modulates Excitability of Principal Neurons in the Rat Entorhinal Cortex. Int J Mol Sci 2021; 22:12174. [PMID: 34830051 PMCID: PMC8621524 DOI: 10.3390/ijms222212174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 12/19/2022] Open
Abstract
Epileptic activity leads to rapid insertion of calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (CP-AMPARs) into the synapses of cortical and hippocampal glutamatergic neurons, which generally do not express them. The physiological significance of this process is not yet fully understood; however, it is usually assumed to be a pathological process that augments epileptic activity. Using whole-cell patch-clamp recordings in rat entorhinal cortex slices, we demonstrate that the timing of epileptiform discharges, induced by 4-aminopyridine and gabazine, is determined by the shunting effect of Ca2+-dependent slow conductance, mediated predominantly by K+-channels. The blockade of CP-AMPARs by IEM-1460 eliminates this extra conductance and consequently increases the rate of discharge generation. The blockade of NMDARs reduced the additional conductance to a lesser extent than the blockade of CP-AMPARs, indicating that CP-AMPARs are a more significant source of intracellular Ca2+. The study's main findings were implemented in a mathematical model, which reproduces the shunting effect of activity-dependent conductance on the generation of discharges. The obtained results suggest that the expression of CP-AMPARs in principal neurons reduces the discharge generation rate and may be considered as a protective mechanism.
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Affiliation(s)
- Dmitry V. Amakhin
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Elena B. Soboleva
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Anton V. Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
- Ioffe Institute, Russian Academy of Sciences, Polytekhnicheskaya 26, 194021 Saint Petersburg, Russia
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
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5
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Zaitsev АV, Amakhin DV, Dyomina AV, Zakharova MV, Ergina JL, Postnikova TY, Diespirov GP, Magazanik LG. Synaptic Dysfunction in Epilepsy. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s002209302103008x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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6
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Mohammad H, Sekar S, Wei Z, Moien-Afshari F, Taghibiglou C. Perampanel but Not Amantadine Prevents Behavioral Alterations and Epileptogenesis in Pilocarpine Rat Model of Status Epilepticus. Mol Neurobiol 2018; 56:2508-2523. [PMID: 30039334 DOI: 10.1007/s12035-018-1230-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/08/2018] [Indexed: 12/26/2022]
Abstract
Pilocarpine-induced status epilepticus (SE), which results in the development of spontaneous recurrent seizures (SRSs) activates glutamatergic receptors that contribute to seizure sustenance and neuronal cell death. In the current study, we evaluate whether the exposure to perampanel, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor blocker, or amantadine, a N-methyl-D-aspartic acid (NMDA) receptor blocker would reduce the SE-induced long-term consequences. SE was induced in adult male Sprague Dawley rats with pilocarpine. Perampanel or amantadine was injected 10 or 60 min after SE onset. The efficacy of either, in overcoming pilocarpine-induced SE was assessed using electroencephalogram (EEG) recordings. In addition, alterations in cognitive function, development of spontaneous recurrent seizures (SRSs), and hippocampal damage that are generally encountered after SE were also assessed at 72 h and 5 weeks after the induction of SE. Our results indicate that both early and late treatment with perampanel but not amantadine significantly reduced seizure activity. Furthermore, perampanel but not amantadine, reversed the memory deficits in Y-maze and novel object recognition (NOR) tests and retarded the appearance of SRSs. Moreover, perampanel treatment led to reduced SE-induced caspase-3 activation in the hippocampal lysates. Taken together, the data obtained from the study reveals that blocking AMPA receptors by perampanel can modify SE-induced long-term consequences. Our results may provide a proof of principle for the potential therapeutic application of perampanel in clinical use for status epilepticus in future.
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Affiliation(s)
- Hanan Mohammad
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Sathiya Sekar
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Zelan Wei
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Farzad Moien-Afshari
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada.
- Department of Medicine, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada.
- Division of Neurology, Department of Medicine, University of British Colombia, 8247-2775 Laurel St, Vancouver, BC, V5Z 1M9, Canada.
| | - Changiz Taghibiglou
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada.
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7
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Pathology of nNOS-Expressing GABAergic Neurons in Mouse Model of Alzheimer's Disease. Neuroscience 2018; 384:41-53. [PMID: 29782905 DOI: 10.1016/j.neuroscience.2018.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/04/2018] [Accepted: 05/10/2018] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia that is often accompanied by mood and emotional disturbances and seizures. There is growing body of evidence that neurons expressing γ-aminobutyric acid (GABA) play an important role in regulation of cognition, mood, and emotion as well as seizure susceptibility, but participation of GABAergic neuronal pathology in Alzheimer's disease (AD) is not understood well at present. Here, we report that transgenic mice expressing human amyloid precursor protein Swedish-Dutch-Iowa mutant (APPSweDI) exhibit early loss of neurons expressing GAD67, a GABA-synthesizing enzyme, in advance of the loss of pyramidal neurons in hippocampal CA1 region. The loss of GAD67+ neurons in APPSweDI mice accompanied with decreased spatial cognition as well as increased anxiety-like behaviors and kainic acid-induced seizure susceptibility at early phase. In the hippocampal CA1 region, GAD67+ neurons expressed high basal levels of neuronal nitric oxide synthase (nNOS) and nitrosative stress (nitrotyrosine). Similarly, GAD67+ neurons in primary cortical and hippocampal neuron cultures also expressed high basal levels of nNOS and degenerated in response to lower Aβ concentrations due to their high basal levels of nitrosative stress. Given the role of GABAergic neurons in cognitive and neuropsychiatric functions, this study reports the role of nNOS-mediated nitrosative stress in dysfunction of GABAergic neurons and its potential participation in early development of cognitive and neuropsychiatric symptoms in AD.
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8
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Leo A, Giovannini G, Russo E, Meletti S. The role of AMPA receptors and their antagonists in status epilepticus. Epilepsia 2018; 59:1098-1108. [DOI: 10.1111/epi.14082] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Antonio Leo
- Department of Science of Health; University Magna Graecia of Catanzaro; Catanzaro Italy
| | - Giada Giovannini
- Department of Biomedical Metabolic and Neural Sciences; University of Modena and Reggio Emilia; Modena Italy
| | - Emilio Russo
- Department of Science of Health; University Magna Graecia of Catanzaro; Catanzaro Italy
| | - Stefano Meletti
- Department of Biomedical Metabolic and Neural Sciences; University of Modena and Reggio Emilia; Modena Italy
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9
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Changes of AMPA receptor properties in the neocortex and hippocampus following pilocarpine-induced status epilepticus in rats. Neuroscience 2016; 327:146-55. [PMID: 27109923 DOI: 10.1016/j.neuroscience.2016.04.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 04/09/2016] [Accepted: 04/14/2016] [Indexed: 11/22/2022]
Abstract
Temporal lobe epilepsy (TLE) is the most common type of epilepsy in humans. The lithium-pilocarpine model in rodents reproduces some of the main features of human TLE. Three-week-old Wistar rats were used in this study. The changes in AMPA receptor subunit composition were investigated in several brain areas, including the medial prefrontal cortex (mPFC), the temporal cortex (TC), and the dorsal (DH) and ventral hippocampus (VH) during the first week following pilocarpine-induced status epilepticus (PILO-induced SE). In the hippocampus, GluA1 and GluA2 mRNA expression slightly decreased after PILO-induced SE and returned to the initial level on the seventh day. We did not detect any significant changes in mRNA expression of the GluA1 and GluA2 subunits in the TC, whereas in the mPFC we observed a significant increase of GluA1 mRNA expression on the third day and a decrease in GluA2 mRNA expression during the entire first week. Accordingly, the GluA1/GluA2 expression ratio increased in the mPFC, and the functional properties of the pyramidal cell excitatory synapses were disturbed. Using whole-cell voltage-clamp recordings, we found that on the third day following PILO-induced SE, isolated mPFC pyramidal neurons showed an inwardly rectifying current-voltage relation of kainate-evoked currents, suggesting the presence of GluA2-lacking calcium-permeable AMPARs (CP-AMPARs). IEM-1460, a selective antagonist of CP-AMPARs, significantly reduced the amplitude of evoked EPSC in pyramidal neurons from mPFC slices on the first and third days, but not on the seventh day. The antagonist had no effects on EPSC amplitude in slices from control animals. Thus, our data demonstrate that PILO-induced SE affects subunit composition of AMPARs in different brain areas, including the mPFC. SE induces transient (up to few days) incorporation of CP-AMPARs in the excitatory synapses of mPFC pyramidal neurons, which may disrupt normal circuitry functions.
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10
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Friedman LK, Slomko AM, Wongvravit JP, Naseer Z, Hu S, Wan WY, Ali SS. Efficacy of Retigabine on Acute Limbic Seizures in Adult Rats. J Epilepsy Res 2015; 5:46-59. [PMID: 26819936 PMCID: PMC4724852 DOI: 10.14581/jer.15010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/01/2015] [Indexed: 12/17/2022] Open
Abstract
Background and Purpose: The efficacy of retigabine (RGB), a positive allosteric modulator of K+ channels indicated for adjunct treatment of partial seizures, was studied in two adult models of kainic acid (KA)-induced status epilepticus to determine it’s toleratbility. Methods: Retigabine was administered systemiclly at high (5 mg/kg) and low (1–2 mg/kg) doses either 30 min prior to or 2 hr after KA-induced status epilepticus. High (1 µg/µL) and low (0.25 µg/µL) concentrations of RGB were also delivered by intrahippocampal microinjection in the presence of KA. Results: Dose-dependent effects of RGB were observed with both models. Lower doses increased seizure behavior latency and reduced the number of single spikes and synchronized burst events in the electroencephalogram (EEG). Higher doses worsened seizure behavior, produced severe ataxia, and increased spiking activity. Animals treated with RGB that were resistant to seizures did not exhibit significant injury or loss in GluR1 expression; however if stage 5–6 seizures were reached, typical hippocampal injury and depletion of GluR1 subunit protein in vulernable pyramidal fields occurred. Conclusions: RGB was neuroprotective only if seizures were significantly attenuated. GluR1 was simultaneously suppressed in the resistant granule cell layer in presence of RGB which may weaken excitatory transmission. Biphasic effects observed herein suggest that the human dosage must be carefully scrutinized to produce the optimal clinical response.
