BACKGROUND

Perampanel is an antagonist of the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. It is currently FDA-approved to treat focal and generalized tonic-clonic seizures in epilepsy, but recent evidence suggests its potential in treating severe and refractory tremors.

OBJECTIVES

To determine the safety and efficacy of perampanel in treating tremors via a systematic review of existing literature. 

METHODS

We performed a literature search on five large databases (PubMed, Cochrane, Google Scholar, HERDIN, and Scopus) for clinical studies within the last 10 years and screened a total of 1,539 unique articles for full assessment. We filtered out papers on epilepsy as well as hypokinetic diseases and assessed nine articles for quality assessment and review.

RESULTS

A total of four case reports/series, four open-label trials, and one randomized controlled trial were assessed to be of fair to good quality. All trials showed that low-dose perampanel (2-4 mg/day) was safe and well-tolerated with minor adverse events reported by participants. A net benefit from baseline was observed in patients with essential and primary orthostatic tremors. However, current evidence is weak because the trials employed a non-randomized before-after study design with a small sample size and significant dropout rates.

CONCLUSION

Low-dose perampanel at 2-4 mg/day shows promising potential in treating refractory tremors and myoclonus in recent clinical studies, but current evidence is weak or anecdotal. Additional randomized controlled trials are needed to determine the conclusive benefit of perampanel for hyperkinesia.

Human ; Perampanel ; Receptors, Ampa ; Dystonia ; Tremor ; Myoclonus ; Hyperkinesia ; Hyperkinesis

BACKGROUND

Perampanel is an antagonist of the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. It is currently FDA-approved to treat focal and generalized tonic-clonic seizures in epilepsy, but recent evidence suggests its potential in treating severe and refractory tremors.

OBJECTIVES

To determine the safety and efficacy of perampanel in treating tremors via a systematic review of existing literature. 

METHODS

We performed a literature search on five large databases (PubMed, Cochrane, Google Scholar, HERDIN, and Scopus) for clinical studies within the last 10 years and screened a total of 1,539 unique articles for full assessment. We filtered out papers on epilepsy as well as hypokinetic diseases and assessed nine articles for quality assessment and review.

RESULTS

A total of four case reports/series, four open-label trials, and one randomized controlled trial were assessed to be of fair to good quality. All trials showed that low-dose perampanel (2-4 mg/day) was safe and well-tolerated with minor adverse events reported by participants. A net benefit from baseline was observed in patients with essential and primary orthostatic tremors. However, current evidence is weak because the trials employed a non-randomized before-after study design with a small sample size and significant dropout rates.

CONCLUSION

Low-dose perampanel at 2-4 mg/day shows promising potential in treating refractory tremors and myoclonus in recent clinical studies, but current evidence is weak or anecdotal. Additional randomized controlled trials are needed to determine the conclusive benefit of perampanel for hyperkinesia.

Human ; Perampanel ; Receptors, Ampa ; Dystonia ; Tremor ; Myoclonus ; Hyperkinesia ; Hyperkinesis

The purpose of this study was to investigate the effect of glutamate and its ionotropic receptor agonists on the response to acute hypoxia in rat carotid body in vitro. Briefly, after SD rats were anesthetized and decapitated, the bilateral carotid bifurcations were rapidly isolated. Then bifurcation was placed into a recording chamber perfused with 95% O₂-5% CO₂ saturated Kreb's solution. The carotid body-sinus nerve complex was dissected, and the carotid sinus nerve discharge was recorded using a suction electrode. To detect the response of carotid body to acute hypoxia, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution for a period of 100 s at an interval of 15 min. To observe the effect of glutamate, ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor agonist AMPA or N-methyl-D-aspartate (NMDA) receptor agonist NMDA on the response to acute hypoxia in rat carotid body, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution containing the corresponding reagent. The results showed that glutamate (20 μmol/L), AMPA (5 μmol/L) or NMDA (10 μmol/L) inhibited the acute hypoxia-induced enhancement of carotid sinus nerve activity, and these inhibitory effects were dose-dependent. In summary, the activation of glutamate ionotropic receptors appears to exert an inhibitory effect on the response to acute hypoxia in carotid body of rats.
Rats ; Animals ; Glutamic Acid/pharmacology* ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology* ; N-Methylaspartate/pharmacology* ; Carotid Body ; Rats, Sprague-Dawley ; Carbon Dioxide ; Receptors, N-Methyl-D-Aspartate ; Receptors, AMPA ; Hypoxia

