Nagisa Clinic

Hirakata, Japan

Nagisa Clinic

Hirakata, Japan
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Ohno Y.,Osaka University of Pharmaceutical Sciences | Okumura T.,Osaka University of Pharmaceutical Sciences | Terada R.,Osaka University of Pharmaceutical Sciences | Ishihara S.,Osaka University of Pharmaceutical Sciences | And 2 more authors.
Neuroscience Letters | Year: 2012

Immunohistochemical studies were performed to analyze the expressional changes in hippocampal synaptic vesicle protein 2A (SV2A) following pentylenetetrazole (PTZ) kindling. Repeated treatments of mice with sub-convulsive PTZ (40. mg/kg, i.p.) for 15 days progressively enhanced seizure susceptibility and induced clonic convulsions in most animals examined. Topographical analysis of hippocampal SV2A-immunoreactivity revealed that SV2A was densely expressed in the hilar region of the dentate gyrus, stratum lucidum of the CA3 field and around the periphery of CA3 pyramidal neurons. PTZ kindling region-specifically increased SV2A expression in the dentate hilus without affecting that in the stratum lucidum or the pyramidal cell layer of the CA3 field. Confocal laser microscopic analysis using PTZ-kindled mice illustrated that most SV2A was co-expressed with glutamic acid decarboxylase 67 in the cell bodies and dendrites of hilar interneurons. However, SV2A-immunoreactivity was negligibly observed in the hilar glutamatergic nerve terminals (mossy fibers) probed with the anti-vesicular glutamate transporter 1 antibody. The present study suggests that SV2A specifically regulates hilar GABAergic neurotransmission in the kindled hippocampus probably as a compensatory or prophylactic mechanism against kindling epileptogenesis. © 2012 Elsevier Ireland Ltd.

Hanaya R.,Kagoshima University | Hosoyama H.,Kagoshima University | Sugata S.,Kagoshima University | Tokudome M.,Kagoshima University | And 6 more authors.
Neuroscience | Year: 2012

The spontaneously epileptic rat (SER) is a double mutant (zi/ zi, tm/ tm) which begins to exhibit tonic convulsions and absence seizures after 6. weeks of age, and repetitive tonic seizures over time induce sclerosis-like changes in SER hippocampus with high brain-derived neurotrophic factor (BDNF) expression. Levetiracetam, which binds to synaptic vesicle protein 2A (SV2A), inhibited both tonic convulsions and absence seizures in SERs. We studied SER brains histologically and immunohistochemically after verification by electroencephalography (EEG), as SERs exhibit seizure-related alterations in the cerebral cortex and hippocampus. SERs did not show interictal abnormal spikes and slow waves typical of focal epilepsy or symptomatic generalized epilepsy. The difference in neuronal density of the cerebral cortex was insignificant between SER and Wistar rats, and apoptotic neurons did not appear in SERs. BDNF distributions portrayed higher values in the entorhinal and piriform cortices which would relate with hippocampal sclerosis-like changes. Similar synaptophysin expression in the cerebral cortex and hippocampus was found in both animals. Low and diffuse SV2A distribution portrayed in the cerebral cortex and hippocampus of SERs was significantly less than that of all cerebral lobes and inner molecular layer (IML) of the dentate gyrus (DG) of Wistar rats. The extent of low SV2A expression/distribution in SERs was particularly remarkable in the frontal (51% of control) and entorhinal cortices (47%). Lower synaptotagmin-1 expression (vs Wistar rats) was located in the frontal (31%), piriform (13%) and entorhinal (39%) cortices, and IML of the DG (38%) in SER. Focal low distribution of synaptotagmin-1 accompanying low SV2A expression may contribute to epileptogenesis and seizure propagation in SER. © 2012 IBRO.

Hanaya R.,Kagoshima University | Kiura Y.,Hiroshima University | Serikawa T.,Kyoto University | Kurisu K.,Hiroshima University | And 2 more authors.
Brain Research Bulletin | Year: 2011

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 (100μM) 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 (100μM, 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. © 2011 Elsevier Inc.