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Affiliation(s)
- L K Friedman
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - A M Slomko
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - J P Wongvravit
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - Z Naseer
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - S Hu
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - W Y Wan
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
| | - S S Ali
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA
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11
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Liang Y, Guo XL, Chen JX, Yue GX. Effects of the chinese traditional prescription xiaoyaosan decoction on chronic immobilization stress-induced changes in behavior and ultrastructure in rat hippocampus. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2013; 2013:984797. [PMID: 24381641 PMCID: PMC3865635 DOI: 10.1155/2013/984797] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 11/01/2013] [Indexed: 01/03/2023]
Abstract
Xiaoyaosan (XYS) decoction has been widely used as a traditional medicine for treating stress and depression-related disorders in China for thousands of years. Aim of the Study. To observe the potential mechanism of XYS decoction's antidepressant-like effect in α -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors related to synaptic plasticity in the hippocampus rats induced by chronic immobilization stress (CIS). Materials and Methods. Animals were randomly divided into five groups: (1) control group; (2) sham-operated group; (3) CIS group, in which rats were conducted CIS for 21 days; (4) XYS decoction treatment group; (5) 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) positive group, in which the amygdala of CIS rats was unilaterally microinjected with a competitive glutamate receptor antagonist, CNQX. After CIS for 21 days, the open field test (OPT) and elevated plus-maze test (EPM) were measured, the ultrastructure of hippocampus CA1 subregion was observed by the electron microscopy; both the GluR1 and GluR2 mRNA level of AMPA receptor subunits in hippocampus CA1 subregion were detected by real-time qPCR. Results. Rats subjected to CIS exhibited increases in time in central zone and decreases in total distance traveled in the OPT. In the EPM, they also showed decreases in center zone time and entries, open arm time and entries, and an increase in close arm time. Ultrastructural damage in the hippocampus CA1 was also observed. XYS decoction and CNQX showed significant improvement behavioral changes and the ultrastructural damage of the hippocampus CA1; XYS decoction also reversed CIS-induced decreases in GluR2 mRNA and increases in GluR1 mRNA in the hippocampus CA1 as well as CNQX. Conclusions. XYS decoction may effectively produce an antidepressant-like effect, which appears to be involved AMPA receptors related synaptic plasticity of hippocampus.
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Affiliation(s)
- Yuan Liang
- School of Pre-Clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
- Institute of Basic Theory in Chinese Medicine, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Xiao-Ling Guo
- School of Pre-Clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
- Fangzhuang Community Health Center, Beijing 100078, China
| | - Jia-Xu Chen
- School of Pre-Clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
- Department of Basic Theory in Chinese Medicine, Henan University of Traditional Chinese Medicine, Zhengzhou 450008, China
| | - Guang-Xin Yue
- Institute of Basic Theory in Chinese Medicine, China Academy of Chinese Medical Sciences, Beijing 100700, China
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12
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Saghyan A, LaTorre GN, Keesey R, Sharma A, Mehta V, Rudenko V, Hallas BH, Rafiuddin A, Goldstein B, Friedman LK. Glutamatergic and morphological alterations associated with early life seizure-induced preconditioning in young rats. Eur J Neurosci 2010; 32:1897-911. [DOI: 10.1111/j.1460-9568.2010.07464.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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13
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Friedman LK, Segal M. Early exposure of cultured hippocampal neurons to excitatory amino acids protects from later excitotoxicity. Int J Dev Neurosci 2009; 28:195-205. [DOI: 10.1016/j.ijdevneu.2009.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 09/10/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022] Open
Affiliation(s)
- Linda K. Friedman
- Neuroscience DepartmentNew York College of Osteopathic Medicine/New York Institute of TechnologyNorthern BoulevardOld WestburyNY11568United States
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14
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Status epilepticus induces a TrkB to p75 neurotrophin receptor switch and increases brain-derived neurotrophic factor interaction with p75 neurotrophin receptor: An initial event in neuronal injury induction. Neuroscience 2008; 154:978-93. [DOI: 10.1016/j.neuroscience.2008.04.038] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 04/03/2008] [Accepted: 04/04/2008] [Indexed: 01/12/2023]
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15
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Zhao Q, Raghavendra M, Holmes GL. Effect of TTX suppression of hippocampal activity following status epilepticus. Seizure 2008; 17:637-45. [PMID: 18486497 DOI: 10.1016/j.seizure.2008.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 01/21/2008] [Accepted: 04/10/2008] [Indexed: 11/17/2022] Open
Abstract
Status epilepticus (SE) is a severe neurological condition that can result in brain damage. In animals, SE is associated with cell loss and aberrant synaptogenesis. These pathological processes appear to be activity-dependent and may continue after the SE has ended. We postulated that suppression of electrical activity following SE at the site of the epileptic focus will reduce seizure-induced damage. To achieve this goal, tetrodotoxin (TTX) was used to suppress electrical activity in the hippocampi bilaterally following SE. Adult rats experienced lithium-pilocarpine-induced SE for 2h while controls underwent sham-SE with saline injections. Starting 12h after the SE or sham-SE rats received either continuous TTX (1 microM) or saline infusions through cannulas implanted in the bilateral hippocampi for 5h daily for 4 days. TTX resulted in significant EEG suppression and reduction in spikes and sharp waves. Rats were sacrificed 2 weeks after SE and the brains examined for cell loss and sprouting. Rats receiving TTX following SE had significantly more cell loss as well as a trend toward more mossy fiber sprouting than saline-treated rats following SE. TTX injection in sham-SE rats caused no cell loss or mossy fiber sprouting. These results suggest that suppression of electrical activity following SE is detrimental.
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Affiliation(s)
- Qian Zhao
- Neuroscience Center at Dartmouth, Department of Neurology, Dartmouth Medical School, Hanover, NH 03756, USA.
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16
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Cosgrave AS, McKay JS, Bubb V, Morris R, Quinn JP, Thippeswamy T. Regulation of activity-dependent neuroprotective protein (ADNP) by the NO-cGMP pathway in the hippocampus during kainic acid-induced seizure. Neurobiol Dis 2008; 30:281-292. [PMID: 18375135 DOI: 10.1016/j.nbd.2008.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 01/30/2008] [Accepted: 02/01/2008] [Indexed: 12/11/2022] Open
Abstract
Activity-dependent neuroprotective protein (ADNP) is widely distributed in the cytoplasm of neurons and astrocytes of the hippocampus. Kainic acid (KA)-induced seizures increases neuronal nitric oxide synthase (nNOS) in neurons and inducible NOS (iNOS) in glia cells which coincides with a reduction in ADNP in the hippocampus. Inhibitors of NOS or soluble guanylyl cyclase (sGC) activity reduce ADNP under basal conditions in the absence of seizures. Treating animals with these inhibitors prior to KA-induced seizure, in particular, L-NAME (N(G)-nitro-l-arginine methyl ester), advances the onset of the first seizure but reverses the loss of ADNP by 3 days after the first seizure. This suggests that the NO-cGMP pathway has a role in regulating ADNP under both basal physiological conditions and in the pathophysiological changes produced during epileptogenesis.
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Affiliation(s)
- Anna S Cosgrave
- Department of Veterinary Preclinical Science, Veterinary Faculty, University of Liverpool, Brownlow Hill, Liverpool, L69 7ZJ, UK
| | - Jennifer S McKay
- AstraZeneca, Department of Pathology Safety Assessment, Alderley Park, Macclesfield, SK10 4TG, UK
| | - Vivien Bubb
- School of Biomedical Sciences, Medical School, University of Liverpool, Liverpool L69 3BX, UK
| | - Richard Morris
- Department of Veterinary Preclinical Science, Veterinary Faculty, University of Liverpool, Brownlow Hill, Liverpool, L69 7ZJ, UK
| | - John P Quinn
- School of Biomedical Sciences, Medical School, University of Liverpool, Liverpool L69 3BX, UK
| | - Thimmasettappa Thippeswamy
- Department of Veterinary Preclinical Science, Veterinary Faculty, University of Liverpool, Brownlow Hill, Liverpool, L69 7ZJ, UK.
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17
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Mukherjee P, Thomas S, Pasinetti GM. Complement anaphylatoxin C5a neuroprotects through regulation of glutamate receptor subunit 2 in vitro and in vivo. J Neuroinflammation 2008; 5:5. [PMID: 18230183 PMCID: PMC2246107 DOI: 10.1186/1742-2094-5-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 01/29/2008] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The complement system is thought to be involved in the pathogenesis of numerous neurological diseases. We previously reported that pre-treatment of murine cortico-hippocampal neuronal cultures with the complement derived anaphylatoxin C5a, protects against glutamate mediated apoptosis. Our present study with C5a receptor knock out (C5aRKO) mice corroborates that the deficiency of C5a renders C5aRKO mouse more susceptible to apoptotic injury in vivo. In this study we explored potential upstream mechanisms involved in C5a mediated neuroprotection in vivo and in vitro. METHODS Based on evidence suggesting that reduced expression of glutamate receptor subunit 2 (GluR2) may influence apoptosis in neurons, we studied the effect of human recombinant C5a on GluR2 expression in response to glutamate neurotoxicity. Glutamate analogs were injected into C5aRKO mice or used to treat in vitro neuronal culture and GluR2 expression were assessed in respect with cell death. RESULTS In C5aRKO mice we found that the neurons are more susceptible to excitotoxicity resulting in apoptotic injury in the absence of the C5a receptor compared to WT control mice. Our results suggest that C5a protects against apoptotic pathways in neurons in vitro and in vivo through regulation of GluR2 receptor expression. CONCLUSION Complement C5a neuroprotects through regulation of GluR2 receptor subunit.
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Affiliation(s)
- Piali Mukherjee
- Department of Psychiatry, Mount Sinai School of Medicine, 1 Gustav L,, Levy Place, New York, NY 10029, USA.
