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Kajita Y, Fukuda Y, Kawamatsu R, Oyanagi T, Mushiake H. Pentylenetetrazole kindling induces dynamic changes in GAD65 expression in hippocampal somatostatin interneurons. Pharmacol Biochem Behav 2024; 239:173755. [PMID: 38527654 DOI: 10.1016/j.pbb.2024.173755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/01/2024] [Accepted: 03/22/2024] [Indexed: 03/27/2024]
Abstract
INTRODUCTION One of the mechanisms of epileptgenesis is impairment of inhibitory neural circuits. Several studies have compared neural changes among subtypes of gamma-aminobutyric acid-related (GABAergic) neurons after acquired epileptic seizure. However, it is unclear that GABAergic neural modifications that occur during acquisition process of epileptic seizure. METHODS Male rats were injected with pentylenetetrazole (PTZ kindling: n = 30) or saline (control: n = 15) every other day to observe the development of epileptic seizure stages. Two time points were identified: the point at which seizures were most difficult to induce, and the point at which seizures were most easy to induce. The expression of GABAergic neuron-related proteins in the hippocampus was immunohistochemically compared among GABAergic subtypes at each of these time points. RESULTS Bimodal changes in seizure stages were observed in response to PTZ kindling. The increase of seizure stage was transiently suppressed after 8 or 10 injections, and then progressed again by the 16th injection. Based on these results, we defined 10 injections as a short-term injection period during which seizures are less likely to occur, and 20 injections as a long-term injection period during which continuous seizures are likely to occur. The immunohistochemical analysis showed that hippocampal glutamic acid decarboxylase 65 (GAD65) expression was increased after short-term kindling but unchanged after long-term kindling. Increased GAD65 expression was limited to somatostatin-positive (SOM+) cells among several GABAergic subtypes. By contrast, GAD, GABA, GABAAR α1, GABABR1, and VGAT cells showed no change following short- or long-term PTZ kindling. CONCLUSION PTZ kindling induces bimodal changes in the epileptic seizure stage. Seizure stage is transiently suppressed after short-term PTZ injection with GAD65 upregulation in SOM+ cells. The seizure stage is progressed again after long-term PTZ injection with GAD65 reduction to baseline level.
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Affiliation(s)
- Yuki Kajita
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
| | - Yuki Fukuda
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Riho Kawamatsu
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Takanori Oyanagi
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Hajime Mushiake
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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Modarres Mousavi SM, Alipour F, Noorbakhsh F, Jafarian M, Ghadipasha M, Gharehdaghi J, Kellinghaus C, Speckmann EJ, Stummer W, Khaleghi Ghadiri M, Gorji A. Clinical Correlation of Altered Molecular Signatures in Epileptic Human Hippocampus and Amygdala. Mol Neurobiol 2024; 61:725-752. [PMID: 37658249 PMCID: PMC10861640 DOI: 10.1007/s12035-023-03583-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 08/14/2023] [Indexed: 09/03/2023]
Abstract
Widespread alterations in the expression of various genes could contribute to the pathogenesis of epilepsy. The expression levels of various genes, including major inhibitory and excitatory receptors, ion channels, cell type-specific markers, and excitatory amino acid transporters, were assessed and compared between the human epileptic hippocampus and amygdala, and findings from autopsy controls. Moreover, the potential correlation between molecular alterations in epileptic brain tissues and the clinical characteristics of patients undergoing epilepsy surgery was evaluated. Our findings revealed significant and complex changes in the expression of several key regulatory genes in both the hippocampus and amygdala of patients with intractable epilepsy. The expression changes in various genes differed considerably between the epileptic hippocampus and amygdala. Different correlation patterns were observed between changes in gene expression and clinical characteristics, depending on whether the patients were considered as a whole or were subdivided. Altered molecular signatures in different groups of epileptic patients, defined within a given category, could be viewed as diagnostic biomarkers. Distinct patterns of molecular changes that distinguish these groups from each other appear to be associated with epilepsy-specific functional consequences.
