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.

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

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.

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.

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.

Growth arrest DNA damage-inducible protein 45 β (GADD45B) has been reported to be a regulatory factor for active DNA demethylation and is implicated in the modulation of synaptic plasticity and chronic stress-related psychopathological processes. However, its precise role and mechanism of action in stress susceptibility remain elusive. In this study, we found a significant reduction in GADD45B expression specifically in the ventral, but not the dorsal hippocampal CA1 (dCA1) of stress-susceptible mice. Furthermore, we demonstrated that GADD45B negatively regulates susceptibility to social stress and NMDA receptor-dependent long-term potentiation (LTP) in the ventral hippocampal CA1 (vCA1). Importantly, through pharmacological inhibition using the NMDA receptor antagonist MK801, we provided further evidence supporting the hypothesis that GADD45B potentially modulates susceptibility to social stress by influencing NMDA receptor-mediated LTP. Collectively, these results suggested that modulation of NMDA receptor-mediated synaptic plasticity is a pivotal mechanism underlying the regulation of susceptibility to social stress by GADD45B.
Animals ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; CA1 Region, Hippocampal/drug effects* ; Male ; Stress, Psychological/physiopathology* ; Mice ; Neuronal Plasticity/drug effects* ; Long-Term Potentiation/drug effects* ; Mice, Inbred C57BL ; Antigens, Differentiation/metabolism* ; Dizocilpine Maleate/pharmacology* ; Excitatory Amino Acid Antagonists/pharmacology* ; GADD45 Proteins

Learning-associated functional plasticity at hippocampal synapses remains largely unexplored. Here, in a single session of reward-based trace conditioning, we examine learning-induced synaptic plasticity in the dorsal CA1 hippocampus (dCA1). Local field-potential recording combined with selective optogenetic inhibition first revealed an increase of dCA1 synaptic responses to the conditioned stimulus (CS) induced during conditioning at both Schaffer collaterals to the stratum radiatum (Rad) and temporoammonic input to the lacunosum moleculare (LMol). At these dCA1 inputs, synaptic potentiation of CS-responding excitatory synapses was further demonstrated by locally blocking NMDA receptors during conditioning and whole-cell recording sensory-evoked synaptic responses in dCA1 neurons from naive animals. An overall similar time course of the induction of synaptic potentiation was found in the Rad and LMol by multiple-site recording; this emerged later and saturated earlier than conditioned behavioral responses. Our experiments demonstrate a cued memory-associated dCA1 synaptic plasticity induced at both Schaffer collaterals and temporoammonic pathways.
Animals ; CA1 Region, Hippocampal/physiology* ; Male ; Association Learning/physiology* ; Neuronal Plasticity/physiology* ; Cues ; Memory/physiology* ; Synapses/physiology* ; Conditioning, Classical/physiology* ; Excitatory Postsynaptic Potentials/physiology* ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; Rats ; Optogenetics

Chronic visceral pain is a persistent and debilitating condition arising from dysfunction or sensitization of the visceral organs and their associated nervous pathways. Increasing evidence suggests that imbalances in central nervous system function play an essential role in the progression of visceral pain, but the exact mechanisms underlying the neural circuitry and molecular targets remain largely unexplored. In the present study, the ventral tegmental area (VTA) was shown to mediate visceral pain in mice. Visceral pain stimulation increased c-Fos expression and Ca²⁺ activity of glutamatergic VTA neurons, and optogenetic modulation of glutamatergic VTA neurons altered visceral pain. In particular, the upregulation of NMDA receptor 2A (NR2A) subunits within the VTA resulted in visceral pain in mice. Administration of a selective NR2A inhibitor decreased the number of visceral pain-induced c-Fos positive neurons and attenuated visceral pain. Pharmacology combined with chemogenetics further demonstrated that glutamatergic VTA neurons regulated visceral pain behaviors based on NR2A. In summary, our findings demonstrated that the upregulation of NR2A in glutamatergic VTA neurons plays a critical role in visceral pain. These insights provide a foundation for further comprehension of the neural circuits and molecular targets involved in chronic visceral pain and may pave the way for targeted therapies in chronic visceral pain.
Animals ; Male ; Visceral Pain/metabolism* ; Up-Regulation/physiology* ; Ventral Tegmental Area/metabolism* ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; Neurons/drug effects* ; Mice, Inbred C57BL ; Mice ; Proto-Oncogene Proteins c-fos/metabolism* ; Chronic Pain/metabolism* ; Glutamic Acid/metabolism*

