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Numakura Y, Uemura R, Tanaka M, Izawa T, Yamate J, Kuramoto T, Kaneko T, Mashimo T, Yamamoto T, Serikawa T, Kuwamura M. PHF24 is expressed in the inhibitory interneurons in rats. Exp Anim 2021; 70:137-143. [PMID: 33115988 PMCID: PMC7887615 DOI: 10.1538/expanim.20-0105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/29/2020] [Indexed: 11/20/2022] Open
Abstract
Noda epileptic rat (NER) is a mutant model for epilepsy that exhibits spontaneous generalized tonic-clonic seizure. Epileptogenesis of NER remains to be elucidated; but it is detected an insertion of an endogenous retrovirus sequence in intron 2 of the PHD finger protein 24 (Phf24) gene, encoding Gαi-interacting protein (GINIP). Phf24 is a strong candidate gene for epileptogenesis in NER. PHF24 modulates GABAB signaling through interacting with Gαi protein. To clarify the epileptogenesis of NER, we investigated a distribution of PHF24-expressing cells in the central nerve system (CNS). While broad expression of PHF24 was observed in the CNS, characteristic expression was noted in the periglomerular layer of the olfactory bulb and the lamina II of the spinal cord in the control rats. These cells showed co-expression with calbindin or calretinin, inhibitory interneuron markers. In the olfactory bulb, 15.6% and 41.2% of PHF24-positive neurons co-expressed calbindin and calretinin, respectively. Immunoelectron microscopy revealed that PHF24 was located in the presynaptic terminals, synaptic membranes and cytoplasmic matrix of neuronal soma. Our data suggested PHF24 is expressed in the inhibitory interneurons and may play important roles in modulation of the GABAB signaling.
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Affiliation(s)
- Yuki Numakura
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
| | - Risa Uemura
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
| | - Miyuu Tanaka
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
| | - Takeshi Izawa
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
| | - Jyoji Yamate
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
- Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
| | - Takehito Kaneko
- Laboratory of Animal Reproduction and Development, Graduate School of Science and Engineering, Iwate University, 4-35 Ueda, Morioka-shi, Iwate 020-8551, Japan
| | - Tomoji Mashimo
- Division of Animal Genetics, Laboratory Animal Research Center, Institute of Medical Science, the University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Takashi Yamamoto
- Molecular Genetics Laboratory, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Tadao Serikawa
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Mitsuru Kuwamura
- Laboratory of Veterinary Pathology, Osaka Prefecture University, 1-58 Ourai-kita, Izumisano, Osaka 598-8531, Japan
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Identification of Candidate Genes for Generalized Tonic-Clonic Seizures in Noda Epileptic Rat. Behav Genet 2017; 47:609-619. [PMID: 28936718 DOI: 10.1007/s10519-017-9870-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/08/2017] [Indexed: 12/31/2022]
Abstract
The Noda epileptic rat (NER) exhibits generalized tonic-clonic seizures (GTCS). A genetic linkage analysis identified two GTCS-associated loci, Ner1 on Chr 1 and Ner3 on Chr 5. The wild-type Ner1 and Ner3 alleles suppressed GTCS when combined in double-locus congenic lines, but not when present in single-locus congenic lines. Global expression analysis revealed that cholecystokinin B receptor (Cckbr) and suppressor of tumorigenicity 5 (St5), which map within Ner1, and PHD finger protein 24 (Phf24), which maps within Ner3, were significantly downregulated in NER. De novo BAC sequencing detected an insertion of an endogenous retrovirus sequence in intron 2 of the Phf24 gene in the NER genome, and PHF24 protein was almost absent in the NER brain. Phf24 encodes a Gαi-interacting protein involved in GABAB receptor signaling pathway. Based on these findings, we conclude that Cckbr, St5, and Phf24 are strong candidate genes for GTCS in NER.
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Serikawa T, Mashimo T, Kuramoro T, Voigt B, Ohno Y, Sasa M. Advances on genetic rat models of epilepsy. Exp Anim 2014; 64:1-7. [PMID: 25312505 PMCID: PMC4329510 DOI: 10.1538/expanim.14-0066] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Considering the suitability of laboratory rats in epilepsy research, we and other groups
have been developing genetic models of epilepsy in this species. After epileptic rats or
seizure-susceptible rats were sporadically found in outbred stocks, the epileptic traits
were usually genetically-fixed by selective breeding. So far, the absence seizure models
GAERS and WAG/Rij, audiogenic seizure models GEPR-3 and GEPR-9, generalized tonic-clonic
seizure models IER, NER and WER, and Canavan-disease related epileptic models TRM and SER
have been established. Dissection of the genetic bases including causative genes in these
epileptic rat models would be a significant step toward understanding epileptogenesis.
