scholarly journals DDRE-27. IDH MUTATED GLIOMAS PROMOTE EPILEPTOGENESIS VIA D-2-HYDROXYGLUTARATE DEPENDENT MTOR HYPERACTIVATION

2020 ◽  
Vol 3 (Supplement_1) ◽  
pp. i12-i12
Author(s):  
Armin Mortazavi ◽  
Islam Fayed ◽  
Muzna Bachani ◽  
Tyrone Dowdy ◽  
Joseph Steiner ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Neuronal Excitability ◽  
Neurological Diseases ◽  
Mtor Signaling ◽  
Neuronal Firing ◽  
Metabolic Reprogramming ◽  
Neuronal Cultures ◽  
Low Grade ◽  
Idh Mutations

Abstract INTRODUCTION Epileptic seizures in patients with low-grade, isocitrate dehydrogenase (IDH) mutated gliomas reach 90%, a major source of morbidity for these patients. Albeit there are multiple features that contribute to tumor related epileptogenesis, IDH mutations are determined to be an independent factor, although the pathogenesis remains poorly understood. We demonstrate IDH-mutated tumors promote epileptogenesis through D-2-hydroxyglutarate (D-2-HG) dependent mTOR hyperactivation and metabolic reprogramming. METHODS Human epileptic and nonepileptic cortex were identified via subdural electrodes in patients with IDH-mutated gliomas (n=5). An in vitro rat cortical neuronal model on microelectrode arrays were utilized to investigate the role of D-2-HG on neuronal excitability. mTOR and lysine demethylase (KDM) modulators were applied to elucidate the epileptogenic mechanism. Tetrodotoxin was utilized to evaluate the contribution of neuronal activity to mTOR signaling and metabolism. mTOR signaling was evaluated through western blot analysis and multiplex immunofluorescence. Metabolic function were analyzed via Seahorse assays and metabolomic analysis. RESULTS D-2-HG increased normalized bursting rate in the neuronal cultures (p<0.0001). Inhibition of mTOR with rapamycin corrected bursting levels to control levels. Furthermore, D-2-HG induced mTOR hyperactivation, independent of bursting activity, which correlated with upregulation of mTOR signaling in human epileptic tissue. KDM inhibition resulted in mTOR hyperactivation and neuronal hyperexcitability, which we demonstrated with D-2-HG, succinate, and PFI-90, a small molecule KDM inhibitor. Epileptic cortex and D-2-HG-treated neurons, have distinct metabolisms independent of neuronal activity compared to peritumoral nonepileptic cortex and control, respectively. CONCLUSION We demonstrate IDH-mutated gliomas promote epileptogenesis through a D-2-HG dependent mTOR hyperactivation via KDM inhibition, a putative mechanism and potential therapeutic targets. Furthermore, we argue mTOR hyperactivation results in metabolic reprogramming, independent of neuronal firing, which may contribute to epileptogenesis, a heretofore unrecognized aspect of pathologic mTOR signaling in neurological diseases.

scholarly journals OTME-4. IDH mutated gliomas promote epileptogenesis via D-2-hydroxyglutarate dependent mTOR hyperactivation

2021 ◽  
Vol 3 (Supplement_2) ◽  
pp. ii14-ii14
Author(s):  
Armin Mortazavi ◽  
Islam Fayed ◽  
Muzna Bachani ◽  
Dragan Maric ◽  
Tyrone Dowdy ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Mtor Signaling ◽  
Metabolic Reprogramming ◽  
Low Grade ◽  
Mtor Inhibition ◽  
Low Grade Gliomas ◽  
Idh Mutations ◽  
Promising Treatment ◽  
Spiking Activity

Abstract Epilepsy in the context of brain tumors provides a great burden in these patients, yet mechanisms underlying this process are poorly understood. It has been demonstrated that isocitrate dehydrogenase (IDH) mutations are an independent factor in epileptogenesis in patients with low grade gliomas. Here, using electrographically sorted human cortical tissue from patients with IDH mutated tumor related epilepsy and in vitro cortical cultures, we explore a metabolic paradigm and its impact on increased neuronal excitability. We hypothesize the IDH mutation promotes epileptogenesis through its neomorphic activity of D-2-hydroxyglutarate (D-2-HG) production in turn interrupts surrounding normal neuronal circuitry potentially through metabolic perturbations. We demonstrate D-2-HG increases neuronal spiking activity, promotes distinct metabolic profiles independent of neuronal spiking activity, as well as increases neuronal mTOR signaling, which is reflected in human peritumoral epileptic cortex. Increased mTOR signaling is sufficient to upregulate neuronal spiking activity and, reciprocally, inhibition of mTOR corrects neuronal activity as well as partially corrects metabolic reprogramming. Our results suggest D-2-HG can lead to mTOR activation within the peritumoral neurons, thereby suggesting an additional possible mechanism of epileptogenesis in patients with IDH mutated low grade gliomas. Ultimately, our results raise the possibility of mTOR inhibition may be a promising treatment of seizures in patients with these tumors.