Epilepsy is a chronic neurological disorder affecting ~65 million individuals worldwide. Abnormal synaptic plasticity is one of the most important pathological features of this condition. We investigated how ubiquitin-specific peptidase 47 (USP47) influences synaptic plasticity and its link to epilepsy. We found that USP47 enhanced excitatory postsynaptic transmission and increased the density of total dendritic spines and the proportion of mature dendritic spines. Furthermore, USP47 inhibited the degradation of the ubiquitinated α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit glutamate receptor 1 (GluR1), which is associated with synaptic plasticity. In addition, elevated levels of USP47 were found in epileptic mice, and USP47 knockdown reduced the frequency and duration of seizure-like events and alleviated epileptic seizures. To summarize, we present a new mechanism whereby USP47 regulates excitatory postsynaptic plasticity through the inhibition of ubiquitinated GluR1 degradation. Modulating USP47 may offer a potential approach for controlling seizures and modifying disease progression in future therapeutic strategies.
Animals ; Receptors, AMPA/metabolism* ; Neuronal Plasticity/physiology* ; Seizures/physiopathology* ; Disease Models, Animal ; Mice, Inbred C57BL ; Mice ; Ubiquitin Thiolesterase/genetics* ; Male ; Excitatory Postsynaptic Potentials/physiology* ; Ubiquitination ; Dendritic Spines/metabolism* ; Hippocampus/metabolism*

Neuropathic pain is frequently comorbidity with cognitive deficits. Neuralized1 (Neurl1)-mediated ubiquitination of CPEB3 in the hippocampus is critical in learning and memory. However, the role of Neurl1 in the cognitive impairment in neuropathic pain remains elusive. Herein, we found that lumbar 5 spinal nerve ligation (SNL) in male rat-induced neuropathic pain was followed by learning and memory deficits and LTP impairment in the hippocampus. The Neurl1 expression in the hippocampal CA1 was decreased after SNL. And this decrease paralleled the reduction of ubiquitinated-CPEB3 level and reduced production of GluA1 and GluA2. Overexpression of Neurl1 in the CA1 rescued cognitive deficits and LTP impairment, and reversed the reduction of ubiquitinated-CPEB3 level and the decrease of GluA1 and GluA2 production following SNL. Specific knockdown of Neurl1 or CPEB3 in bilateral hippocampal CA1 in naïve rats resulted in cognitive deficits and impairment of synaptic plasticity. The rescued cognitive function and synaptic plasticity by the treatment of overexpression of Neurl1 before SNL were counteracted by the knockdown of CPEB3 in the CA1. Collectively, the above results suggest that the downregulation of Neurl1 through reducing CPEB3 ubiquitination and, in turn, repressing GluA1 and GluA2 production and mediating synaptic plasticity impairment in hippocampal CA1 leads to the genesis of cognitive deficits in neuropathic pain.
Animals ; Male ; Neuralgia/metabolism* ; Rats ; Down-Regulation/physiology* ; Ubiquitination/physiology* ; Neuronal Plasticity/physiology* ; Rats, Sprague-Dawley ; CA1 Region, Hippocampal/metabolism* ; Cognitive Dysfunction/metabolism* ; RNA-Binding Proteins/metabolism* ; Receptors, AMPA/metabolism*

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.

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

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.

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.

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.

OBJECTIVES: To investigate the effects of hyperoxia on the expression of N-methyl-D-aspartate receptor 1 (NMDAR1) and its synapse-associated molecules, including cannabinoid receptor 1 (CB1R), postsynaptic density 95 (PSD95), and synapsin (SYN), in the hippocampus of neonatal rats. METHODS: One-day-old Sprague-Dawley neonatal rats were randomly divided into a hyperoxia group and a control group (n=8 per group). The hyperoxia group was exposed to 80% ± 5% oxygen continuously, while the control group was exposed to room air, for 7 days. At 1, 3, and 7 days after hyperoxia exposure, hematoxylin and eosin (HE) staining was used to observe histopathological changes in the brain. The expression levels of NMDAR1, CB1R, PSD95, and SYN proteins and mRNAs in the hippocampus were detected by immunohistochemistry, Western blotting, and quantitative real-time PCR. RESULTS: After 7 days of hyperoxia exposure, the hyperoxia group showed decreased neuronal density and disordered arrangement in brain tissue. Compared with the control group, after 1 day of hyperoxia exposure, CB1R mRNA and both NMDAR1 and CB1R protein expression in the hyperoxia group were significantly downregulated, while SYN protein expression was significantly upregulated (P<0.05). After 3 days, mRNA expression of NMDAR1, CB1R, and SYN was significantly decreased (P<0.05); NMDAR1 and CB1R protein expression was significantly downregulated (P<0.05), while PSD95 and SYN protein expression was significantly upregulated (P<0.05). After 7 days of hyperoxia, the protein expression of NMDAR1 and CB1R was significantly upregulated (P<0.05). CONCLUSIONS Continuous hyperoxia exposure induces time-dependent changes in the expression levels of NMDAR1 and its synapse-associated molecules in the hippocampus of neonatal rats.
Animals ; Receptors, N-Methyl-D-Aspartate/genetics* ; Rats, Sprague-Dawley ; Hippocampus/pathology* ; Rats ; Animals, Newborn ; Receptor, Cannabinoid, CB1/genetics* ; Hyperoxia/metabolism* ; Disks Large Homolog 4 Protein/genetics* ; Synapsins/genetics* ; Synapses ; Male ; Female ; RNA, Messenger/analysis*

