Sleep deprivation decreases neuronal excitability and responsiveness in rats both in vivo and ex vivo

2018 ◽  
Vol 137 ◽  
pp. 166-177 ◽  
Author(s):  
Sándor Borbély ◽  
Ildikó Világi ◽  
Zsófia Haraszti ◽  
Örs Szalontai ◽  
Tünde Hajnik ◽  
...  
Keyword(s):  
Sleep Deprivation ◽  
Neuronal Excitability ◽  
Ex Vivo

scholarly journals Non-synaptic Cell-Autonomous Mechanisms Underlie Neuronal Hyperactivity in a Genetic Model of PIK3CA-Driven Intractable Epilepsy

2021 ◽  
Vol 14 ◽  
Author(s):  
Achira Roy ◽  
Victor Z. Han ◽  
Angela M. Bard ◽  
Devin T. Wehle ◽  
Stephen E. P. Smith ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Pyramidal Neurons ◽  
Genetic Model ◽  
Ex Vivo ◽  
Significant Proportion ◽  
Intractable Epilepsy ◽  
Therapeutic Interventions ◽  
Hippocampal Pyramidal Neurons ◽  
Phosphoinositide 3 Kinase

Patients harboring mutations in the PI3K-AKT-MTOR pathway-encoding genes often develop a spectrum of neurodevelopmental disorders including epilepsy. A significant proportion remains unresponsive to conventional anti-seizure medications. Understanding mutation-specific pathophysiology is thus critical for molecularly targeted therapies. We previously determined that mouse models expressing a patient-related activating mutation in PIK3CA, encoding the p110α catalytic subunit of phosphoinositide-3-kinase (PI3K), are epileptic and acutely treatable by PI3K inhibition, irrespective of dysmorphology. Here we report the physiological mechanisms underlying this dysregulated neuronal excitability. In vivo, we demonstrate epileptiform events in the Pik3ca mutant hippocampus. By ex vivo analyses, we show that Pik3ca-driven hyperactivation of hippocampal pyramidal neurons is mediated by changes in multiple non-synaptic, cell-intrinsic properties. Finally, we report that acute inhibition of PI3K or AKT, but not MTOR activity, suppresses the intrinsic hyperactivity of the mutant neurons. These acute mechanisms are distinct from those causing neuronal hyperactivity in other AKT-MTOR epileptic models and define parameters to facilitate the development of new molecularly rational therapeutic interventions for intractable epilepsy.

scholarly journals Vasopressin acts as a synapse organizer in limbic regions by boosting PSD95 and GluA1 expression

2020 ◽  
Author(s):  
Limei Zhang ◽  
Teresa Padilla-Flores ◽  
Vito S. Hernández ◽  
Elba Campos-Lira ◽  
Mario A. Zetter ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Pyramidal Neurons ◽  
Ex Vivo ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Synaptic Proteins ◽  
Scaffolding Protein ◽  
Synaptic Organization ◽  
Limbic Regions

AbstractHypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behavior and fear responses. The purpose of the present work is to characterize the dynamics of expression changes of two postsynaptic density (PSD) proteins, AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), which are known to be key determinants for synaptic strength, in response to in vivo and ex vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP, metabolites and some signaling pathway inhibitors. Both long term water deprivation in vivo, which powerfully upregulates AVPMNN activity, and exogenous APV application ex vivo in brain slices, increased GluA1 and PSD95 expression and enhanced neuronal excitability in ventral hippocampal CA1 pyramidal neurons. Involvement of PI3k signaling in AVP-dependent plasticity is suggested by blockade of both AVP-induced protein up-regulation and enhanced neuronal excitability by the PI3k blocker wortmannin in hippocampal slices. We interpret these results as part of vasopressin’s central effects on synaptic organization in limbic regions modulating the strength of a specific set of synaptic proteins in hypothalamic-limbic circuits.Supported by grantsUNAM-DGAPA-PAPIIT-IN216918 & CONACYT-CB-238744.

