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Zhang Y, Garcia E, Sack AS, Snutch TP. L-type calcium channel contributions to intrinsic excitability and synaptic activity during basolateral amygdala postnatal development. J Neurophysiol 2020; 123:1216-1235. [PMID: 31967931 DOI: 10.1152/jn.00606.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The amygdala contributes toward emotional processes such as fear, anxiety, and social cognition. Furthermore, evidence suggests that increased excitability of basolateral amygdala (BLA) principal neurons underlie certain neuropsychiatric disorders. Gain-of-function mutations in neuronal L-type calcium channels (LTCCs) are linked to neurodevelopmental diseases, including autism spectrum disorders (ASDs). While LTCCs are expressed throughout the BLA, direct evidence for increased LTCC activity affecting BLA excitability and potentially contributing to disease pathophysiology is lacking. In this study, we utilized a pharmacological approach to examine the contributions of LTCCs to BLA principal cell excitability and synaptic activity at immature (postnatal day 7, P7) and juvenile (P21) developmental stages. Acute upregulation of LTCC activity in brain slices by application of the agonist (S)-Bay K 8644 resulted in increased intrinsic excitability properties including firing frequency response, plateau potential, and spike-frequency adaptation selectively in P7 neurons. Contrastingly, for P21 neurons, the main effect of (S)-Bay K 8644 was to enhance burst firing. (S)-Bay K 8644 increased spontaneous inhibitory synaptic currents at both P7 and P21 but did not affect evoked synaptic currents at either stage. (S)-Bay K 8644 did not alter P7 spontaneous excitatory synaptic currents, although it increased current amplitude in P21 neurons. Overall, the results provide support for the notion that alteration of LTCC activity at specific periods of early brain development may lead to functional alterations to neuronal network activity and subsequently contribute to underlying mechanisms of amygdala-related neurological disorders.NEW & NOTEWORTHY The role of L-type calcium channels (LTCCs) in regulating neuronal electrophysiological properties during development remains unclear. We show that in basolateral amygdala principal neurons, an increase of LTCC activity alters both neuronal excitability and synaptic activity. The results also provide evidence for the distinct contributions of LTCCs at different stages of neurodevelopment and shed insight into our understanding of LTCC dysfunction in amygdala-related neurological disorders.
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Affiliation(s)
- Yiming Zhang
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Esperanza Garcia
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anne-Sophie Sack
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
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Stiglbauer V, Hotka M, Ruiß M, Hilber K, Boehm S, Kubista H. Ca v 1.3 channels play a crucial role in the formation of paroxysmal depolarization shifts in cultured hippocampal neurons. Epilepsia 2017; 58:858-871. [PMID: 28295232 DOI: 10.1111/epi.13719] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2017] [Indexed: 11/30/2022]
Abstract
OBJECTIVE An increase of neuronal Cav 1.3 L-type calcium channels (LTCCs) has been observed in various animal models of epilepsy. However, LTCC inhibitors failed in clinical trials of epileptic treatment. There is compelling evidence that paroxysmal depolarization shifts (PDSs) involve Ca2+ influx through LTCCs. PDSs represent a hallmark of epileptiform activity. In recent years, a probable epileptogenic role for PDSs has been proposed. However, the implication of the two neuronal LTCC isoforms, Cav 1.2 and Cav 1.3, in PDSs remained unknown. Moreover, Ca2+ -dependent nonspecific cation (CAN) channels have also been suspected to contribute to PDSs. Nevertheless, direct experimental support of an important role of CAN channel activation in PDS formation is still lacking. METHODS Primary neuronal networks derived from dissociated hippocampal neurons were generated from mice expressing a dihydropyridine-insensitive Cav 1.2 mutant (Cav 1.2DHP-/- mice) or from Cav 1.3-/- knockout mice. To investigate the role of Cav 1.2 and Cav 1.3, perforated patch-clamp recordings were made of epileptiform activity, which was elicited using either bicuculline or caffeine. LTCC activity was modulated using the dihydropyridines Bay K 8644 (agonist) and isradipine (antagonist). RESULTS Distinct PDS could be elicited upon LTCC potentiation in Cav 1.2DHP-/- neurons but not in Cav 1.3-/- neurons. In contrast, when bicuculline led to long-lasting, seizure-like discharge events rather than PDS, these were prolonged in Cav 1.3-/- neurons but not in Cav 1.2DHP-/- neurons. Because only the Cav 1.2 isoform is functionally coupled to CAN channels in primary hippocampal networks, PDS formation does not require CAN channel activity. SIGNIFICANCE Our data suggest that the LTCC requirement of PDS relates primarily to Cav 1.3 channels rather than to Cav 1.2 channels and CAN channels in hippocampal neurons. Hence, Cav 1.3 may represent a new therapeutic target for suppression of PDS development. The proposed epileptogenic role of PDSs may allow for a prophylactic rather than the unsuccessful seizure suppressing application of LTCC inhibitors.
