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1.
Brain Res ; 1783: 147849, 2022 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-35231419

RESUMO

Chronic subconvulsive activity in early life leads to sex-related autistic-like deficits in handling, object recognition, and social performance in pre-pubertal rats. Since autism and epilepsy are common neurodevelopmental disorders with high coincidence, we tested whether early-life chronic subconvulsive activity compared to convulsive activity alters handling, spatial memory, lateralization, coping strategy and the seizure threshold in a sex-dependent manner. A hypothesis is that convulsive seizures may alter sex differences induced by subconvulsive (SC) activity. Serial subconvulsive doses of kainic acid (KA) were administered postnatally (0.25-1 mg/kg) for 15 days to induce the chronic subconvulsive phenotype (SC group). Age-matched controls and a subset of SC pups were exposed to a convulsive dose of KA (KA and SC + KA groups; 7.5 mg/kg) or flurothyl vapors. In our open handling test, controls and the ASD groups escaped to a similar degree whereas after convulsive seizures, the pups exhibited freezing behavior; no escapes occurred. In the spontaneous alternating T-Maze control males and females entered the left arm with higher frequency. The SC males but not SC females entered left and right arms to a similar degree; alternation rates were reduced to chance revealing a sex difference. However, in KA and SC + KA groups, there was a sharp loss of spontaneous alternation rates. The rapid repetitive entries shifted to the right in both sexes possibly be due to hippocampal injury and changes in network activity induced by status epilepticus. In the forced swim test (FST), control and CS females were more active than corresponding males. After convulsions, immobility was reduced and vertical mobility was increased in SC and SC + KA males suggesting an elevated coping strategy compared to females. Onset and severity of KA induced status epilepticus was delayed in SC males and females possibly due to desensitization of KA receptors. Following flurothyl exposure, control males had faster onset of twitches and clonic seizures than control females which disappeared after the sub-convulsive pre-treatment. Data suggest that behavioral manifestations are more readily detectable between males and females when low levels of hyperexcitation are present chronically in early postnatal development but diminished after tonic-clonic convulsions persist. Therefore, therapeutic interventions may benefit patients if initiated upon the initial onset of sex-related autistic pathologies, particularly in males, which may reduce subsequent vulnerability to seizures.


Assuntos
Epilepsia , Estado Epiléptico , Animais , Epilepsia/induzido quimicamente , Epilepsia/patologia , Feminino , Flurotila/efeitos adversos , Hipocampo , Humanos , Ácido Caínico/farmacologia , Masculino , Ratos , Convulsões/induzido quimicamente , Caracteres Sexuais , Estado Epiléptico/tratamento farmacológico
2.
Epilepsy Res ; 181: 106867, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35131691

RESUMO

Memory deficits are a prevalent and pervasive comorbidity of epilepsy that significantly decrease an individual's quality of life. Numerous studies have investigated the effects of a seizure on the encoding process of memory; however, few studies have assessed the effect of a seizure on the reconsolidation process of memory. We investigated how a single seizure affects memory reconsolidation in C57BL/6 J adult mice using a predominately hippocampal-dependent paradigm. Mice were presented with a tone (conditioned stimulus), that was proceeded by a mild shock (unconditioned stimulus) occurring 20 s after the tone. Three days later, a flurothyl-induced seizure was administered 1-h before a memory reconsolidation trial. The learned association was assessed by presenting a conditioned stimulus in a new context 24 h or 1-week after memory reconsolidation. We found that there were no differences in memory present between seizure and control mice at the 24 h or 1-week timepoints. Wheel running was also assessed to ensure that the seizure did not alter locomotion and bias the measure in the memory task. No differences in locomotion between seizure and control mice were observed at any timepoint. Altogether, these findings suggest that hippocampal dependent memory reconsolidation is resistant to flurothyl-induced seizure disruption.


Assuntos
Medo , Flurotila , Animais , Flurotila/toxicidade , Hipocampo , Memória , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora , Qualidade de Vida , Convulsões/induzido quimicamente
3.
Epilepsia ; 62(7): 1701-1714, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34002378

RESUMO

OBJECTIVE: Early life seizures (ELSs) alter activity-dependent maturation of neuronal circuits underlying learning and memory. The pathophysiological mechanisms underpinning seizure-induced cognitive impairment are not fully understood, and critical variables such as sex and dynamic brain states with regard to cognitive outcomes have not been explored. We hypothesized that in comparison to control (CTL) rats, ELS rats would exhibit deficits in spatial cognition correlating with impaired dynamic neural signal coordination between the hippocampus and medial prefrontal cortex (mPFC). METHODS: Male and female rat pups were given 50 flurothyl-induced seizures over 10 days starting at postnatal Day 15. As adults, spatial cognition was tested through active avoidance on a rotating arena. Microwire tetrodes were implanted in the mPFC and CA1 subfield. Single cells and local field potentials were recorded and analyzed in each region during active avoidance and sleep. RESULTS: ELS males exhibited avoidance impairments, whereas female rats were unaffected. During avoidance, hippocampus-mPFC coherence was higher in CTL females than CTL males across bandwidths. In comparison to CTL males, ELS male learners exhibit increased coherence within theta bandwidth as well as altered burst-timing in mPFC cell activity. Hippocampus-mPFC coherence levels are predictive of cognitive outcome in the active avoidance spatial task. SIGNIFICANCE: Spatial cognitive outcome post-ELS is sex-dependent, as females fare better than males. ELS males that learn the task exhibit increased mPFC coherence levels at low-theta frequency, which may compensate for ELS effects on mPFC cell timing. These results suggest that coherence may serve as a biomarker for spatial cognitive outcome post-ELS and emphasize the significance of analyzing sex and dynamic cognition as variables in understanding seizure effects on the developing brain.