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18
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El-Hassar L, Esclapez M, Bernard C. Hyperexcitability of the CA1 hippocampal region during epileptogenesis. Epilepsia 2007; 48 Suppl 5:131-9. [PMID: 17910593 DOI: 10.1111/j.1528-1167.2007.01301.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Temporal Lobe Epilepsy (TLE) is often preceded by a latent (seizure-free) period during which complex network reorganizations occur. In experimental epilepsy, network hyperexcitability is already present during the latent period, suggesting a modification of information processing. The purpose of this study was to assess the input/output relationship in the hippocampal CA1 region during epileptogenesis. Field recordings in strata pyramidale and radiatum were used to measure the output of CA1 pyramidal cells as a function of the synaptic inputs they receive following the stimulation of Shaffer collaterals in slices obtained from sham and pilocarpine-treated animals during the latent and chronic periods. We show that there is a transient increase of the input and output field responses during the latent period as compared to sham and epileptic animals. The coupling between excitatory inputs and cell firing was also increased during the latent period. This increase persisted in epileptic animals, although to a lesser extent. We also confirm that paired-pulse facilitation occurs before the chronic phase. The present data further support the view that hyperexcitability is present at an early stage of epileptogenesis. Network output is more facilitated during the latent than during the chronic period. Hyperexcitability may participate to epileptogenesis, but it is not sufficient in itself to produce seizures.
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Affiliation(s)
- Lynda El-Hassar
- INMED-INSERM U29, Université de la Méditerranée, Marseille, France
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19
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NR1 Knockdown Reveals CA1 Injuryduring a Developmental Period of High Seizure Susceptibility Despite Reduced Seizure Activity. Neuromolecular Med 2007; 9:298-314. [DOI: 10.1007/s12017-007-8009-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Accepted: 07/05/2007] [Indexed: 11/24/2022]
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20
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Gashi E, Avallone J, Webster T, Friedman LK. Altered excitability and distribution of NMDA receptor subunit proteins in cortical layers of rat pups following multiple perinatal seizures. Brain Res 2007; 1145:56-65. [PMID: 17320824 DOI: 10.1016/j.brainres.2007.01.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/18/2007] [Accepted: 01/29/2007] [Indexed: 11/19/2022]
Abstract
During a critical period of postnatal development the epileptogenic focus is thought to be of cortical origin. We used immunohistochemistry and Western blotting to elucidate potential mechanisms underlying an increased state of susceptibility to seizures in immature animals. Distribution patterns of N-methyl-D-aspartic acid (NMDA) (NR1 and NR2A/B) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) (GluR1 and GluR2) subunits were analyzed in retrosplenial, parietal and temporal cortices during the first two postnatal weeks following three episodes of status-epilepticus. Rat pups were injected three times with kainic acid (3x KA) on P6, P9, and P13 and subsequently sacrificed 48 h after the third seizure. Cortical electroencephalography (EEG) showed increased number of spikes and bursts of longer duration after 3x KA. Immunodensity measurements after 3x KA revealed a robust increase in NR2A/B labeling specific to cortical layer V throughout the retrosplenial, parietal, and temporal cortices, with no changes noted in piriform cortex. NR1 layer V immunoreactivity was also simultaneously increased in serial sections but to a lesser degree; heightened immunodensities were specific to retrosplenial and temporal cortices. The NR1:NR2 ratio was decreased in cortical layer V of the temporal and retrosplenial cortices but not in parietal cortex despite elevated immunoreactivity. Steady levels of GluR1 and GluR2 subunits were noted in all cortical areas studied in the same animals. Thus, recurrent perinatal seizures led to selective and layer-specific increases in NMDA receptor proteins. These changes may be responsible for lowering the seizure threshold in deeper cortical areas and eventually contribute to the cortical epileptogenic focus.
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Affiliation(s)
- Eleonora Gashi
- Neuroscience Department, New York Institute of Technology, NY College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY 11568, USA
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21
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Scantlebury MH, Heida JG, Hasson HJ, Velísková J, Velísek L, Galanopoulou AS, Moshé SL. Age-Dependent Consequences of Status Epilepticus: Animal Models. Epilepsia 2007; 48 Suppl 2:75-82. [PMID: 17571355 DOI: 10.1111/j.1528-1167.2007.01069.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Status epilepticus (SE) is a significant neurological emergency that occurs most commonly in children. Although SE has been associated with an elevated risk of brain injury, it is unclear from clinical studies in whom and under what circumstances brain injury will occur. The purpose of this review is to evaluate the effects of age on the consequences of SE. In this review, we focus mainly on the animal data that describe the consequences of a single episode of SE induced in the adult and immature rat brain. The experimental data suggest that the risk of developing SE-induced brain damage, subsequent epilepsy and cognitive deficits in large part depends on the age in which the SE occurs. Younger rats are more resistant to seizure-induced brain damage than older rats; however, when SE occurs in immature rats with abnormal brains, there is an increase in the severity of seizure-induced brain injury. Better understanding of the pathophysiologic mechanisms underlying the age-specific alterations to the brain induced by SE will lead to the development of novel and effective strategies to improve the deleterious consequences.
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Affiliation(s)
- Morris H Scantlebury
- Korey Department of Neurology, Albert Einstein College of Medicine, Pelham Parkway South, Kennedy Center, Bronx, NY, USA.
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22
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Friedman LK, Avallone JM, Magrys B. Maturational Effects of Single and Multiple Early-Life Seizures on AMPA Receptors in Prepubescent Hippocampus. Dev Neurosci 2007; 29:427-37. [PMID: 17314473 DOI: 10.1159/000100078] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 07/22/2006] [Indexed: 11/19/2022] Open
Abstract
The effects of single versus multiple episodes of status epilepticus on the expression of AMPA receptors during a critical growth spurt are unknown. To determine whether the pattern of hippocampal AMPA receptor subunit expression depends upon the age of the animal, timing and number of perinatal seizures, we characterized maturational changes in AMPA receptor protein levels of the hippocampus with immunohistochemistry and Western blotting in rats of juvenile ages with and without a history of neonatal seizures. Kainic acid (KA) was used to induce a single episode of status epilepticus (1 x KA) in rats on P20 or P30. Animals with a history of multiple seizures (3 x KA) were given KA on P6, P9, and then on P20 or P30. After 1 x KA, in P20 and P30 rats that are preferentially sensitive to CA1 damage, GluR1 immunoreactivity was depleted remarkably in CA1 stratum pyramidale and stratum lucidum and only morphologically healthy cells were faintly labeled. At P30, GluR2 subunit expression was nearly absent in the healthy cells and increased within the injured CA1 neuronal population. Western blot analysis confirmed that the GluR1/GluR2 ratio was decreased at P20 and further decreased at P30. A history of perinatal seizures (3 x KA) prevented the age-dependent alterations in the CA1. Except for areas of cell loss, NR1 and NR2A/B antibody labeling was relatively stable throughout the hippocampus at both ages and conditions examined. Data suggest that (i) Ca2+ permeable AMPA receptors may not be responsible for neuronal injury or irreversible cell loss and that (ii) the expression of AMPA receptors after status epilepticus depends upon the age of the animal, the timing of the first insult and subsequent formation of AMPA receptor subunit compositions within specific populations of hippocampal neurons.
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Affiliation(s)
- L K Friedman
- New York College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA.
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23
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Shimshek DR, Jensen V, Celikel T, Geng Y, Schupp B, Bus T, Mack V, Marx V, Hvalby Ø, Seeburg PH, Sprengel R. Forebrain-specific glutamate receptor B deletion impairs spatial memory but not hippocampal field long-term potentiation. J Neurosci 2006; 26:8428-40. [PMID: 16914668 PMCID: PMC6674347 DOI: 10.1523/jneurosci.5410-05.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate the fundamental importance of glutamate receptor B (GluR-B) containing AMPA receptors in hippocampal function by analyzing mice with conditional GluR-B deficiency in postnatal forebrain principal neurons (GluR-B(deltaFb)). These mice are as adults sufficiently robust to permit comparative cellular, physiological, and behavioral studies. GluR-B loss induced moderate long-term changes in the hippocampus of GluR-B(deltaFb) mice. Parvalbumin-expressing interneurons in the dentate gyrus and the pyramidal cells in CA3 were decreased in number, and neurogenesis in the subgranular zone was diminished. Excitatory synaptic CA3-to-CA1 transmission was reduced, although synaptic excitability, as quantified by the lowered threshold for population spike initiation, was increased compared with control mice. These changes did not alter CA3-to-CA1 long-term potentiation (LTP), which in magnitude was similar to LTP in control mice. The altered hippocampal circuitry, however, affected spatial learning in GluR-B(deltaFb) mice. The primary source for the observed changes is most likely the AMPA receptor-mediated Ca2+ signaling that appears after GluR-B depletion, because we observed similar alterations in GluR-B(QFb) mice in which the expression of Ca2+-permeable AMPA receptors in principal neurons was induced by postnatal activation of a Q/R-site editing-deficient GluR-B allele.
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24
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Jia YH, Zhu X, Li SY, Ni JH, Jia HT. Kainate exposure suppresses activation of GluR2 subunit promoter in primary cultured cerebral cortical neurons through induction of RE1-silencing transcription factor. Neurosci Lett 2006; 403:103-8. [PMID: 16701950 DOI: 10.1016/j.neulet.2006.04.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 11/24/2022]
Abstract
The AMPA receptor subunit GluR2 is downregulated in neurons following a wide range of neurological insults. Here we report that suppression of GluR2 gene promoter activity is associated with kainate (KA)-induced downregulation of GluR2 subunit levels in primary cultured cortical neurons. RT-PCR and Northern blotting showed a significant decrease in GluR2 mRNA in cultured neurons after KA exposure. Transfection of cultured neurons with an expression vector pGL3-GluR2(-298/+283), where the reporter gene firefly luciferase was driven by the GluR2 promoter, revealed that KA exposure suppressed the transcriptional activation of the GluR2 promoter. Furthermore, the expression of the RE1-silencing transcription factor (REST) was increased in KA-exposed cortical neurons; enhanced binding of REST to RE1-like silencer element in the proximal promoter of the GluR2 subunit gene was evidenced by electrophoresis mobility shift assay. Chromatin immunoprecipitation showed that suppressed activity of the GluR2 promoter in cultured neurons after KA exposure was related to deacetylation of histone H4. These results indicate that REST as a crucial factor binds to RE1-like silencer element in the GluR2 promoter, suppressing transcription of the GluR2 subunit gene during KA exposure. Our data suggest that transcriptional suppression of the GluR2 subunit gene may contribute at least in part to downregulation of GluR2 subunit protein in neurons during KA exposure. Because our experiments showed a reduction of glutamate release in KA-exposed cortical neurons, REST may play a latent role in delayed neuronal death or in seizure-induced tolerance.