NCMP-07. IDH MUTANT GLIOMAS PROMOTE EPILEPTOGENESIS VIA D-2-HYDROXYGLUTARATE DEPENDENT MTOR HYPER-ACTIVATION

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi148-vi148
Author(s):  
Armin Mortazavi ◽  
Islam Fayed ◽  
Muzna Bachani ◽  
Tyrone Dowdy ◽  
Jahandar Jahanipour ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Mtor Signaling ◽  
Low Grade ◽  
Mtor Inhibition ◽  
Multiple Features ◽  
Low Grade Gliomas ◽  
Idh Mutations ◽  
Complementary Study

Abstract Uncontrolled seizures in patients with low grade gliomas have a significant impact on quality of life and morbidity, yet the mechanisms through which these tumors cause seizures remain unknown. Albeit there are multiple features that contribute to tumor related epileptogenesis, IDH mutations are determined to be an independent factor, although the pathogenesis remains poorly understood. Here, we hypothesize that the active metabolite D-2-hydroxyglutarate (D-2-HG) produced by the IDH-mutant enzyme leads to metabolic disruptions in surrounding cortical neurons that consequently promote seizures. We use a complementary study of in vitro cortical cultures and electrographically sorted human cortical tissue from patients (n=5) with IDH-mutant gliomas to test this hypothesis. We demonstrate that D-2-HG leads to increased neuronal spiking activity (p< 0.0001) and promotes a distinct metabolic profile in surrounding neurons and upregulation of mTOR signaling (p< 0.0001), which is consistent in human epileptic cortex compared to peritumoral nonepileptic cortex. Furthermore, increases in neuronal activity are induced by mTOR activation and reversed with mTOR inhibition. Together, our data suggest that metabolic disruptions and mTOR signaling upregulation in the surrounding cortex due to D-2-HG may be a driving event for epileptogenesis in patients with IDH-mutant low grade gliomas.

scholarly journals Astrocytic and Neuronal Apolipoprotein E Isoforms Differentially Affect Neuronal Excitability

2021 ◽  
Vol 15 ◽  
Author(s):  
Sabine C. Konings ◽  
Laura Torres-Garcia ◽  
Isak Martinsson ◽  
Gunnar K. Gouras
Keyword(s):  
Neuronal Activity ◽  
Neuronal Excitability ◽  
Specific Effect ◽  
Synaptic Function ◽  
Neuronal Firing ◽  
Wild Type ◽  
Neuron Models ◽  
Apoe Isoforms ◽  
Cellular Source

Synaptic changes and neuronal network dysfunction are among the earliest changes in Alzheimer’s disease (AD). Apolipoprotein E4 (ApoE4), the major genetic risk factor in AD, has been shown to be present at synapses and to induce hyperexcitability in mouse knock-in brain regions vulnerable to AD. ApoE in the brain is mainly generated by astrocytes, however, neurons can also produce ApoE under stress conditions such as aging. The potential synaptic function(s) of ApoE and whether the cellular source of ApoE might affect neuronal excitability remain poorly understood. Therefore, the aim of this study was to elucidate the synaptic localization and effects on neuronal activity of the two main human ApoE isoforms from different cellular sources in control and AD-like in vitro cultured neuron models. In this study ApoE is seen to localize at or near to synaptic terminals. Additionally, we detected a cellular source-specific effect of ApoE isoforms on neuronal activity measured by live cell Ca2+ imaging. Neuronal activity increases after acute but not long-term administration of ApoE4 astrocyte medium. In contrast, ApoE expressed by neurons appears to induce the highest neuronal firing rate in the presence of ApoE3, rather than ApoE4. Moreover, increased neuronal activity in APP/PS1 AD transgenic compared to wild-type neurons is seen in the absence of astrocytic ApoE and the presence of astrocytic ApoE4, but not ApoE3. In summary, ApoE can target synapses and differentially induce changes in neuronal activity depending on whether ApoE is produced by astrocytes or neurons. Astrocytic ApoE induces the strongest neuronal firing with ApoE4, while the most active and efficient neuronal activity induced by neuronal ApoE is caused by ApoE3. ApoE isoforms also differentially affect neuronal activity in AD transgenic compared to wild-type neurons.