Assuntos
Encéfalo/patologia , Hipocampo/patologia , Rede Nervosa/patologia , Córtex Pré-Frontal/patologia , Convulsões/patologia , Animais , Aprendizagem da Esquiva , Encéfalo/fisiopatologia , Região CA1 Hipocampal/patologia , Cognição , Convulsivantes , Eletrodos Implantados , Eletroencefalografia , Feminino , Flurotila , Masculino , Aprendizagem em Labirinto , Ratos , Ratos Sprague-Dawley , Convulsões/induzido quimicamente , Convulsões/psicologia , Caracteres Sexuais , Sono , Percepção Espacial , Ritmo Teta
4.
Behav Brain Res ; 410: 113317, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-33910029

RESUMO

Epilepsy is one of the most common neurological disorders, with individuals having an increased susceptibility of seizures in the first few years of life, making children at risk of developing a multitude of cognitive and behavioral comorbidities throughout development. The present study examined the role of PI3K/Akt/mTOR pathway activity and neuroinflammatory signaling in the development of autistic-like behavior following seizures in the neonatal period. Male and female C57BL/6J mice were administered 3 flurothyl seizures on postnatal (PD) 10, followed by administration of minocycline, the mTOR inhibitor rapamycin, or a combined treatment of both therapeutics. On PD12, isolation-induced ultrasonic vocalizations (USVs) of mice were examined to determine the impact of seizures and treatment on communicative behaviors, a component of the autistic-like phenotype. Seizures on PD10 increased the quantity of USVs in female mice and reduced the amount of complex call types emitted in males compared to controls. Inhibition of mTOR with rapamycin significantly reduced the quantity and duration of USVs in both sexes. Changes in USVs were associated with increases in mTOR and astrocyte levels in male mice, however, three PD10 seizures did not result in enhanced proinflammatory cytokine expression in either sex. Beyond inhibition of mTOR activity by rapamycin, both therapeutics did not demonstrate beneficial effects. These findings emphasize the importance of differences that may exist across preclinical seizure models, as three flurothyl seizures did not induce as drastic of changes in mTOR activity or inflammation as observed in other rodent models.


Assuntos
Epilepsia , Fatores Imunológicos/farmacologia , Minociclina/farmacologia , Convulsões , Sirolimo/farmacologia , Vocalização Animal/efeitos dos fármacos , Animais , Convulsivantes/farmacologia , Modelos Animais de Doenças , Epilepsia/induzido quimicamente , Epilepsia/imunologia , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Feminino , Flurotila/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Convulsões/induzido quimicamente , Convulsões/imunologia , Convulsões/metabolismo , Convulsões/fisiopatologia , Fatores Sexuais
5.
Brain Dev ; 43(4): 515-520, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33408038

RESUMO

INTRODUCTION: Epilepsy is one of the main clinical problems in Angelman syndrome (AS). Seizures typically start in early childhood then decrease or are often alleviated by young adulthood. Several studies using AS model mice showed comparable seizure susceptibility during young adulthood. In contrast, the course of epilepsy post young adulthood differs from persistently relieved to rerising among reports. To elucidate this, we evaluated the seizure susceptibility of AS model mice of two different ages. METHODS: Mice lacking maternal Ube3a gene (Ube3am-/p+) of C57BL/6 background or their littermate wild type (WT) were divided into two groups by age, 2 to 3 months (2-3 M) and 6 to 12 months (6-12 M), corresponding to adolescent to young adult aged and middle aged humans, respectively. Seizure susceptibility was evaluated by flurothyl inhalation or intraperitoneal injection of pentylenetetrazole (PTZ IP)-induced acute seizure protocol. RESULTS: In the flurothyl-induced seizure paradigm, the latency to seizure occurrence had a significant interaction with genotype and age. Post-hoc analysis revealed that the latency was significantly shorter at 6-12 M than at 2-3 M in Ube3am-/p+ mice, and in Ube3am-/p+ mice than in WT mice at 6-12 M. No significant interaction or difference was observed by PTZ IP. CONCLUSION: The flurothyl-induced seizure paradigm revealed that seizure susceptibility of Ube3am-/p+ mice increased with age, similar to clinical studies reporting the reappearance of epilepsy in older age. The flurothyl-induced seizure paradigm applied to middle-aged Ube3am-/p+ mice could be a suitable protocol for screening drugs against seizures in AS.


Assuntos
Síndrome de Angelman/fisiopatologia , Convulsões/fisiopatologia , Síndrome de Angelman/genética , Animais , Modelos Animais de Doenças , Suscetibilidade a Doenças , Flurotila , Masculino , Camundongos , Convulsões/induzido quimicamente , Tetrazóis , Ubiquitina-Proteína Ligases/genética
6.
Neurobiol Dis ; 148: 105222, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33309937

RESUMO

Since neonatal hypoxia-ischemia (HI) disrupts the hippocampal (Hp) GABAergic network in the mouse and Hp injury in this model correlates with flurothyl seizure susceptibility only in male mice, we hypothesized that GABAergic disruption correlates with flurothyl seizure susceptibility in a sex-specific manner. C57BL6 mice were exposed to HI (Vannucci model) versus sham procedures at P10, randomized to normothermia (NT) or therapeutic hypothermia (TH), and subsequently underwent flurothyl seizure testing at P18. Only in male mice, Hp atrophy correlated with seizure susceptibility. The number of Hp parvalbumin positive interneurons (PV+INs) decreased after HI in both sexes, but TH attenuated this deficit only in females. In males only, seizure susceptibility directly correlated with the number of PV+INs, but not somatostatin or calretinin expressing INs. Hp GABAB receptor subunit levels were decreased after HI, but unrelated to later seizure susceptibility. In contrast, Hp GABAA receptor α1 subunit (GABAARα1) levels were increased after HI. Adjusting the number of PV+ INs for their GABAARα1 expression strengthened the correlation with seizure susceptibility in male mice. Thus, we identified a novel Hp sex-specific GABA-mediated mechanism of compensation after HI that correlates with flurothyl seizure susceptibility warranting further study to better understand potential clinical translation.