scholarly journals In vivo CRISPRa decreases seizures and rescues cognitive deficits in a rodent model of epilepsy

2018 ◽  
Author(s):  
Gaia Colasante ◽  
Yichen Qiu ◽  
Luca Massimino ◽  
Claudia Di Berardino ◽  
Jonathan H. Cornford ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Focal Epilepsy ◽  
Ex Vivo ◽  
Neurological Diseases ◽  
Focal Treatment ◽  
Important Challenge ◽  
Endogenous Genes ◽  
Clonic Seizures

AbstractEpilepsy is a major health burden, calling for new mechanistic and therapeutic insights. CRISPR–mediated gene editing shows promise to cure genetic pathologies, although hitherto it has mostly been applied ex-vivo. Its translational potential for treating non-genetic pathologies is still unexplored. Furthermore, neurological diseases represent an important challenge for the application of CRISPR, because of the need in many cases to manipulate gene function of neurons in situ. A variant of CRISPR, CRISPRa, offers the possibility to modulate the expression of endogenous genes by directly targeting their promoters. We asked if this strategy can effectively treat acquired focal epilepsy, focusing on ion channels because their manipulation is known be effective in changing network hyperactivity and hypersynchronisation. We applied a doxycycline-inducible CRISPRa technology to increase the expression of the potassium channel gene Kcna1 (encoding Kv1.1) in mouse hippocampal excitatory neurons. CRISPRa-mediated Kv1.1 upregulation led to a substantial decrease in neuronal excitability. Continuous video-EEG telemetry showed that AAV9-mediated delivery of CRISPRa, upon doxycycline administration, decreased spontaneous generalized tonic-clonic seizures in a model of temporal lobe epilepsy, and rescued cognitive impairment and transcriptomic alterations associated with chronic epilepsy. The focal treatment minimizes concerns about off-target effects in other organs and brain areas. This study provides the proof of principle for a translational CRISPR-based approach to treat neurological diseases characterized by abnormal circuit excitability.

scholarly journals Chronic in vivo optogenetic stimulation modulates neuronal excitability, spine morphology and Hebbian plasticity in the mouse hippocampus

2018 ◽  
Author(s):  
Thiago C. Moulin ◽  
Lyvia L. Petiz ◽  
Danielle Rayêe ◽  
Jessica Winne ◽  
Roberto G. Maia ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Pyramidal Neurons ◽  
Ex Vivo ◽  
Morphological Changes ◽  
Spine Density ◽  
Optogenetic Stimulation ◽  
Light Pulses ◽  
Ca1 Region ◽  
Hebbian Plasticity

AbstractProlonged increases in excitation can trigger cell-wide homeostatic responses in neurons, altering membrane channels, promoting morphological changes and ultimately reducing synaptic weights. However, how synaptic downscaling interacts with classical forms of Hebbian plasticity is still unclear. In this study, we investigated whether chronic optogenetic stimulation of hippocampus CA1 pyramidal neurons in freely-moving mice could (a) cause morphological changes reminiscent of homeostatic scaling, (b) modulate synaptic currents that might compensate for chronic excitation, and (c) lead to alterations in Hebbian plasticity. After 24 h of stimulation with 15-ms blue light pulses every 90 s, dendritic spine density and area were reduced in the CA1 region of mice expressing channelrhodopsin-2 (ChR2) when compared to controls. This protocol also reduced the amplitude of mEPSCs for both the AMPA and NMDA components in ex vivo slices obtained from ChR2-expressing mice immediately after the end of stimulation. Lastly, chronic stimulation impaired the induction of LTP and facilitated that of LTD in these slices. Our results indicate that neuronal responses to prolonged network excitation can modulate subsequent Hebbian plasticity in the hippocampus.

scholarly journals Functional spreading of hyperexcitability induced by human and synthetic intracellular Aβ oligomers