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Affiliation(s)
- Victoria Stiglbauer
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Matej Hotka
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Manuel Ruiß
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Karlheinz Hilber
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Stefan Boehm
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Helmut Kubista
- Department of Neurophysiology and Neuropharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Lv X, Guo F, Xu X, Chen Z, Sun X, Min D, Cao Y, Shi X, Wang L, Chen T, Shaw C, Gao H, Hao L, Cai J. Abnormal alterations in the Ca²⁺/CaV1.2/calmodulin/caMKII signaling pathway in a tremor rat model and in cultured hippocampal neurons exposed to Mg²⁺-free solution. Mol Med Rep 2015; 12:6663-71. [PMID: 26299765 PMCID: PMC4626152 DOI: 10.3892/mmr.2015.4227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 07/21/2015] [Indexed: 11/05/2022] Open
Abstract
Voltage-dependent calcium channels (VDCCs) are key elements in epileptogenesis. There are several binding-sites linked to calmodulin (CaM) and several potential CaM-dependent protein kinase II (CaMKII)-mediated phosphorylation sites in CaV1.2. The tremor rat model (TRM) exhibits absence‑like seizures from 8 weeks of age. The present study was performed to detect changes in the Ca2+/CaV1.2/CaM/CaMKII pathway in TRMs and in cultured hippocampal neurons exposed to Mg2+‑free solution. The expression levels of CaV1.2, CaM and phosphorylated CaMKII (p‑CaMKII; Thr‑286) in these two models were examined using immunofluorescence and western blotting. Compared with Wistar rats, the expression levels of CaV1.2 and CaM were increased, and the expression of p‑CaMKII was decreased in the TRM hippocampus. However, the expression of the targeted proteins was reversed in the TRM temporal cortex. A significant increase in the expression of CaM and decrease in the expression of CaV1.2 were observed in the TRM cerebellum. In the cultured neuron model, p‑CaMKII and CaV1.2 were markedly decreased. In addition, neurons exhibiting co‑localized expression of CaV1.2 and CaM immunoreactivities were detected. Furthermore, intracellular calcium concentrations were increased in these two models. For the first time, o the best of our knowledge, the data of the present study suggested that abnormal alterations in the Ca2+/CaV1.2/CaM/CaMKII pathway may be involved in epileptogenesis and in the phenotypes of TRMs and cultured hippocampal neurons exposed to Mg2+‑free solution.
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Affiliation(s)
- Xintong Lv
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Feng Guo
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiaoxue Xu
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zaixing Chen
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xuefei Sun
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Dongyu Min
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yonggang Cao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xianbao Shi
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Lei Wang
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Tianbao Chen
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Chris Shaw
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Huiling Gao
- College of Life and Health Sciences, Northeastern University, Shenyang, Liaoning 110001, P.R. China
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Jiqun Cai
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
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Raised activity of L-type calcium channels renders neurons prone to form paroxysmal depolarization shifts. Neuromolecular Med 2013; 15:476-92. [PMID: 23695859 PMCID: PMC3732764 DOI: 10.1007/s12017-013-8234-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/08/2013] [Indexed: 12/31/2022]
Abstract
Neuronal L-type voltage-gated calcium channels (LTCCs) are involved in several physiological functions, but increased activity of LTCCs has been linked to pathology. Due to the coupling of LTCC-mediated Ca2+ influx to Ca2+-dependent conductances, such as KCa or non-specific cation channels, LTCCs act as important regulators of neuronal excitability. Augmentation of after-hyperpolarizations may be one mechanism that shows how elevated LTCC activity can lead to neurological malfunctions. However, little is known about other impacts on electrical discharge activity. We used pharmacological up-regulation of LTCCs to address this issue on primary rat hippocampal neurons. Potentiation of LTCCs with Bay K8644 enhanced excitatory postsynaptic potentials to various degrees and eventually resulted in paroxysmal depolarization shifts (PDS). Under conditions of disturbed Ca2+ homeostasis, PDS were evoked frequently upon LTCC potentiation. Exposing the neurons to oxidative stress using hydrogen peroxide also induced LTCC-dependent PDS. Hence, raising LTCC activity had unidirectional effects on brief electrical signals and increased the likeliness of epileptiform events. However, long-lasting seizure-like activity induced by various pharmacological means was affected by Bay K8644 in a bimodal manner, with increases in one group of neurons and decreases in another group. In each group, isradipine exerted the opposite effect. This suggests that therapeutic reduction in LTCC activity may have little beneficial or even adverse effects on long-lasting abnormal discharge activities. However, our data identify enhanced activity of LTCCs as one precipitating cause of PDS. Because evidence is continuously accumulating that PDS represent important elements in neuropathogenesis, LTCCs may provide valuable targets for neuroprophylactic therapy.