Assuntos
Neurônios GABAérgicos/metabolismo , Hipocampo/metabolismo , Hipóxia-Isquemia Encefálica/metabolismo , Interneurônios/metabolismo , Animais , Animais Recém-Nascidos , Convulsivantes/toxicidade , Suscetibilidade a Doenças , Flurotila/toxicidade , Neurônios GABAérgicos/fisiologia , Hipocampo/fisiopatologia , Hipóxia-Isquemia Encefálica/fisiopatologia , Interneurônios/fisiologia , Camundongos , Parvalbuminas , Convulsões/induzido quimicamente , Fatores Sexuais
7.
Epilepsia ; 61(9): 2010-2021, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32852103

RESUMO

OBJECTIVE: Animal studies remain essential for understanding mechanisms of epilepsy and identifying new therapeutic targets. However, existing animal models of epilepsy do not reflect the high level of genetic diversity found in the human population. The Collaborative Cross (CC) population is a genetically diverse recombinant inbred panel of mice. The CC offers large genotypic and phenotypic diversity, inbred strains with stable genomes that allow for repeated phenotypic measurements, and genomic tools including whole genome sequence to identify candidate genes and candidate variants. METHODS: We evaluated multiple complex epileptic traits in a sampling of 35 CC inbred strains using the flurothyl-induced seizure and kindling paradigm. We created an F2 population of 297 mice with extreme seizure susceptibility and performed quantitative trait loci (QTL) mapping to identify genomic regions associated with seizure sensitivity. We used quantitative RNA sequencing from CC hippocampal tissue to identify candidate genes and whole genome sequence to identify genetic variants likely affecting gene expression. RESULTS: We identified new mouse models with extreme seizure susceptibility, seizure propagation, epileptogenesis, and SUDEP (sudden unexpected death in epilepsy). We performed QTL mapping and identified one known and seven novel loci associated with seizure sensitivity. We combined whole genome sequencing and hippocampal gene expression to pinpoint biologically plausible candidate genes (eg, Gabra2) and variants associated with seizure sensitivity. SIGNIFICANCE: New mouse models of epilepsy are needed to better understand the complex genetic architecture of seizures and to identify therapeutics. We performed a phenotypic screen utilizing a novel genetic reference population of CC mice. The data we provide enable the identification of protective/risk genes and novel molecular mechanisms linked to complex seizure traits that are currently challenging to study and treat.


Assuntos
Camundongos de Cruzamento Colaborativo/genética , Modelos Animais de Doenças , Epilepsia/genética , Hipocampo/metabolismo , Camundongos , Convulsões/genética , Animais , Mapeamento Cromossômico , Convulsivantes , Epilepsia/induzido quimicamente , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Agonistas de Aminoácidos Excitatórios , Flurotila , Expressão Gênica , Perfilação da Expressão Gênica , Predisposição Genética para Doença , Genótipo , Ácido Caínico , Camundongos Endogâmicos , Pentilenotetrazol , Fenótipo , Locos de Características Quantitativas , Convulsões/induzido quimicamente , Convulsões/metabolismo , Convulsões/fisiopatologia , Morte Súbita Inesperada na Epilepsia , Sequenciamento Completo do Genoma
8.
Learn Mem ; 27(9): 340-345, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32817300

RESUMO

Memory deficits significantly decrease an individual's quality of life and are a pervasive comorbidity of epilepsy. Despite the various distinct processes of memory, the majority of epilepsy research has focused on seizures during the encoding phase of memory, therefore the effects of a seizure on other memory processes is relatively unknown. In the present study, we investigated how a single seizure affects memory reactivation in C57BL/6J adult mice using an associative conditioning paradigm. Initially, mice were trained to associate a tone (conditioned stimulus), with the presence of a shock (unconditioned stimulus). Flurothyl was then administered 1 h before, 1 h after, or 6 h before a memory reactivation trial. The learned association was then assessed by presenting a conditioned stimulus in a new context 24 h or 1 wk after memory reactivation. We found that mice receiving a seizure 1 h prior to reactivation exhibited a deficit in memory 24 h later but not 1 wk later. When mice were administered a seizure 6 h before or 1 h after reactivation, there were no differences in memory between seizure and control animals. Altogether, our study indicates that an acute seizure during memory reactivation leads to a temporary deficit in associative memory in adult mice. These findings suggest that the cognitive impact of a seizure may depend on the timing of the seizure relative to the memory process that is active.


