Perampanel in real-world clinical care of patients with epilepsy: Interim analysis of a phase IV study.

Objective: To assess the retention rate, efficacy, safety, and dosing of perampanel administered to patients with epilepsy during routine clinical care in the retrospective phase IV, PROVE Study (NCT03208660). Methods: Exposure, efficacy, and safety data were obtained from the medical records of patients initiating perampanel after January 1, 2014, across 29 US study sites. The cutoff date for this interim analysis was October 10, 2018. The primary efficacy endpoint was retention rate. Secondary efficacy endpoints included median percent changes in seizure frequency, seizure-freedom rate, and overall investigator impression of seizure effect. Results: All enrolled patients (N = 1121) received perampanel. Mean (standard deviation [SD]) cumulative duration of exposure to perampanel was 16.6 (14.7) months; overall mean (SD) daily perampanel dose was 5.7 (2.7) mg. Perampanel uptitration occurred weekly (21.1%), biweekly (23.8%), every 3 weeks (1.5%), other (43.3%), and unknown (10.3%). Across the Safety Analysis Set (N = 1121), retention rate on perampanel at 24 months was 49.5% (n = 319/645).At 12 months, the median reduction in seizure frequency per 28 days from baseline in the small number of patients for whom data were available was 75.0% (n = 85), and 30/85 (35.3%) patients were seizure free. Based on investigator impression at the end of treatment, improvement, no change (ie, stable), or worsening of seizures was reported in 54.3%, 33.7%, and 12.0% of patients, respectively.Treatment-emergent adverse events occurred in 500 (44.6%) patients; the most common were dizziness (9.2%), aggression (5.4%), and irritability (4.5%). Serious treatment-emergent adverse events occurred in 32 (2.9%) patients. Significance: Favorable retention and sustained efficacy were demonstrated for ≥12 months following initiation of perampanel during routine clinical care in patients with epilepsy.

Effectiveness of perampanel in managing chronic pain caused by the complex regional pain syndrome: A case report.

RATIONALE: The α-amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) receptor plays a critical role in the development and persistence of pain, and AMPA receptor antagonists are considered possible therapeutic targets for controlling pain. This report describes a patient with complex regional pain syndrome (CRPS) type I in the right lower leg and foot who responded well to perampanel, an AMPA receptor antagonist, for managing the chronic pain. PATIENT CONCERN: A 61-year-old woman complained of pain in her right lower leg and foot over a period of 7 year (numeric rating scale: 8) due to CRPS type I. DIAGNOSIS: CRPS type 1. INTERVENTIONS: Despite the combination of 300 mg pregabalin, 225 mg/1950 mg tramadol/acetaminophen, and 10 mg nortriptyline per day, her right lower leg and foot were nearly disabled due to the severity of the pain. High-dose prednisolone was found to be ineffective. Then, perampanel (4 mg; 2 mg twice) was administered to this patient daily. OUTCOMES: The day after treatment with perampanel, her pain completely disappeared. Additionally, at day 7 and 1 month follow-up, she reported no pain in the right lower leg and foot. Moreover, no adverse effects were reported after the application of perampanel. LESSONS: These results suggest that perampanel may potentially be used to treat centralized pain.

A parallel panning scheme used for selection of a GluA4-specific Fab targeting the ligand-binding domain.

A method for development of murine Fab fragments towards extracellular domains of a surface receptor is presented. The GluA4 ionotropic glutamate receptor is used as a model system. Recombinant GluA4 ectodomain comprising both the N-terminal domain (NTD) and the ligand-binding domain (LBD) in one molecule was used for immunization. A Fab-phage library was constructed and a parallel panning approach enabled selection of murine Fab fragments towards either intact ectodomain or the isolated LBD of the GluA4 receptor. One LBD-Fab (FabL9) showed exclusive selectivity for the GluA4 LBD, over a panel of LBDs from GluA2, GluK1, GluK2 and GluD2. Soluble FabL9 was produced in amounts suitable for characterization. Competitive ELISA and rat-brain immunoprecipitation experiments confirmed that the FabL9 epitope is conserved in the LBD and in the intact native receptor. By an alignment of GluA2 and GluA4, the likely binding epitope for FabL9 was predicted. This study demonstrates a simple approach for development of antibody fragments towards specific sub-domains of a large ligand-gated ion channel, and this method could be utilized for all multi-domain surface receptors where antibody domain-selectivity may be desirable. Furthermore, we present for the first time a GluA4 subtype-specific murine Fab fragment targeting the LBD of the receptor.