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Yan HD, Ishihara K, Seki T, Hanaya R, Kurisu K, Arita K, Serikawa T, Sasa M. Inhibitory effects of levetiracetam on the high-voltage-activated L-type Ca²⁺ channels in hippocampal CA3 neurons of spontaneously epileptic rat (SER). Brain Res Bull 2012; 90:142-8. [PMID: 23107646 DOI: 10.1016/j.brainresbull.2012.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
Abstract
Levetiracetam (LEV) is a widely used antiepileptic agent for partial refractory epilepsy in humans. LEV has unique antiepileptic effects in that it does not inhibit electroshock- or pentylenetetrazol-induced convulsion, but does inhibit seizures in kindling animal and spontaneously epileptic rat (SER: zi/zi, tm/tm) that shows both tonic convulsion and absence-like seizures. LEV also has unique characteristics in terms of its antiepileptic mechanism; it has no activity on Na⁺ and K⁺ channels or on glutamate and GABA(A) receptors. Recently, we found that LEV inhibits the depolarization shift and accompanying repetitive firing induced by mossy fiber stimulation in CA3 neurons of SER hippocampal slices. Therefore, this study was performed to determine whether LEV could inhibit the voltage-activated L-type Ca²⁺ current of hippocampal CA3 neurons obtained from SER and the non-epileptic Wistar rat. As previously reported, SER CA3 neurons were classified into type 1 and type 2 neurons. The application of LEV (100 μM) elevated the threshold for activation of the Ca²⁺ current, which was lowered in SER type 1 neurons and reduced the current size. Type 2 neurons of SER have a similar current-voltage relationship to Wistar rat neurons and the decay component of Ca²⁺ current during depolarization pulse in type 2 neurons was found to be smaller than that in Wistar rat neurons. LEV (100 μM) also reduced Ca²⁺ current in SER type 2 neurons. The effects of LEV were examined on such type 2 SER hippocampal CA3 neurons, compared with those on Wistar rat CA3 neurons. Application of LEV (10 μM) produced a significant decrease of amplitude of the Ca²⁺ current in SER neurons, although at this concentration of LEV there was no statistically significant decrease in the amplitude of Ca²⁺ current in Wistar rat neurons. Furthermore, LEV (100 nM-1 mM) reduced the Ca²⁺ current in a concentration-dependent manner in both SER and Wistar rat neurons, but the inhibition was much more potent in the former neurons than in the latter. Under the condition that the Ca²⁺ current had already been inhibited by LEV (10 μM), the addition of nifedipine (10 μM) did not cause further inhibition. Conversely, LEV had no effects on the current that had already been decreased by nifedipine (10 μM) given before LEV treatment (10 μM), indicating that LEV could act on the L-type Ca²⁺ channel. LEV elevated the threshold potential level for activation of the Ca²⁺ current and reduced the L-type Ca²⁺ current in type 1 neurons of SER, and the inhibitory action in type 2 neurons was much more potent than that in Wistar rat neurons, suggesting that these effects contribute, at least partly, to the antiepileptic action of LEV.