Assuntos
Aprendizagem por Associação/fisiologia , Comportamento Animal/fisiologia , Condicionamento Clássico/fisiologia , Transtornos da Memória/fisiopatologia , Convulsões/fisiopatologia , Animais , Convulsivantes/farmacologia , Modelos Animais de Doenças , Medo/fisiologia , Feminino , Flurotila/farmacologia , Masculino , Transtornos da Memória/etiologia , Camundongos Endogâmicos C57BL , Convulsões/induzido quimicamente , Convulsões/complicações , Fatores de Tempo
9.
Epilepsy Res ; 163: 106328, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32283447

RESUMO

OBJECTIVE: Recurrent seizures can cause brain damage and affect the cognitive outcome, particularly in developing children. We aimed to determine the effects of recurrent seizures on the expression of gamma-aminobutyric acid A receptor (GABAAR) α1 and γ2 subunit and neurodevelopment in immature rats. The role of the GABAAR agonist clonazepam and antagonist/partial agonist flumazenil in seizure-induced brain injury was also studied. METHODS: Recurrent seizures (RS) were induced by flurothyl inhalation in immature rats. Clonazepam (CZP) and flumazenil (FMZ) were administered to modulate GABAAR subunit expression in different experimental groups. Neurobehavioral changes and GABAAR α1 and γ2 subunit expression were studied. RESULTS: Inhalation of flurothyl for five days triggered RS and caused reflex delay, inability to adapt to new environments in adulthood, and deficits in long-term learning and memory ability in rats. Down-regulation of GABAAR α1 and γ2 subunits occurred after seizure onset and persisted for a long time. CZP treatment decreased the expression of GABAAR α1 and γ2 subunits and delayed neurodevelopment of the immature rats, whereas FMZ did not show any significant effects. CONCLUSIONS: Changes in GABAAR α1 and γ2 subunit expression and neurodevelopment were related to recurrent seizures and administration of CZP. Thus, GABAAR α1 and γ2 subunits likely play a significant role in the development of immature rats with RS and provide a novel target for therapeutic intervention.


Assuntos
Lesões Encefálicas/tratamento farmacológico , Epilepsia Generalizada/tratamento farmacológico , Hipocampo/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Convulsões/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Lesões Encefálicas/metabolismo , Epilepsia Generalizada/metabolismo , Feminino , Flurotila/farmacologia , Hipocampo/metabolismo , Masculino , Ratos Wistar , Convulsões/tratamento farmacológico , Ácido gama-Aminobutírico/metabolismo , Ácido gama-Aminobutírico/farmacologia
10.
Epilepsia ; 61(5): 892-902, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32301507

RESUMO

OBJECTIVE: BRD2 is a human gene repeatedly linked to and associated with juvenile myoclonic epilepsy (JME). Here, we define the developmental stage when increased seizure susceptibility first manifests in heterozygous Brd2+/- mice, an animal model of JME. We wanted to determine (1) whether seizure susceptibility correlates with the proven decrease of γ-aminobutyric acidergic (GABAergic) neuron numbers and (2) whether the seizure phenotype can be affected by sex hormones. METHODS: Heterozygous (Brd2+/-) and wild-type (wt) mice of both sexes were tested for flurothyl-induced seizure susceptibility at postnatal day 15 (P15; wt, n = 13; Brd2+/-, n = 20), at P30 (wt, n = 20; Brd2+/-, n = 20), and in adulthood (5-6 months of age; wt, n = 10; Brd2+/-, n = 12). We measured latency to clonic and tonic-clonic seizure onset (flurothyl threshold). We also compared relative density of parvalbumin-positive (PVA+) and GAD67+ GABA neurons in the striatum and primary motor (M1) neocortex of P15 (n = 6-13 mice per subgroup) and P30 (n = 7-10 mice per subgroup) mice. Additional neonatal Brd2+/- mice were injected with testosterone propionate (females) or formestane (males) and challenged with flurothyl at P30. RESULTS: P15 Brd2+/- mice showed no difference in seizure susceptibility compared to P15 wt mice. However, even at this early age, Brd2+/- mice showed fewer PVA+ neurons in the striatum and M1 neocortex. Compared to wt, the striatum in Brd2+/- mice showed an increased proportion of immature PVA+ neurons, with smaller cell bodies and limited dendritic arborization. P30 Brd2+/- mice displayed increased susceptibility to flurothyl-induced clonic seizures compared to wt. Both genotype and sex strongly influenced the density of PVA+ neurons in the striatum. Susceptibility to clonic seizures remained increased in adult Brd2+/- mice, and additionally there was increased susceptibility to tonic-clonic seizures. In P30 females, neonatal testosterone reduced the number of flurothyl-induced clonic seizures. SIGNIFICANCE: A decrease in striatal PVA+ GABAergic neurons developmentally precedes the onset of increased seizure susceptibility and likely contributes to the expression of the syndrome.


Assuntos
Flurotila/farmacologia , Epilepsia Mioclônica Juvenil/patologia , Neurônios/patologia , Parvalbuminas/metabolismo , Convulsões/induzido quimicamente , Androstenodiona/análogos & derivados , Androstenodiona/farmacologia , Animais , Modelos Animais de Doenças , Feminino , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Epilepsia Mioclônica Juvenil/induzido quimicamente , Neurônios/efeitos dos fármacos , Convulsões/patologia , Propionato de Testosterona/farmacologia , Fatores de Transcrição/metabolismo
11.
Int J Dev Neurosci ; 75: 13-18, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30940500

RESUMO

Undernourishment is a global issue, especially in developing countries, affecting newborns and children in a vulnerable period of brain development. Previous studies of undernourishment models suggested a relationship between undernourishment and epilepsy. The exposure to both undernourishment and recurrent seizures early in life appears to have detrimental effects on the developing brain. This study aims to investigate the neurobiological consequences of undernourishment and recurrent seizures exposure early in life, investigating Long-Term Potentiation (LTP) induction and gene expression of NMDA receptor subunits in the hippocampus during adulthood (P60). Animals were exposed to maternal deprivation protocol from P2 to P15 to control food intake in rat pups and Flurothyl-induced seizures from P7 to P10. Electrophysiological records of hippocampal slices were recorded and gene expression of NR1A, NR2A, NR2B, NR2C, NR2D and BDNF were investigated. Animals exposed to undernourishment or recurrent seizures failed to promote LTP after stimulation. Furthermore, seizure exposure early in life led to increased expression of hippocampal NR1A, NR2A, NR2B, NR2C and NR2D when compared to controls. Interestingly, when animals were exposed to undernourishment paradigm early in life, this upregulation of NDMA subunits was absent. In conclusion, our study showed impaired LTP after undernourishment and recurrent seizures early in life, together with differential expression of NDMA expression in the hippocampus during adulthood.