Panel de auto-anticuerpos para encefalitis autoinmune / Autoantibody panel for autoimmune encephalitis

CONTEXTO CLÍNICO: La encefalitis autoinmune (EA) es un desorden neurológico debilitante que se desarrolla como una encefalopatía rápidamente progresiva y es causada por inflamación cerebral de etiología autoinmune. Se estima que la incidencia anual de encefalitis de cualquier causa en Europa es de 2 a 3 por 100.000 habitantes. De todas las encefalitis, 20% son inmunomediadas y la más común es la encefalitis anti-NMDA (4%). Entre las EA más frecuentes se encuentra la encefalitis anti-NMDA, encefalitis límbica, encefalitis de ganglios basales, síndrome de Morvan, entre otros. Todas estas se han asociado a una seria de auto-anticuerpos ya sean detectados en sangre o en LCR. La EA involucra una serie de enfermedades que son provocadas por auto-anticuerpos dirigidos a epítopes extracelulares de canales de iones, receptores celulares y otras proteínas. La asociación con cáncer es variable en estas patologías y el pronóstico es bueno pudiendo tener efectos reversibles en la función sináptica neuronal. Después de haber excluido las causas más frecuentes de encefalitis como causas infecciosas, se sospecha de una EA cuando el paciente presenta: disminución progresiva de niveles de la conciencia (en días a semanas) con fluctuaciones y alteración de la cognición; alteración de la memoria, especialmente la retención de nueva información; síntomas psiquiátricos; entre otros. Debido a que la sintomatología no es específica, el diagnóstico se realiza con al menos uno de los siguientes: evidencia de nueva lesión focal del sistema nervioso central, convulsiones no explicadas por un desorden convulsivo previo, pleocitosis en el líquido cefalorraquídeo (LCR) o hallazgos sugestivos de encefalitis por resonancia magnética nuclear. En la mayoría de los casos el tratamiento de la EA (ya sea ante la sospecha de EA o con un diagnóstico establecido) se basa en el manejo con corticoesteroides, plasmaféresis y/o inmunoglobulina G endovenosa. Se postula que la detección de un panel de auto-anticuerpos es una herramienta fundamental para el diagnóstico y evaluación de respuesta al tratamiento para pacientes con encefalitis autoinmune. TECNOLOGÍA: Los auto-anticuerpos involucrados en la fisiopatología de la EA se pueden clasificar según su objetivo en: a) anticuerpos contra antígenos intracelulares como anti-GAD; b) anticuerpos contra receptores de sinapsis como: anti-NMDA, anti-AMPA, anti-GABA, entre otros; c) anticuerpos contra canales de iones como: anti-LGI1, anti CASPR-2; y, d) anticuerpos contra otras proteinas de superficie como: antififisina y anti receptor de la glicina. OBJETIVO: Evaluar la evidencia disponible acerca de la eficacia, seguridad y aspectos relacionados a las políticas de cobertura del panel de auto-anticuerpos para encefalitis autoinmune. MÉTODOS: Se realizó una búsqueda en las principales bases de datos bibliográficas (incluyendo Medline, Cochrane y CRD), en buscadores genéricos de Internet, agencias de evaluación de tecnologías sanitarias y financiadores de salud utilizando la siguiente estrategia: (Anti-N-Methyl-D-Aspartate Receptor Encephalitis[MeSH] OR Limbic Encephalitis[MeSH] OR Autoimmune Encephalitis [tiab]) AND (Autoantibodies[Mesh] OR Autoantibod*[tiab] OR autoantibody panel[tiab]) AND (Sensitivity and Specificity[Mesh] OR Sensitivity[tiab] OR Specificity[tiab]). Se priorizó la inclusión de revisiones sistemáticas (RS), estudios clínicos aleatorizados controlados, evaluaciones de tecnologías sanitarias y económicas, guías de práctica clínica y políticas de cobertura de otros sistemas de salud cuando estaban disponibles. RESULTADOS: Para el siguiente informe se incluyeron tres estudios observacionales, dos guías de práctica clínica y tres políticas de cobertura. No se encontraron revisiones sistemáticas, estudios clínicos controlados aleatorizados ni evaluaciones de tecnologías sanitarias que evalúen la detección de algún auto-anticuerpo para EA. De los anticuerpos listados en el Anexo 1, sólo se encontró evidencia con suficiente calidad respecto a la utilización de auto-anticuerpo anti-NMDA, anti-LGI1, anti-CASPR2, anti-GABA y anti-AMPA. CONCLUSIONES: La evidencia con respecto a la utilización de auto-anticuerpos para el diagnóstico de encefalitis autoinmune es de baja calidad. No se encontraron estudios clínicos aleatorizados controlados que evaluaran desenlaces clínicos tras un cambio de estrategia terapéutica guiada por auto-anticuerpos. Para la mayoría de los auto-anticuerpos no se encontraron estudios de precisión diagnóstica. Los estudios observacionales seleccionados sólo evidencian asociación entre la frecuencia de detección de diferentes auto-anticuerpos y encefalitis autoinmune. No se encontraron evaluaciones de tecnologías sanitarias que evalúen algún auto-anticuerpo para encefalitis autoinmune. Las guías de práctica clínica recomiendan anti-NMDA para el diagnóstico definitivo de encefalitis anti-NMDA y; auto-anticuerpos anti-LGI1, anti-GABA y anti-AMPA cuando hay un diagnóstico probable de encefalitis límbica.

