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OBJECTIVE: Infantile spasms are associated with a wide variety of clinical conditions, including perinatal brain injuries. We have created a model in which prolonged infusion of tetrodotoxin (TTX) into the neocortex, beginning in infancy, produces a localized lesion and reproduces the behavioral spasms, electroencephalogram (EEG) abnormalities, and drug responsiveness seen clinically. Here, we undertook experiments to explore the possibility that the growth factor IGF-1 plays a role in generating epileptic spasms. METHODS: We combined long-term video EEG recordings with quantitative immunohistochemical and biochemical analyses to unravel IGF-1's role in spasm generation. Immunohistochemistry was undertaken in surgically resected tissue from infantile spasms patients. We used viral injections in neonatal conditional IGF-1R knock-out mice to show that an IGF-1-derived tripeptide (1-3)IGF-1, acts through the IGF-1 receptor to abolish spasms. RESULTS: Immunohistochemical methods revealed widespread loss of IGF-1 from cortical neurons, but an increase in IGF-1 in the reactive astrocytes in the TTX-induced lesion. Very similar changes were observed in the neocortex from patients with spasms. In animals, we observed reduced signaling through the IGF-1 growth pathways in areas remote from the lesion. To show the reduction in IGF-1 expression plays a role in spasm generation, epileptic rats were treated with (1-3)IGF-1. We provide 3 lines of evidence that (1-3)IGF-1 activates the IGF-1 signaling pathway by acting through the receptor for IGF-1. Treatment with (1-3)IGF-1 abolished spasms and hypsarrhythmia-like activity in the majority of animals. INTERPRETATION: Results implicate IGF-1 in the pathogenesis of infantile spasms and IGF-1 analogues as potential novel therapies for this neurodevelopmental disorder. ANN NEUROL 2022;92:45-60.
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Espasmos Infantis , Animais , Modelos Animais de Doenças , Eletroencefalografia/métodos , Humanos , Lactente , Fator de Crescimento Insulin-Like I , Camundongos , Ratos , Espasmo/induzido quimicamente , Espasmos Infantis/induzido quimicamente , Espasmos Infantis/tratamento farmacológico , Tetrodotoxina/farmacologiaRESUMO
Hyperactivation of the mTOR pathway during foetal neurodevelopment alters neuron structure and function, leading to focal malformation of cortical development and intractable epilepsy. Recent evidence suggests a role for dysregulated cap-dependent translation downstream of mTOR signalling in the formation of focal malformation of cortical development and seizures. However, it is unknown whether modifying translation once the developmental pathologies are established can reverse neuronal abnormalities and seizures. Addressing these issues is crucial with regards to therapeutics because these neurodevelopmental disorders are predominantly diagnosed during childhood, when patients present with symptoms. Here, we report increased phosphorylation of the mTOR effector and translational repressor, 4E-BP1, in patient focal malformation of cortical development tissue and in a mouse model of focal malformation of cortical development. Using temporally regulated conditional gene expression systems, we found that expression of a constitutively active form of 4E-BP1 that resists phosphorylation by focal malformation of cortical development in juvenile mice reduced neuronal cytomegaly and corrected several neuronal electrophysiological alterations, including depolarized resting membrane potential, irregular firing pattern and aberrant expression of HCN4 ion channels. Further, 4E-BP1 expression in juvenile focal malformation of cortical development mice after epilepsy onset resulted in improved cortical spectral activity and decreased spontaneous seizure frequency in adults. Overall, our study uncovered a remarkable plasticity of the juvenile brain that facilitates novel therapeutic opportunities to treat focal malformation of cortical development-related epilepsy during childhood with potentially long-lasting effects in adults.