Post-traumatic stress disorder (PTSD) has been reported to be associated with a higher risk of cardiovascular disease. The amygdala may have an important role in regulating cardiovascular function. This study aims to explore the effect of amygdala glutamate receptors (GluRs) on cardiovascular activity in a rat model of PTSD. A compound stress method combining electrical stimulation and single prolonged stress was used to prepare the PTSD model, and the difference of weight gain before and after modeling and the elevated plus maze were used to assess the PTSD model. In addition, the distribution of retrogradely labeled neurons was observed using the FluoroGold (FG) retrograde tracking technique. Western blot was used to analyze the changes of amygdala GluRs content. To further investigate the effects, artificial cerebrospinal fluid (ACSF), non-selective GluR blocker kynurenic acid (KYN) and AMPA receptor blocker CNQX were microinjected into the central nucleus of the amygdala (CeA) in the PTSD rats, respectively. The changes in various indices following the injection were observed using in vivo multi-channel synchronous recording technology. The results indicated that, compared with the control group, the PTSD group exhibited significantly lower weight gain (P < 0.01) and significantly decreased ratio of open arm time (OT%) (P < 0.05). Retrograde labeling of neurons was observed in the CeA after microinjection of 0.5 µL FG in the rostral ventrolateral medulla (RVLM). The content of AMPA receptor in the PTSD group was lower than that in the control group (P < 0.05), while there was no significant differences in RVLM neuron firing frequency and heart rate (P > 0.05) following ACSF injection. However, increases in RVLM neuron firing frequency and heart rate were observed after the injection of KYN or CNQX into the CeA (P < 0.05) in the PTSD group. These findings suggest that AMPA receptors in the amygdala are engaged in the regulation of cardiovascular activity in PTSD rats, possibly by acting on inhibitory pathways.
Rats ; Animals ; Rats, Sprague-Dawley ; Stress Disorders, Post-Traumatic ; Receptors, AMPA ; 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology* ; Receptors, Glutamate/metabolism* ; Amygdala ; Weight Gain ; Medulla Oblongata/physiology* ; Blood Pressure

Mutations in genes encoding amyloid precursor protein (APP) and presenilins (PSs) cause familial forms of Alzheimer's disease (AD), a neurodegenerative disorder strongly associated with aging. It is currently unknown whether and how AD risks affect early brain development, and to what extent subtle synaptic pathology may occur prior to overt hallmark AD pathology. Transgenic mutant APP/PS1 over-expression mouse lines are key tools for studying the molecular mechanisms of AD pathogenesis. Among these lines, the 5XFAD mice rapidly develop key features of AD pathology and have proven utility in studying amyloid plaque formation and amyloid β (Aβ)-induced neurodegeneration. We reasoned that transgenic mutant APP/PS1 over-expression in 5XFAD mice may lead to neurodevelopmental defects in early cortical neurons, and performed detailed synaptic physiological characterization of layer 5 (L5) neurons from the prefrontal cortex (PFC) of 5XFAD and wild-type littermate controls. L5 PFC neurons from 5XFAD mice show early APP/Aβ immunolabeling. Whole-cell patch-clamp recording at an early post-weaning age (P22-30) revealed functional impairments; although 5XFAD PFC-L5 neurons exhibited similar membrane properties, they were intrinsically less excitable. In addition, these neurons received smaller amplitude and frequency of miniature excitatory synaptic inputs. These functional disturbances were further corroborated by decreased dendritic spine density and spine head volumes that indicated impaired synapse maturation. Slice biotinylation followed by Western blot analysis of PFC-L5 tissue revealed that 5XFAD mice showed reduced synaptic AMPA receptor subunit GluA1 and decreased synaptic NMDA receptor subunit GluN2A. Consistent with this, patch-clamp recording of the evoked L23>L5 synaptic responses revealed a reduced AMPA/NMDA receptor current ratio, and an increased level of AMPAR-lacking silent synapses. These results suggest that transgenic mutant forms of APP/PS1 overexpression in 5XFAD mice leads to early developmental defects of cortical circuits, which could contribute to the age-dependent synaptic pathology and neurodegeneration later in life.
Mice ; Animals ; Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Amyloid beta-Protein Precursor/metabolism* ; Mice, Transgenic ; Neurons/metabolism* ; Receptors, AMPA/metabolism* ; Disease Models, Animal

CaMKII is essential for long-term potentiation (LTP), a process in which synaptic strength is increased following the acquisition of information. Among the four CaMKII isoforms, γCaMKII is the one that mediates the LTP of excitatory synapses onto inhibitory interneurons (LTP_E→I). However, the molecular mechanism underlying how γCaMKII mediates LTP_E→I remains unclear. Here, we show that γCaMKII is highly enriched in cultured hippocampal inhibitory interneurons and opts to be activated by higher stimulating frequencies in the 10-30 Hz range. Following stimulation, γCaMKII is translocated to the synapse and becomes co-localized with the postsynaptic protein PSD-95. Knocking down γCaMKII prevents the chemical LTP-induced phosphorylation and trafficking of AMPA receptors (AMPARs) in putative inhibitory interneurons, which are restored by overexpression of γCaMKII but not its kinase-dead form. Taken together, these data suggest that γCaMKII decodes NMDAR-mediated signaling and in turn regulates AMPARs for expressing LTP in inhibitory interneurons.
Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism* ; Hippocampus/metabolism* ; Interneurons/physiology* ; Long-Term Potentiation/physiology* ; N-Methylaspartate/metabolism* ; Receptors, AMPA/physiology* ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Synapses/physiology*