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Affiliation(s)
| | - Fatemeh Alipour
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Farshid Noorbakhsh
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Maryam Jafarian
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Masoud Ghadipasha
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
| | - Jaber Gharehdaghi
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
| | | | - Erwin-Josef Speckmann
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Walter Stummer
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | | | - Ali Gorji
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran.
- Department of Neurosurgery, Westfälische Wilhelms-Universität Münster, Münster, Germany.
- Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany.
- Department of Neuroscience, Mashhad University of Medical Sciences, Mashhad, Iran.
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Bahabry R, Hauser RM, Sánchez RG, Jago SS, Ianov L, Stuckey RJ, Parrish RR, Hoef LV, Lubin FD. Alterations in DNA 5-hydroxymethylation Patterns in the Hippocampus of an Experimental Model of Refractory Epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.03.560698. [PMID: 37873276 PMCID: PMC10592907 DOI: 10.1101/2023.10.03.560698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Temporal lobe epilepsy (TLE) is a type of focal epilepsy characterized by spontaneous recurrent seizures originating from the hippocampus. The epigenetic reprogramming hypothesis of epileptogenesis suggests that the development of TLE is associated with alterations in gene transcription changes resulting in a hyperexcitable network in TLE. DNA 5-methylcytosine (5-mC) is an epigenetic mechanism that has been associated with chronic epilepsy. However, the contribution of 5-hydroxymethylcytosine (5-hmC), a product of 5-mC demethylation by the Ten-Eleven Translocation (TET) family proteins in chronic TLE is poorly understood. 5-hmC is abundant in the brain and acts as a stable epigenetic mark altering gene expression through several mechanisms. Here, we found that the levels of bulk DNA 5-hmC but not 5-mC were significantly reduced in the hippocampus of human TLE patients and in the kainic acid (KA) TLE rat model. Using 5-hmC hMeDIP-sequencing, we characterized 5-hmC distribution across the genome and found bidirectional regulation of 5-hmC at intergenic regions within gene bodies. We found that hypohydroxymethylated 5-hmC intergenic regions were associated with several epilepsy-related genes, including Gal , SV2, and Kcnj11 and hyperdroxymethylation 5-hmC intergenic regions were associated with Gad65 , TLR4 , and Bdnf gene expression. Mechanistically, Tet1 knockdown in the hippocampus was sufficient to decrease 5-hmC levels and increase seizure susceptibility following KA administration. In contrast, Tet1 overexpression in the hippocampus resulted in increased 5-hmC levels associated with improved seizure resiliency in response to KA. These findings suggest an important role for 5-hmC as an epigenetic regulator of epilepsy that can be manipulated to influence seizure outcomes.