Chronic Ampakine Treatments Stimulate Dendritic Growth and Promote Learning in Middle-Aged Rats.

Positive allosteric modulators of AMPA-type glutamate receptors (ampakines) have been shown to rescue synaptic plasticity and reduce neuropathology in rodent models of cognitive disorders. Here we tested whether chronic ampakine treatment offsets age-related dendritic retraction in middle-aged (MA) rats. Starting at 10 months of age, rats were housed in an enriched environment and given daily treatment with a short half-life ampakine or vehicle for 3 months. Dendritic branching and spine measures were collected from 3D reconstructions of Lucifer yellow-filled CA1 pyramidal cells. There was a substantial loss of secondary branches, relative to enriched 2.5-month-old rats, in apical and basal dendritic fields of vehicle-treated, but not ampakine-treated, 13-month-old rats. Baseline synaptic responses in CA1 were only subtly different between the two MA groups, but long-term potentiation was greater in ampakine-treated rats. Unsupervised learning of a complex environment was used to assess treatment effects on behavior. Vehicle- and drug-treated rats behaved similarly during a first 30 min session in the novel environment but differed markedly on subsequent measures of long-term memory. Markov sequence analysis uncovered a clear increase in the predictability of serial movements between behavioral sessions 2 and 3 in the ampakine, but not vehicle, group. These results show that a surprising degree of dendritic retraction occurs by middle age and that this can be mostly offset by pharmacological treatments without evidence for unwanted side effects. The functional consequences of rescue were prominent with regard to memory but also extended to self-organization of behavior. SIGNIFICANCE STATEMENT: Brain aging is characterized by a progressive loss of dendritic arbors and the emergence of impairments to learning-related synaptic plasticity. The present studies show that dendritic losses are evident by middle age despite housing in an enriched environment and can be mostly reversed by long-term, oral administration of a positive allosteric modulator of AMPA-type glutamate receptors. Dendritic recovery was accompanied by improvements to both synaptic plasticity and the encoding of long-term memory of a novel, complex environment. Because the short half-life compound had no evident negative effects, the results suggest a plausible strategy for treating age-related neuronal deterioration.