Trigeminal satellite cells modulate neuronal responses to triptans: relevance for migraine therapy

2011 ◽  
Vol 7 (2-4) ◽  
pp. 109-116 ◽  
Author(s):  
Alice de Corato ◽  
Alessandro Capuano ◽  
Diego Currò ◽  
Giuseppe Tringali ◽  
Pierluigi Navarra ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Primary Cultures ◽  
Neuronal Cultures ◽  
Neuronal Responses ◽  
Satellite Glial Cells ◽  
Cgrp Release ◽  
Trigeminal Neurons ◽  
Trigeminal Neuron ◽  
Anti Migraine Drug

In the present paper, we have further developed an in vitro model to study neuronal–glial interaction at trigeminal level by characterizing the effects of conditioned medium (CM) collected from activated primary cultures of satellite glial cells (SGCs) on calcitonin gene-related peptide (CGRP) release from rat trigeminal neurons. Moreover, we investigated whether such release is inhibited by a clinically relevant anti-migraine drug, sumatriptan. CM effects were tested on trigeminal neuronal cultures in different conditions of activation and at different time points. Long-term exposures of trigeminal neurons to CM increased directly neuronal CGRP release, which was further enhanced by the exposure to capsaicin. In this framework, the anti-migraine drug sumatriptan was able to inhibit the evoked CGRP release from naïve trigeminal neuron cultures, as well as from trigeminal cultures pre-exposed for 30 min to CM. On the contrary, sumatriptan failed to inhibit evoked CGRP release from trigeminal neurons after prolonged (4 and 8 h) pre-exposures to CM. These findings were confirmed in co-culture experiments (neurons and SGCs), where activation of SGCs or a bradykinin priming were used. Our data demonstrate that SGCs activation could influence neuronal excitability, and that this event affects the neuronal responses to triptans.

scholarly journals FGCaMP7, an Improved Version of Fungi-Based Ratiometric Calcium Indicator for In Vivo Visualization of Neuronal Activity

2020 ◽  
Vol 21 (8) ◽  
pp. 3012 ◽  
Author(s):  
Natalia V. Barykina ◽  
Vladimir P. Sotskov ◽  
Anna M. Gruzdeva ◽  
You Kure Wu ◽  
Ruben Portugues ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Dynamic Range ◽  
Fluorescent Proteins ◽  
Confocal Imaging ◽  
Ion Concentration ◽  
Neuronal Cultures ◽  
Two Phase ◽  
Intracellular Environment

Genetically encoded calcium indicators (GECIs) have become a widespread tool for the visualization of neuronal activity. As compared to popular GCaMP GECIs, the FGCaMP indicator benefits from calmodulin and M13-peptide from the fungi Aspergillus niger and Aspergillus fumigatus, which prevent its interaction with the intracellular environment. However, FGCaMP exhibits a two-phase fluorescence behavior with the variation of calcium ion concentration, has moderate sensitivity in neurons (as compared to the GCaMP6s indicator), and has not been fully characterized in vitro and in vivo. To address these limitations, we developed an enhanced version of FGCaMP, called FGCaMP7. FGCaMP7 preserves the ratiometric phenotype of FGCaMP, with a 3.1-fold larger ratiometric dynamic range in vitro. FGCaMP7 demonstrates 2.7- and 8.7-fold greater photostability compared to mEGFP and mTagBFP2 fluorescent proteins in vitro, respectively. The ratiometric response of FGCaMP7 is 1.6- and 1.4-fold higher, compared to the intensiometric response of GCaMP6s, in non-stimulated and stimulated neuronal cultures, respectively. We reveal the inertness of FGCaMP7 to the intracellular environment of HeLa cells using its truncated version with a deleted M13-like peptide; in contrast to the similarly truncated variant of GCaMP6s. We characterize the crystal structure of the parental FGCaMP indicator. Finally, we test the in vivo performance of FGCaMP7 in mouse brain using a two-photon microscope and an NVista miniscope; and in zebrafish using two-color ratiometric confocal imaging.