N-ethyl-N-nitrosourea (ENU) mutagenesis provides a systematic approach which allowed us to
develop two novel epileptic rat models: heat-induced seizure susceptible (Hiss) rats with
an Scn1a missense mutation and autosomal dominant lateral temporal epilepsy (ADLTE) model
rats with an Lgi1 missense mutation. In addition, we have established episodic ataxia type
1 (EA1) model rats with a Kcna1 missense mutation derived from the ENU-induced rat mutant
stock, and identified a Cacna1a missense mutation in a N-Methyl-N-nitrosourea
(MNU)-induced mutant rat strain GRY, resulting in the discovery of episodic ataxia type 2
(EA2) model rats. Thus, epileptic rat models have been established on the two paths:
‘phenotype to gene’ and ‘gene to phenotype’. In the near future, development of novel
epileptic rat models will be extensively promoted by the use of sophisticated genome
editing technologies.
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Affiliation(s)
- Tadao Serikawa
- Graduate School of Medicine, Kyoto University, Sakyo-ku 606-8501; Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki 569-1094, Japan
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Anticonvulsant effects of bis-1,4-dihydropyridines and the probable role of L-type calcium channels suggested by docking simulations. Med Chem Res 2014. [DOI: 10.1007/s00044-014-1083-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Enhanced susceptibility to spontaneous seizures of noda epileptic rats by loss of synaptic zn(2+). PLoS One 2013; 8:e71372. [PMID: 23951148 PMCID: PMC3741169 DOI: 10.1371/journal.pone.0071372] [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: 11/01/2012] [Accepted: 07/04/2013] [Indexed: 01/21/2023] Open
Abstract
Zinc homeostasis in the brain is associated with the etiology and manifestation of epileptic seizures. Adult Noda epileptic rats (NER, >12-week-old) exhibit spontaneously generalized tonic-clonic convulsion about once a day. To pursue the involvement of synaptic Zn2+ signal in susceptibility to spontaneous seizures, in the present study, the effect of zinc chelators on epileptogenesis was examined using adult NER. Clioquinol (CQ) and TPEN are lipophilic zinc chelotors, transported into the brain and reduce the levels of synaptic Zn2+. The incidence of tonic-clonic convulsion was markedly increased after i.p. injection of CQ (30–100 mg/kg) and TPEN (1 mg/kg). The basal levels of extracellular Zn2+ measured by ZnAF-2 were decreased before tonic-clonic convulsion was induced with zinc chelators. The hippocampal electroencephalograms during CQ (30 mg/kg)-induced convulsions were similar to those during sound-induced convulsions in NER reported previously. Exocytosis of hippocampal mossy fibers, which was measured with FM4-64, was significantly increased in hippocampal slices from CQ-injected NER that did not show tonic-clonic convulsion yet. These results indicate that the abnormal excitability of mossy fibers is induced prior to epileptic seizures by injection of zinc chelators into NER. The incidence of tonic-clonic convulsion induced with CQ (30 mg/kg) was significantly reduced by co-injection with aminooxyacetic acid (5–10 mg/kg), an anticonvulsant drug enhancing GABAergic activity, which did not affect locomotor activity. The present paper demonstrates that the abnormal excitability in the brain, especially in mossy fibers, which is potentially associated with the insufficient GABAergic neuron activity, may be a factor to reduce the threshold for epileptogenesis in NER.
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Harada Y, Nagao Y, Shimizu S, Serikawa T, Terada R, Fujimoto M, Okuda A, Mukai T, Sasa M, Kurachi Y, Ohno Y. Expressional analysis of inwardly rectifying Kir4.1 channels in Noda epileptic rat (NER). Brain Res 2013; 1517:141-9. [PMID: 23603404 DOI: 10.1016/j.brainres.2013.04.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 03/31/2013] [Accepted: 04/09/2013] [Indexed: 11/30/2022]
Abstract
The inwardly rectifying potassium channel subunit Kir4.1 is expressed in brain astrocytes and involved in spatial K(+) buffering, regulating neural activity. To explore the pathophysiological alterations of Kir4.1 channels in epileptic disorders, we analyzed interictal expressional levels of Kir4.1 in the Noda epileptic rat (NER), a hereditary animal model for generalized tonic-clonic (GTC) seizures. Western blot analysis showed that Kir4.1 expression in NERs was significantly reduced in the occipito-temporal cortical region and thalamus. However, the expression of Kir5.1, another Kir subunit mediating spatial K(+) buffering, remained unaltered in any brain regions examined. Immunohistochemical analysis revealed that Kir4.1 was primarily expressed in glial fibrillary acidic protein (GFAP)-positive astrocytes (somata) and foot processes clustered around neurons proved with anti-neuronal nuclear antigen (NeuN) antibody. In NERs, Kir4.1 expression in astrocytic processes was region-selectively diminished in the amygdaloid nuclei (i.e., medial amygdaloid nucleus and basomedial amygdaloid nucleus) while Kir4.1 expression in astrocytic somata was unchanged. Furthermore, the amygdala regions with reduced Kir4.1 expression showed a marked elevation of Fos protein expression following GTC seizures. The present results suggest that reduced activity of astrocytic Kir4.1 channels in the amygdala is involved in limbic hyperexcitability in NERs.