Ohno Y.,Osaka University of Pharmaceutical Sciences | Okano M.,Osaka University of Pharmaceutical Sciences | Masui A.,Osaka University of Pharmaceutical Sciences | Imaki J.,Osaka University of Pharmaceutical Sciences | And 6 more authors.
Neuropharmacology | Year: 2012

Spontaneously hypertensive rats (SHR) are widely used as a rat model of attention deficit/hyperactivity disorder (AD/HD). Here, we conducted neurochemical and behavioral studies in SHR to clarify the topographical alterations in neurotransmissions linked to their behavioral abnormalities. In the open-field test, juvenile SHR showed a significant hyperactivity in ambulation and rearing as compared with Wistar Kyoto rats (WKY). Brain mapping analysis of Fos-immunoreactivity (IR) revealed that SHR showed a marked increase in Fos expression in the core part (AcC) of the nucleus accumbens (NAc). Small to moderate increases were also observed in the shell part of the NAc and some regions of the cerebral cortex (e.g., parietal association cortex). These changes in Fos expression were region-specific and the Fos-IR levels in other brain regions (e.g., hippocampus, amygdala, striatum, thalamus and hypothalamus) were unaltered. In addition, treatment of SHR with the selective D1 antagonist SCH-23390 significantly reversed both behavioral hyperactivity and elevated Fos expression in the AcC and cerebral cortex. The present study suggests that D1 receptor-mediated neurotransmission in the AcC is region-specifically elevated in SHR, which could be responsible for behavioral hyperactivity. © 2012 Elsevier Ltd. All rights reserved.

Ohno Y.,Osaka University of Pharmaceutical Sciences | Ishihara S.,Osaka University of Pharmaceutical Sciences | Mashimo T.,Kyoto University | Sofue N.,Osaka University of Pharmaceutical Sciences | And 5 more authors.
Neurobiology of Disease | Year: 2011

Mutations of the voltage-gated sodium (Na v) channel subunit SCN1A have been implicated in the pathogenesis of human febrile seizures including generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy in infancy (SMEI). Hyperthermia-induced seizure-susceptible (Hiss) rats are the novel rat model carrying a missense mutation (N1417H) of Scn1a, which is located in the third pore-forming region of the Na v1.1 channel. Here, we conducted behavioral and neurochemical studies to clarify the functional relevance of the Scn1a mutation in vivo and the mechanism underlying the vulnerability to hyperthermic seizures. Hiss rats showed markedly high susceptibility to hyperthermic seizures (mainly generalized clonic seizures) which were synchronously associated with paroxysmal epileptiform discharges. Immunohistochemical analysis of brain Fos expression revealed that hyperthermic seizures induced a widespread elevation of Fos-immunoreactivity in the cerebral cortices including the motor area, piriform, and insular cortex. In the subcortical regions, hyperthermic seizures enhanced Fos expression region-specifically in the limbic and paralimbic regions (e.g., hippocampus, amygdala, and perirhinal-entorhinal cortex) without affecting other brain regions (e.g., basal ganglia, diencephalon, and lower brainstem), suggesting a primary involvement of limbic system in the induction of hyperthermic seizures. In addition, Hiss rats showed a significantly lower threshold than the control animals in inducing epileptiform discharges in response to local stimulation of the hippocampus (hippocampal afterdischarges). Furthermore, hyperthermic seizures in Hiss rats were significantly alleviated by the antiepileptic drugs, diazepam and sodium valproate, while phenytoin or ethosuximide were ineffective. The present findings support the notion that Hiss rats are useful as a novel rat model of febrile seizures and suggest that hyperexcitability of limbic neurons associated with Scn1a missense mutation plays a crucial role in the pathogenesis of febrile seizures. © 2010 Elsevier Inc.

