scholarly journals Alterations in Oscillatory Behavior of Central Medial Thalamic Neurons Demonstrate a Key Role of CaV3.1 Isoform of T-Channels During Isoflurane-Induced Anesthesia

2019 ◽  
Vol 29 (11) ◽  
pp. 4679-4696 ◽  
Author(s):  
Tamara Timic Stamenic ◽  
Simon Feseha ◽  
Robert Valdez ◽  
Wanzhu Zhao ◽  
Jost Klawitter ◽  
...  
Keyword(s):  
Brain Slices ◽  
Field Potential ◽  
Volatile Anesthetic ◽  
Rhythmic Activity ◽  
Oscillatory Behavior ◽  
Mouse Genetics ◽  
Thalamic Nuclei ◽  
Medial Nucleus

Abstract Although the central medial nucleus (CeM) of the thalamus is an essential part of the arousal system for sleep and anesthesia initiation, the precise mechanisms that regulate its activity are not well studied. We examined the role of CaV3.1 isoform of T-type calcium channels (T-channels) in the excitability and rhythmic activity of CeM neurons during isoflurane (ISO)-induced anesthesia by using mouse genetics and selective pharmacology. Patch-clamp recordings taken from acute brain slices revealed that CaV3.1 channels in CeM are inhibited by prototypical volatile anesthetic ISO (250 and 500 μM) and selective T-channels blocker 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2). Both TTA-P2 and ISO attenuated tonic and burst firing modes, and hyperpolarized CeM neurons from wild type (WT) mice. These effects were greatly diminished or abolished in CaV3.1 null mice. Our ensuing in vivo local field potential (LFP) recordings from CeM indicated that the ability of TTA-P2 and anesthetic concentrations of ISO to promote δ oscillation was substantially weakened in CaV3.1 null mice. Furthermore, escalating ISO concentrations induced stronger burst-suppression LFP pattern in mutant than in WT mice. Our results demonstrate for the first time the importance of CaV3.1 channels in thalamocortical oscillations from the non-specific thalamic nuclei that underlie clinically important effects of ISO.

scholarly journals Modified Sawhorse Waveform for the Voltammetric Detection of Oxytocin

2022 ◽  
Author(s):  
Favian Liu ◽  
Negar Ghasem Ardabili ◽  
Izaiah Brown ◽  
Harmain Rafi ◽  
Clarice Cook ◽  
...  
Keyword(s):  
Brain Slices ◽  
Physiological Role ◽  
Peptide Hormone ◽  
Protective Effects ◽  
Fast Scan Cyclic Voltammetry ◽  
The Past ◽  
Voltammetric Detection ◽  
Carbon Fiber Microelectrodes

Abstract Carbon fiber microelectrodes (CFMEs) have been used to detect neurotransmitters and other biomolecules using fast-scan cyclic voltammetry (FSCV) for the past few decades. This technique measures neurotransmitters such as dopamine and, more recently, physiologically relevant neuropeptides. Oxytocin, a pleiotropic peptide hormone, is physiologically important for adaptation, development, reproduction, and social behavior. This neuropeptide functions as a stress-coping molecule, an anti-inflammatory agent, and serves as an antioxidant with protective effects especially during adversity or trauma. Here, we measure tyrosine using the Modified Sawhorse Waveform (MSW), enabling enhanced electrode sensitivity for the amino acid and oxytocin peptide. Applying the MSW, decreased surface fouling and enabled codetection with other monoamines. As oxytocin contains tyrosine, the MSW was also used to detect oxytocin. The sensitivity of oxytocin detection was found to be 3.99 ± 0.49 nA/µM, (n=5). Additionally, we demonstrate that applying the MSW on CFMEs allows for real time measurements of exogenously applied oxytocin on rat brain slices. These studies may serve as novel assays for oxytocin detection in a fast, sub-second timescale with possible implications for in vivo measurements and further understanding of the physiological role of oxytocin.