2020 ◽  
Author(s):  
Eduardo Javier Fernandez-Perez ◽  
Braulio Muñoz ◽  
Denisse Andrea Bascuñan ◽  
Christian Peters ◽  
Nicolas Osiel Riffo-Lepe ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Neuronal Excitability ◽  
Ex Vivo ◽  
Synaptic Activity ◽  
No Production ◽  
Synaptic Currents ◽  
Aβ Oligomers ◽  
Brain Hyperexcitability

Abstract Background: Intracellular amyloid-beta oligomers (iAβo) accumulation and neuronal hyperexcitability are two crucial events at early stages of Alzheimer’s disease (AD). However, to date, no mechanism linking them has been reported. Methods: Here, the effects of human AD brain-derived (h-iAβo) and synthetic (iAβo) peptides on synaptic currents and action potential (AP) firing were investigated in hippocampal neurons in vitro , ex vivo and in vivo. Results: Starting from 500 pM, iAβo rapidly increased the frequency of synaptic currents and higher concentrations potentiated the AMPA receptor-mediated current. Both effects were PKC-dependent. Parallel recordings of synaptic currents and nitric oxide (NO)-related fluorescence changes indicated that the increased frequency, related to pre-synaptic release, was dependent on a NO-mediated retrograde signaling. Moreover, increased synchronization in NO production was also observed in neurons neighboring those dialyzed with iAβo, indicating that iAβo can increase network excitability at a distance. Current-clamp recordings suggested that iAβo increased neuronal excitability via AMPA-driven synaptic activity without altering membrane intrinsic properties. Conclusion: These results strongly indicate that iAβo causes functional spreading of hyperexcitability through a synaptic-driven mechanism and offer an important neuropathological significance to intracellular species in the initial stages of AD, which include brain hyperexcitability and seizures.

scholarly journals Combined In Silico, Ex Vivo, and In Vivo Assessment of L-17, a Thiadiazine Derivative with Putative Neuro- and Cardioprotective and Antidepressant Effects

2021 ◽  
Vol 22 (24) ◽  
pp. 13626
Author(s):  
Alexey Sarapultsev ◽  
Pavel Vassiliev ◽  
Daniil Grinchii ◽  
Alexander Kiss ◽  
Mojmir Mach ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
In Silico ◽  
Neuronal Excitability ◽  
Medical Condition ◽  
Ex Vivo ◽  
Treatment Strategies ◽  
Neural Mechanism ◽  
Special Treatment ◽  
Early Assessment

Depression associated with poor general medical condition, such as post-stroke (PSD) or post-myocardial infarction (PMID) depression, is characterized by resistance to classical antidepressants. Special treatment strategies should thus be developed for these conditions. Our study aims to investigate the mechanism of action of 2-morpholino-5-phenyl-6H-1,3,4-thiadiazine, hydrobromide (L-17), a recently designed thiadiazine derivative with putative neuro- and cardioprotective and antidepressant-like effects, using combined in silico (for prediction of the molecular binding mechanisms), ex vivo (for assessment of the neural excitability using c-Fos immunocytochemistry), and in vivo (for direct examination of the neuronal excitability) methodological approaches. We found that the predicted binding affinities of L-17 to serotonin (5-HT) transporter (SERT) and 5-HT3 and 5-HT1A receptors are compatible with selective 5-HT serotonin reuptake inhibitors (SSRIs) and antagonists of 5-HT3 and 5-HT1A receptors, respectively. L-17 robustly increased c-Fos immunoreactivity in the amygdala and decreased it in the hippocampus. L-17 dose-dependently inhibited 5-HT neurons of the dorsal raphe nucleus; this inhibition was partially reversed by the 5-HT1A antagonist WAY100135. We suggest that L-17 is a potent 5-HT reuptake inhibitor and partial antagonist of 5-HT3 and 5-HT1A receptors; the effects of L-17 on amygdaloid and hippocampal excitability might be mediated via 5-HT, and putatively mediate the antidepressant-like effects of this drug. Since L-17 also possesses neuro- and cardioprotective properties, it can be beneficial in PSD and PMID. Combined in silico predictions with ex vivo neurochemical and in vivo electrophysiological assessments might be a useful strategy for early assessment of the efficacy and neural mechanism of action of novel CNS drugs.