Assuntos
Hipocampo/metabolismo , Potenciação de Longa Duração/fisiologia , Desnutrição/fisiopatologia , Receptores de AMPA/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Convulsões/fisiopatologia , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Flurotila , Expressão Gênica , Desnutrição/metabolismo , Privação Materna , Ratos , Receptores de AMPA/genética , Receptores de N-Metil-D-Aspartato/genética , Convulsões/induzido quimicamente , Convulsões/metabolismo
12.
Mol Neurobiol ; 56(6): 4163-4174, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30288695

RESUMO

Rapid antidepressant effects of ketamine become most evident when its psychotomimetic effects subside, but the neurobiological basis of this "lag" remains unclear. Laughing gas (N2O), another NMDA-R (N-methyl-D-aspartate receptor) blocker, has been reported to bring antidepressant effects rapidly upon drug discontinuation. We took advantage of the exceptional pharmacokinetic properties of N2O to investigate EEG (electroencephalogram) alterations and molecular determinants of antidepressant actions during and immediately after NMDA-R blockade. Effects of the drugs on brain activity were investigated in C57BL/6 mice using quantitative EEG recordings. Western blot and qPCR were used for molecular analyses. Learned helplessness (LH) was used to assess antidepressant-like behavior. Immediate-early genes (e.g., bdnf) and phosphorylation of mitogen-activated protein kinase-markers of neuronal excitability-were upregulated during N2O exposure. Notably, phosphorylation of BDNF receptor TrkB and GSK3ß (glycogen synthase kinase 3ß) became regulated only gradually upon N2O discontinuation, during a brain state dominated by slow EEG activity. Subanesthetic ketamine and flurothyl-induced convulsions (reminiscent of electroconvulsive therapy) also evoked slow oscillations when their acute pharmacological effects subsided. The correlation between ongoing slow EEG oscillations and TrkB-GSK3ß signaling was further strengthened utilizing medetomidine, a hypnotic-sedative agent that facilitates slow oscillations directly through the activation of α2-adrenergic autoreceptors. Medetomidine did not, however, facilitate markers of neuronal excitability or produce antidepressant-like behavioral changes in LH. Our results support a hypothesis that transient cortical excitability and the subsequent regulation of TrkB and GSK3ß signaling during homeostatic emergence of slow oscillations are critical components for rapid antidepressant responses.


Assuntos
Antidepressivos/farmacologia , Córtex Cerebral/metabolismo , Eletroencefalografia , Neurônios/metabolismo , Receptor trkB/metabolismo , Transdução de Sinais , Anestésicos/farmacologia , Animais , Biomarcadores/metabolismo , Córtex Cerebral/efeitos dos fármacos , Relação Dose-Resposta a Droga , Flurotila/farmacologia , Glicogênio Sintase Quinase 3 beta/metabolismo , Homeostase/efeitos dos fármacos , Ketamina/farmacologia , Medetomidina/farmacologia , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Óxido Nitroso/farmacologia , Transdução de Sinais/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
13.
Epilepsy Res ; 146: 103-111, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30092488

RESUMO

Metabolic disorders play an important role in the pathogenesis of many neurological diseases. Recent evidence suggests that leptin levels in peripheral blood and brain are lower in patients with epilepsy. Leptin is an energy-regulating hormone that plays a neuroprotective role in neurodegenerative diseases and brain trauma. However, little is known about the effects and molecular mechanisms of leptin treatment on long-term neurobehavioral impairment caused by developmental seizures. The present study evaluated whether chronic leptin treatment protected against neurobehavioral impairments induced by recurrent seizures in newborns treated with flurothyl. We also examined the effect of leptin on the expression of zinc/cPLA2-related autophagy signaling molecules and CaMKII in the cerebral cortex. Twenty Sprague-Dawley rats (6 days after birth, P6) were randomly divided into two groups, a neonatal seizure group and control group. Rats were subdivided on P13 into control, control + leptin (leptin, 2 mg/kg/day, continuous 10 days), seizure (RS), and seizure + leptin group (RS + leptin, 2 mg/kg/day for 10 consecutive days). Neurological behavioral parameters (negative geotaxis reaction reflex, righting reflex, cliff avoidance reflex, forelimb suspension reflex and open field test) were observed from P23 to P30. mRNA and protein levels in the cerebral cortex were detected using real-time RT-PCR and Western blotting, respectively. Flurothyl-induced seizures (RS group) produced long-term abnormal neurobehavior, which was improved with leptin treatment. Chronic leptin treatment restored several expression parameters affected by neonatal seizures, including seizure-induced up-regulated zinc transporter ZnT1/ZIP7, lipid membrane injury-related cPLA2, autophagy marker beclin-1/bcl2, LC3II/LC3I, and its execution molecule cathepsin-E, and down-regulated memory marker CaMK II alpha. Our results suggest that the early use of leptin after neonatal recurrent seizures may exert neuroprotective effects and antagonize the long-term neurobehavioral impairment caused by seizures. Autophagy-mediated Zn/cPLA2 and CaMK II signaling in the cerebral cortex may be involved in the neuroprotective effect of leptin. Our results provide new clues for anti-epileptogenetic treatment.