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Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Ciclo Celular , Epilepsia , Serina-Treonina Quinases TOR , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Encéfalo/patologia , Proteínas de Ciclo Celular/genética , Epilepsia/patologia , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Camundongos , Neurônios/metabolismo , Fosforilação , Convulsões/induzido quimicamente , Convulsões/genética , Convulsões/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
OBJECTIVE: Epileptic spasms are a hallmark of severe seizure disorders. The neurophysiological mechanisms and the neuronal circuit(s) that generate these seizures are unresolved and are the focus of studies reported here. METHODS: In the tetrodotoxin model, we used 16-channel microarrays and microwires to record electrophysiological activity in neocortex and thalamus during spasms. Chemogenetic activation was used to examine the role of neocortical pyramidal cells in generating spasms. Comparisons were made to recordings from infantile spasm patients. RESULTS: Current source density and simultaneous multiunit activity analyses indicate that the ictal events of spasms are initiated in infragranular cortical layers. A dramatic pause of neuronal activity was recorded immediately prior to the onset of spasms. This preictal pause is shown to share many features with the down states of slow wave sleep. In addition, the ensuing interictal up states of slow wave rhythms are more intense in epileptic than control animals and occasionally appear sufficient to initiate spasms. Chemogenetic activation of neocortical pyramidal cells supported these observations, as it increased slow oscillations and spasm numbers and clustering. Recordings also revealed a ramp-up in the number of neocortical slow oscillations preceding spasms, which was also observed in infantile spasm patients. INTERPRETATION: Our findings provide evidence that epileptic spasms can arise from the neocortex and reveal a previously unappreciated interplay between brain state physiology and spasm generation. The identification of neocortical up states as a mechanism capable of initiating epileptic spasms will likely provide new targets for interventional therapies. ANN NEUROL 2021;89:226-241.
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Ondas Encefálicas/fisiologia , Neocórtex/fisiopatologia , Células Piramidais/fisiologia , Espasmos Infantis/fisiopatologia , Tálamo/fisiopatologia , Animais , Modelos Animais de Doenças , Eletrocorticografia , Feminino , Humanos , Lactente , Masculino , Neocórtex/efeitos dos fármacos , Células Piramidais/efeitos dos fármacos , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , Convulsões/fisiopatologia , Bloqueadores dos Canais de Sódio/toxicidade , Espasmo/induzido quimicamente , Espasmo/fisiopatologia , Espasmos Infantis/induzido quimicamente , Tetrodotoxina/toxicidade , Tálamo/efeitos dos fármacosRESUMO
[This corrects the article DOI: 10.1371/journal.pbio.1002466.].
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[This corrects the article DOI: 10.1371/journal.pbio.1002466.].
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Phagocytosis is essential to maintain tissue homeostasis in a large number of inflammatory and autoimmune diseases, but its role in the diseased brain is poorly explored. Recent findings suggest that in the adult hippocampal neurogenic niche, where the excess of newborn cells undergo apoptosis in physiological conditions, phagocytosis is efficiently executed by surveillant, ramified microglia. To test whether microglia are efficient phagocytes in the diseased brain as well, we confronted them with a series of apoptotic challenges and discovered a generalized response. When challenged with excitotoxicity in vitro (via the glutamate agonist NMDA) or inflammation in vivo (via systemic administration of bacterial lipopolysaccharides or by omega 3 fatty acid deficient diets), microglia resorted to different strategies to boost their phagocytic efficiency and compensate for the increased number of apoptotic cells, thus maintaining phagocytosis and apoptosis tightly coupled. Unexpectedly, this coupling was chronically lost in a mouse model of mesial temporal lobe epilepsy (MTLE) as well as in hippocampal tissue resected from individuals with MTLE, a major neurological disorder characterized by seizures, excitotoxicity, and inflammation. Importantly, the loss of phagocytosis/apoptosis coupling correlated with the expression of microglial proinflammatory, epileptogenic cytokines, suggesting its contribution to the pathophysiology of epilepsy. The phagocytic blockade resulted from reduced microglial surveillance and apoptotic cell recognition receptor expression and was not directly mediated by signaling through microglial glutamate receptors. Instead, it was related to the disruption of local ATP microgradients caused by the hyperactivity of the hippocampal network, at least in the acute phase of epilepsy. Finally, the uncoupling led to an accumulation of apoptotic newborn cells in the neurogenic niche that was due not to decreased survival but to delayed cell clearance after seizures. These results demonstrate that the efficiency of microglial phagocytosis critically affects the dynamics of apoptosis and urge to routinely assess the microglial phagocytic efficiency in neurodegenerative disorders.