scholarly journals Cytoplasmic Expression of the ALS/FTD-Related Protein TDP-43 Decreases Global Translation Both in vitro and in vivo

2020 ◽  
Vol 14 ◽  
Author(s):  
Santiago E. Charif ◽  
Luciana Luchelli ◽  
Antonella Vila ◽  
Matías Blaustein ◽  
Lionel M. Igaz
Keyword(s):  
De Novo ◽  
Brain Slices ◽  
Mrna Translation ◽  
Hek293 Cells ◽  
Cytoplasmic Inclusions ◽  
Cytoplasmic Expression ◽  
Global Translation

TDP-43 is a major component of cytoplasmic inclusions observed in neurodegenerative diseases like frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). To further understand the role of TDP-43 in mRNA/protein metabolism and proteostasis, we used a combined approach with cellular and animal models overexpressing a cytoplasmic form of human TDP-43 (TDP-43-ΔNLS), recapitulating ALS/FTD features. We applied in HEK293 cells a method for labeling de novo translation, surface sensing of translation (SUnSET), based on puromycin (PURO) incorporation. While control cells displayed robust puromycilation, TDP-43-ΔNLS transfected cells exhibited reduced ongoing protein synthesis. Next, by using a transgenic mouse overexpressing cytoplasmic TDP-43 in the forebrain (TDP-43-ΔNLS mice) we assessed whether cytoplasmic TDP-43 regulates global translation in vivo. Polysome profiling of brain cortices from transgenic mice showed a shift toward non-polysomal fractions as compared to wild-type littermates, indicating a decrease in global translation. Lastly, cellular level translational assessment by SUNSET was performed in TDP-43-ΔNLS mice brain slices. Control mice slices incubated with PURO exhibited robust cytoplasmic PURO signal in layer 5 neurons from motor cortex, and normal nuclear TDP-43 staining. Neurons in TDP-43-ΔNLS mice slices incubated with PURO exhibited high cytoplasmic expression of TDP-43 and reduced puromycilation respect to control mice. These in vitro and in vivo results indicate that cytoplasmic TDP-43 decreases global translation and potentially cause functional/cytotoxic effects as observed in ALS/FTD. Our study provide in vivo evidence (by two independent and complementary methods) for a role of mislocalized TDP-43 in the regulation of global mRNA translation, with implications for TDP-43 proteinopathies.

scholarly journals Suprachiasmatic nucleus-dependent and independent outputs driving rhythmic activity in hypothalamic and thalamic neurons

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Court Harding ◽  
David A. Bechtold ◽  
Timothy M. Brown
Keyword(s):  
Suprachiasmatic Nucleus ◽  
Circadian Variation ◽  
Brain Slices ◽  
Rhythmic Activity ◽  
The Body ◽  
Inhibitory Input ◽  
Thalamic Nuclei ◽  
Thalamic Neurons ◽  
Ventral Thalamus ◽  
Central Clock

Abstract Background Daily variations in mammalian physiology are under control of a central clock in the suprachiasmatic nucleus (SCN). SCN timing signals are essential for coordinating cellular clocks and associated circadian variations in cell and tissue function across the body; however, direct SCN projections primarily target a restricted set of hypothalamic and thalamic nuclei involved in physiological and behavioural control. The role of the SCN in driving rhythmic activity in these targets remains largely unclear. Here, we address this issue via multielectrode recording and manipulations of SCN output in adult mouse brain slices. Results Electrical stimulation identifies cells across the midline hypothalamus and ventral thalamus that receive inhibitory input from the SCN and/or excitatory input from the retina. Optogenetic manipulations confirm that SCN outputs arise from both VIP and, more frequently, non-VIP expressing cells and that both SCN and retinal projections almost exclusively target GABAergic downstream neurons. The majority of midline hypothalamic and ventral thalamic neurons exhibit circadian variation in firing and those receiving inhibitory SCN projections consistently exhibit peak activity during epochs when SCN output is low. Physical removal of the SCN confirms that neuronal rhythms in ~ 20% of the recorded neurons rely on central clock input but also reveals many neurons that can express circadian variation in firing independent of any SCN input. Conclusions We identify cell populations across the midline hypothalamus and ventral thalamus exhibiting SCN-dependent and independent rhythms in neural activity, providing new insight into the mechanisms by which the circadian system generates daily physiological rhythms.