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MESH Headings
- Acetylation
- Animals
- Blotting, Northern
- Cells, Cultured
- Cerebral Cortex/cytology
- Cerebral Cortex/metabolism
- Chromatin Immunoprecipitation
- Down-Regulation
- Electrophoretic Mobility Shift Assay
- Genes, Reporter
- Histones/metabolism
- Kainic Acid/metabolism
- Kainic Acid/toxicity
- Luciferases, Firefly/antagonists & inhibitors
- Luciferases, Firefly/genetics
- Neurons/drug effects
- Neurons/metabolism
- Promoter Regions, Genetic
- Protein Subunits/antagonists & inhibitors
- Protein Subunits/genetics
- RNA, Messenger/antagonists & inhibitors
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/genetics
- Repressor Proteins/biosynthesis
- Reverse Transcriptase Polymerase Chain Reaction
- Silencer Elements, Transcriptional
- Transcription Factors/biosynthesis
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Affiliation(s)
- Yu-Hong Jia
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Xue Yuan Road 38, Beijing 100083, PR China
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25
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Wang Q, Yu S, Simonyi A, Sun GY, Sun AY. Kainic acid-mediated excitotoxicity as a model for neurodegeneration. Mol Neurobiol 2006; 31:3-16. [PMID: 15953808 DOI: 10.1385/mn:31:1-3:003] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 11/15/2004] [Indexed: 02/06/2023]
Abstract
Neuronal excitation involving the excitatory glutamate receptors is recognized as an important underlying mechanism in neurodegenerative disorders. Excitation resulting from stimulation of the ionotropic glutamate receptors is known to cause the increase in intracellular calcium and trigger calcium-dependent pathways that lead to neuronal apoptosis. Kainic acid (KA) is an agonist for a subtype of ionotropic glutamate receptor, and administration of KA has been shown to increase production of reactive oxygen species, mitochondrial dysfunction, and apoptosis in neurons in many regions of the brain, particularly in the hippocampal subregions of CA1 and CA3, and in the hilus of dentate gyrus (DG). Systemic injection of KA to rats also results in activation of glial cells and inflammatory responses typically found in neurodegenerative diseases. KA-induced selective vulnerability in the hippocampal neurons is related to the distribution and selective susceptibility of the AMPA/kainate receptors in the brain. Recent studies have demonstrated ability of KA to alter a number of intracellular activities, including accumulation of lipofuscin-like substances, induction of complement proteins, processing of amyloid precursor protein, and alteration of tau protein expression. These studies suggest that KA-induced excitotoxicity can be used as a model for elucidating mechanisms underlying oxidative stress and inflammation in neurodegenerative diseases. The focus of this review is to summarize studies demonstrating KA-induced excitotoxicity in the central nervous system and possible intervention by anti-oxidants.
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Affiliation(s)
- Qun Wang
- Department of Medical Pharmacology, University of Missouri School of Medicine, Columbia, MO, USA
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26
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Angehagen M, Rönnbäck L, Hansson E, Ben-Menachem E. Topiramate reduces AMPA-induced Ca(2+) transients and inhibits GluR1 subunit phosphorylation in astrocytes from primary cultures. J Neurochem 2005; 94:1124-30. [PMID: 16092949 DOI: 10.1111/j.1471-4159.2005.03259.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Topiramate (TPM) is a structurally novel broad spectrum anticonvulsant known to have a negative modulatory effect on the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate subtypes of glutamate receptors and some types of voltage-gated Na(+) and Ca(2+) channels, and a positive modulatory effect on some types of gamma-aminobutyric acid(A) (GABA(A)) receptors and at least one type of K(+) channels in neurons. In an earlier work, we showed that the negative modulatory effect of TPM (100 mum) on AMPA/kainate receptors in neurons is dependent on TPM modulation of the phosphorylation state of these receptors. In this work, we investigated the effect of TPM on AMPA-induced intracellular calcium ([Ca(2+)](i)) responses in cultured rat cortical astrocytes, with special interest in intracellular mechanisms. Here, we report that the ability of TPM (1-100 mum) to inhibit AMPA-induced accumulation of Ca(2+) in astrocytes is inversely related to the level of protein kinase A (PKA) -mediated phosphorylation of channels activated by AMPA. The level of receptor phosphorylation was further determined with western blot using phosphorylation specific antibodies that recognize the glutamate receptor 1 (GluR1) subunit phosphorylated on Ser845. These results demonstrated that, even in cultured cortical astrocytes, TPM significantly reduced the phophorylation level of GluR1 subunits. Furthermore, it was shown that TPM binds to AMPA receptors in the dephosphorylated state and thereby exerts an allosteric modulatory effect on the ion channel.
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Affiliation(s)
- Mikael Angehagen
- Institute of Clinical Neuroscience, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
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27
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Noh KM, Yokota H, Mashiko T, Castillo PE, Zukin RS, Bennett MVL. Blockade of calcium-permeable AMPA receptors protects hippocampal neurons against global ischemia-induced death. Proc Natl Acad Sci U S A 2005; 102:12230-5. [PMID: 16093311 PMCID: PMC1189338 DOI: 10.1073/pnas.0505408102] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transient global or forebrain ischemia induced experimentally in animals can cause selective, delayed neuronal death of hippocampal CA1 pyramidal neurons. A striking feature is a delayed rise in intracellular free Zn(2+) in CA1 neurons just before the onset of histologically detectable cell death. Here we show that alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) at Schaffer collateral to CA1 synapses in postischemic hippocampus exhibit properties of Ca(2+)/Zn(2+)-permeable, Glu receptor 2 (GluR2)-lacking AMPARs before the rise in Zn(2+) and cell death. At 42 h after ischemia, AMPA excitatory postsynaptic currents exhibited pronounced inward rectification and marked sensitivity to 1-naphthyl acetyl spermine (Naspm), a selective channel blocker of GluR2-lacking AMPARs. In control hippocampus, AMPA excitatory postsynaptic currents were electrically linear and relatively insensitive to Naspm. Naspm injected intrahippocampally at 9-40 h after insult greatly reduced the late rise in intracellular free Zn(2+) in postischemic CA1 neurons and afforded partial protection against ischemia-induced cell death. These results implicate GluR2-lacking AMPA receptors in the ischemia-induced rise in free Zn(2+) and death of CA1 neurons, although a direct action at the time of the rise in Zn(2+) is unproven. This receptor subtype appears to be an important therapeutic target for intervention in ischemia-induced neuronal death in humans.
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Affiliation(s)
- Kyung-Min Noh
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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28
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Yu MF, Chien CL, Lee WT, Yin HS. Effects of acute amphetamine administration on AMPA-mediated synaptic activity and expression of AMPA receptor subunit 2 of brain neurons. J Mol Neurosci 2005; 25:171-81. [PMID: 15784965 DOI: 10.1385/jmn:25:2:171] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2004] [Accepted: 05/12/2004] [Indexed: 11/11/2022]
Abstract
We investigated the role of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor (AMPAR) in mechanisms underlying the action of amphetamine (Amph) on brain neurons, for AMPAR has been proposed to participate in psychotic and neurodegenerative disorders. In the cultured rat brain cortical neurons pretreated with 1 microM Amph for 1 h, the accumulation of 45Ca2+ driven by 10 min incubation with 100 microM AMPA was reduced by about 36%. This Amph-induced decrease seems to involve L-type voltage-gated Ca2+ channels, because the AMPA-induced 45Ca2+ uptake was blocked by 70% and 80%, respectively, for untreated and Amph-treated neurons in the presence of nifedipine (1 microM), an antagonist to L-type calcium channels. Whole-cell, patch-clamp recording revealed that AMPA-elicited current amplitude became 26% lower than the control in Amph-treated cultured neurons. Moreover, Amph treatment down-regulated the level of flip-form glutamate receptor 2 (GluR2) mRNA by 27% in cultured neurons but did not change the expression of GluR2 proteins and flop-form mRNA, as detected by quantitative immunocytochemistry and in situ hybridization. In contrast, in postnatal day 4 rats at 1 h after receiving one intraperitoneal injection of 5 mg/kg of Amph, levels of flip GluR2 mRNA were up-regulated by 13% and 18% in neurons of motor cortex layer 5 and pyramidal neurons of hippocampal CA3, respectively. The data suggest that acute action of Amph on brain neurons is possibly associated with decreased AMPA-mediated Ca2+ influx and current amplitude, as well as modified expression of the GluR2 mRNA.
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Affiliation(s)
- Meng-Fen Yu
- Chang Gang Institute of Technology, School of Nursing, Tao-Yuan, Taiwan, ROC
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29
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Kang TC, Kim DS, Yoo KY, Hwang IK, Kwak SE, Kim JE, Jung JY, Won MH, Suh JG, Oh YS. Elevated voltage-gated Ca2+ channel immunoreactivities in the hippocampus of seizure-prone gerbil. Brain Res 2005; 1029:168-78. [PMID: 15542071 DOI: 10.1016/j.brainres.2004.09.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2004] [Indexed: 11/20/2022]
Abstract
In present study, we investigated voltage-gated Ca2+ channel (VGCC) expressions in the hippocampus of the Mongolian gerbil and its association with different sequelae of spontaneous seizures, in an effort to identify the epileptogenesis in this animal. In the hippocampus of pre-seizure seizure sensitive (SS) gerbils, VGCC subunit expressions were significantly elevated, as compared with seizure-resistant (SR) gerbils. In 3 h postictal group, the alteration of VGCC expressions showed regional- and neuronal-specific manners; VGCC immunoreactivities in principal neurons were markedly decreased; however, their immunoreactivities in interneurons were significantly elevated. These results are the first comprehensive description of the distribution of VGCC immunoreactivities in the normal and epileptic hippocampus of gerbils, and suggest that these alterations in the hippocampus of the SS gerbil may be related with tissue excitability and have a role in modulating recurrent excitation following seizures.