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Trifosfato de Adenosina/metabolismo , Epilepsia do Lobo Temporal/fisiopatologia , Microglia/patologia , Neurônios/metabolismo , Fagocitose/fisiologia , Adulto , Animais , Apoptose/fisiologia , Receptor 1 de Quimiocina CX3C , Humanos , Ácido Caínico/toxicidade , Antígenos Comuns de Leucócito/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/metabolismo , Monócitos/patologia , Neurônios/patologia , Receptores CCR2/genética , Receptores CCR2/metabolismo , Receptores de Quimiocinas/genética , Receptores de Quimiocinas/metabolismo , Convulsões/induzido quimicamente , Convulsões/fisiopatologiaRESUMO
Excitotoxicity caused by excessive stimulation of glutamate receptors, resulting in pathologically increased Ca2+-concentrations, is a decisive factor in neurodegenerative diseases. We investigated long-term changes in synaptic contents of AMPA receptor subunits that play important roles in calcium regulation in chronic epilepsy. Such plastic changes may be either adaptive or detrimental. We used a kainic acid (KA)-based rat model of chronic temporal lobe epilepsy (TLE). Using hippocampal synaptosomes, we found significant reductions in the concentration of the AMPA receptor subunits GluA1 and GluA2, and the NMDA receptor subunit NR2B. The relative size of GluA1 and GluA2 reductions were almost identical, at 28% and 27%, respectively. In order to determine whether the synaptic reduction of the AMPA receptor subunits actually reflected the pool of receptors present along the postsynaptic density (PSD), as opposed to cytoplasmic or extrasynaptic pools, we performed postembedding immunogold electron microscopy (EM) of GluA1 and GluA2 in Schaffer collateral synapses in the hippocampal CA1 area. We found significant reductions, at 32% and 52% of GluA1 and GluA2 subunits, respectively, along the PSD, indicating that these synapses undergo lasting changes in glutamatergic neurotransmission during chronic TLE. When compared to the overall concentration and composition of AMPA receptors expressed in the brain, there was a relative increase in GluA2-lacking AMPA receptor subunits following chronic epilepsy. These changes in synaptic AMPA receptor subunits may possibly contribute to further aggravate the excitotoxic vulnerability of the neurons as well as have significant implications for hippocampal cognitive functions.
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Epilepsia do Lobo Temporal/metabolismo , Receptores de AMPA/metabolismo , Sinapses/metabolismo , Animais , Epilepsia do Lobo Temporal/etiologia , Potenciais Pós-Sinápticos Excitadores , Hipocampo/metabolismo , Ácido Caínico/toxicidade , Masculino , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/genética , Sinapses/fisiologia , Sinapses/ultraestruturaRESUMO
Synaptotagmin 1 is a presynaptic calcium sensor, regulating SNARE-mediated vesicle exocytosis of transmitter. Increasing evidence indicate roles of SNARE proteins in postsynaptic glutamate receptor trafficking. However, a possible postsynaptic expression of synaptotagmin 1 has not been demonstrated previously. Here, we used postembedding immunogold electron microscopy to determine the subsynaptic localization of synaptotagmin 1 in rat hippocampal CA1 Schaffer collateral synapses. We report for the first time that synaptotagmin 1 is present in rat hippocampal postsynaptic spines, both on cytoplasmic vesicles and at the postsynaptic density. We further investigated whether postsynaptic synaptotagmin 1 is regulated during synaptic plasticity. In a rat model of chronic temporal lobe epilepsy, we found that presynaptic and postsynaptic concentrations of the protein are reduced compared to control animals. This downregulation may possibly be an adaptive measure to decrease both presynaptic and postsynaptic calcium sensitivity in excitotoxic conditions.