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Affiliation(s)
- Hai-Dun Yan
- Department of Pharmacology, Hiroshima University School of Medicine, Hiroshima 734-8551, Japan
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Hanaya R, Hosoyama H, Sugata S, Tokudome M, Hirano H, Tokimura H, Kurisu K, Serikawa T, Sasa M, Arita K. Low distribution of synaptic vesicle protein 2A and synaptotagimin-1 in the cerebral cortex and hippocampus of spontaneously epileptic rats exhibiting both tonic convulsion and absence seizure. Neuroscience 2012; 221:12-20. [DOI: 10.1016/j.neuroscience.2012.06.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/25/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
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Hanaya R, Kiura Y, Serikawa T, Kurisu K, Arita K, Sasa M. Modulation of abnormal synaptic transmission in hippocampal CA3 neurons of spontaneously epileptic rats (SERs) by levetiracetam. Brain Res Bull 2011; 86:334-9. [PMID: 21968023 DOI: 10.1016/j.brainresbull.2011.09.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 09/17/2011] [Accepted: 09/19/2011] [Indexed: 11/18/2022]
Abstract
Levetiracetam (LEV) inhibits partial refractory epilepsy in human, and both convulsive and absence-like seizures in the spontaneously epileptic rat (SER). Two-thirds of hippocampal CA3 neurons in SER show a long-lasting depolarization shift, with accompanying repetitive firing upon mossy fiber stimulation. This abnormal excitability is probably attributable to abnormalities in the L-type Ca(2+) channels. We performed electrophysiological studies to elucidate the mechanism underlying the antiepileptic effects of LEV via intracellular recording from the hippocampal CA3 neurons in slice preparations of SER and non-epileptic Wistar rats. LEV (100 μM) inhibited the depolarization shift with repetitive firing by mossy fiber stimulation (MFS), without affecting the first spike in SER CA3 neurons. At a higher dose (1mM), LEV suppressed the first spike in all SER neurons (including the CA3 neurons which showed only a single action potential by MFS), while the single action potential of Wistar rat CA3 neurons remained unaffected. SER CA3 neurons with MFS-induced abnormal firing exhibited a higher number of repetitive spikes when a depolarization pulse was applied in the SER CA3 neurons. LEV (100 μM, 1mM) reduced the repetitive firing induced by a depolarization pulse applied without affecting Ca(2+) spike in SER neurons. LEV is known not to bind glutamate and gamma-aminobutyric acid (GABA) receptors. These findings suggest that the therapeutic concentration of LEV inhibits abnormal firing of the CA3 neurons by modulating abnormal synaptic transmission and abnormal Na(+) channels in SER.
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Affiliation(s)
- Ryosuke Hanaya
- Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan.
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Sugata S, Hanaya R, Kumafuji K, Tokudome M, Serikawa T, Kurisu K, Arita K, Sasa M. Neuroprotective effect of levetiracetam on hippocampal sclerosis-like change in spontaneously epileptic rats. Brain Res Bull 2011; 86:36-41. [DOI: 10.1016/j.brainresbull.2011.05.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 05/16/2011] [Accepted: 05/30/2011] [Indexed: 10/18/2022]
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Shin EJ, Jeong JH, Chung YH, Kim WK, Ko KH, Bach JH, Hong JS, Yoneda Y, Kim HC. Role of oxidative stress in epileptic seizures. Neurochem Int 2011; 59:122-37. [PMID: 21672578 PMCID: PMC3606551 DOI: 10.1016/j.neuint.2011.03.025] [Citation(s) in RCA: 286] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 03/27/2011] [Accepted: 03/28/2011] [Indexed: 11/16/2022]
Abstract
Oxidative stress resulting from excessive free-radical release is likely implicated in the initiation and progression of epilepsy. Therefore, antioxidant therapies aimed at reducing oxidative stress have received considerable attention in epilepsy treatment. However, much evidence suggests that oxidative stress does not always have the same pattern in all seizures models. Thus, this review provides an overview aimed at achieving a better understanding of this issue. We summarize work regarding seizure models (i.e., genetic rat models, kainic acid, pilocarpine, pentylenetetrazol, and trimethyltin), oxidative stress as an etiologic factor in epileptic seizures (i.e., impairment of antioxidant systems, mitochondrial dysfunction, involvement of redox-active metals, arachidonic acid pathway activation, and aging), and antioxidant strategies for seizure treatment. Combined, this review highlights pharmacological mechanisms associated with oxidative stress in epileptic seizures and the potential for neuroprotection in epilepsy that targets oxidative stress and is supported by effective antioxidant treatment.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharamcology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 200-701, South Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul 156-756, South Korea