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Liu D, Fujihara K, Yanagawa Y, Mushiake H, Ohshiro T. Gad1 knock-out rats exhibit abundant spike-wave discharges in EEG, exacerbated with valproate treatment. Front Neurol 2023; 14:1243301. [PMID: 37830095 PMCID: PMC10566305 DOI: 10.3389/fneur.2023.1243301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/29/2023] [Indexed: 10/14/2023] Open
Abstract
Objective To elucidate the functional role of gamma-aminobutyric acid (GABA)-ergic inhibition in suppressing epileptic brain activities such as spike-wave discharge (SWD), we recorded electroencephalogram (EEG) in knockout rats for Glutamate decarboxylase 1 (Gad1), which encodes one of the two GABA-synthesizing enzymes in mammals. We also examined how anti-epileptic drug valproate (VPA) acts on the SWDs present in Gad1 rats and affects GABA synthesis in the reticular thalamic nucleus (RTN), which is known to play an essential role in suppressing SWD. Methods Chronic EEG recordings were performed in freely moving control rats and homozygous knockout Gad1 (-/-) rats. Buzzer tones (82 dB) were delivered to the rats during EEG monitoring to test whether acoustic stimulation could interrupt ongoing SWDs. VPA was administered orally to the rats, and the change in the number of SWDs was examined. The distribution of GABA in the RTN was examined immunohistochemically. Results SWDs were abundant in EEG from Gad1 (-/-) rats as young as 2 months old. Although SWDs were universally detected in older rats irrespective of their Gad1 genotype, SWD symptom was most severe in Gad1 (-/-) rats. Acoustic stimulation readily interrupted ongoing SWDs irrespective of the Gad1 genotype, whereas SWDs were more resistant to interruption in Gad1 (-/-) rats. VPA treatment alleviated SWD symptoms in control rats, however, counterintuitively exacerbated the symptoms in Gad1 (-/-) rats. The immunohistochemistry results indicated that GABA immunoreactivity was significantly reduced in the somata of RTN neurons in Gad1 (-/-) rats but not in their axons targeting the thalamus. VPA treatment greatly increased GABA immunoreactivity in the RTN neurons of Gad1 (-/-) rats, which is likely due to the intact GAD2, another GAD isozyme, in these neurons. Discussion Our results revealed two opposing roles of GABA in SWD generation: suppression and enhancement of SWD. To account for these contradictory roles, we propose a model in which GABA produced by GAD1 in the RTN neuronal somata is released extrasynaptically and mediates intra-RTN inhibition.
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Affiliation(s)
- Dongyu Liu
- Department of Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Kazuyuki Fujihara
- Department of Psychiatry and Neuroscience, Graduate School of Medicine, Gunma University, Maebashi, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Graduate School of Medicine, Gunma University, Maebashi, Japan
| | - Hajime Mushiake
- Department of Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Tomokazu Ohshiro
- Department of Physiology, Graduate School of Medicine, Tohoku University, Sendai, Japan
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Jiang W, Kakizaki T, Fujihara K, Miyata S, Zhang Y, Suto T, Kato D, Saito S, Shibasaki K, Ishizaki Y, Isoda K, Yokoo H, Obinata H, Hirano T, Miyasaka Y, Mashimo T, Yanagawa Y. Impact of GAD65 and/or GAD67 deficiency on perinatal development in rats. FASEB J 2022; 36:e22123. [PMID: 34972242 DOI: 10.1096/fj.202101389r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/26/2021] [Accepted: 12/13/2021] [Indexed: 11/11/2022]
Abstract
GABA is a major neurotransmitter in the mammalian central nervous system. Glutamate decarboxylase (GAD) synthesizes GABA from glutamate, and two isoforms of GAD, GAD65, and GAD67, are separately encoded by the Gad2 and Gad1 genes, respectively. The phenotypes differ in severity between GAD single isoform-deficient mice and rats. For example, GAD67 deficiency causes cleft palate and/or omphalocele in mice but not in rats. In this study, to further investigate the functional roles of GAD65 and/or GAD67 and to determine the contribution of these isoforms to GABA synthesis during development, we generated various kinds of GAD isoform(s)-deficient rats and characterized their phenotypes. The age of death was different among Gad mutant rat genotypes. In particular, all Gad1-/- ; Gad2-/- rats died at postnatal day 0 and showed little alveolar space in their lungs, suggesting that the cause of their death was respiratory failure. All Gad1-/- ; Gad2-/- rats and 18% of Gad1-/- ; Gad2+/- rats showed cleft palate. In contrast, none of the Gad mutant rats including Gad1-/- ; Gad2-/- rats, showed omphalocele. These results suggest that both rat GAD65 and GAD67 are involved in palate formation, while neither isoform is critical for abdominal wall formation. The GABA content in Gad1-/- ; Gad2-/- rat forebrains and retinas at embryonic day 20 was extremely low, indicating that almost all GABA was synthesized from glutamate by GADs in the perinatal period. The present study shows that Gad mutant rats are a good model for further defining the role of GABA during development.