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Vesículas Citoplasmáticas/metabolismo , Espinhas Dendríticas/metabolismo , Hipocampo/metabolismo , Densidade Pós-Sináptica/metabolismo , Sinaptotagmina I/metabolismo , Animais , Células Cultivadas , Doença Crônica , Vesículas Citoplasmáticas/ultraestrutura , Espinhas Dendríticas/ultraestrutura , Modelos Animais de Doenças , Regulação para Baixo , Epilepsia do Lobo Temporal/metabolismo , Epilepsia do Lobo Temporal/patologia , Hipocampo/ultraestrutura , Imuno-Histoquímica , Ácido Caínico , Masculino , Camundongos Knockout , Microscopia Eletrônica , Densidade Pós-Sináptica/ultraestrutura , Terminações Pré-Sinápticas/metabolismo , Terminações Pré-Sinápticas/ultraestrutura , Ratos Sprague-Dawley , Ratos Wistar , Sinaptotagmina I/deficiência , Sinaptotagmina I/genéticaRESUMO
Mitochondrial dysfunction plays a central role in the neuropathology associated with status epilepticus (SE) and is implicated in the development of epilepsy. While excitotoxic mechanisms are well-known mediators affecting mitochondrial health following SE, whether hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) also contributes to SE-induced mitochondrial dysfunction remains to be examined. Here we first evaluated the temporal evolution of poly-ADP-ribosylated protein levels in hippocampus following kainic acid-induced SE as a marker for PARP-1 activity, and found that PARP-1 was hyperactive at 24 h following SE. We evaluated oxidative metabolism and found decreased NAD⺠levels by enzymatic cycling, and impaired NADâº-dependent mitochondrial respiration as measured by polarography at 24 h following SE. Stereological estimation showed significant cell loss in the hippocampal CA1 and CA3 subregions 72 h following SE. PARP-1 inhibition using N-(6-Oxo-5,6-dihydro-phenanthridin-2-yl)- N,N-dimethylacetamide (PJ-34) in vivo administration was associated with preserved NAD⺠levels and NADâº-dependent mitochondrial respiration, and improved CA1 neuronal survival. These findings suggest that PARP-1 hyperactivation contributes to SE-associated mitochondrial dysfunction and CA1 hippocampal damage. The deleterious effects of PARP-1 hyperactivation on mitochondrial respiration are in part mediated through intracellular NAD⺠depletion. Therefore, modulating PARP-1 activity may represent a potential therapeutic target to preserve intracellular energetics and mitochondrial function following SE.
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Hipocampo/metabolismo , Hipocampo/patologia , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Neurônios/metabolismo , Neurônios/patologia , Poli(ADP-Ribose) Polimerase-1/metabolismo , Estado Epiléptico/metabolismo , Estado Epiléptico/patologia , Animais , Western Blotting , Eletroencefalografia , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVES: A myriad of acute and chronic cardiac alterations are associated with status epilepticus (SE) including increased sympathetic tone, rhythm and ventricular repolarization disturbances. Despite these observations, the molecular processes underlying SE-associated myocardial remodeling remain to be identified. Here we determined early SE-associated myocardial electrical and molecular alterations using a model of SE and acquired epilepsy. METHODS: We performed electrocardiography (ECG) assessments in rats beginning at 2 weeks following kainate-induced SE, and calculated short-term variability (STV) of the corrected QT intervals (QTc) as a marker of ventricular stability. Using western blotting, we quantified myocardial ß1-adrenergic receptors (ß1-AR) and ventricular gap junction protein connexin 43 (Cx43) levels as makers of increased sympathetic tone. We determined the activation status of three kinases associated with sympathetic stimulation and their downstream ion channel targets: extracellular signal-regulated kinase (ERK), protein kinase A (PKA), Ca2+ /calmodulin-dependent protein kinase II (CamKII), hyperpolarization-activated cyclic nucleotide-gated channel subunit 2 (HCN2), and voltage-gated potassium channels 4.2 (Kv4.2 ). We investigated whether SE was associated with altered Ca2+ homeostasis by determining select Ca2+ -handling protein levels using western blotting. RESULTS: Compared with the sham group, SE animals exhibited higher heart rate, longer QTc interval, and higher STV beginning at 2 weeks following SE. Concurrently, the myocardium of SE rats showed lower ß1-AR and higher Cx43 protein levels, higher levels of phosphorylated ERK, PKA, and CamKII along with decreased HCN2 and Kv4.2 channel levels. In addition, the SE rats had altered proteins levels of Ca2+ -handling proteins, with decreased Na+ /Ca2+ exchanger-1 and increased calreticulin. SIGNIFICANCE: SE triggers early molecular alterations in the myocardium consistent with increased sympathetic tone and altered Ca2+ homeostasis. These changes, coupled with early and persistent ECG abnormalities, suggest that the observed molecular alterations may contribute to SE-associated cardiac remodeling. Additional mechanistic studies are needed to determine potential causal roles.
