iem-1460 and Disease-Models--Animal

Many antiseizure drugs (ASDs) act on voltage-dependent sodium channels, and the molecular basis of these effects is well established. In contrast, how ASDs act on the level of neuronal networks is much less understood.. In the present study, we determined the effects of eslicarbazepine (S-Lic) on different types of inhibitory neurons, as well as inhibitory motifs. Experiments were performed in hippocampal slices from both sham-control and chronically epileptic pilocarpine-treated rats.. We found that S-Lic causes an unexpected reduction of feed-forward inhibition in the CA1 region at high concentrations (300 µM), but not at lower concentrations (100 µM). Concurrently, 300 but not 100 μM S-Lic significantly reduced maximal firing rates in putative feed-forward interneurons located in the CA1 stratum radiatum of sham-control and epileptic animals. In contrast, feedback inhibition was not inhibited by S-Lic. Instead, application of S-Lic, in contrast to previous data for other drugs like carbamazepine (CBZ), resulted in a lasting potentiation of feedback inhibitory post-synaptic currents (IPSCs) only in epileptic and not in sham-control animals, which persisted after washout of S-Lic. We hypothesized that this plasticity of inhibition might rely on anti-Hebbian potentiation of excitatory feedback inputs onto oriens-lacunosum moleculare (OLM) interneurons, which is dependent on Ca. These results suggest that S-Lic affects inhibitory circuits in the CA1 hippocampal region in unexpected ways. In addition, ASD actions may not be sufficiently explained by acute effects on their target channels, rather, it may be necessary to take plasticity of inhibitory circuits into account.

Topics: Adamantane; Animals; Anticonvulsants; CA1 Region, Hippocampal; Calcium; Dibenzazepines; Disease Models, Animal; Dose-Response Relationship, Drug; Epilepsy; Feedback, Physiological; Hippocampus; Inhibitory Postsynaptic Potentials; Interneurons; Long-Term Potentiation; Muscarinic Agonists; Neural Inhibition; Neuronal Plasticity; Neurons; Pilocarpine; Pyramidal Cells; Rats; Receptors, AMPA

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Chronic stress is a precipitating factor for disorders including depression. The basolateral amygdala (BLA) is a critical substrate that interconnects with stress-modulated neural networks to generate emotion- and mood-related behaviors. The current study shows that 3 h per day of restraint stress for 14 days caused mice to exhibit long-term depressive behaviors, manifested by disrupted sociality and despair levels, which were rescued by fluoxetine. These behavioral changes corresponded with morphological and molecular changes in BLA neurons, including chronic stress-elicited increases in arborization, dendritic length, and spine density of BLA principal neurons. At the molecular level, calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (CP-AMPARs) within the synaptosome exhibited an increased GluR1:GluR2 subunit ratio. We also observed increased GluR1 phosphorylation at Ser 845 and enhanced cyclic AMP-dependent protein kinase (PKA) activity in the BLA. These molecular changes reverted to the basal state post-treatment with fluoxetine. The expression of synaptophysin (SYP) and postsynaptic density protein 95 (PSD-95) at BLA neuronal synapses was also enhanced by chronic stress, which was reversed post-treatment. Finally, chronic stress-provoked depressive behavior was overcome by local blockage of CP-AMPARs in the BLA via stereotaxic injection (IEM-1460). Chronic stress-elicited depressive behavior may be due to hypertrophy of BLA neuronal dendrites and increased of PKA-dependent CP-AMPAR levels in BLA neurons. Furthermore, fluoxetine can reverse chronic stress-triggered cytoarchitectural and functional changes of BLA neurons. These findings provide insights into depression-linked structural and functional changes in BLA neurons.

Topics: Adamantane; Animals; Antidepressive Agents; Basolateral Nuclear Complex; Cyclic AMP-Dependent Protein Kinases; Depression; Disease Models, Animal; Disks Large Homolog 4 Protein; Fluoxetine; Gene Expression Regulation; Guanylate Kinases; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Neurons; Phosphorylation; Post-Synaptic Density; Receptors, AMPA; Signal Transduction; Stress, Psychological; Synapses; Synaptophysin; Synaptosomes