OBJECTIVE: To explore the influence of electroacupuncture (EA) on the expression of AMPA receptor subunit GluR1 in the rats with acute spinal cord injury (SCI) and explore the potential effect mechanism of EA in treatment of acute SCI. METHODS: A total of 80 SD rats were randomly divided into five groups, i.e. a sham-operation group, a model group, an AMPA antagonist (DNQX) group, an EA group and a DNQX+EA group, 16 rats in each group. The modified Allen's impacting method was adopted to prepare the rat model of acute SCI at T RESULTS: Compared to the sham-operation group in 6 h, 24 h and 48 h after modeling, the BBB scores were all significantly decreased in the model group ( CONCLUSION The intervention with EA at "Dazhui" and "Mingmen" promotes the repair of the injured nerve in the spinal anterior horn probably through inhibiting GluR1 expression in the spinal injured area in the rats with acute SCI.
Animals ; Electroacupuncture ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA/genetics* ; Spinal Cord ; Spinal Cord Injuries/therapy*

OBJECTIVE: To explore the genetic basis for a family affected with mental retardation combined with autism. METHODS: For the family featuring X-linked recessive inheritance of mental retardation combined with autism, clinical data and peripheral blood samples were collected. Potential mutations of genes associated with intellectual impairment were sequenced with an Ion PGM platform. Suspected mutations were verified with a PCR-Sanger sequencing method. RESULTS: The patient with mental retardation had mild abnormal electroencephalograph(EEG), while brain MRI and CT scans showed no obvious abnormality. Two ABC (autism behavior checklist) testing scores were 73 and 66 when he was 7- and 13-year-old, respectively. A novel hemizygous mutation, c.64C>T (p.L22F), was detected in the GRIA3 gene in the patient, for which his mother was a heterozygous carrier. The mutation site was predicted to be possibly damaging and disease causing by PolyPhen_2 and MutationTaster. CONCLUSION The novel hemizygous c.64C>T (p.L22F) mutation of the GRIA3 gene probably underlies the phenotypes of mental retardation combined with autism in this family. Considering the variable clinical manifestation of mental retardation and genetic heterogeneity of autism, genetic testing is essential for making the correct diagnosis.
Adolescent ; Autistic Disorder ; genetics ; Child ; Humans ; Intellectual Disability ; genetics ; Male ; Mental Retardation, X-Linked ; genetics ; Mutation ; Receptors, AMPA ; genetics

It is known that top-down associative inputs terminate on distal apical dendrites in layer 1 while bottom-up sensory inputs terminate on perisomatic dendrites of layer 2/3 pyramidal neurons (L2/3 PyNs) in primary sensory cortex. Since studies on synaptic transmission in layer 1 are sparse, we investigated the basic properties and cholinergic modulation of synaptic transmission in layer 1 and compared them to those in perisomatic dendrites of L2/3 PyNs of rat primary visual cortex. Using extracellular stimulations of layer 1 and layer 4, we evoked excitatory postsynaptic current/potential in synapses in distal apical dendrites (L1-EPSC/L1-EPSP) and those in perisomatic dendrites (L4-EPSC/L4-EPSP), respectively. Kinetics of L1-EPSC was slower than that of L4-EPSC. L1-EPSC showed presynaptic depression while L4-EPSC was facilitating. In contrast, inhibitory postsynaptic currents showed similar paired-pulse ratio between layer 1 and layer 4 stimulations with depression only at 100 Hz. Cholinergic stimulation induced presynaptic depression by activating muscarinic receptors in excitatory and inhibitory synapses to similar extents in both inputs. However, nicotinic stimulation enhanced excitatory synaptic transmission by ~20% in L4-EPSC. Rectification index of AMPA receptors and AMPA/NMDA ratio were similar between synapses in distal apical and perisomatic dendrites. These results provide basic properties and cholinergic modulation of synaptic transmission between distal apical and perisomatic dendrites in L2/3 PyNs of the visual cortex, which might be important for controlling information processing balance depending on attentional state.
Animals ; Automatic Data Processing ; Dendrites ; Depression ; Inhibitory Postsynaptic Potentials ; Kinetics ; Pyramidal Cells ; Rats ; Receptors, AMPA ; Receptors, Muscarinic ; Synapses ; Synaptic Transmission ; Visual Cortex

OBJECTIVETo explore the clinical and genetic features of a Chinese boy featuring X-linked mental retardation.

METHODSClinical features of the patient were analyzed. The DNA of the patient and his parents was extracted and sequenced by next generation sequencing. The results were validated and analyzed with software.

RESULTSThe child displayed X-linked mental retardation. Sequencing showed the patient has carried a c.455T>C (p.L152P) mutation of the GRIA3 gene inherited from his mother.

CONCLUSIONThe c.455T>C (p.L152P) mutation of the GRIA3 gene probably underlies the X-linked mental retardation in this child.

Child, Preschool ; High-Throughput Nucleotide Sequencing ; methods ; Humans ; Male ; Mental Retardation, X-Linked ; genetics ; Mutation ; Receptors, AMPA ; genetics