scholarly journals Selective corticostriatal plasticity during acquisition of an auditory discrimination task

2014 ◽  
Author(s):  
Qiaojie Xiong ◽  
Petr Znamenskiy ◽  
Anthony Zador
Keyword(s):  
Cortical Neurons ◽  
Brain Slices ◽  
Frequency Discrimination ◽  
Auditory Discrimination ◽  
Low Frequencies ◽  
Reward Contingencies ◽  
Corticostriatal Plasticity

Perceptual decisions are based on the activity of sensory cortical neurons, but how organisms learn to transform this activity into appropriate actions remains unknown. Projections from the auditory cortex to the auditory striatum carry information that drives decisions in an auditory frequency discrimination task1. To assess the role of these projections in learning, we developed a Channelrhodopsin-2-based assay to selectively probe for synaptic plasticity associated with corticostriatal neurons representing different frequencies. Here we report that learning this auditory discrimination preferentially potentiates corticostriatal synapses from neurons representing either high or low frequencies, depending on reward contingencies. We observed frequency-dependent corticostriatal potentiation in vivo over the course of training, and in vitro in striatal brain slices. Our findings suggest a model in which selective potentiation of inputs representing different components of a sensory stimulus enables the learned transformation of sensory input into actions.

scholarly journals Role of astrocytes in cerebrovascular regulation

2006 ◽  
Vol 100 (1) ◽  
pp. 307-317 ◽  
Author(s):  
Raymond C. Koehler ◽  
Debebe Gebremedhin ◽  
David R. Harder
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Neurovascular Unit ◽  
Brain Slices ◽  
Calcium Oscillations ◽  
Synaptic Activity

Astrocytes send processes to synapses and blood vessels, communicate with other astrocytes through gap junctions and by release of ATP, and thus are an integral component of the neurovascular unit. Electrical field stimulations in brain slices demonstrate an increase in intracellular calcium in astrocyte cell bodies transmitted to perivascular end-feet, followed by a decrease in vascular smooth muscle calcium oscillations and arteriolar dilation. The increase in astrocyte calcium after neuronal activation is mediated, in part, by activation of metabotropic glutamate receptors. Calcium signaling in vitro can also be influenced by adenosine acting on A2B receptors and by epoxyeicosatrienoic acids (EETs) shown to be synthesized in astrocytes. Prostaglandins, EETs, arachidonic acid, and potassium ions are candidate mediators of communication between astrocyte end-feet and vascular smooth muscle. In vivo evidence supports a role for cyclooxygenase-2 metabolites, EETs, adenosine, and neuronally derived nitric oxide in the coupling of increased blood flow to increased neuronal activity. Combined inhibition of the EETs, nitric oxide, and adenosine pathways indicates that signaling is not by parallel, independent pathways. Indirect pharmacological results are consistent with astrocytes acting as intermediaries in neurovascular signaling within the neurovascular unit. For specific stimuli, astrocytes are also capable of transmitting signals to pial arterioles on the brain surface for ensuring adequate inflow pressure to parenchymal feeding arterioles. Therefore, evidence from brain slices and indirect evidence in vivo with pharmacological approaches suggest that astrocytes play a pivotal role in regulating the fundamental physiological response coupling dynamic changes in cerebral blood flow to neuronal synaptic activity. Future work using in vivo imaging and genetic manipulation will be required to provide more direct evidence for a role of astrocytes in neurovascular coupling.