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Eletrocardiografia , Frequência Cardíaca/fisiologia , Estado Epiléptico/fisiopatologia , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Conexina 43/metabolismo , Modelos Animais de Doenças , Agonistas de Aminoácidos Excitatórios/toxicidade , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Coração/efeitos dos fármacos , Coração/fisiopatologia , Ácido Caínico/toxicidade , Masculino , Miocárdio/metabolismo , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Adrenérgicos beta 1/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Estado Epiléptico/induzido quimicamente , Fatores de TempoRESUMO
Neuropathology of resected brain tissue has revealed an association of focal cortical dysplasia (FCD) with drug-resistant epilepsy (DRE). Recent studies have shown that the mechanistic target of rapamycin (mTOR) pathway is hyperactivated in FCD as evidenced by increased phosphorylation of the ribosomal protein S6 (S6) at serine 240/244 (S(240/244) ), a downstream target of mTOR. Moreover, extracellular regulated kinase (ERK) has been shown to phosphorylate S6 at serine 235/236 (S(235/236) ) and tuberous sclerosis complex 2 (TSC2) at serine 664 (S(664) ) leading to hyperactive mTOR signaling. We evaluated ERK phosphorylation of S6 and TSC2 in two types of FCD (FCD I and FCD II) as a candidate mechanism contributing to mTOR pathway dysregulation. Tissue samples from patients with tuberous sclerosis (TS) served as a positive control. Immunostaining for phospho-S6 (pS6(240/244) and pS6(235/236) ), phospho-ERK (pERK), and phospho-TSC2 (pTSC2) was performed on resected brain tissue with FCD and TS. We found increased pS6(240/244) and pS6(235/236) staining in FCD I, FCD II and TS compared to normal-appearing tissue, while pERK and pTSC2 staining was increased only in FCD IIb and TS tissue. Our results suggest that both the ERK and mTOR pathways are dysregulated in FCD and TS; however, the signaling alterations are different for FCD I as compared to FCD II and TS.
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Epilepsia/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Malformações do Desenvolvimento Cortical do Grupo I/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Adolescente , Criança , Pré-Escolar , Ativação Enzimática , Epilepsia/patologia , Feminino , Humanos , Imuno-Histoquímica , Lactente , Sistema de Sinalização das MAP Quinases/fisiologia , Imageamento por Ressonância Magnética , Masculino , Malformações do Desenvolvimento Cortical do Grupo I/patologia , Fosforilação , Proteína S6 Ribossômica/metabolismo , Proteína 2 do Complexo Esclerose Tuberosa , Proteínas Supressoras de Tumor/metabolismoRESUMO
The Reelin signaling pathway is implicated in processes controlling synaptic plasticity and hippocampus-dependent learning and memory. A single direct in vivo application of Reelin enhances long-term potentiation, increases dendritic spine density and improves associative and spatial learning and memory. Angelman syndrome (AS) is a neurological disorder that presents with an overall defect in synaptic function, including decreased long-term potentiation, reduced dendritic spine density, and deficits in learning and memory, making it an attractive model in which to examine the ability of Reelin to recover synaptic function and cognitive deficits. In this study, we investigated the effects of Reelin administration on synaptic plasticity and cognitive function in a mouse model of AS and demonstrated that bilateral, intraventricular injections of Reelin recover synaptic function and corresponding hippocampus-dependent associative and spatial learning and memory. Additionally, we describe alteration of the Reelin profile in tissue from both the AS mouse and post-mortem human brain.
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Síndrome de Angelman/fisiopatologia , Síndrome de Angelman/psicologia , Moléculas de Adesão Celular Neuronais/administração & dosagem , Proteínas da Matriz Extracelular/administração & dosagem , Hipocampo/efeitos dos fármacos , Potenciação de Longa Duração/efeitos dos fármacos , Proteínas do Tecido Nervoso/administração & dosagem , Serina Endopeptidases/administração & dosagem , Síndrome de Angelman/tratamento farmacológico , Animais , Moléculas de Adesão Celular Neuronais/metabolismo , Córtex Cerebral/metabolismo , Espinhas Dendríticas/efeitos dos fármacos , Modelos Animais de Doenças , Proteínas da Matriz Extracelular/metabolismo , Feminino , Células HEK293 , Hipocampo/fisiopatologia , Hipocampo/ultraestrutura , Humanos , Injeções Intraventriculares , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Proteína Reelina , Serina Endopeptidases/metabolismo , Aprendizagem Espacial/efeitos dos fármacos , Memória Espacial/efeitos dos fármacosRESUMO