Sugata S.,Kagoshima University | Hanaya R.,Kagoshima University | Kumafuji K.,Kyoto University | Tokudome M.,Kagoshima University | And 4 more authors.
Brain Research Bulletin | Year: 2011

The spontaneously epileptic rat (SER) begins to exhibit both tonic convulsions and absence seizures from 6 weeks of age and SERs have stable seizures after 10 weeks of age. Low-dose administrations of levetiracetam (LEV) for 4- to 5-weeks-old SERs which did not show spontaneous seizures reduced both seizures 5 weeks after termination of administration. The hippocampus of SER exhibited decreased CA3 neurons, sprouting of mossy fibers, and hyperexpression of the brain-derived neurotrophic factor (BDNF). We attempted prophylactic LEV administrations in preseizure-manifesting SERs to evaluate if such a treatment regimen would protect the hippocampal sclerosis-like changes observed in SERs. The osmotic mini-pump administered LEV dissolved in saline to 4-weeks-old SERs for 4 weeks at 2.5 μl/h. LEV was administered at 420. mg/ml for 4 weeks in Group A. In Group B, LEV was given at 420. mg/ml for the first 2 weeks followed by doubling the dosage (840. mg/ml) in the following 2 weeks. LEV administrations in preseizure-manifesting SERs reduced the decrease of CA3 neurons and mossy fibers sprouting at 10-11 weeks of age in both group A and B. LEV attenuated BDNF expression in inner molecular layers of the dentate gyrus, striatum radiatum, and CA3 in 10- to 11- and 14- to 15-weeks-old SERs. In group B, LEV decreased BDNF expression in hilus and CA1 of 10- to 11- weeks-old SER. The present results suggest that prophylactic treatment with LEV in preseizure-manifesting SERs inhibits hippocampal sclerosis-like neuronal degeneration and/or regeneration. © 2011 Elsevier Inc.

Ohno Y.,Osaka University of Pharmaceutical Sciences | Sofue N.,Osaka University of Pharmaceutical Sciences | Imaoku T.,Osaka University of Pharmaceutical Sciences | Morishita E.,Osaka University of Pharmaceutical Sciences | And 3 more authors.
Journal of Pharmacological Sciences | Year: 2010

To explore the role of the serotonergic system in modulating absence seizures, we examined the effects of 5-HT1A and 5-HT2 agonists on the incidence of spike-and-wave discharges (SWD) in Groogy (GRY) rats, a novel rat model of absence-like epilepsy. GRY rats exhibited spontaneous absence-like seizures characterized by the incidence of sudden immobile posture and synchronously-associated SWD. The total duration of SWD in GRY rats was about 300 - 400 s/15-min observation period under the control conditions. However, the incidence of SWD was markedly reduced either by the 5-HT1A agonist (±)-8-hydroxy-2-(di-n-propylamino)-tetralin [(±)8-OH-DPAT] or the 5-HT2 agonist (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(±)DOI]. The 5-HT reuptake inhibitors, fluoxetine and clomipramine, also inhibited the SWD generation. In addition, the inhibitory effects of (±)8-OH-DPAT and (±)DOI were reversed by WAY-100135 (5-HT1A antagonist) and ritanserin (5-HT2 antagonist), respectively. The present results suggest that the serotonergic system negatively regulates the incidence of absence seizures by stimulation of 5-HT1A and 5-HT2 receptors. ©2010 The Japanese Pharmacological Society.

Ohno Y.,Osaka University of Pharmaceutical Sciences | Sofue N.,Osaka University of Pharmaceutical Sciences | Ishihara S.,Osaka University of Pharmaceutical Sciences | Mashimo T.,Kyoto University | And 2 more authors.
Biochemical and Biophysical Research Communications | Year: 2010