Kv1.1-Containing Channels Are Critical for Temporal Precision During Spike Initiation

2006 ◽  
Vol 96 (3) ◽  
pp. 1203-1214 ◽  
Author(s):  
Joshua X. Gittelman ◽  
Bruce L Tempel
Keyword(s):  
Brain Slices ◽  
Temporal Precision ◽  
Medial Nucleus ◽  
Whole Cell Patch Clamp ◽  
Latency Variability ◽  
Low Threshold ◽  
Rapid Stimulation ◽  
Spike Initiation ◽  
Selective Blocker

Low threshold, voltage-gated potassium currents ( Ikl) are widely expressed in auditory neurons that can fire temporally precise action potentials (APs). In the medial nucleus of the trapezoid body (MNTB), channels containing the Kv1.1 subunit (encoded by the Kcna1 gene) underlie Ikl. Using pharmacology, genetics and whole cell patch-clamp recordings in mouse brain slices, we tested the role of Ikl in limiting AP latency-variability (jitter) in response to trains of single inputs at moderate to high stimulation rates. With dendrotoxin-K (DTX-K, a selective blocker of Kv1.1-containing channels), we blocked Ikl maximally (≈80% with 100 nM DTX-K) or partially (≈50% with 1-h incubation in 3 nM DTX-K). Ikl was similar in 3 nM DTX-K–treated cells and cells from Kcna1−/− mice, allowing a comparison of these two different methods of Ikl reduction. In response to current injection, Ikl reduction increased the temporal window for AP initiation and increased jitter in response to the smallest currents that were able to drive APs. While 100 nM DTX-K caused the largest increases, latency and jitter in Kcna1 −/ − cells and in 3 nM DTX-K–treated cells were similar to each other but increased compared with +/+. The near-phenocopy of the Kcna1−/− cells with 3 nM DTX-K shows that acute blockade of a subset of the Kv1.1-containing channels is functionally similar to the chronic elimination of all Kv1.1 subunits. During rapid stimulation (100–500 Hz), Ikl reduction increased jitter in response to both large and small inputs. These data show that Ikl is critical for maintaining AP temporal precision at physiologically relevant firing rates.

scholarly journals Characterization of pruriceptive trigeminothalamic tract neurons in rats

2014 ◽  
Vol 111 (8) ◽  
pp. 1574-1589 ◽  
Author(s):  
Hannah R. Moser ◽  
Glenn J. Giesler
Keyword(s):  
Discharge Rate ◽  
Response Duration ◽  
Spike Timing ◽  
Thalamic Nuclei ◽  
Medial Nucleus ◽  
The Face ◽  
Deep Layers ◽  
Noxious Stimuli

Rodent models of facial itch and pain provide a valuable tool for distinguishing between behaviors related to each sensation. In rats, pruritogens applied to the face elicit scratching using the hindlimb while algogens elicit wiping using the forelimb. We wished to determine the role of trigeminothalamic tract (VTT) neurons in carrying information regarding facial itch and pain to the forebrain. We have characterized responses to facially applied pruritogens (serotonin, BAM8–22, chloroquine, histamine, capsaicin, and cowhage) and noxious stimuli in 104 VTT neurons recorded from anesthetized rats. Each VTT neuron had a mechanically sensitive cutaneous receptive field on the ipsilateral face. All pruriceptive VTT neurons also responded to noxious mechanical and/or thermal stimulation. Over half of VTT neurons responsive to noxious stimuli also responded to at least one pruritogen. Each tested pruritogen, with the exception of cowhage, produced an increase in discharge rate in a subset of VTT neurons. The response to each pruritogen was characterized, including maximum discharge rate, response duration, and spike timing dynamics. Pruriceptive VTT neurons were recorded from throughout superficial and deep layers of the spinal trigeminal nucleus and were shown to project via antidromic mapping to the ventroposterior medial nucleus or posterior thalamic nuclei. These results indicate that pruriceptive VTT neurons are a subset of polymodal nociceptive VTT neurons and characterize a system conducive to future experiments regarding the similarities and differences between facial itch and pain.

scholarly journals Mechanism of antiseizure effect of isoflurane in the immature rat hippocampus