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Affiliation(s)
- Tae-Cheon Kang
- Department of Anatomy, College of Medicine, Hallym University, Chunchon, Kangwon-Do 200-702, South Korea.
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30
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Myers SJ, Huang Y, Genetta T, Dingledine R. Inhibition of glutamate receptor 2 translation by a polymorphic repeat sequence in the 5'-untranslated leaders. J Neurosci 2004; 24:3489-99. [PMID: 15071096 PMCID: PMC6729757 DOI: 10.1523/jneurosci.4127-03.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous studies have identified multiple transcription initiation sites for the glutamate receptor 2 (GluR2) gene, resulting in a heterogeneous population of GluR2 transcripts in vivo that differ in the length of their 5'-untranslated leaders (5'-UTR). We designed a series of monocistronic and dicistronic GluR2 cDNA constructs that model the natural in vivo transcripts and investigated their translation efficiencies in rabbit reticulocyte lysates, Xenopus oocytes, and primary cultured neurons. Transcripts containing long 5' leaders (429 and 481 bases) were translated poorly compared with those with shorter leaders (341 or fewer bases). None of the five initiation codons in the 5'-UTR or the leader length per se were responsible for translation regulation. Rather, control of translation was mediated by a sequence containing a 34-42 nucleotide imperfect GU repeat predicted to form secondary structure in vivo. This translation suppression domain is included in some but not all rat and human GluR2 transcripts in vivo, depending on the site of transcription initiation. Rat cortex GluR2 transcripts that lack the translation suppression sequence were preferentially associated with polyribosomes. Furthermore, the GU-repeat cluster was found to be polymorphic in humans, raising the possibility that expansion or contraction of the GU-repeat cluster in certain populations might modify the level of GluR2 protein expression in neurons.
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Affiliation(s)
- Scott J Myers
- Department of Pharmacology, Emory University, Atlanta, Georgia 30322, USA
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Abstract
Status epilepticus (SE) is a frequent neurological emergency associated with a significant risk of morbidity in survivors. Impairment of hippocampal-specific memory is a common and serious deficit occurring in many of the survivors. However, the pathophysiological basis of cognitive deficits after SE is not clear. To directly address the cellular concomitants of spatial memory impairment, we recorded the activity of place cells from CA1 in freely moving rats subjected to SE during early development and compared this activity to that in control rats. Place cells discharge rapidly only when the rat's head is in a cell-specific part of the environment called the "firing field." This firing field remains stable over time. Normal place cell function seems to be essential for stable spatial memory for the environment. We, therefore, compared place cell firing patterns with visual-spatial memory in the water maze in SE and control rats. Compared with controls, place cells from the SE rats were less precise and less stable. Concordantly, the water maze performance was also impaired. There was a close relationship between precision and stability of place cells and water maze performance. In contrast, a single, acute, chemically induced seizure produced cessation of place cell activity and spatial memory impairment in water maze performance that reversed within 24 hr. These results strongly bolster the idea that there is a relationship between abnormal place cells and spatial memory. Our findings also suggest that the defects in place cell and spatial memory after SE and acute chemically induced seizures result from different processes.
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Zemlan FP, Mulchahey JJ, Gudelsky GA. Quantification and localization of kainic acid-induced neurotoxicity employing a new biomarker of cell death: cleaved microtubule-associated protein-tau (c-tau). Neuroscience 2003; 121:399-409. [PMID: 14521998 DOI: 10.1016/s0306-4522(03)00459-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous studies of neuronal degeneration induced by the neurotoxin, kainic acid, employed silver stain techniques that are non-quantitative or ELISA measurement of the non-neuronal protein, glial fibrillary acidic protein. As previous studies employed biomarkers that were either non-quantitative or non-neuronal, the present study employed a new neuronally localized biomaker of neuronal damage, cleaved microtubule-associated protein (MAP)-tau (C-tau). The time course of kainate neurotoxicity was quantitatively determined in several brain regions in the present study employing a C-tau specific ELISA. Differences in ELISA determined regional brain levels of C-tau were compared with the density of somatodendritic C-tau labeling qualitatively determined in immunohistochemical anatomical mapping studies of kainic acid-treated animals. Immunoblot studies revealed that the C-tau antibodies employed in the present study were highly specific for proteolytic cleaved C-tau. Immunolabeling of 45 kD-50 kD C-tau proteins was observed only in brain samples from kainic acid-treated but not vehicle-treated rats. Time course studies revealed that C-tau levels determined by ELISA were maximal 3 days after kainic acid with C-tau levels increasing 26-fold in hippocampus, 16-fold in cortex and four-fold in both striatum and hypothalamus. These statistical differences in maximal C-tau levels observed in the ELISA studies were similar to differences qualitatively observed in C-tau immunohistochemical studies. C-tau immunohistochemistry revealed extensive damage in hippocampal regions CA1 and 3, moderate damage in several cortical regions and mild damage in striatum and hypothalamus. Similar cleavage of rat MAP-tau to C-tau has been reported after neuronal degeneration induced by neurotoxic doses of methamphetamine and neuronal degeneration resulting from bacterial meningitis. In humans, C-tau proteolysis has been demonstrated to be a reliable biomarker of neuronal damage in traumatic brain injury and stroke where cerebrospinal C-tau levels are correlated with patient clinical outcome. These data suggest that C-tau proteolysis may prove a reliable species independent biomarker of neuronal degeneration regardless of source of injury.
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Affiliation(s)
- F P Zemlan
- Department of Psychiatry, College of Medicine, 231 Sabin Avenue, University of Cincinnati, Cincinnati, OH 45267, USA.
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Friedman LK, Velísková J, Kaur J, Magrys BW, Liu H. GluR2(B) knockdown accelerates CA3 injury after kainate seizures. J Neuropathol Exp Neurol 2003; 62:733-50. [PMID: 12901700 DOI: 10.1093/jnen/62.7.733] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ca2+ currents are thought to enhance glutamate excitotoxicity. To investigate whether reduced expression of the Ca2+ limiting GluR2(B) subunit enhances seizure-induced vulnerability to either CA1 or CA3 neurons, we delivered GluR2(B) oligodeoxynucleotides (AS-ODNs) to the dorsal hippocampus of adult rats before inducing kainate (KA) seizures. After knockdown, no changes in behavior, electrographic activity, or histology were observed. In contrast, GluR2(B) knockdown and KA-induced status epilepticus produced accelerated histological injury to the ipsilateral CA3a-b and hilar subregions. At 8 to 12 h, the CA3a was preferentially labeled by both silver and TUNEL methods. TUNEL staining revealed 2 types of nuclei. They were round with uniform label, features of necrosis, or had DNA clumping or speckled chromatin deposits within surrounding cytosol, features of apoptosis. At 16 to 24 h, many CA3a-c neurons were shrunken, eosinophilic, argyrophilic, or completely absent. Immunohistochemistry revealed marked decreases in GluR2(B) subunits throughout the hippocampus, NR1 immunoreactivity was also reduced but to a lesser extent. In contrast, GluR1 and NR2A/B immunohistochemistry was relatively uniform except in regions of cell loss or within close proximity to the CA1 infusion site. At 144 h, the CA3 was still preferentially injured although bilateral CA1 injury was also observed in some AS-ODN-, S-ODN-, and KA-only-treated animals. Glutamate receptor antibodies revealed generalized decreases in the CA3 with all probes tested at this delayed time. In contrast, GluR2(B) expression was increased within CA1 irregularly shaped, injured neurons. Therefore, hippocampal deprivation of GluR2(B) subunits is insufficient to induce cell death in mature animals but may accelerate the already known CA3/hilar lesion, possibly by triggering apoptosis within CA3 neurons. CA1 and DG survive the first week despite their loss of GluR2(B) subunits, suggesting that other intrinsic properties such as increased Na+ conductance and reduced ability of the GluR2(B) subunit to interact with certain cytoplasmic proteins may be responsible for the augmented cell death rather than changes in AMPA receptor-mediated Ca2+ permeability. Alternatively, changes in allosteric interactions that affect other receptor classes of high density at the mossy fiber synapse (e.g. KA receptors) may augment KA neurotoxicity. Latent GluR2(B) increases in CA1 injured neurons support a role for AMPA receptor subunit alterations in seizure-induced tolerance.
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Affiliation(s)
- Linda K Friedman
- Department of Neuroscience, Seton Hall University, South Orange, New Jersey 07079, USA.
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34
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Schauwecker PE. Differences in ionotropic glutamate receptor subunit expression are not responsible for strain-dependent susceptibility to excitotoxin-induced injury. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 112:70-81. [PMID: 12670704 DOI: 10.1016/s0169-328x(03)00048-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Systemic administration of kainic acid in C57BL/6 and FVB/N mice induces a comparable level of seizure induction yet results in differential susceptibility to seizure-induced cell death. While kainate administration causes severe hippocampal damage in mice of the FVB/N strain, C57BL/6 mice display no demonstrable cell loss or damage. At present, while the cellular mechanisms underlying strain-dependent differences in susceptibility remain unclear, some of this variation is assumed to have a genetic basis. As glutamate receptors are thought to participate in seizure induction and the subsequent neuronal degeneration that ensues, previous studies have proposed that variation in the precise subunit composition of glutamate receptors may result in differential susceptibility to excitotoxic cell death. Thus, we chose to examine the relationship between the cellular distribution and expression of glutamate receptor subunit proteins and cell loss within the hippocampus in mouse strains resistant and susceptible to kainate-induced excitotoxicity. Using semi-quantitative Western blot techniques and immunohistochemistry with the use of antibodies that recognize subunits of the KA (GluR5,6,7), AMPA (GluR1, GluR2, and GluR4), and NMDA (NMDAR1 and NMDAR2A/2B) receptors, we found no significant strain-dependent differences in the expression or distribution of these glutamate receptor subunits in the intact hippocampus. Following kainate administration, expression changes in ionotropic glutamate receptor subunits paralleled the development of susceptibility to cell death in the FVB/N strain only. Strain differences in hippocampal vulnerability to kainate-induced status epilepticus are not due to glutamate receptor protein expression.