Immunization with the glutamate receptor-derived peptide GluR3B induces neuronal death and reactive gliosis, but confers partial protection from pentylenetetrazole-induced seizures.

Do autoantibodies (Ab's) against glutamate/AMPA receptor subtype 3 affect the severity of seizures? Rats immunized with the GluR3B-peptide (amino acids (aa) 372-395) or with the control GluR3A-peptide (aa 245-274) produced the respective anti-GluR3B and anti-GluR3A Ab's (both types of Ab's found in some epilepsy patients). The GluR3B-immunized rats exhibited neuronal death and reactive gliosis in the brain, but not overt spontaneous seizures. Surprisingly, in response to the chemoconvulsant pentylenetetrazole, the GluR3B-immunized rats displayed fewer jerks, a lower percentage of generalized seizures, and a lower overall seizure-severity score than GluR3A-immunized, scrambled GluR3B-immunized or non-immunized control rats. These findings, combined with the previously demonstrated ability of anti-GluR3B Ab's to bind, activate, and kill neurons and glia, suggest that if these Ab's are present in the brain they may cause neuronal death, which by itself may be pro-epileptic, but they may also decrease the excitability of seizure-related neural circuits, thereby conferring partial protection from seizures induced by other exogenously applied epileptogenic stimuli. The present results could have clinical implications for epilepsy.

Acute and late effects on induction of allodynia by acromelic acid, a mushroom poison related structurally to kainic acid.

1. Ingestion of a poisonous mushroom Clitocybe acromelalga is known to cause severe tactile pain (allodynia) in the extremities for a month and acromelic acid (ACRO), a kainate analogue isolated from the mushroom, produces selective damage of interneurons of the rat lower spinal cord when injected either systemically or intrathecally. Since ACRO has two isomers, ACRO-A and ACRO-B, here we examined their acute and late effects on induction of allodynia. 2. Intrathecal administration of ACRO-A and ACRO-B provoked marked allodynia by the first stimulus 5 min after injection, which lasted over the 50-min experimental period. Dose-dependency of the acute effect of ACRO-A on induction of allodynia showed a bell-shaped pattern from 50 ag x kg(-1) to 0.5 pg x kg(-1) and the maximum effect was observed at 50 fg x kg(-1). On the other hand, ACRO-B induced allodynia in a dose-dependent manner from 50 pg x kg(-1) to 50 ng x kg(-1). 3. N-methyl-d-aspartate (NMDA) receptor antagonists and Joro spider toxin, a Ca(2+)-permeable AMPA receptor antagonist, inhibited the allodynia induced by ACRO-A, but not by ACRO-B. However, other AMPA/kainate antagonists did not affect the allodynia induced by ACRO. 4. Whereas no neuronal damage was observed in the spinal cord in ACRO-A-treated mice, induction of allodynia by ACRO-A (50 fg x kg(-1)) and ACRO-B (50 ng x kg(-1)) was selectively lost 1 week after i.t. injection of a sublethal dose of ACRO-A (50 ng x kg(-1)) or ACRO-B (250 ng x kg(-1)). Higher doses of ACRO-A, however, could evoke allodynia dose-dependently from 50 pg x kg(-1) to 500 ng x kg(-1) in the ACRO-A-treated mice. The allodynia induced by ACRO-A (500 ng x kg(-1)) was not inhibited by Joro spider toxin or NMDA receptor antagonists. These properties of the late allodynia induced by ACRO-A were quite similar to those of the acute allodynia induced by ACRO-B. 5. ACRO-A could increase [Ca(2+)](i) in the deeper laminae, rather than in the superficial laminae, of the spinal cord. This increase was not blocked by the AMPA-preferring antagonist GYKI52466 and Joro spider toxin. 6. Taken together, these results demonstrate the stereospecificity of ACRO for the induction of allodynia and suggest the presence of a receptor specific to ACRO.