AMPA receptors lacking GluA2 subunit are widely distributed in developing brain. IEM1460 as a specific antagonist of these receptors might be a potential age-specific anticonvulsant. Possible anticonvulsant action was assessed in two models of epileptic seizures: pentylenetetrazol (PTZ) - induced convulsions and cortical afterdischarges elicited in 12-, 18- and 25-day-old rats. IEM1460 was administered intraperitoneally in doses of 3, 10 and 20mg/kg. Pretreatment with IEM1460 at the dose of 20mg/kg resulted in delayed onset of PTZ-induced minimal clonic seizures in all age groups. PTZ-induced generalized tonic-clonic seizures were suppressed in 18- and 25-day-old rats by 10 and 20mg/kg doses of IEM1460. Duration of cortical afterdischarges progressively increased with repeated stimulations in control 12-day-old rats. The IEM1460 dose of 10mg/kg fully blocked this prolongation and the 20-mg/kg dose partly suppressed it. Administration of IEM1460 had moderate proconvulsant effect on 18- and 25-day-old animals - afterdischarges were prolonged with repeated stimulations. The duration of cortical epileptic afterdischarges in adult (80-day-old) animals was not affected by IEM1460. Effects of IEM1460 are dependent on the model of seizures used, their ictogenic structures and developmental changes in subunit composition of AMPA receptors.

Topics: Adamantane; Animals; Anticonvulsants; Brain; Disease Models, Animal; Dose-Response Relationship, Drug; Electrodes, Implanted; Electroencephalography; Male; Pentylenetetrazole; Rats, Wistar; Receptors, AMPA; Seizures

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders and it causes long-lasting visceral pain and discomfort. AMPA receptor mediated long-term potentiation (LTP) has been shown to play a critical role in animal models of neuropathic and inflammatory pain. No report is available for central changes in the ACC of mice with chronic visceral pain.. In this study, we used integrative methods to investigate potential central plastic changes in the anterior cingulate cortex (ACC) of a visceral pain mouse model induced by intracolonic injection of zymosan. We found that visceral pain induced an increased expression of AMPA receptors (at the post synapses) in the ACC via an enhanced trafficking of the AMPA receptors to the membrane. Both GluA1 and GluA2/3 subunits were significantly increased. Supporting biochemical changes, excitatory synaptic transmission in the ACC were also significantly enhanced. Microinjection of AMPA receptor inhibitor IEM1460 into the ACC inhibited visceral and spontaneous pain behaviors. Furthermore, we found that the phosphorylation of GluA1 at the Ser845 site was increased, suggesting that GluA1 phosphorylation may contribute to AMPA receptor trafficking. Using genetically knockout mice lacking calcium-calmodulin stimulated adenylyl cyclase subtype 1 (AC1), we found that AMPA receptor phosphorylation and its membrane trafficking induced by zymosan injection were completely blocked.. Our results provide direct evidence for cortical AMPA receptors to contribute to zymosan-induced visceral and spontaneous pain and inhibition of AC1 activity may help to reduce chronic visceral pain.

Topics: Adamantane; Adenylyl Cyclases; Animals; Behavior, Animal; Calcium; Cell Membrane; Chronic Pain; Disease Models, Animal; Excitatory Postsynaptic Potentials; Gene Deletion; Glutamates; Gyrus Cinguli; Injections; Irritable Bowel Syndrome; Mice; Models, Biological; Phosphorylation; Phosphoserine; Protein Transport; Receptors, AMPA; Synaptic Transmission; Time Factors; Up-Regulation; Visceral Pain; Zymosan

Whereas kainate (KA)-induced neurodegeneration has been intensively investigated, the contribution of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in neuronal Ca2+ overload ([Ca2+]i) is still controversial. Using Ca2+ imaging and patch-clamp techniques, we found different types of Ca2+ entry in cultured rat cortical neurons. The presence of Ca2+ in the extracellular solution was required to generate the [Ca2+]i responses to 30 μM N-methyl-d-aspartate (NMDA) or KA. The dynamics of NMDA-induced [Ca2+]i responses were fast, while KA-induced responses developed slower reaching high [Ca2+]i. Ifenprodil, a specific inhibitor of the GluN2B subunit of NMDARs, reduced NMDA-induced [Ca2+]i responses suggesting expression of GluN1/GluN2B receptors. Using IEM-1460, a selective blocker of Ca(2+)-permeable GluA2-subunit lacking AMPARs, we found three neuronal responses to KA: (i) IEM-1460 resistant neurons which are similar to pyramidal neurons expressing Ca(2+)-impermeable GluA2-rich AMPARs; (ii) Neurons exhibiting nearly complete block of both KA-induced currents and [Ca2+]i signals by IEM-1460 may represent interneurons expressing GluA2-lacking AMPARs and (iii) neurons with moderate sensitivity to IEM-1460. Ouabain at 1 nM prevented the neuronal Ca2+ overload induced by KA. The data suggest, that cultured rat cortical neurons maintain functional phenotypes of the adult brain cortex, and demonstrate the key contribution of the Na/K-ATPase in neuroprotection against KA excitotoxicity.