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Affiliation(s)
- Yuya Harada
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan
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Ishimaru Y, Chiba S, Serikawa T, Sasa M, Inaba H, Tamura Y, Ishimoto T, Takasaki H, Sakamoto K, Yamaguchi K. Effects of levetiracetam on hippocampal kindling in Noda epileptic rats. Brain Res 2010; 1309:104-9. [DOI: 10.1016/j.brainres.2009.10.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 10/16/2009] [Accepted: 10/22/2009] [Indexed: 10/20/2022]
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Ohno Y, Shimizu S, Harada Y, Morishita M, Ishihara S, Kumafuji K, Sasa M, Serikawa T. Regional expression of Fos-like immunoreactivity following seizures in Noda epileptic rat (NER). Epilepsy Res 2009; 87:70-6. [PMID: 19713079 DOI: 10.1016/j.eplepsyres.2009.07.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 07/22/2009] [Accepted: 07/29/2009] [Indexed: 11/24/2022]
Abstract
Noda epileptic rat (NER) is a genetic rat model of epilepsy that exhibit spontaneous generalized tonic-clonic (GTC) seizures with paroxysmal discharges. We analyzed the regional expression of Fos-like immunoreactivity (Fos-IR) following GTC seizures in NER to clarify the brain regions involved in the seizure generation. GTC seizures in NER elicited a marked increase in Fos expression in the piriform cortex, perirhinal-entorhinal cortex, insular cortex and other cortices including the motor cortex. In the limbic regions, Fos-IR was highest in the amygdalar nuclei (e.g., basomedial amygdaloid nucleus), followed by the cingulate cortex and hippocampus (i.e., dentate gyrus and CA3). As compared to the above forebrain regions, NER either with or without GTC seizures exhibited only marginal Fos expression in the basal ganglia (e.g., accumbens, striatum and globus pallidus), diencephalon (e.g., thalamus and hypothalamus) and lower brain stem structures (e.g., pons-medulla oblongata). These results suggest that GTC seizures in NER are of forebrain origin and are evoked primarily by activation of the limbic and/or cortical seizure circuits.
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Affiliation(s)
- Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan.
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Abstract
Principles of complex mechanisms of action of anticonvulsants including latest reports concerning new antiepileptic drugs (AED) are considered. Different aspects of new anticonvulsant drugs (2nd generation) from preclinical and clinical testing, pharmacokinetics, and mono or combination therapy in children and adults are summarized. In the following condensed synopsis pharmacological and clinical characteristics of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), pregabalin (PGB) and tiagabine (TGB) as well as topiramate (TPM) and zonisamide (ZNS) are discussed. In addition to the mechanisms of action, pharmacokinetics, interactions, indications and dosages as well as side effects are considered. Important data concerning the effect and tolerability of anticonvulsant drugs can be obtained from controlled studies. In comparison to drugs of the first generation (phenobarbital [PB], primidon [PRD], phenytoin [PHT], carbamazepine [CBZ] and valproic acid [VPA]) the potential for interactions and side effects due to enzyme induction or inhibition is reduced by most of the anticonvulsant drugs of the second generation. New anticonvulsant drugs increase the spectrum of treatment and represent further steps with regard to the optimization of an individual therapy of the epilepsies.
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Affiliation(s)
- H Stefan
- University Clinic Erlangen, Epilepsy Center-Neurological Department, Schwabachanlage 6, D-91054 Erlangen, Germany
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Chanut E, Labarthe B, Lacroix B, Noda A, Gasdeblay S, Bondier JR, Versaux-Botteri C. Variations of dopamine, serotonin, and amino acid concentrations in Noda epileptic rat (NER) retina. Brain Res 2006; 1070:56-64. [PMID: 16403472 DOI: 10.1016/j.brainres.2005.11.032] [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: 05/23/2005] [Revised: 11/08/2005] [Accepted: 11/11/2005] [Indexed: 10/25/2022]
Abstract
Noda epileptic rats (NER) exhibit frequent spontaneous tonic-clonic convulsions which represent a valuable model of human epilepsy. If implication of brain neurotransmitters was largely reported, little is known about retina. However, it has been reported that human epilepsy syndrome varies not only with the location of seizure foci but also according to rhythmic patterns, for which retina has a major role in the transmission of external light-dark cycle information. The purpose of this work was to evaluate dopamine (DA), DA metabolites, serotonin (5-HT), and amino acid [glutamate, aspartate, glycine, gamma aminobutyric acid (GABA), and taurine] level variations in retina from NER, at two different nycthemeral periods (11 a.m. and 11 p.m.) and at different ages (2, 6, and 12 months). In NER, retinal dopaminergic function was decreased as soon as 2 months, whereas GABA levels were increased, even if no differences among the different ages could be distinguished. These variations were associated to a slight increase in 5-HT. Other amino acids tested were not affected by epilepsy, whereas taurine decreased with aging in NER as well as in control rats. Retinal 5-HT occurs principally as a precursor of melatonin (MEL). A triangular interaction may be hypothesized: MEL could decrease DA synthesis or release by enhancing GABA activity. Taken together, these results suggest that the retinal physiology is affected by the epileptic status and that information transmitted from retina to the brain should be affected by epilepsy in NER.
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Affiliation(s)
- Evelyne Chanut
- Laboratoire de Pharmacologie, Faculté de Pharmacie, 92296 Châtenay-Malabry, France.
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