OBJECTIVE: Hyperactivation of the mechanistic target of rapamycin (mTOR; also known as mammalian target of rapamycin) pathway has been demonstrated in human cortical dysplasia (CD) as well as in animal models of epilepsy. Although inhibition of mTOR signaling early in epileptogenesis suppressed epileptiform activity in the neuron subset-specific Pten knockout (NS-Pten KO) mouse model of CD, the effects of mTOR inhibition after epilepsy is fully established were not previously examined in this model. Here, we investigated whether mTOR inhibition suppresses epileptiform activity and other neuropathological correlates in adult NS-Pten KO mice with severe and well-established epilepsy. METHODS: The progression of epileptiform activity, mTOR pathway dysregulation, and associated neuropathology with age in NS-Pten KO mice were evaluated using video-electroencephalography (EEG) recordings, Western blotting, and immunohistochemistry. A cohort of NS-Pten KO mice was treated with the mTOR inhibitor rapamycin (10 mg/kg i.p., 5 days/week) starting at postnatal week 9 and video-EEG monitored for epileptiform activity. Western blotting and immunohistochemistry were performed to evaluate the effects of rapamycin on the associated pathology. RESULTS: Epileptiform activity worsened with age in NS-Pten KO mice, with parallel increases in the extent of hippocampal mTOR complex 1 and 2 (mTORC1 and mTORC2, respectively) dysregulation and progressive astrogliosis and microgliosis. Rapamycin treatment suppressed epileptiform activity, improved baseline EEG activity, and increased survival in severely epileptic NS-Pten KO mice. At the molecular level, rapamycin treatment was associated with a reduction in both mTORC1 and mTORC2 signaling and decreased astrogliosis and microgliosis. SIGNIFICANCE: These findings reveal a wide temporal window for successful therapeutic intervention with rapamycin in the NS-Pten KO mouse model, and they support mTOR inhibition as a candidate therapy for established, late-stage epilepsy associated with CD and genetic dysregulation of the mTOR pathway.
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Modelos Animais de Doenças , Epilepsia/metabolismo , Malformações do Desenvolvimento Cortical/metabolismo , PTEN Fosfo-Hidrolase/deficiência , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Animais , Epilepsia/tratamento farmacológico , Feminino , Masculino , Malformações do Desenvolvimento Cortical/tratamento farmacológico , Camundongos , Camundongos Knockout , Sirolimo/farmacologia , Sirolimo/uso terapêuticoRESUMO
OBJECTIVE: Epilepsy is a major manifestation of tuberous sclerosis complex (TSC). Everolimus is an mammalian target of rapamycin complex 1 inhibitor with demonstrated benefit in several aspects of TSC. We report the first prospective human clinical trial to directly assess whether everolimus will also benefit epilepsy in TSC patients. METHODS: The effect of everolimus on seizure control was assessed using a prospective, multicenter, open-label, phase I/II clinical trial. Patients≥2 years of age with confirmed diagnosis of TSC and medically refractory epilepsy were treated for a total of 12 weeks. The primary endpoint was percentage of patients with a ≥50% reduction in seizure frequency over a 4-week period before and after treatment. Secondary endpoints assessed impact on electroencephalography (EEG), behavior, and quality of life. RESULTS: Twenty-three patients were enrolled, and 20 patients were treated with everolimus. Seizure frequency was reduced by ≥50% in 12 of 20 subjects. Overall, seizures were reduced in 17 of the 20 by a median reduction of 73% (p<0.001). Seizure frequency was also reduced during 23-hour EEG monitoring (p=0.007). Significant reductions in seizure duration and improvement in parent-reported behavior and quality of life were also observed. There were 83 reported adverse events that were thought to be treatment-related, all of which were mild or moderate in severity. INTERPRETATION: Seizure control improved in the majority of TSC patients with medically refractory epilepsy following treatment with everolimus. Everolimus demonstrated additional benefits on behavior and quality of life. Treatment was safe and well tolerated. Everolimus may be a therapeutic option for refractory epilepsy in this population.