scholarly journals In vivo CRISPRa decreases seizures and rescues cognitive deficits in a rodent model of epilepsy

Brain ◽  
2020 ◽  
Vol 143 (3) ◽  
pp. 891-905 ◽  
Author(s):  
Gaia Colasante ◽  
Yichen Qiu ◽  
Luca Massimino ◽  
Claudia Di Berardino ◽  
Jonathan H Cornford ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Focal Epilepsy ◽  
Ex Vivo ◽  
Neurological Diseases ◽  
Focal Treatment ◽  
Important Challenge ◽  
Endogenous Genes ◽  
Clonic Seizures

Abstract Epilepsy is a major health burden, calling for new mechanistic insights and therapies. CRISPR-mediated gene editing shows promise to cure genetic pathologies, although hitherto it has mostly been applied ex vivo. Its translational potential for treating non-genetic pathologies is still unexplored. Furthermore, neurological diseases represent an important challenge for the application of CRISPR, because of the need in many cases to manipulate gene function of neurons in situ. A variant of CRISPR, CRISPRa, offers the possibility to modulate the expression of endogenous genes by directly targeting their promoters. We asked if this strategy can effectively treat acquired focal epilepsy, focusing on ion channels because their manipulation is known be effective in changing network hyperactivity and hypersynchronziation. We applied a doxycycline-inducible CRISPRa technology to increase the expression of the potassium channel gene Kcna1 (encoding Kv1.1) in mouse hippocampal excitatory neurons. CRISPRa-mediated Kv1.1 upregulation led to a substantial decrease in neuronal excitability. Continuous video-EEG telemetry showed that AAV9-mediated delivery of CRISPRa, upon doxycycline administration, decreased spontaneous generalized tonic-clonic seizures in a model of temporal lobe epilepsy, and rescued cognitive impairment and transcriptomic alterations associated with chronic epilepsy. The focal treatment minimizes concerns about off-target effects in other organs and brain areas. This study provides the proof-of-principle for a translational CRISPR-based approach to treat neurological diseases characterized by abnormal circuit excitability.

scholarly journals Functional spreading of hyperexcitability induced by human and synthetic intracellular Aβ oligomers

2020 ◽  
Author(s):  
Eduardo J. Fernandez-Perez ◽  
Braulio Muñoz ◽  
Denisse A. Bascuñan ◽  
Christian Peters ◽  
Nicolas O. Riffo-Lepe ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Neuronal Excitability ◽  
Ex Vivo ◽  
Synaptic Activity ◽  
No Production ◽  
Synaptic Currents ◽  
Aβ Oligomers ◽  
Brain Hyperexcitability

AbstractBackgroundIntracellular amyloid-beta oligomers (iAβo) accumulation and neuronal hyperexcitability are two crucial events at early stages of Alzheimer’s disease (AD). However, to date, no mechanism linking them has been reported.MethodsHere, the effects of human AD brain-derived (h-iAβo) and synthetic (iAβo) peptides on synaptic currents and action potential (AP) firing were investigated in hippocampal neurons in vitro, ex vivo and in vivo.ResultsStarting from 500 pM, iAβo rapidly increased the frequency of synaptic currents and higher concentrations potentiated the AMPA receptor-mediated current. Both effects were PKC-dependent. Parallel recordings of synaptic currents and nitric oxide (NO)-related fluorescence changes indicated that the increased frequency, related to pre-synaptic release, was dependent on a NO-mediated retrograde signaling. Moreover, increased synchronization in NO production was also observed in neurons neighboring those dialyzed with iAβo, indicating that iAβo can increase network excitability at a distance. Current-clamp recordings suggested that iAβo increased neuronal excitability via AMPA-driven synaptic activity without altering membrane intrinsic properties.ConclusionThese results strongly indicate that iAβo causes functional spreading of hyperexcitability through a synaptic-driven mechanism and offer an important neuropathological significance to intracellular species in the initial stages of AD, which include brain hyperexcitability and seizures.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

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