Assuntos
Autofagia/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Leptina/farmacologia , Fármacos Neuroprotetores/farmacologia , Convulsões/tratamento farmacológico , Animais , Animais Recém-Nascidos , Autofagia/fisiologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Proteínas de Transporte/metabolismo , Córtex Cerebral/metabolismo , Modelos Animais de Doenças , Flurotila , Fosfolipases A2 do Grupo IV/metabolismo , Leptina/metabolismo , Masculino , Atividade Motora/efeitos dos fármacos , Neuroproteção/fisiologia , Distribuição Aleatória , Ratos Sprague-Dawley , Convulsões/metabolismo , Transdução de Sinais
14.
Epilepsy Res ; 145: 77-81, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29913407

RESUMO

A recent report has found that glucose oxidation and the activity of pyruvate dehydrogenase (PDH) are reduced in the chronic stage of the pilocarpine mouse epilepsy model. This is likely caused by increased phosphorylation by PDH kinase of the E1α subunit of PDH, downregulating its activity. Inhibition of this phosphorylation has not yet been explored as a possible approach to treat epilepsy. Chronic dichloroacetate (DCA, 50 and 100 mg/kg/day) treatment was tested in acute seizure and the chronic pilocarpine models. We also determined the effects on phosphorylation state, activity and protein levels of PDH in the chronic stage of the pilocarpine model. DCA treatment did not increase latencies to seizures in the acute flurothyl seizure test and was slightly proconvulsant in the 6 Hz test. The latencies to seizures in a second-hit flurothyl test were decreased in SE vs. No SE mice in the chronic stage, but were not restored by DCA. In mice that had experienced pilocarpine-induced SE and were in the chronic "epileptic" stage of the model, PDH activity was reduced by 65% compared to "healthy" No SE mice. This was partially alleviated with DCA treatment. Also, PDH protein levels were decreased by 37% and phosphorylation at Ser300 of PDH was increased by 52% in SE mice, but were not significantly changed with DCA. Moreover DCA treatment decreased the amounts of total PDH by 23% in No SE mice, which may explain the proconvulsant effects in the 6 Hz test. The reduction in PDH protein levels during the chronic epileptic stage suggests increased degradation of the protein, which may contribute to the deficient glucose oxidation found in epilepsy. Taken together, DCA did not have any anti-convulsant effects in the tested models. Future studies utilising other PDH kinase inhibitors are required to determine whether this treatment approach is viable.


Assuntos
Anticonvulsivantes/uso terapêutico , Ácido Dicloroacético/uso terapêutico , Epilepsia/tratamento farmacológico , Análise de Variância , Animais , Convulsivantes/toxicidade , Modelos Animais de Doenças , Estimulação Elétrica , Epilepsia/induzido quimicamente , Flurotila/toxicidade , Cetona Oxirredutases/metabolismo , Masculino , Camundongos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Pilocarpina/toxicidade
15.
G3 (Bethesda) ; 7(8): 2545-2558, 2017 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-28620084

RESUMO

Epilepsy has many causes and comorbidities affecting as many as 4% of people in their lifetime. Both idiopathic and symptomatic epilepsies are highly heritable, but genetic factors are difficult to characterize among humans due to complex disease etiologies. Rodent genetic studies have been critical to the discovery of seizure susceptibility loci, including Kcnj10 mutations identified in both mouse and human cohorts. However, genetic analyses of epilepsy phenotypes in mice to date have been carried out as acute studies in seizure-naive animals or in Mendelian models of epilepsy, while humans with epilepsy have a history of recurrent seizures that also modify brain physiology. We have applied a repeated seizure model to a genetic reference population, following seizure susceptibility over a 36-d period. Initial differences in generalized seizure threshold among the Hybrid Mouse Diversity Panel (HMDP) were associated with a well-characterized seizure susceptibility locus found in mice: Seizure susceptibility 1 Remarkably, Szs1 influence diminished as subsequent induced seizures had diminishing latencies in certain HMDP strains. Administration of eight seizures, followed by an incubation period and an induced retest seizure, revealed novel associations within the calmodulin-binding transcription activator 1, Camta1 Using systems genetics, we have identified four candidate genes that are differentially expressed between seizure-sensitive and -resistant strains close to our novel Epileptogenesis susceptibility factor 1 (Esf1) locus that may act individually or as a coordinated response to the neuronal stress of seizures.


Assuntos
Epilepsia/genética , Loci Gênicos , Predisposição Genética para Doença , Variação Genética , Convulsões/genética , Alelos , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Cromossomos de Mamíferos/genética , Cruzamentos Genéticos , Modelos Animais de Doenças , Epistasia Genética , Feminino , Flurotila , Estudo de Associação Genômica Ampla , Excitação Neurológica/genética , Masculino , Camundongos , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética , Análise de Regressão
16.
Epilepsia ; 58(7): 1172-1180, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28632902