Mutations of the Nav1.1 channel subunit SCN1A have been implicated in the pathogenesis of human febrile seizures (FS). We have recently developed hyperthermia-induced seizure-susceptible (Hiss) rat, a novel rat model of FS, which carries a missense mutation (N1417H) in Scn1a [1]. Here, we conducted electrophysiological studies to clarify the influences of the Scn1a mutation on the hippocampal synaptic transmission, specifically focusing on the GABAergic system. Hippocampal slices were prepared from Hiss or F344 (control) rats and maintained in artificial cerebrospinal fluid saturated with 95% O2 and 5% CO2 in vitro. Single neuron activity was recorded from CA1 pyramidal neurons and their responses to the test (unconditioned) or paired pulse (PP) stimulation of the Schaffer collateral/commissural fibers were evaluated. Hiss rats were first tested for pentylenetetrazole-induced seizures and confirmed to show high seizure susceptibility to the blockade of GAGAA receptors. The Scn1a mutation in Hiss rats did not directly affect spike generation (i.e., number of evoked spikes and firing threshold) of the CA1 pyramidal neurons elicited by the Schaffer collateral/commissural stimulation. However, GABAA receptor-mediated inhibition of pyramidal neurons by the PP stimulation was significantly disrupted in Hiss rats, yielding a significant increase in the number of PP-induced firings at PP intervals of 32-256ms. The present study shows that the Scn1a missense mutation preferentially impairs GABAA receptor-mediated synaptic transmission without directly altering the excitability of the pyramidal neurons in the hippocampus, which may be linked to the pathogenesis of FS. © 2010 Elsevier Inc.

Ohno Y.,Osaka University of Pharmaceutical Sciences | Ishihara S.,Osaka University of Pharmaceutical Sciences | Terada R.,Osaka University of Pharmaceutical Sciences | Serikawa T.,Kyoto University | Sasa M.,Nagisa Clinic
Epilepsy Research | Year: 2010

Levetiracetam (LEV) is a unique antiepileptic drug that preferentially interacts with synaptic vesicle protein 2A (SV2A). To evaluate the antiepileptogenic action of LEV, we studied its effects on the development and acquisition of pentylenetetrazole (PTZ) kindling and compared them to those of sodium valproate (VPA). Anticonvulsive actions of LEV in PTZ-kindled animals were also determined. LEV did not affect PTZ seizures in naïve animals even at high doses (≈300. mg/kg, i.p.). However, combined treatment of LEV (30 and 100. mg/kg, i.p.) with PTZ significantly suppressed the development and acquisition of PTZ kindling. In addition, LEV at relatively low doses (3-30. mg/kg, i.p.) inhibited PTZ-evoked seizures in fully kindled animals. In contrast to LEV, VPA at sub-anticonvulsive doses (30 and 100. mg/kg, i.p.) failed to prevent the development of PTZ kindling and its anticonvulsive potency was similar in PTZ-kindled and naïve mice. The present study shows that LEV contrasts VPA by preventing the development of PTZ kindling and inhibiting seizures selectively in kindled animals. © 2010 Elsevier B.V.

PubMed | Nagisa Clinic, Kyoto University and Osaka University of Pharmaceutical Sciences
Type: | Journal: Scientific reports | Year: 2016

Synaptic vesicle glycoprotein 2A (SV2A) is a prototype synaptic vesicle protein regulating action potential-dependent neurotransmitters release. SV2A also serves as a specific binding site for certain antiepileptics and is implicated in the treatment of epilepsy. Here, to elucidate the role of SV2A in modulating epileptogenesis, we generated a novel rat model (Sv2a(L174Q) rat) carrying a Sv2a-targeted missense mutation (L174Q) and analyzed its susceptibilities to kindling development. Although animals homozygous for the Sv2a(L174Q) mutation exhibited normal appearance and development, they are susceptible to pentylenetetrazole (PTZ) seizures. In addition, development of kindling associated with repeated PTZ treatments or focal stimulation of the amygdala was markedly facilitated by the Sv2a(L174Q) mutation. Neurochemical studies revealed that the Sv2a(L174Q) mutation specifically reduced depolarization-induced GABA, but not glutamate, release in the hippocampus without affecting basal release or the SV2A expression level in GABAergic neurons. In addition, the Sv2a(L174Q) mutation selectively reduced the synaptotagmin1 (Syt1) level among the exocytosis-related proteins examined. The present results demonstrate that dysfunction of SV2A due to the Sv2a(L174Q) mutation impairs the synaptic GABA release by reducing the Syt1 level and facilitates the kindling development, illustrating the crucial role of SV2A-GABA system in modulating kindling epileptogenesis.

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