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MESH Headings
- Animals
- Cell Death/genetics
- Disease Models, Animal
- Drug Resistance/genetics
- Epilepsy/genetics
- Epilepsy/metabolism
- Epilepsy/physiopathology
- Genetic Predisposition to Disease/genetics
- Glutamic Acid/metabolism
- Glutamic Acid/toxicity
- Immunohistochemistry
- Kainic Acid/metabolism
- Kainic Acid/toxicity
- Male
- Mice
- Mice, Inbred C57BL
- Nerve Degeneration/genetics
- Nerve Degeneration/metabolism
- Nerve Degeneration/physiopathology
- Neurotoxins/metabolism
- Neurotoxins/toxicity
- Protein Subunits/genetics
- Protein Subunits/metabolism
- Receptors, AMPA/genetics
- Receptors, AMPA/metabolism
- Receptors, Glutamate/genetics
- Receptors, Glutamate/metabolism
- Receptors, Kainic Acid/genetics
- Receptors, Kainic Acid/metabolism
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Species Specificity
- Synaptic Transmission/drug effects
- Synaptic Transmission/genetics
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Affiliation(s)
- Paula Elyse Schauwecker
- Department of Cell and Neurobiology, University of Southern California, Keck School of Medicine, BMT 401, 1333 San Pablo Street, Los Angeles, CA 90089-9112, USA.
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Mikati MA, Abi-Habib RJ, El Sabban ME, Dbaibo GS, Kurdi RM, Kobeissi M, Farhat F, Asaad W. Hippocampal programmed cell death after status epilepticus: evidence for NMDA-receptor and ceramide-mediated mechanisms. Epilepsia 2003; 44:282-91. [PMID: 12614382 DOI: 10.1046/j.1528-1157.2003.22502.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE Status epilepticus (SE) can result in acute neuronal injury with subsequent long-term age-dependent behavioral and histologic sequelae. To investigate potential mechanisms that may underlie SE-related neuronal injury, we studied the occurrence of programmed cell death (PCD) in the hippocampus in the kainic acid (KA) model. METHODS In adult rats, KA-induced SE resulted in DNA fragmentation documented at 30 h after KA injection. Ceramide, a known mediator of PCD in multiple neural and nonneural tissues, increased at 2-3 h after KA intraperitoneal injection, and then decreased to control levels before increasing again from 12 to 30 h after injection. MK801 pretreatment prevented KA-induced increases in ceramide levels and DNA fragmentation, whether there was reduction in seizure severity or not (achieved with 5 mg/kg and 1 mg/kg of MK801, respectively). RESULTS Both ceramide increases and DNA fragmentation were observed after KA-induced SE in adult and in P35 rats. Ceramide did not increase after KA-induced SE in P7 pups, which also did not manifest any DNA fragmentation. Intrahippocampal injection of the active ceramide analogue C2-ceramide produced widespread DNA fragmentation, whereas the inactive ceramide analogue C2-dihydroceramide did not. CONCLUSIONS Our data support the hypotheses that (a) N-methyl-d-aspartate-receptor activation results in ceramide increases and in DNA fragmentation; (b) ceramide is a mediator of PCD after SE; and (c) there are age-related differences in PCD and in the ceramide response after SE. Differences in the ceramide response could, potentially, be responsible for observed age-related differences in the response to SE.
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Affiliation(s)
- Mohamad A Mikati
- Adult and Pediatric Epilepsy Program, Department of Pediatrics, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
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36
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Wang S, Jia Z, Roder J, Murphy TH. AMPA receptor-mediated miniature synaptic calcium transients in GluR2 null mice. J Neurophysiol 2002; 88:29-40. [PMID: 12091530 DOI: 10.1152/jn.2002.88.1.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
AMPA-type glutamate receptors are normally Ca(2+) impermeable due to the expression of the GluR2 receptor subunit. By using GluR2 null mice we were able to detect miniature synaptic Ca(2+) transients (MSCTs) associated with AMPA-type receptor-mediated miniature synaptic currents at single synapses in primary cortical cultures. MSCTs and associated Ca(2+) transients were monitored under conditions that isolated responses mediated by AMPA or N-methyl-D-aspartate (NMDA) receptors. As expected, addition of the antagonist 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX, 3 microM) blocked the AMPA receptor-mediated MSCTs. Voltage-gated Ca(2+) channels did not contribute to AMPA MSCTs because CdCl(2) (0.1-0.2 mM) did not significantly alter the frequency or the amplitude of the MSCTs. The amplitude of AMPA MSCTs appeared to be regulated independently from event frequency since the two measures were not correlated (R = 0.023). Synapses were identified that only expressed MSCTs attributed to either NMDA or AMPA receptors. At synapses with only NMDA responses, MSCT amplitude was significantly lower (by 40%) than synapses expressing both NMDA and AMPA responses. At synapses that showed MSCTs mediated by both AMPA and NMDA receptors, the amplitude of the transients in each condition was positively correlated (R = 0.94). Our results suggest that when AMPA and NMDA receptors are co-expressed at synapses, mechanisms exist to ensure proportional scaling of each receptor type that are distinct from the presynaptic factors controlling the frequency of miniature release.
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Affiliation(s)
- Sabrina Wang
- Kinsmen Laboratory, Department of Psychiatry, University of British Columbia, Vancouver, British Columbia V6T 1Z3
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37
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Abstract
AMPA receptor (AMPAR)-mediated ionic currents that govern gene expression, synaptic strength, and plasticity also can trigger excitotoxicity. However, native AMPARs exhibit heterogeneous pharmacological, biochemical, and ionic permeability characteristics, which are governed partly by receptor subunit composition. Consequently, the mechanisms governing AMPAR-mediated excitotoxicity have been difficult to elucidate. The GluR2 subunit is of particular interest because it influences AMPAR pharmacology, Ca(2+) permeability, and AMPAR interactions with intracellular proteins. In this paper we used mutant mice lacking the AMPAR subunit GluR2 to study AMPAR-mediated excitotoxicity in cultured cortical neurons and in hippocampal neurons in vivo. We examined the hypothesis that in these mice the level of GluR2 expression governs the vulnerability of neurons to excitotoxicity and further examined the ionic mechanisms that are involved. In cortical neuronal cultures AMPAR-mediated neurotoxicity paralleled the magnitude of kainate-evoked AMPAR-mediated currents, which were increased in neurons lacking GluR2. Ca(2+) permeability, although elevated in GluR2-deficient neurons, did not correlate with excitotoxicity. However, toxicity was reduced by removal of extracellular Na(+), the main charge carrier of AMPAR-mediated currents. In vivo, the vulnerability of CA1 hippocampal neurons to stereotactic kainate injections and of CA3 neurons to intraperitoneal kainate administration was independent of GluR2 level. Neurons lacking the GluR2 subunit did not demonstrate compensatory changes in the distribution, expression, or function of AMPARs or of Ca(2+)-buffering proteins. Thus GluR2 level may influence excitotoxicity by effects additional to those on Ca(2+) permeability, such as effects on agonist potency, ionic currents, and synaptic reorganization.
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38
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Grossman SD, Rosenberg LJ, Wrathall JR. Relationship of altered glutamate receptor subunit mRNA expression to acute cell loss after spinal cord contusion. Exp Neurol 2001; 168:283-9. [PMID: 11259116 DOI: 10.1006/exnr.2001.7629] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Alterations in the expression of ionotropic glutamate receptors (GluR) contribute to neuronal loss after brain ischemia and epilepsy. In order to determine whether altered expression of GluR subunits might contribute to cell loss after spinal cord injury (SCI), we performed a time course study of subunit mRNA expression using quantitative in situ hybridization. Expression was studied in ventral horn motor neurons (VMN) and glia in adjacent ventral white matter at 15 min and 4, 8, and 24 h after SCI in tissue sections 4 mm rostral and caudal to the injury epicenter. We found that the AMPA subunit GluR2 was significantly down-regulated in VMN at 24 h, but not at the earlier times examined, although half the loss of VMN in these locations occurs by 8 h after injury. No changes in the normal expression of GluR2 or GluR4 were found in white matter where glial loss occurs after SCI. NMDA subunits NR1 and NR2A were significantly and rapidly up-regulated in VMN after SCI, but only caudal to the lesion site, while VMN loss is similar rostral and caudal to the epicenter. Thus, the temporal pattern of AMPA and the spatial pattern of NMDA subunit expression changes were distinct from the pattern of VMN loss after SCI. We conclude that altered GluR subunit expression after SCI is unlikely to be involved in secondary cell loss and instead may be involved with plasticity and reorganization of the injured spinal cord.