RESUMO

OBJECTIVE: To determine changes in glucose metabolism and the enzymes involved in the hippocampus ictally and postictally in the acute mouse flurothyl seizure model. METHODS: [U-13 C]-Glucose was injected (i.p.) prior to, or following a 5 min flurothyl-induced seizure. Fifteen minutes later, mice were killed and the total metabolite levels and % 13 C enrichment were analyzed in the hippocampal formation using gas chromatography-mass spectrometry. Activities of key metabolic and antioxidant enzymes and the phosphorylation status of pyruvate dehydrogenase were measured, along with lipid peroxidation. RESULTS: During seizures, total lactate levels increased 1.7-fold; however, [M + 3] enrichment of both lactate and alanine were reduced by 30% and 43%, respectively, along with a 28% decrease in phosphofructokinase activity. Postictally the % 13 C enrichments of all measured tricarboxylic acid (TCA) cycle intermediates and the amino acids were reduced by 46-93%. At this time, pyruvate dehydrogenase (PDH) activity was 56% of that measured in controls, and there was a 1.9-fold increase in the phosphorylation of PDH at ser232. Phosphorylation of PDH is known to decrease its activity. SIGNIFICANCE: Here, we show that the increase of lactate levels during flurothyl seizures is from a source other than [U-13 C]-glucose, such as glycogen. Surprisingly, although we saw a reduction in phosphofructokinase activity during the seizure, metabolism of [U-13 C]-glucose into the TCA cycle seemed unaffected. Similar to our recent findings in the chronic phase of the pilocarpine model, postictally the metabolism of glucose by glycolysis and the TCA cycle was impaired along with reduced PDH activity. Although this decrease in activity may be a protective mechanism to reduce oxidative stress, which is observed in the flurothyl model, ATP is critical to the recovery of ion and neurotransmitter balance and return to normal brain function. Thus we identified promising novel strategies to enhance energy metabolism and recovery from seizures.


Assuntos
Glicemia/metabolismo , Flurotila , Hipocampo/efeitos dos fármacos , Hipocampo/fisiopatologia , Complexo Piruvato Desidrogenase/metabolismo , Convulsões/induzido quimicamente , Convulsões/fisiopatologia , Alanina/metabolismo , Aminoácidos/metabolismo , Animais , Antioxidantes/metabolismo , Ciclo do Ácido Cítrico/efeitos dos fármacos , Ciclo do Ácido Cítrico/fisiologia , Cromatografia Gasosa-Espectrometria de Massas , Glicogênio/metabolismo , Ácido Láctico/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos , Fosfofrutoquinases/metabolismo , Fosforilação/fisiologia , Convulsões/patologia , Superóxido Dismutase/metabolismo
17.
Epilepsia ; 58(8): 1440-1450, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28555877

RESUMO

OBJECTIVE: We have previously found that the transcription factor peroxisome proliferator-activated receptor γ (PPARγ) contributes to the mechanism of action of the ketogenic diet (KD), an established treatment for pediatric refractory epilepsy. We have found that the KD increases brain PPARγ and that inhibition or genetic loss of PPARγ prevents the antiseizure effects of the KD on (1) acutely induced seizures in nonepileptic mice and (2) spontaneous recurrent seizures in epileptic mice. Here, we tested the hypothesis that adjuvant treatment of KD-treated mice with a PPARγ agonist, pioglitazone, would result in an additive effect. METHODS: Acute seizures were induced in three groups of C57Bl/6 mice by inhalation exposure to flurothyl gas. In Group 1, mice were weaned onto either a standard diet or KD comprised of a fat:carbohydrate/protein ratio of either 6:1, 3:1, or 1:1 for 2 weeks. In Group 2, vehicle or pioglitazone (0.1, 1, 10, 80 mg/kg) was administered 4 h prior to flurothyl exposure. In Group 3, vehicle or increasing doses of pioglitazone were administered to KD-treated mice 4 h prior to flurothyl exposure. Latency times to clonic seizures and generalized tonic-clonic (GTC) seizures were recorded, and isobolographic analysis was used to determine combinatorial interactions. RESULTS: Neither KD treatment nor pioglitazone alone or in combination affected clonic seizures. However, the latency to GTC seizures was dose-dependently and significantly increased by both KD (~57%, p < 0.05) and pioglitazone (~28%, p < 0.05). Coadministration of an ineffective 1:1 KD and pioglitazone resulted in ~47-55% (p < 0.05) increase in latency to GTC. Isobolographic analysis indicated a synergistic interaction of the KD and pioglitazone. SIGNIFICANCE: These results suggest coadministration may enable reduction of the KD ratio without loss of seizure protection. Such adjuvant treatment could improve quality of life and limit adverse effects of a classic KD or high-dose pioglitazone.


Assuntos
Dieta Cetogênica/métodos , Hipoglicemiantes/uso terapêutico , Convulsões/dietoterapia , Convulsões/tratamento farmacológico , Tiazolidinedionas/uso terapêutico , Ácido 3-Hidroxibutírico/sangue , Animais , Glicemia/metabolismo , Peso Corporal/efeitos dos fármacos , Peso Corporal/fisiologia , Convulsivantes , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Feminino , Flurotila/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pioglitazona , Tempo de Reação/efeitos dos fármacos , Convulsões/induzido quimicamente
18.
Exp Neurol ; 293: 159-171, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28373025

RESUMO

Mutations in the voltage-gated sodium channel (VGSC) gene SCN1A, encoding the Nav1.1 channel, are responsible for a number of epilepsy disorders including genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). Patients with SCN1A mutations often experience prolonged early-life febrile seizures (FSs), raising the possibility that these events may influence epileptogenesis and lead to more severe adult phenotypes. To test this hypothesis, we subjected 21-23-day-old mice expressing the human SCN1A GEFS+ mutation R1648H to prolonged hyperthermia, and then examined seizure and behavioral phenotypes during adulthood. We found that early-life FSs resulted in lower latencies to induced seizures, increased severity of spontaneous seizures, hyperactivity, and impairments in social behavior and recognition memory during adulthood. Biophysical analysis of brain slice preparations revealed an increase in epileptiform activity in CA3 pyramidal neurons along with increased action potential firing, providing a mechanistic basis for the observed worsening of adult phenotypes. These findings demonstrate the long-term negative impact of early-life FSs on disease outcomes. This has important implications for the clinical management of this patient population and highlights the need for therapeutic interventions that could ameliorate disease progression.