scholarly journals Ps in the (Channel) Pod Are Not Alike …

2007 ◽  
Vol 7 (5) ◽  
pp. 136-137
Author(s):  
Yoav Noam ◽  
Tallie Z. Baram
Keyword(s):  
Neuronal Activity ◽  
Hippocampal Neurons ◽  
Neuronal Excitability ◽  
Phosphorylation Sites ◽  
Voltage Dependent ◽  
Activity Dependent ◽  
Stimulation Of ◽  
Cultured Hippocampal Neurons

Bidirectional Activity-Dependent Regulation of Neuronal Ion Channel Phosphorylation. Misonou H, Menegola M, Mohapatra DP, Guy LK, Park KS, Trimmer JS. J Neurosci 2006;26(52):13505–13514. Activity-dependent dephosphorylation of neuronal Kv2.1 channels yields hyperpolarizing shifts in their voltage-dependent activation and homoeostatic suppression of neuronal excitability. We recently identified 16 phosphorylation sites that modulate Kv2.1 function. Here, we show that in mammalian neurons, compared with other regulated sites, such as serine (S)563, phosphorylation at S603 is supersensitive to calcineurin-mediated dephosphorylation in response to kainate-induced seizures in vivo, and brief glutamate stimulation of cultured hippocampal neurons. In vitro calcineurin digestion shows that supersensitivity of S603 dephosphorylation is an inherent property of Kv2.1. Conversely, suppression of neuronal activity by anesthetic in vivo causes hyperphosphorylation at S603 but not S563. Distinct regulation of individual phosphorylation sites allows for graded and bidirectional homeostatic regulation of Kv2.1 function. S603 phosphorylation represents a sensitive bidirectional biosensor of neuronal activity.

scholarly journals ubtor Mutation Causes Motor Hyperactivity by Activating mTOR Signaling in Zebrafish

2021 ◽  
Author(s):  
Tiantian Wang ◽  
Mingshan Zhou ◽  
Quan Zhang ◽  
Cuizhen Zhang ◽  
Gang Peng
Keyword(s):  
Neuronal Activity ◽  
Neurological Diseases ◽  
Epileptic Encephalopathy ◽  
Mtor Signaling ◽  
Negative Regulator ◽  
Zebrafish Embryos ◽  
Zebrafish Model ◽  
Spinal Interneurons ◽  
Motor Hyperactivity ◽  
Increased Sensitivity

AbstractMechanistic target of rapamycin (mTOR) signaling governs important physiological and pathological processes key to cellular life. Loss of mTOR negative regulators and subsequent over-activation of mTOR signaling are major causes underlying epileptic encephalopathy. Our previous studies showed that UBTOR/KIAA1024/MINAR1 acts as a negative regulator of mTOR signaling, but whether UBTOR plays a role in neurological diseases remains largely unknown. We therefore examined a zebrafish model and found that ubtor disruption caused increased spontaneous embryonic movement and neuronal activity in spinal interneurons, as well as the expected hyperactivation of mTOR signaling in early zebrafish embryos. In addition, mutant ubtor larvae showed increased sensitivity to the convulsant pentylenetetrazol, and both the motor activity and the neuronal activity were up-regulated. These phenotypic abnormalities in zebrafish embryos and larvae were rescued by treatment with the mTORC1 inhibitor rapamycin. Taken together, our findings show that ubtor regulates motor hyperactivity and epilepsy-like behaviors by elevating neuronal activity and activating mTOR signaling.

scholarly journals Interleukin-1β Protects Neurons against Oxidant-Induced Injury via the Promotion of Astrocyte Glutathione Production

Antioxidants ◽  
2018 ◽  
Vol 7 (8) ◽  
pp. 100 ◽  
Author(s):  
Twinkle Chowdhury ◽  
Matthew Allen ◽  
Trista Thorn ◽  
Yan He ◽  
Sandra Hewett
Keyword(s):  
Neurological Diseases ◽  
Oxidant Stress ◽  
Cortical Cell ◽  
Mixed Cultures ◽  
Interleukin 1Β ◽  
Neuronal Cultures ◽  
Dependent Manner ◽  
Protective Effects ◽  
Oxidant Injury