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Affiliation(s)
- S D Grossman
- Department of Cell Biology, Georgetown University Medical Center, 3970 Reservoir Road, Washington, DC 20007, USA
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39
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Suzuki F, Hirai H, Onteniente B, Riban V, Matsuda M, Kurokawa K. Long-term increase of GluR2 alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunit in the dispersed dentate gyrus after intrahippocampal kainate injection in the mouse. Neuroscience 2001; 101:41-50. [PMID: 11068135 DOI: 10.1016/s0306-4522(00)00359-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intrahippocampal injection of a subtoxic dose of kainate in mice has been shown to induce a dispersion of granule cells of the dentate gyrus, which is a characteristic morphological change often seen in human hippocampal sclerosis. In addition, it has been shown recently that such injections lead to recurrent hippocampal seizures and changes in glucose metabolism, which are reminiscent of temporal lobe epilepsy. Previous reports on human hippocampal sclerosis have shown an increase of the expression of the GluR2 alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate subunits in the dispersed granule cell somata. However, no such changes have been observed so far in animal models of epilepsy with hippocampal sclerosis. In this study, the expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunits was examined by immunohistochemistry following intrahippocampal injection of kainate in mice and rats. In mice, such injection induced a persistent increase of GluR2 immunoreactivity in the granule cells for up to 180 days. By contrast, GluR1 immunoreactivity was transiently increased during the first four days after the injection and progressively decreased thereafter. By contrast, intrahippocampal injection of kainate in rats did not result in granule cell dispersion and no changes in GluR1 immunoreactivity or GluR2 immunoreactivity were observed. These results show that, in addition to morphological, clinical and metabolical similarities, intrahippocampal injection of kainate results in a persistent increase of GluR2 associated with granule cell dispersion, as in human hippocampal sclerosis. These data suggest the existence of common mechanisms between granule cell dispersion and regulation of GluR2 subunits associated with hippocampal sclerosis.
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Affiliation(s)
- F Suzuki
- Department of Neurosurgery and Anatomy, Shiga University of Medical Science, Seta-Tsukinowa-cho, Ohtsu, Shiga 520-2192, Japan.
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40
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Friedman LK, Ginsberg MD, Belayev L, Busto R, Alonso OF, Lin B, Globus MY. Intraischemic but not postischemic hypothermia prevents non-selective hippocampal downregulation of AMPA and NMDA receptor gene expression after global ischemia. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 86:34-47. [PMID: 11165369 DOI: 10.1016/s0169-328x(00)00252-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hypothermia may afford histological neuroprotection induced by ischemia by preventing aberrant Ca2+ influx through NMDA (N-methyl-D-aspartic acid) or Ca2+-permeable AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptors. Expression of hippocampal GluR1A, GluR2B, GluR3C and NMDAR1 (NR1) subunits was investigated by in situ hybridization at 1 and 7 days after 10-min transient global ischemia in the presence and absence of intraischemic or postischemic brain hypothermia (30 degrees C). At 1 day, normothermic ischemia markedly suppressed the expression of GluR1A, GluR2B, and GluR3C receptor mRNAs to a similar degree in the vulnerable CA1. Less vulnerable CA3a-c subregions were also acutely downregulated. NR1 mRNA expression was reduced in CA1 but to a lesser extent than AMPA mRNAs. At 7 days after normothermic ischemia, a time of marked CA1 cell loss, all three AMPA transcripts were nearly absent in CA1 while a percentage (33.9+/-7.2%) of NR1 mRNA remained. Intraischemic hypothermia fully blocked the damage and non-selective mRNA downregulations at 1 and 7 days. By contrast, postischemic hypothermia postponed neurodegeneration but only partially rescued the expression of AMPA and NR1 mRNAs at 7 days and not at 1 day after the insult. Therefore, hippocampal AMPA receptor mRNAs decline at a relatively similar rate after normothermic global ischemia and cellular neuroprotection by intraischemic hypothermia occurred independently of altered subunit composition of AMPA receptors. Since decreases persist within resistant neurons under the postischemic condition, AMPA receptor-mediated Ca2+ currents probably do not contribute to selective vulnerability.
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Affiliation(s)
- L K Friedman
- Department of Neuroscience, Seton Hall University/NJ Neuroscience Institute at JFK Medical Center, 400 South Orange Avenue, South Orange, NJ 07079, USA.
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41
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Vellucci SV, Parrott RF. Gene expression in the forebrain of dexamethasone-treated pigs: effects on stress neuropeptides in the hypothalamus and hippocampus and glutamate receptor subunits in the hippocampus. Res Vet Sci 2000; 69:25-31. [PMID: 10924390 DOI: 10.1053/rvsc.2000.0380] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Gene expression studies advance our understanding of the effects of stress and glucocorticoids on brain function and give a new direction to animal welfare research. In this context, the presence of messenger RNA s (m RNA s) for corticotrophin releasing hormone (CRH) and vasopressin (VP) in the porcine hypothalamus has recently been documented. This study investigated the expression of CRH, VP and ionotropic glutamate receptor (iGluR) subunit m RNA s in the brains of pigs treated with the synthetic glucocorticoid dexamethasone (Dex; 5 mg kg(-1)i.v.). In the hypothalamus, VP, but not CRH, m RNA was reduced 3 hours after Dex. In the hippocampus, expression of m RNA s for some iGluR subunits appeared to be differentially regulated 6 hours after Dex. In addition, CRH message was detected in the hippocampus and significantly upregulated in the CA1 region 3 hours after Dex. The relevance of these findings to stress neurobiology of the growing pig is discussed.
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MESH Headings
- Animals
- Corticotropin-Releasing Hormone/biosynthesis
- Corticotropin-Releasing Hormone/chemistry
- Corticotropin-Releasing Hormone/genetics
- DNA Probes/chemistry
- Dexamethasone/pharmacology
- Gene Expression Regulation/drug effects
- Glucocorticoids/pharmacology
- Hippocampus/drug effects
- Hippocampus/metabolism
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Image Processing, Computer-Assisted
- In Situ Hybridization/veterinary
- Male
- RNA, Messenger/biosynthesis
- Receptors, AMPA/biosynthesis
- Receptors, AMPA/chemistry
- Receptors, AMPA/genetics
- Receptors, N-Methyl-D-Aspartate/biosynthesis
- Receptors, N-Methyl-D-Aspartate/chemistry
- Receptors, N-Methyl-D-Aspartate/genetics
- Stress, Physiological/metabolism
- Stress, Physiological/veterinary
- Swine/physiology
- Vasopressins/biosynthesis
- Vasopressins/chemistry
- Vasopressins/genetics
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Affiliation(s)
- S V Vellucci
- MAFF Welfare and Behaviour Laboratory, Department of Neurobiology, The Babraham Institute, Cambridge, UK.
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42
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Grooms SY, Opitz T, Bennett MV, Zukin RS. Status epilepticus decreases glutamate receptor 2 mRNA and protein expression in hippocampal pyramidal cells before neuronal death. Proc Natl Acad Sci U S A 2000; 97:3631-6. [PMID: 10725374 PMCID: PMC16291 DOI: 10.1073/pnas.97.7.3631] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kainic acid (KA)-induced status epilepticus in adult rats leads to delayed, selective death of pyramidal neurons in the hippocampal CA1 and CA3. Death is preceded by down-regulation of glutamate receptor 2 (GluR2) mRNA and protein [the subunit that limits Ca(2+) permeability of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] in CA1 and CA3, as indicated by in situ hybridization, immunolabeling, and quantitative Western blotting. GluR1 mRNA and protein are unchanged or slightly increased before cell death. These changes could lead to formation of GluR2-lacking, Ca(2+)-permeable AMPA receptors and increased toxicity of endogenous glutamate. GluR2 immunolabeling is unchanged in granule cells of the dentate gyrus, which are resistant to seizure-induced death. Thus, formation of Ca(2+)-permeable AMPA receptors may be a critical mediator of delayed neurodegeneration after status epilepticus.
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Affiliation(s)
- S Y Grooms
- Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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43
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Status epilepticus decreases glutamate receptor 2 mRNA and protein expression in hippocampal pyramidal cells before neuronal death. Proc Natl Acad Sci U S A 2000. [PMID: 10725374 PMCID: PMC16291 DOI: 10.1073/pnas.050586497] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kainic acid (KA)-induced status epilepticus in adult rats leads to delayed, selective death of pyramidal neurons in the hippocampal CA1 and CA3. Death is preceded by down-regulation of glutamate receptor 2 (GluR2) mRNA and protein [the subunit that limits Ca(2+) permeability of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] in CA1 and CA3, as indicated by in situ hybridization, immunolabeling, and quantitative Western blotting. GluR1 mRNA and protein are unchanged or slightly increased before cell death. These changes could lead to formation of GluR2-lacking, Ca(2+)-permeable AMPA receptors and increased toxicity of endogenous glutamate. GluR2 immunolabeling is unchanged in granule cells of the dentate gyrus, which are resistant to seizure-induced death. Thus, formation of Ca(2+)-permeable AMPA receptors may be a critical mediator of delayed neurodegeneration after status epilepticus.
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Friedman LK, Belayev L, Alfonso OF, Ginsberg MD. Distribution of glutamate and preproenkephalin messenger RNAs following transient focal cerebral ischemia. Neuroscience 2000; 95:841-57. [PMID: 10670452 DOI: 10.1016/s0306-4522(99)00452-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Middle cerebral artery occlusion may result in increased activation of N-methyl-D-aspartate- or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)-type receptors by glutamate and lead to neuronal cell death. To characterize molecular events that precede cell death following transient focal ischemia, in situ hybridization histochemistry was used to measure levels of glutamate receptor subunit 1 (GluR1), GluR2, GluR3, N-methyl-D-aspartate receptor subunit 1 (NR1) and preproenkephalin messenger RNAs in adult rats at various recirculation times (1.5, 3 and 24 h) following a 90-min period of middle cerebral artery occlusion. At 1.5 and 3 h recirculation, autoradiography showed pronounced but differential decreases in AMPA, NR1 and preproenkephalin messenger RNA expression throughout the infarcted ipsilateral striatum. Non-uniform patterns of in situ hybridization grains emerged such that many striatal neurons were depleted of AMPA and preproenkephalin messenger RNAs, while others retained control levels. In cortical regions destined to undergo infarction, GluR2 and NR1 messenger RNAs were preferentially reduced relative to the contralateral side (to 75+/-8.5% and 66+/-4.5%, respectively); GluR1, GluR3 and preproenkephalin messenger RNAs were unaltered. At 24 h recirculation, depletion of striatal and cortical messenger RNAs became less selective. GluR3 and preproenkephalin messenger RNAs were up-regulated in ipsilateral spared regions of the striatum, and GluR1 and GluR2 messenger RNAs increased bilaterally in the cingulate cortex and in selective nuclei of the amygdala. Histological cell death or neurodegeneration was not detected in areas of reduced glutamate and preproenkephalin messenger RNA expression in either the ipsilateral striatum or cortex before 24 h. These findings suggest that complex and long-lasting decreases in messenger RNA expression occur prior to significant cell loss in regions destined to undergo infarction. Increased formation of Ca2+-permeable AMPA receptor assemblies may occur in "unspared" and "spared" regions via different mechanisms and contribute to alterations in post-ischemic synaptic activity. The possibility arises that there may be altered relationships between glutamatergic and enkephalin synapses, since the dorsolateral striatum, where preproenkephalin messenger RNA expression is acutely reduced, receives innervation by the affected ipsilateral cortical region.