| | - Yoon Hee Chung
- Department of Anatomy, College of Medicine, Chung-Ang University, Seoul 156-756, South Korea
| | - Won-Ki Kim
- Department of Neuroscience, College of Medicine, Korea University, Seoul 136-705, South Korea
| | - Kwang-Ho Ko
- Pharmacology Laboratory, College of Pharmacy, Seoul National University, Seoul 143-701, South Korea
| | - Jae-Hyung Bach
- Neuropsychopharamcology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 200-701, South Korea
| | - Jau-Shyong Hong
- Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
| | - Yukio Yoneda
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa 920-1192, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharamcology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 200-701, South Korea
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Hanaya R, Sasa M, Sugata S, Tokudome M, Serikawa T, Kurisu K, Arita K. Hippocampal cell loss and propagation of abnormal discharges accompanied with the expression of tonic convulsion in the spontaneously epileptic rat. Brain Res 2010; 1328:171-80. [DOI: 10.1016/j.brainres.2010.02.086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 02/25/2010] [Accepted: 02/28/2010] [Indexed: 12/01/2022]
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Abnormal expressions of glutamate transporters and metabotropic glutamate receptor 1 in the spontaneously epileptic rat hippocampus. Brain Res Bull 2010; 81:510-6. [DOI: 10.1016/j.brainresbull.2009.10.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Revised: 10/11/2009] [Accepted: 10/11/2009] [Indexed: 11/22/2022]
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N-Acetyl-l-aspartate activates hippocampal CA3 neurons in rodent slice preparations. Brain Res Bull 2008; 75:663-7. [DOI: 10.1016/j.brainresbull.2007.10.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 10/22/2007] [Accepted: 10/26/2007] [Indexed: 11/17/2022]
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Guo F, Yu N, Cai JQ, Quinn T, Zong ZH, Zeng YJ, Hao LY. Voltage-gated sodium channel Nav1.1, Nav1.3 and beta1 subunit were up-regulated in the hippocampus of spontaneously epileptic rat. Brain Res Bull 2007; 75:179-87. [PMID: 18158113 DOI: 10.1016/j.brainresbull.2007.10.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 10/05/2007] [Accepted: 10/06/2007] [Indexed: 01/22/2023]
Abstract
The spontaneously epileptic rat (SER), a double mutant (zi/zi, tm/tm), exhibits both tonic convulsions and absence-like seizures from the age of 8 weeks. Since the first point mutation in the voltage-gated sodium channel (VGSC) beta(1) subunit in human generalized epilepsy with febrile seizures plus (GEFS+) was identified, more and more types of genetic epilepsy have been causally suggested to be related to gene changes in VGSC. However, there are no reports that can elucidate the effects of VGSC in SER. The present study was undertaken to detect sodium channel I alpha-isoform (Na(v)1.1), sodium channel III alpha-isoform (Na(v)1.3) and beta(1) subunit from both the level of mRNA and protein in SERs hippocampus compared with control Wistar rats. In this study, the mRNA expressions of Na(v)1.1, Na(v)1.3 and beta(1) subunit in SERs hippocampus were significantly higher than those in control rats hippocampus by real-time RT-PCR; The protein distributions and expressions of Na(v)1.1, Na(v)1.3 and beta(1) subunit in SERs hippocampus were detected by immunofluorescence, immunohistochemistry and western blot, and the protein expressions of Na(v)1.1, Na(v)1.3 and beta(1) subunit were significantly increased. In conclusion, our study suggested for the first time that sodium channel Na(v)1.1, Na(v)1.3 and beta(1) subunit up-regulation at the mRNA and protein levels of SER hippocampus might contribute to the generation of epileptiform activity and underlie the observed seizure phenotype in SER. The results of this study may be of value in revealing components of the molecular mechanisms of hippocampal excitation that are related to genetic epilepsy.
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Affiliation(s)
- Feng Guo
- Department of Pharmaceutical Toxicology, School of Pharmaceutical Science, China Medical University, Shenyang 110001, China
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