Development of behavioral sensitization to the cocaine-like fungicide triadimefon is prevented by AMPA, NMDa, DA D1 but not DA D2 receptor antagonists.

Triadimefon (TDF) is a triazole fungicide that blocks the reuptake of dopamine (DA) and leads to increased locomotor activity levels in mice and rats, effects similar to those of indirect DA agonists such as cocaine. We recently found in mice that intermittent TDF administration led to robust locomotor sensitization, a phenomenon reflecting neuronal plasticity, following challenge with the same TDF dose after a 2-week withdrawal period. The current study sought to determine whether antagonists to DA D1-like receptors (SCH 23390; SCH), DA D2-like receptors (remoxipride; Rem), ionotropic glutamate n-methyl-d-aspartate (NMDA) receptors (CPP), or ionotropic glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (NBQX) could prevent the development of TDF behavioral sensitization, therefore indicating their mechanistic involvement in TDF sensitization. Mice were treated with either vehicle, SCH (0.015 mg/kg), remoxipride (Rem, 0.3 mg/kg), CPP (2.5 mg/kg) or NBQX (10.0 mg/kg), followed 30 min later by vehicle or 75 mg/kg TDF (TDF), twice a week for 7 weeks, with locomotor activity measured post-dosing once a week. After a 2-week withdrawal period, mice were challenged with 75 mg/kg TDF or vehicle, to test for the presence of behavioral sensitization. Pretreatment with SCH, CPP, or NBQX, but not Rem, blocked the development of behavioral sensitization to TDF specifically for vertical activity. Antagonists that blocked TDF vertical sensitization also attenuated the increase in extracellular DA turnover (homovanillic acid [HVA]/DA) normally associated with this behavioral response. Therefore, DA D1, NMDA and AMPA receptors appear to be necessary for the development of behavioral sensitization to TDF. As such, TDF may be considered an environmental risk factor for behavioral dysfunctions linked to glutamatergic and dopaminergic systems.

Overexpression of Ca2+-permeable AMPA receptor promotes delayed cell death of hippocampal CA1 neurons following transient forebrain ischemia.

To examine the role of Ca(2+) entry through AMPA receptors in the pathogenesis of the ischemia-induced cell death of hippocampal neurons, we delivered cDNA of Q/R site-unedited form (GluR2Q) of AMPA receptor subunit GluR2 in the hippocampus by using an HVJ-liposome-mediated gene transfer technique. Two days prior to transient forebrain ischemia, we injected an HVJ-liposome containing cDNA of the GluR2Q-myc fusion gene into a rat unilateral hippocampus. In the absence of ischemic insult, overexpression of Ca(2+)-permeable GluR2Q did not cause any neurodegeneration in the cDNA-injected hippocampus. In ischemic rats, overexpression of Ca(2+)-permeable GluR2Q markedly promoted ischemic cell death of CA1 pyramidal neurons, while complete rescue of CA1 pyramidal neurons from ischemic damage occurred in the hippocampal hemisphere opposite the GluR2Q expression. Overexpression of the Q/R-site edited form (GluR2R) of subunit GluR2 did not affect the ischemia-induced damage of CA1 pyramidal neurons. From these results, we suggest that the Ca(2+)-permeability of AMPA receptors does not have a direct contribution to glutamate receptor-mediated neurotoxicity but has a promotive action in the evolution of ischemia-induced neurodegeneration of vulnerable neurons.

The AMPA receptor subunit GluR1 regulates dendritic architecture of motor neurons.