2009 ◽  
Vol 55 (1) ◽  
pp. 57-60
Author(s):  
E.V. Isaeva. ◽  
Keyword(s):  
Field Potential ◽  
Volatile Anesthetic ◽  
Refractory Status Epilepticus ◽  
Volatile Anesthetic Agent ◽  
Immature Rat ◽  
Whole Cell Patch Clamp ◽  
Early Brain Development ◽  
Potential Recording ◽  
Field Potential Recording

The volatile anesthetic isoflurane is often used in children in the management of refractory status epilepticus. However the mechanism of anticonvulsant action of isoflurane during early brain development is not clear. In this study we explore the role of excitatory and inhibitory conductances in antiseizure effect of isoflurane using combination of whole-cell patch-clamp and extracellular field potential recording techniques on two models of epilepsy in a hippocampal slice preparation from immature rat. Our data demonstrated that decreasing of excitatory sy-naptic transmission does not account for antiseizure effect of this volatile anesthetic agent. Isoflurane decreases the synchro­nization of neuronal activity mainly through the enhancing of GABAergic inhibition by influencing both phasic and tonic chloride conductances.

Methods for In Vivo Gene Manipulation

2017 ◽  
Author(s):  
Lisa M. Monteggia ◽  
Wei Xu
Keyword(s):  
Nervous System ◽  
Gene Function ◽  
Neural Circuits ◽  
Mouse Genetics ◽  
Specific Gene ◽  
Complex Behavior ◽  
Recent Advances ◽  
The Brain

Recent advances in mouse genetics have opened many new avenues of research in which to explore gene function in the brain, and contributions to the pathophysiology and treatment of psychiatric disorders. The use of the mouse to explore gene function has contributed a better understanding of the role of specific genes in the nervous system including their influence on neural circuits and complex behavior.This chapter explores current approaches to manipulate gene function in a mouse. Genetically modified mice allow for the investigation of a particular gene in vivo. The approaches discussed highlight recent advances to specifically overexpress or disrupt a specific gene of interest in the brain. We also highlight viral-mediated gene transfer approaches to allow for spatial and temporal control of gene function.

scholarly journals NMDA Receptors in Astrocytes: In Search for Roles in Neurotransmission and Astrocytic Homeostasis

2019 ◽  
Vol 20 (2) ◽  
pp. 309 ◽  
Author(s):  
Katarzyna Skowrońska ◽  
Marta Obara-Michlewska ◽  
Magdalena Zielińska ◽  
Jan Albrecht
Keyword(s):  
Nmda Receptors ◽  
Brain Slices ◽  
Cultured Astrocytes ◽  
Specific Proteins ◽  
Homeostatic Function ◽  
Inward Rectifying Potassium Channel ◽  
And Function

Studies of the last two decades have demonstrated the presence in astrocytic cell membranes of N-methyl-d-aspartate (NMDA) receptors (NMDARs), albeit their apparently low abundance makes demonstration of their presence and function more difficult than of other glutamate (Glu) receptor classes residing in astrocytes. Activation of astrocytic NMDARs directly in brain slices and in acutely isolated or cultured astrocytes evokes intracellular calcium increase, by mutually unexclusive ionotropic and metabotropic mechanisms. However, other than one report on the contribution of astrocyte-located NMDARs to astrocyte-dependent modulation of presynaptic strength in the hippocampus, there is no sound evidence for the significant role of astrocytic NMDARs in astrocytic-neuronal interaction in neurotransmission, as yet. Durable exposure of astrocytic and neuronal co-cultures to NMDA has been reported to upregulate astrocytic synthesis of glutathione, and in this way to increase the antioxidative capacity of neurons. On the other hand, overexposure to NMDA decreases, by an as yet unknown mechanism, the ability of cultured astrocytes to express glutamine synthetase (GS), aquaporin-4 (AQP4), and the inward rectifying potassium channel Kir4.1, the three astroglia-specific proteins critical for homeostatic function of astrocytes. The beneficial or detrimental effects of astrocytic NMDAR stimulation revealed in the in vitro studies remain to be proven in the in vivo setting.

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