OBJECTIVE: To illustrate the role of dehydrocorydaline (DHC) in chronic constriction injury (CCI)-induced neuropathic pain and the underlying mechanism. METHODS: C57BL/6J mice were randomly divided into 3 groups by using a random number table, including sham group (sham operation), CCI group [intrathecal injection of 10% dimethyl sulfoxide (DMSO)], and CCI+DHC group (intrathecal injection of DHC), 8 mice in each group. A CCI mouse model was conducted to induce neuropathic pain through ligating the right common sciatic nerve. On day 14 after CCI modeling or sham operation, mice were intrathecal injected with 5 µL of 10% DMSO or 10 mg/kg DHC (5 µL) into the 5th to 6th lumbar intervertebral space (L5-L6). Pregnant ICR mice were sacrificed for isolating primary spinal neurons on day 14 of embryo development for in vitro experiment. Pain behaviors were evaluated by measuring the paw withdrawal mechanical threshold (PWMT) of mice. Immunofluorescence was used to observe the activation of astrocytes and microglia in mouse spinal cord. Protein expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), phosphorylation of N-methyl-D-aspartate receptor subunit 2B (p-NR2B), and NR2B in the spinal cord or primary spinal neurons were detected by Western blot. RESULTS: In CCI-induced neuropathic pain model, mice presented significantly decreased PWMT, activation of glial cells, overexpressions of iNOS, TNF-α, IL-6, and higher p-NR2B/NR2B ratio in the spinal cord (P<0.05 or P<0.01), which were all reversed by a single intrathecal injection of DHC (P<0.05 or P<0.01). The p-NR2B/NR2B ratio in primary spinal neurons were also inhibited after DHC treatment (P<0.05). CONCLUSION An intrathecal injection of DHC relieved CCI-induced neuropathic pain in mice by inhibiting the neuroinflammation and neuron hyperactivity.
Animals ; Neuralgia/etiology* ; Mice, Inbred C57BL ; Analgesics/pharmacology* ; Neuroinflammatory Diseases/pathology* ; Constriction ; Male ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Nitric Oxide Synthase Type II/metabolism* ; Mice, Inbred ICR ; Microglia/pathology* ; Spinal Cord/drug effects* ; Female ; Mice ; Tumor Necrosis Factor-alpha/metabolism* ; Disease Models, Animal ; Constriction, Pathologic/complications* ; Interleukin-6/metabolism* ; Astrocytes/metabolism* ; Chronic Disease ; Neurons/metabolism*

OBJECTIVES: To observe the effect of 4-(arylethynyl)-pyrrolo[2,3-d] pyrimidine (10b) on post-traumatic stress disorder (PTSD)-like behaviors and ERK1/2-SGK1 signaling pathway in mice. METHODS: C57BL/6 mouse models exposed to single prolonged stress (SPS) were treated with daily gavage of saline, 10b at low, moderate and high doses, or paroxetine for 14 days. The changes in PTSD-like behaviors of SPS mice with different treatments were observed using behavioral tests. Western blotting and immunofluorescence assay were used to detect the protein expression levels of mGluR5, p-ERK, and SGK1 in the hippocampus of the mice. Pathological changes in the liver and kidney tissues of the mice were examined using HE staining. Molecular docking and molecular dynamics analyses were employed to evaluate the binding stability between the compound 10b and mGluR5. RESULTS: Compared to the normal control mice, the SPS mice exhibited obvious PTSD-like behaviors with increased hippocampal expressions of mGluR5 and p-ERK proteins and decreased SGK1 protein expression. Compound 10b significantly ameliorated behavioral abnormalities in SPS mice, inhibited mGluR5 expression, and reversed the dysregulation of p-ERK and SGK1. No obvious liver or kidney toxicity was observed after 10b treatment. Molecular docking and dynamics studies demonstrated a stable interaction between 10b and mGluR5. CONCLUSIONS The compound 10b ameliorates PTSD-like behaviors induced by SPS in mice possibly by inhibiting mGluR5 expression to modulate the ERK1/2-SGK1 signaling pathway.
Animals ; Stress Disorders, Post-Traumatic/drug therapy* ; Receptor, Metabotropic Glutamate 5/metabolism* ; Mice, Inbred C57BL ; Mice ; Protein Serine-Threonine Kinases/metabolism* ; Pyrimidines/pharmacology* ; Immediate-Early Proteins/metabolism* ; Signal Transduction/drug effects* ; MAP Kinase Signaling System/drug effects* ; Male ; Molecular Docking Simulation ; Hippocampus/metabolism*