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Affiliation(s)
- Weiru Jiang
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Toshikazu Kakizaki
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kazuyuki Fujihara
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Shigeo Miyata
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yue Zhang
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan.,Liaoning Provincial Key Laboratory of Cerebral Diseases, Department of Physiology, Dalian Medical University, Dalian, China
| | - Takashi Suto
- Department of Anesthesiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Daiki Kato
- Department of Anesthesiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Shigeru Saito
- Department of Anesthesiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Koji Shibasaki
- Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yasuki Ishizaki
- Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Koji Isoda
- Department of Human Pathology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Hideaki Yokoo
- Department of Human Pathology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Hideru Obinata
- Laboratory for Analytical Instruments, Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Touko Hirano
- Laboratory for Analytical Instruments, Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yoshiki Miyasaka
- Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Tomoji Mashimo
- Laboratory Animal Research Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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Panthi S, Lyons NMA, Leitch B. Impact of Dysfunctional Feed-Forward Inhibition on Glutamate Decarboxylase Isoforms and γ-Aminobutyric Acid Transporters. Int J Mol Sci 2021; 22:ijms22147740. [PMID: 34299369 PMCID: PMC8306481 DOI: 10.3390/ijms22147740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/16/2021] [Indexed: 12/02/2022] Open
Abstract
Absence seizures are associated with generalised synchronous 2.5–4 Hz spike-wave discharges causing brief and sudden alteration of awareness during childhood, which is known as childhood absence epilepsy (CAE). CAE is also associated with impaired learning, psychosocial challenges, and physical danger. Absence seizures arise from disturbances within the cortico-thalamocortical (CTC) network, including dysfunctional feed-forward inhibition (FFI); however, the precise mechanisms remain unclear. In epileptic stargazers, a genetic mouse model of CAE with chronic seizures, levels of γ-aminobutyric acid (GABA), and expression of GABA receptors are altered within the CTC network, implicating altered GABAergic transmission in absence seizures. However, the expression of GABA synthesising enzymes (GAD65 and GAD67) and GABA transporters (GAT-1 and 3) have not yet been characterised within absence seizure models. We found a specific upregulation of GAD65 in the somatosensory cortex but not the thalamus of epileptic stargazer mice. No differences were detected in GAD67 and GAT-3 levels in the thalamus or somatosensory cortex. Then, we assessed if GAD65 upregulation also occurred in Gi-DREADD mice exhibiting acute absence seizures, but we found no change in the expression profiles of GAD65/67 or GAT-3. Thus, the upregulation of GAD65 in stargazers may be a compensatory mechanism in response to long-term dysfunctional FFI and chronic absence seizures.
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Affiliation(s)
| | | | - Beulah Leitch
- Correspondence: ; Tel.: +64-3-479-7618; Fax: +64-3-479-7254
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Szpirer C. Rat Models of Human Diseases and Related Phenotypes: A Novel Inventory of Causative Genes. Mamm Genome 2021; 33:88-90. [PMID: 34184128 DOI: 10.1007/s00335-021-09876-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 05/11/2021] [Indexed: 10/21/2022]
Abstract
The laboratory rat (Rattus norvegicus) has been used for a long time as the model of choice in several biomedical disciplines. In 2020, I made an inventory of rat genes that had been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases. Over 350 genes could be found, a significant number of which have similar effects in rat and humans (Szpirer in J Biomed Sci 27:84-155, 2020). However, a few rat disease genes were unintentionally overlooked; in addition, since this review was published, numerous rat genes were inactivated by targeted mutations, revealing their potential role in diseases. It thus seems appropriate to update these data, which is the aim of this paper.
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Affiliation(s)
- Claude Szpirer
- Université Libre de Bruxelles, B-6041, Gosselies, Belgium. .,, Avenue Jassogne, 27, B-1410, Waterloo, Belgium.
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