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Anticonvulsivantes/uso terapêutico , Encéfalo/efeitos dos fármacos , Epilepsia/tratamento farmacológico , Qualidade de Vida , Sirolimo/análogos & derivados , Esclerose Tuberosa/tratamento farmacológico , Adolescente , Encéfalo/fisiopatologia , Criança , Pré-Escolar , Eletroencefalografia , Epilepsia/etiologia , Epilepsia/fisiopatologia , Everolimo , Feminino , Humanos , Masculino , Sirolimo/uso terapêutico , Resultado do Tratamento , Esclerose Tuberosa/complicações , Esclerose Tuberosa/fisiopatologia , Adulto JovemRESUMO
PURPOSE: Cardiac abnormalities resulting from chronic epilepsy ("the epileptic heart") constitute a well-recognized comorbidity. However, the association of cardiac alterations with epilepsy duration remains understudied. We sought to evaluate this association using electrocardiogram (ECG). METHODS: We prospectively enrolled children between 1 months and 18 years of age without known cardiac conditions or ion channelopathies during routine clinic visits. ECGs were categorized as abnormal if there were alterations in rhythm; PR, QRS, or corrected QT interval; QRS axis or morphology; ST segment or T wave. An independent association between ECG abnormalities and epilepsy duration was evaluated using multivariable logistic regression modeling. RESULTS: 213 children were enrolled. 100 ECGs (47%) exhibited at least one alteration; most commonly in the ST segment (37, 17%) and T wave (29, 11%). Children with normal ECGs had shorter epilepsy duration as compared to those with ECG abnormalities (46 [18-91] months vs. 73 [32-128 months], p = 0.004). A multivariable logistic regression model demonstrated that increasing epilepsy duration was independently associated with the presence of ECG abnormalities (OR=1.09, 95% CI=1.02-1.16, p = 0.008), adjusted for seizure frequency, generalized tonic-clonic/focal to bilateral tonic-clonic seizures as the predominant seizure type, and number of channel-modifying anti-seizure medications. Increasing epilepsy duration was also independently associated with the presence of ST/T wave abnormalities (OR=1.09, 95% CI=1.01-1.16, p = 0.017), adjusted for the same covariates. SIGNIFICANCE: Increasing epilepsy duration is independently associated with the presence of minor ECG abnormalities. Additional studies are needed to evaluate whether this finding may represent a manifestation of the "epileptic heart".
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Eletrocardiografia , Epilepsia , Humanos , Masculino , Feminino , Criança , Epilepsia/fisiopatologia , Epilepsia/diagnóstico , Pré-Escolar , Adolescente , Lactente , Estudos Prospectivos , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/etiologiaRESUMO
When we speak, we not only make movements with our mouth, lips, and tongue, but we also hear the sound of our own voice. Thus, speech production in the brain involves not only controlling the movements we make, but also auditory and sensory feedback. Auditory responses are typically suppressed during speech production compared to perception, but how this manifests across space and time is unclear. Here we recorded intracranial EEG in seventeen pediatric, adolescent, and adult patients with medication-resistant epilepsy who performed a reading/listening task to investigate how other auditory responses are modulated during speech production. We identified onset and sustained responses to speech in bilateral auditory cortex, with a selective suppression of onset responses during speech production. Onset responses provide a temporal landmark during speech perception that is redundant with forward prediction during speech production. Phonological feature tuning in these "onset suppression" electrodes remained stable between perception and production. Notably, the posterior insula responded at sentence onset for both perception and production, suggesting a role in multisensory integration during feedback control.
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The dorsal and ventral regions of the hippocampus perform different functions. Whether the integrative properties of hippocampal cells reflect this heterogeneity is unknown. We focused on dendrites where most synaptic input integration takes place. We report enhanced backpropagation and theta resonance and decreased summation of synaptic inputs in ventral versus dorsal CA1 pyramidal cell distal dendrites. Transcriptional Kv4.2 down-regulation and post-transcriptional hyperpolarization-activated cyclic AMP-gated channel (HCN1/2) up-regulation may underlie these differences, respectively. Our results reveal differential dendritic integrative properties along the dorso-ventral axis, reflecting diverse computational needs.
Assuntos
Canais de Cátion Regulados por Nucleotídeos Cíclicos/biossíntese , Dendritos/metabolismo , Regulação para Baixo/fisiologia , Canais Iônicos/biossíntese , Proteínas do Tecido Nervoso/biossíntese , Canais de Potássio/biossíntese , Células Piramidais/metabolismo , Canais de Potássio Shal/biossíntese , Regulação para Cima/fisiologia , Animais , Dendritos/genética , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Especificidade de Órgãos , Células Piramidais/citologia , Ratos , Transcrição Gênica/fisiologiaRESUMO
Kv4.2 channels contribute to the transient, outward K(+) current (A-type current) in hippocampal dendrites, and modulation of this current substantially alters dendritic excitability. Using Kv4.2 knockout (KO) mice, we examined the role of Kv4.2 in hippocampal-dependent learning and memory. We found that Kv4.2 KO mice showed a deficit in the learning phase of the Morris water maze (MWM) and significant impairment in the probe trial compared with wild type (WT). Kv4.2 KO mice also demonstrated a specific deficit in contextual learning in the fear-conditioning test, without impairment in the conditioned stimulus or new context condition. Kv4.2 KO mice had normal activity, anxiety levels, and prepulse inhibition compared with WT mice. A compensatory increase in tonic inhibition has been previously described in hippocampal slice recordings from Kv4.2 KO mice. In an attempt to decipher whether increased tonic inhibition contributed to the learning and memory deficits in Kv4.2 KO mice, we administered picrotoxin to block GABA(A) receptors (GABA(A)R), and thereby tonic inhibition. This manipulation had no effect on behavior in the WT or KO mice. Furthermore, total protein levels of the α5 or δ GABA(A)R subunits, which contribute to tonic inhibition, were unchanged in hippocampus. Overall, our findings add to the growing body of evidence, suggesting an important role for Kv4.2 channels in hippocampal-dependent learning and memory.