Assuntos
Mutação/genética , Canal de Sódio Disparado por Voltagem NAV1.1/genética , Convulsões Febris/complicações , Convulsões Febris/genética , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/genética , Fatores Etários , Animais , Animais Recém-Nascidos , Arginina/genética , Convulsivantes/toxicidade , Modelos Animais de Doenças , Progressão da Doença , Comportamento Exploratório/efeitos dos fármacos , Comportamento Exploratório/fisiologia , Feminino , Flurotila/toxicidade , Hipocampo/patologia , Histidina/genética , Humanos , Hipertermia Induzida/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/genética , Reconhecimento Psicológico/efeitos dos fármacos , Reconhecimento Psicológico/fisiologia , Convulsões Febris/etiologia , Convulsões Febris/patologia
19.
Exp Neurol ; 287(Pt 1): 54-64, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27527983

RESUMO

The ketogenic diet (KD) is an effective therapy primarily used in pediatric patients whom are refractory to current anti-seizure medications. The mechanism of the KD is not completely understood, but is thought to involve anti-inflammatory and anti-oxidant processes. The nutritionally-regulated transcription factor peroxisome proliferator activated receptor gamma, PPARγ, regulates genes involved in anti-inflammatory and anti-oxidant pathways. Moreover, endogenous ligands of PPARγ include fatty acids suggesting a potential role in the effects of the KD. Here, we tested the hypothesis that PPARγ contributes to the anti-seizure efficacy of the KD. We found that the KD increased nuclear protein content of the PPARγ2 splice variant by 2-4 fold (P<0.05) in brain homogenates from wild-type (WT) and epileptic Kv1.1 knockout (KO) mice, while not affecting PPARγ1. The KD reduced the frequency of seizures in Kv1.1KO mice by ~70% (P<0.01). GW9662, a PPARγ antagonist, prevented KD-mediated changes in PPARγ2 expression and prevented the anti-seizure efficacy of the KD in Kv1.1KO mice. Further supporting the association of PPARγ2 in mediating KD actions, the KD significantly prolonged the latency to flurothyl-induced seizure in WT mice by ~20-35% (P<0.01), but was ineffective in PPARγ2KO mice and neuron-specific PPARγKO mice. Finally, administering the PPARγ agonist pioglitazone increased PPARγ2 expression by 2-fold (P<0.01) and reduced seizures in Kv1.1KO mice by ~80% (P<0.01). Our findings implicate brain PPARγ2 among the mechanisms by which the KD reduces seizures and strongly support the development of PPARγ2 as a therapeutic target for severe, refractory epilepsy.


Assuntos
Encéfalo/metabolismo , Dieta Cetogênica/métodos , Epilepsia/dietoterapia , Epilepsia/patologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , PPAR gama/metabolismo , Ácido 3-Hidroxibutírico/sangue , Fatores Etários , Anilidas/farmacologia , Anilidas/uso terapêutico , Animais , Animais Recém-Nascidos , Anticonvulsivantes/farmacologia , Anticonvulsivantes/uso terapêutico , Glicemia/efeitos dos fármacos , Glicemia/genética , Encéfalo/efeitos dos fármacos , Convulsivantes/toxicidade , Modelos Animais de Doenças , Ingestão de Líquidos/efeitos dos fármacos , Ingestão de Líquidos/fisiologia , Epilepsia/induzido quimicamente , Epilepsia/tratamento farmacológico , Flurotila/toxicidade , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Hipoglicemiantes/farmacologia , Canal de Potássio Kv1.1/deficiência , Canal de Potássio Kv1.1/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , PPAR gama/genética , Pioglitazona , Tiazolidinedionas/farmacologia , Tiazolidinedionas/uso terapêutico
20.
BMC Neurosci ; 17(1): 56, 2016 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-27514646

RESUMO

BACKGROUND: Recurrent convulsions can cause irreversible astrocyte death, impede neuron regeneration, and further aggravate brain damage. MicroRNAs have been revealed as players in the progression of numerous diseases including cancer and Alzheimer's disease. Particularly, microRNA has been found linked to seizure-induced neuronal death. In this study, a rat model of recurrent convulsions induced by flurothyl treatments was utilised to assess the alterations of microRNA expressions in hippocampus tissues. We also applied an in vitro model in which primary astrocytes were exposed to kainic acid to verify the targets of miR-34b-5p identified in the animal model. RESULTS: We discovered that miR-34b-5p, a member of the miR-34 family, increased significantly in flurothyl-treated rat hippocampus tissue. More surprisingly, this upregulation occurred concurrently with accumulating astrocyte apoptosis, indicating the involvement of miR-34b-5p in seizures caused astrocyte apoptosis. Results from the in vitro experiments further demonstrated that miR-34b-5p directly targeted Bcl-2 mRNA, translationally repressed Bcl-2 protein, and thus modulated cell apoptosis by influencing Bcl-2, Bax, and Caspase-3. CONCLUSION: Our findings prove microRNAs play a role in mediating recurrent convulsions-induced astrocyte death and further indicate that miR-34b-5p could acts as a regulator for astrocyte apoptosis induced by recurrent seizures.


Assuntos
Apoptose/fisiologia , Astrócitos/metabolismo , Hipocampo/metabolismo , MicroRNAs/metabolismo , Convulsões/metabolismo , Animais , Astrócitos/patologia , Western Blotting , Caspase 3/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Flurotila , Hipocampo/patologia , Marcação In Situ das Extremidades Cortadas , Ácido Caínico , Análise em Microsséries , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA Mensageiro/metabolismo , Distribuição Aleatória , Ratos Sprague-Dawley , Convulsões/patologia , Transcriptoma , Proteína X Associada a bcl-2/metabolismo
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