Topics: Adamantane; Animals; Calcium; Calcium Signaling; Cells, Cultured; Cerebral Cortex; Disease Models, Animal; Down-Regulation; Enzyme Inhibitors; Female; In Vitro Techniques; Kainic Acid; Nerve Degeneration; Neurons; Ouabain; Patch-Clamp Techniques; Piperidines; Pregnancy; Rats; Rats, Wistar; Receptors, AMPA

Abnormal corticostriatal plasticity is a key mechanism of L-DOPA-induced dyskinesia (LID) in Parkinson's disease (PD). Antagonists at glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, such as IEM 1460, reduce induction and expression of dyskinesia in rat and non-human primate models of PD. AMPA receptor function is regulated by post-transcriptional splicing of subunit mRNA to produce flip and flop isoforms, which may therefore influence corticostriatal plasticity. The aim of this work was to evaluate alterations in alternative splicing of striatal AMPA receptor subunits in the unilateral 6-hydroxydopamine (6-OHDA)-lesioned rat model of LID and PD. Male Sprague-Dawley rats received 12.5 μg 6-OHDA injections into the right medial forebrain bundle. In experiment 1, to assess acute dyskinesia, rats received L-DOPA/benserazide (6/15 mg/kg, i.p.) or vehicle for 21 days. In experiment 2, to assess dyskinesia priming, rats received vehicle, L-DOPA+vehicle or L-DOPA+IEM 1460 (3 mg/kg, i.p.) for 21 days. Animals were humanely killed 1h following final treatment in experiment 1, and 48 h following final treatment in experiment 2. Coronal sections of rostral striatum were processed for in situ hybridisation histochemistry, using oligonucleotide probes specific for the GluR1 and GluR2 subunits and their flip and flop isoforms. L-DOPA treatment increased GluR2-flip mRNA expression in the lesioned striatum of both groups; this was blocked by the Ca(2+)-permeable AMPA receptor antagonist IEM 1460. GluR1-flip expression was increased after 48 h drug washout but not in acute LID. There were no changes in expression of flop isoforms. Alternative splicing of AMPAR subunits contributes to abnormal striatal plasticity in the induction and expression of LID. Increases in GluR2-flip expression depend on activation of Ca(2+)-permeable AMPA receptors, which are a potential target of anti-dyskinetic therapies.

Topics: Adamantane; Alternative Splicing; Animals; Antiparkinson Agents; Cocaine; Corpus Striatum; Disease Models, Animal; Dose-Response Relationship, Drug; Dyskinesia, Drug-Induced; Excitatory Amino Acid Antagonists; Gene Expression Regulation; Iodine Isotopes; Levodopa; Male; Motor Activity; Oxidopamine; Parkinson Disease; Rats; Rats, Sprague-Dawley; Receptors, AMPA; RNA, Messenger; Sympatholytics

Fast-spiking interneurons (FSIs) can exert powerful control over striatal output, and deficits in this cell population have been observed in human patients with Tourette syndrome and rodent models of dystonia. However, a direct experimental test of striatal FSI involvement in motor control has never been performed. We applied a novel pharmacological approach to examine the behavioral consequences of selective FSI suppression in mouse striatum. IEM-1460, an inhibitor of GluA2-lacking AMPARs, selectively blocked synaptic excitation of FSIs but not striatal projection neurons. Infusion of IEM-1460 into the sensorimotor striatum reduced the firing rate of FSIs but not other cell populations, and elicited robust dystonia-like impairments. These results provide direct evidence that hypofunction of striatal FSIs can produce movement abnormalities, and suggest that they may represent a novel therapeutic target for the treatment of hyperkinetic movement disorders.

Topics: Action Potentials; Adamantane; Analysis of Variance; Animals; Area Under Curve; Cholinergic Antagonists; Corpus Striatum; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Dyskinesias; Excitatory Amino Acid Antagonists; Excitatory Postsynaptic Potentials; Female; Functional Laterality; Green Fluorescent Proteins; Interneurons; LIM-Homeodomain Proteins; Male; Mecamylamine; Mice; Mice, Transgenic; N-Methylaspartate; Nerve Tissue Proteins; Scopolamine; Transcription Factors