Assuntos
Hipocampo/metabolismo , Aprendizagem/fisiologia , Memória/fisiologia , Canais de Potássio Shal/metabolismo , Animais , Western Blotting , Condicionamento Clássico/fisiologia , Transtornos da Memória/etiologia , Transtornos da Memória/metabolismo , Camundongos , Camundongos Knockout , Atividade Motora/fisiologia , Canais de Potássio Shal/deficiênciaRESUMO
Expression of immediate early genes (IEGs) in the brain is important for synaptic plasticity, and probably also in neurodegenerative conditions. To understand the cellular mechanisms of the underlying neuropathophysiological processes in epilepsy, we need to pinpoint changes in concentration of synaptic plasticity-related proteins at subsynaptic levels. In this study, we examined changes in synaptic expression of Activity-regulated cytoskeleton-associated (Arc) and Brai Derived Neurotrophic Factor (BDNF) in a rat model of kainate-induced temporal lobe epilepsy (TLE). Western blotting showed reduced concentrations of Arc and increased concentrations of BDNF in hippocampal synaptosomes in chronic TLE rats. Then, using quantitative electron microscopy, we found corresponding changes in subsynaptic regions in the hippocampus. Specifically, we detected significant reductions in the concentrations of Arc in the presynaptic terminal of Schaffer collateral glutamatergic synapses in the stratum radiatum of the CA1 area in TLE, as well as in their adjacent postsynaptic spines. In CA3, there was a significant reduction of Arc only in the presynaptic terminal cytoplasm. Conversely, in CA3, there was a significant increase in the expression of BDNF in the presynaptic terminal, but not in the postsynaptic spine. Significant increase in BDNF concentration in the CA1 postsynaptic density was also obtained. We hypothesize that the observed changes in Arc and BDNF may contribute to both cognitive impairment and increased excitotoxic vulnerability in chronic epilepsy.
Assuntos
Epilepsia do Lobo Temporal , Epilepsia , Ratos , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Epilepsia do Lobo Temporal/induzido quimicamente , Epilepsia do Lobo Temporal/metabolismo , Hipocampo/metabolismo , Sinapses/fisiologia , Epilepsia/metabolismoRESUMO
The goal of these studies was to use quantitative (q)EEG techniques on data from children with Angelman syndrome (AS) using spectral power analysis, and to evaluate this as a potential biomarker and quantitative method to evaluate therapeutics. Although characteristic patterns are evident in visual inspection, using qEEG techniques has the potential to provide quantitative evidence of treatment efficacy. We first assessed spectral power from baseline EEG recordings collected from children with AS compared to age-matched neurotypical controls, which corroborated the previously reported finding of increased total power driven by elevated delta power in children with AS. We then retrospectively analyzed data collected during a clinical trial evaluating the safety and tolerability of minocycline (3 mg/kg/d) to compare pretreatment recordings from children with AS (4-12 years of age) to EEG activity at the end of treatment and following washout for EEG spectral power and epileptiform events. At baseline and during minocycline treatment, the AS subjects demonstrated increased delta power; however, following washout from minocycline treatment the AS subjects had significantly reduced EEG spectral power and epileptiform activity. Our findings support the use of qEEG analysis in evaluating AS and suggest that this technique may be useful to evaluate therapeutic efficacy in AS. Normalizing EEG power in AS therefore may become an important metric in screening therapeutics to gauge overall efficacy. As therapeutics transition from preclinical to clinical studies, it is vital to establish outcome measures that can quantitatively evaluate putative treatments for AS and neurological disorders with distinctive EEG patterns.