Interleukin-1β (IL-1β), a key cytokine that drives neuroinflammation in the Central Nervous System (CNS), is enhanced in many neurological diseases/disorders. Although IL-1β contributes to and/or sustains pathophysiological processes in the CNS, we recently demonstrated that IL-1β can protect cortical astrocytes from oxidant injury in a glutathione (GSH)-dependent manner. To test whether IL-1β could similarly protect neurons against oxidant stress, near pure neuronal cultures or mixed cortical cell cultures containing neurons and astrocytes were exposed to the organic peroxide, tert-butyl hydroperoxide (t-BOOH), following treatment with IL-1β or its vehicle. Neurons and astrocytes in mixed cultures, but not pure neurons, were significantly protected from the toxicity of t-BOOH following treatment with IL-1β in association with enhanced GSH production/release. IL-1β failed to increase the GSH levels or to provide protection against t-BOOH toxicity in chimeric mixed cultures consisting of IL-1R1+/+ neurons plated on top of IL-1R1−/− astrocytes. The attenuation of GSH release via block of multidrug resistance-associated protein 1 (MRP1) transport also abrogated the protective effect of IL-1β. These protective effects were not strictly an in vitro phenomenon as we found an increased striatal vulnerability to 3-nitropropionic acid-mediated oxidative stress in IL-1R1 null mice. Overall, our data indicate that IL-1β protects neurons against oxidant injury and that this likely occurs in a non-cell-autonomous manner that relies on an increase in astrocyte GSH production and release.

scholarly journals Direct Evaluation of L-DOPA Actions on Neuronal Activity of Parkinsonian TissueIn Vitro

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Víctor Plata ◽  
Mariana Duhne ◽  
Jesús E. Pérez-Ortega ◽  
Janet Barroso-Flores ◽  
Elvira Galarraga ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neuronal Activity ◽  
Calcium Imaging ◽  
Neuronal Excitability ◽  
Imaging Techniques ◽  
Direct Evaluation ◽  
Disease Evolution

Physiological and biochemical experimentsin vivoandin vitrohave explored striatal receptor signaling and neuronal excitability to posit pathophysiological models of Parkinson's disease. However, when therapeutic approaches, such as dopamine agonists, need to be evaluated, behavioral tests using animal models of Parkinson's disease are employed. To our knowledge, recordings of population neuronal activityin vitroto assess anti-Parkinsonian drugs and the correlation of circuit dynamics with disease state have only recently been attempted. We have shown that Parkinsonian pathological activity of neuronal striatal circuits can be characterized inin vitrocerebral tissue. Here, we show that calcium imaging techniques, capable of recording dozens of neurons simultaneously with single-cell resolution, can be extended to assess the action of therapeutic drugs. We used L-DOPA as a prototypical anti-Parkinsonian drug to show the efficiency of this proposed bioassay. In a rodent model of early Parkinson's disease, Parkinsonian neuronal activity can be returned to control levels by the bath addition of L-DOPA in a reversible way. This result raises the possibility to use calcium imaging techniques to measure, quantitatively, the actions of anti-Parkinsonian drugs over time and to obtain correlations with disease evolution and behavior.

Do the suprachiasmatic nuclei oscillate in old rats as they do in young ones?

1993 ◽  
Vol 265 (5) ◽  
pp. R1216-R1222 ◽  
Author(s):  
E. Satinoff ◽  
H. Li ◽  
T. K. Tcheng ◽  
C. Liu ◽  
A. J. McArthur ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Brain Slices ◽  
Neuronal Firing ◽  
Suprachiasmatic Nuclei ◽  
Firing Rates ◽  
Behavioral Rhythms ◽  
Behavioral Rhythm ◽  
Old Rats ◽  
The Brain

The basis of the decline in circadian rhythms with aging was addressed by comparing the patterns of three behavioral rhythms in young and old rats with the in vitro rhythm of neuronal activity in the suprachiasmatic nuclei (SCN), the primary circadian pacemaker. In some old rats, rhythms of body temperature, drinking, and activity retained significant 24-h periodicities in entraining light-dark cycles; in others, one or two of the rhythms became aperiodic. When these rats were 23-27.5 mo old they were killed, and single-unit firing rates in SCN brain slices were recorded continuously for 30 h. There was significant damping of mean peak neuronal firing rates in old rats compared with young. SCN neuronal activities were analyzed with reference to previous entrained behavioral rhythm patterns of individual rats as well. Neuronal activity from rats with prior aperiodic behavioral rhythms was erratic, as expected. Neuronal activity from rats that were still maintaining significant 24-h behavioral rhythmicity at the time they were killed was erratic in most cases but normally rhythmic in others. Thus there was no more congruence between the behavioral rhythms and the brain slice rhythms than there was among the behavioral rhythms alone. These results, the first to demonstrate aberrant SCN firing patterns and a decrease in amplitude in old rats, imply that aging could either disrupt coupling between SCN pacemaker cells or their output, or cause deterioration of the pacemaking properties of SCN cells.

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