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Affiliation(s)
- L K Friedman
- Department of Neuroscience, Seton Hall University/NJ Neuroscience Institute, JFK Medical Center, Edison 08818, USA.
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Lees GJ. Pharmacology of AMPA/kainate receptor ligands and their therapeutic potential in neurological and psychiatric disorders. Drugs 2000; 59:33-78. [PMID: 10718099 DOI: 10.2165/00003495-200059010-00004] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
It has been postulated, consistent with the ubiquitous presence of glutamatergic neurons in the brain, that defects in glutamatergic neurotransmission are associated with many human neurological and psychiatric disorders. This review evaluates the possible application of ligands acting on glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and kainate (KA) receptors to minimise the pathology and/or symptoms of various diseases. Glutamate activation of AMPA receptors is thought to mediate most fast synaptic neurotransmission in the brain, while transmission via KA receptors contributes only a minor component. Variants of the protein subunits forming these receptors greatly extend the pharmacological and electrophysiological properties of AMPA/KA receptors. Disease and drug use can differentially affect the expression of the subunits and their variants. Ligands bind to AMPA receptors by competing with glutamate at the glutamate binding site, or non-competitively at other sites on the proteins (allosteric modulators). Ligands showing selective competitive antagonist actions at the AMPA/ KA class of glutamate receptors were first reported in 1988, and the systemically active antagonist 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline (NBQX) was first shown to have useful therapeutic effects on animal models of neurological diseases in 1990. Since then, newer antagonists with increased potency, higher specificity, increased water solubility, and a longer duration of action in vivo have been developed. Negative allosteric modulators such as the prototype GYKI-52466 also block AMPA receptors but have little action at KA receptors. Positive allosteric modulators enhance glutamatergic neurotransmission at AMPA receptors. Polyamines and adamantane derivatives bind within the ion channel of calcium-permeable AMPA receptors. The latest developments include ligands selective for KA receptors containing Glu-R5 subunits. Evidence for advantages of AMPA receptor antagonists over N-methyl-D-aspartate (NMDA) receptor antagonists for symptomatic treatment of neurological and psychiatric conditions, and for minimising neuronal loss occurring after acute neurological diseases, such as physical trauma, ischaemia or status epilepticus, have been shown in animal models. However, as yet AMPA receptor antagonists have not been shown to be effective in clinical trials. On the other hand, a limited number of clinical trials have been reported for AMPA receptor ligands that enhance glutamatergic neurotransmission by extending the ion channel opening time (positive allosteric modulators). These acute studies demonstrate enhanced memory capability in both young and aged humans, without any apparent serious adverse effects. The use of these allosteric modulators as antipsychotic drugs is also possible. However, the long term use of both direct agonists and positive allosteric modulators must be approached with considerable caution because of potential adverse effects.
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Affiliation(s)
- G J Lees
- Department of Psychiatry and Behavioural Science, University of Auckland School of Medicine, New Zealand.
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Abstract
Kainic acid (KA) induces status epilepticus in both adult and young rats but with different consequences on pathology and gene expression. In adults, GluR2(B) AMPA subunit expression is markedly reduced in CA3 neurons before neurodegeneration. In pups, the GluR2(B) subunit is sustained, possibly contributing to neuronal survival. Mechanisms underlying the reduced vulnerability of developing neurons to seizures was investigated by examining the effects of unilateral microinfusions of GluR2(B) antisense oligodeoxynucleotides (AS-ODNs) into the hippocampus of young rats in the presence or absence of a subconvulsive dose of KA. GluR2(B) AS-ODN infusions resulted in spontaneous seizure-like behavior, high stimulus intensity population spikes in the absence of long-term potentiation, and neurodegeneration of CA3 neurons lateral to the infusion site. Electroencephalography revealed paroxysmal activity and high-frequency high-amplitude discharges associated with vigorous and continuous scratching, wild running, or bilateral jerking movements. Pups lacking phenotypic behavior exhibited high-rhythmic oscillations and status epilepticus by the dose of KA used. Radiolabeled AS-ODNs accumulated throughout the ipsilateral dorsal hippocampus. GluR2(B) but not GluR1(A) receptor protein was markedly reduced after GluR2(B) knockdown. In contrast, GluR1(A) knockdown reduced GluR1(A) but not GluR2(B) protein without change in behavior or morphology. Therefore, unilateral downregulation of hippocampal GluR2(B) but not GluR1(A) protein reduces the seizure threshold and survival of CA3 neurons in the immature hippocampus, possibly providing a novel partial seizure model in the developing rat.
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Lee YS, Ha JH, Yong CS, Lee DU, Huh K, Kang YS, Lee SH, Jung MW, Kim JA. Inhibitory effects of constituents of Gastrodia elata Bl. on glutamate-induced apoptosis in IMR-32 human neuroblastoma cells. Arch Pharm Res 1999; 22:404-9. [PMID: 10489882 DOI: 10.1007/bf02979066] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The inhibitory effects of the constituents of Gastrodia elata Bl. (GE) on glutamate-induced apoptosis in human neuronal cells were investigated using IMR32 human neuroblastoma cells. Glutamate (GLU) induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. GLU also induced a slow and sustained increase in intracellular Ca2+ concentration. Treatment with EGTA, an extracellular Ca2+ chelator, in a nominal Ca2+-free buffer solution abolished the GLU-induced intracellular Ca2+ increase, indicating that GLU stimulated Ca2+ influx pathway in the IMR32 cells. BAPTA, an intracellular Ca2+ chelator, significantly inhibited the GLU-induced apoptosis assessed by the flow cytometry measuring hypodiploid DNA content indicative of apoptosis, implying that intracellular Ca2+ rise may mediate the apoptotic action of GLU. Vanillin (VAN) and p-hydroxybenzaldehyde (p-HB), known constituents of GE, significantly inhibited both intracellular Ca2+ rise and apoptosis induced by GLU. These results suggest that the apoptosis-inhibitory actions of the constituents of GE may account, at least in part, for the basis of their antiepileptic activities. These results further suggest that intracellular Ca2+ signaling pathway may be a molecular target of the constituents of GE.
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Affiliation(s)
- Y S Lee
- Department of Physiology, College of Medicine, Kwandong University, Kangnung, Korea
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Friedman LK, Velísková A. GluR2 antisense knockdown produces seizure behavior and hippocampal neurodegeneration during a critical window. Ann N Y Acad Sci 1999; 868:541-5. [PMID: 10414332 DOI: 10.1111/j.1749-6632.1999.tb11324.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- L K Friedman
- Department of Neuroscience, New Jersey Neuroscience Institute/Seton Hall University, Edison 08818, USA.
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Abstract
There has been direct evidence of gamma-aminobutyric acidA receptor modification during status epilepticus. Neuropeptides galanin and neuropeptide Y were demonstrated to play a role in terminating status epilepticus. Many of the CA3 pyramidal neurons destined to die as a consequence of status epilepticus were demonstrated to diminish expression of the GluR2 subunit of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors. It was demonstrated that the pattern of cell loss due to status epilepticus is distinct in immature pups compared with adult rats. The genetic basis for susceptibility to neuronal loss during status epilepticus was described. There was increasing evidence of unique receptors and ion channels in the epileptic brain. The molecular studies of epileptic gamma-aminobutyric acidA receptors present on dentate granule cells of rats with temporal lobe epilepsy revealed altered gene and receptor expression before onset of recurrent spontaneous seizures. They also revealed insertion of new gamma-aminobutyric acidA receptors in the inhibitory synapses present on soma and proximal dendrites of dentate granule cells.
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Affiliation(s)
- J Kapur
- Department of Neurology, University of Virginia Health Sciences Center, Charlottesville 229089, USA.
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Abstract
Studies dating back more than 150 years reported a relationship between hippocampal sclerosis and epilepsy. Retrospective studies of patients who underwent temporal lobectomy for intractable partial epilepsy found a relationship between a history of early childhood convulsions, hippocampal sclerosis, and the development of temporal lobe epilepsy. Many believe that febrile seizures lead to hippocampal damage and this in turn predisposes the patient to the development of temporal lobe epilepsy. Studies in adult rats have shown that seizures can lead to hippocampal damage and unprovoked recurrent seizures. However, many questions remain as to the relevance of early childhood seizures to hippocampal sclerosis and temporal lobe epilepsy. Human prospective epidemiologic studies have not shown a relationship between early childhood seizures and temporal lobe epilepsy. Recent MRI studies in humans suggest that a preexisting hippocampal lesion may predispose infants to experience febrile seizures, later on hippocampal sclerosis, and possibly temporal lobe epilepsy may occur. Unlike the studies in adult rats, normal immature rats with seizures have not been shown to develop hippocampal damage or unprovoked seizures in adulthood. Furthermore, animal studies reveal that preexisting brain abnormalities can predispose to hippocampal damage following seizures early in life. This paper reviews evidence for and against the view that early childhood convulsions, hippocampal sclerosis, and temporal lobe epilepsy are related, while also exploring clinical and animal studies on how seizures can lead to hippocampal damage, and how this can result in temporal lobe epilepsy. By better understanding the cause and effect relationship between early childhood seizures and hippocampal injury in normal and abnormal brains specific treatments can be developed that target the pathogenesis of epilepsy.
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Affiliation(s)
- P D Fisher
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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