The morphology of the mature motor neuron dendritic arbor is determined by activity-dependent processes occurring during a critical period in early postnatal life. The abundance of the AMPA receptor subunit GluR1 in motor neurons is very high during this period and subsequently falls to a negligible level. To test the role of GluR1 in dendrite morphogenesis, we reintroduced GluR1 into rat motor neurons at the end of the critical period and quantitatively studied the effects on dendrite architecture. Two versions of GluR1 were studied that differed by the amino acid in the "Q/R" editing site. The amino acid occupying this site determines single-channel conductance, ionic permeability, and other essential electrophysiologic properties of the resulting receptor channels. We found large-scale remodeling of dendritic architectures in a manner depending on the amino acid occupying the Q/R editing site. Alterations in the distribution of dendritic arbor were not prevented by blocking NMDA receptors. These observations suggest that the expression of GluR1 in motor neurons modulates a component of the molecular substrate of activity-dependent dendrite morphogenesis. The control of these events relies on subunit-specific properties of AMPA receptors.

Amphetamine-induced plasticity of AMPA receptors in the ventral tegmental area: effects on extracellular levels of dopamine and glutamate in freely moving rats.

Previous electrophysiological studies suggested that the initiation of behavioral sensitization to cocaine and amphetamine involves a transient increase in AMPA receptor responsiveness in the ventral tegmental area (VTA). To test this, we used in vivo microdialysis to examine the effects of intra-VTA administration of AMPA (10 microm) and NMDA (100 microm) on dopamine (DA) and glutamate efflux in the VTA and the nucleus accumbens (NAC), an important target of VTA DA neurons. We compared rats treated for 5 d with saline or 5 mg/kg amphetamine and withdrawn for 3 or 10-14 d. After 3 d of withdrawal, intra-VTA AMPA increased both NAC and VTA DA levels to a greater extent in the amphetamine group, whereas NMDA produced similar effects in the saline and amphetamine groups. This enhanced responsiveness to AMPA was no longer evident in rats tested 10-14 d after the last injection. In addition, intra-VTA AMPA but not NMDA increased both VTA and NAC glutamate levels in rats tested 3 d after the last injection of amphetamine but not in saline controls. After 10-14 d, the responsiveness of glutamate levels to AMPA was no longer evident in the NAC but persisted in the VTA. Additional studies indicated that the glutamate effect in the NAC may involve increased responsiveness of DA receptors within the NAC. These findings establish an in vivo animal model with which to explore the consequences of repeated drug administration for AMPA receptor plasticity in the VTA. They also indicate that repeated amphetamine leads to potentiated interactions between DA and glutamate transmission.

Neuroadaptaciones en los sistemas Glutamatérgico y Dopaminérgico durante la abstinencia de cocaína / Neuroadaptative changes in dopaminergic and glutamatergic receptor subtypesafter extinction of cocaine self-administration behavior

El fenómeno de las recaídas en la adicción a drogas tras un periodo de abstinencia mantenido sigue siendo uno de los retos más difíciles de resolver. La vuelta al consumo produce, entre otros efectos, un gran desconcierto en el ex-abstinente y desorientación y desmotivación en los profesionales y el entorno familiar. Los factores que pueden facilitar un proceso de recaída son múltiples pero, en general, se incluyen en dos grandes grupos: los exógenos (fácil acceso a la sustancia; pertenencia a determinados grupos sociales...etc) y los endógenos (disfunciones de sistemas de neurotransmisores; condicionamiento a estímulos externos, la personalidad del sujeto; el estado mental...etc). Siendo obvia la importancia de los factores exógenos, hay cada día mayor cantidad de trabajos en la literatura científica que resaltan la posible función de los factores endógenos. En este trabajo presentaremos datos que demuestran la existencia de neuroadapataciones en los sistemas glutamatérgico y dopaminérgico tras la extinción de la conducta de autoadministración de cocaína en diversas regiones cerebrales de roedores de laboratorio. Esas neuroadaptaciones son más permanentes y duraderas en el sistema dopaminérgico. Considerados globalmente, estos resultados sugieren que durante la abstinencia de psicoestimulantes pueden producirse neuroadaptaciones en distintos sistemas de neurotransmisores que pueden mantener el deseo por la droga, exacerbar la potencialidad de los estímulos condicionados, incrementar la ansiedad...etc, y favorecer, en definitiva, una mayor vulnerabilidad a la recaída (AU)