Neurotransmitter Receptor Bases of the Long-Rage Interactions of Cat Striate Cortical Neurons Revealed by In-Vivo Intracellular Injection

AbstractNeuronal apoptosis has an important role in early brain injury (EBI) following subarachnoid hemorrhage (SAH). TRAF3 was reported as a promising therapeutic target for stroke management, which covered several neuronal apoptosis signaling cascades. Hence, the present study is aimed to determine whether downregulation of TRAF3 could be neuroprotective in SAH-induced EBI. An in vivo SAH model in mice was established by endovascular perforation. Meanwhile, primary cultured cortical neurons of mice treated with oxygen hemoglobin were applied to mimic SAH in vitro. Our results demonstrated that TRAF3 protein expression increased and expressed in neurons both in vivo and in vitro SAH models. TRAF3 siRNA reversed neuronal loss and improved neurological deficits in SAH mice, and reduced cell death in SAH primary neurons. Mechanistically, we found that TRAF3 directly binds to TAK1 and potentiates phosphorylation and activation of TAK1, which further enhances the activation of NF-κB and MAPKs pathways to induce neuronal apoptosis. Importantly, TRAF3 expression was elevated following SAH in human brain tissue and was mainly expressed in neurons. Taken together, our study demonstrates that TRAF3 is an upstream regulator of MAPKs and NF-κB pathways in SAH-induced EBI via its interaction with and activation of TAK1. Furthermore, the TRAF3 may serve as a novel therapeutic target in SAH-induced EBI.

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Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

Nature Communications ◽

10.1038/s41467-021-25035-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Cody L. Call ◽

Dwight E. Bergles

Keyword(s):

Cortical Neurons ◽

Regional Differences ◽

Brain Regions ◽

Axon Diameter ◽

Neuronal Identity ◽

Cortical Areas ◽

Myelin Sheaths ◽

Parvalbumin Interneurons ◽

Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

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Machine learning-based classification of mitochondrial morphology in primary neurons and brain

Scientific Reports ◽

10.1038/s41598-021-84528-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Garrett M. Fogo ◽

Anthony R. Anzell ◽

Kathleen J. Maheras ◽

Sarita Raghunayakula ◽

Joseph M. Wider ◽

...

Keyword(s):

Image Analysis ◽

Cortical Neurons ◽

Mitochondrial Dynamics ◽

Automated Image Analysis ◽

Mitochondrial Morphology ◽

Analysis Pipeline ◽

Genetic Ablation ◽

Block Face

AbstractThe mitochondrial network continually undergoes events of fission and fusion. Under physiologic conditions, the network is in equilibrium and is characterized by the presence of both elongated and punctate mitochondria. However, this balanced, homeostatic mitochondrial profile can change morphologic distribution in response to various stressors. Therefore, it is imperative to develop a method that robustly measures mitochondrial morphology with high accuracy. Here, we developed a semi-automated image analysis pipeline for the quantitation of mitochondrial morphology for both in vitro and in vivo applications. The image analysis pipeline was generated and validated utilizing images of primary cortical neurons from transgenic mice, allowing genetic ablation of key components of mitochondrial dynamics. This analysis pipeline was further extended to evaluate mitochondrial morphology in vivo through immunolabeling of brain sections as well as serial block-face scanning electron microscopy. These data demonstrate a highly specific and sensitive method that accurately classifies distinct physiological and pathological mitochondrial morphologies. Furthermore, this workflow employs the use of readily available, free open-source software designed for high throughput image processing, segmentation, and analysis that is customizable to various biological models.

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Differential pial and penetrating arterial responses examined by optogenetic activation of astrocytes and neurons

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x211010355 ◽

2021 ◽

pp. 0271678X2110103

Author(s):

Nao Hatakeyama ◽

Miyuki Unekawa ◽

Juri Murata ◽

Yutaka Tomita ◽

Norihiro Suzuki ◽

...

Keyword(s):

Cortical Neurons ◽

Acetylcholine Receptors ◽

Step Function ◽

Muscarinic Acetylcholine Receptors ◽

Cell Type ◽

Function Type ◽

Neuron Activation ◽

Cell Type Specific ◽

Arterial Responses

A variety of brain cells participates in neurovascular coupling by transmitting and modulating vasoactive signals. The present study aimed to probe cell type-dependent cerebrovascular (i.e., pial and penetrating arterial) responses with optogenetics in the cortex of anesthetized mice. Two lines of the transgenic mice expressing a step function type of light-gated cation channel (channelrhodopsine-2; ChR2) in either cortical neurons (muscarinic acetylcholine receptors) or astrocytes (Mlc1-positive) were used in the experiments. Photo-activation of ChR2-expressing astrocytes resulted in a widespread increase in cerebral blood flow (CBF), extending to the nonstimulated periphery. In contrast, photo-activation of ChR2-expressing neurons led to a relatively localized increase in CBF. The differences in the spatial extent of the CBF responses are potentially explained by differences in the involvement of the vascular compartments. In vivo imaging of the cerebrovascular responses revealed that ChR2-expressing astrocyte activation led to the dilation of both pial and penetrating arteries, whereas ChR2-expressing neuron activation predominantly caused dilation of the penetrating arterioles. Pharmacological studies showed that cell type-specific signaling mechanisms participate in the optogenetically induced cerebrovascular responses. In conclusion, pial and penetrating arterial vasodilation were differentially evoked by ChR2-expressing astrocytes and neurons.

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Neuron-specific activation of necroptosis signaling in multiple sclerosis cortical grey matter

Acta Neuropathologica ◽

10.1007/s00401-021-02274-7 ◽

2021 ◽

Vol 141 (4) ◽

pp. 585-604 ◽

Cited By ~ 1

Author(s):

Carmen Picon ◽

Anusha Jayaraman ◽

Rachel James ◽

Catriona Beck ◽

Patricia Gallego ◽

...

Keyword(s):

Multiple Sclerosis ◽

Signaling Pathway ◽

Cortical Neurons ◽

Grey Matter ◽

Molecular Mechanisms ◽

Fold Increase ◽

Cell Types ◽

Meningeal Inflammation ◽

Cortical Grey Matter

AbstractSustained exposure to pro-inflammatory cytokines in the leptomeninges is thought to play a major role in the pathogenetic mechanisms leading to cortical pathology in multiple sclerosis (MS). Although the molecular mechanisms underlying neurodegeneration in the grey matter remain unclear, several lines of evidence suggest a prominent role for tumour necrosis factor (TNF). Using cortical grey matter tissue blocks from post-mortem brains from 28 secondary progressive MS subjects and ten non-neurological controls, we describe an increase in expression of multiple steps in the TNF/TNF receptor 1 signaling pathway leading to necroptosis, including the key proteins TNFR1, FADD, RIPK1, RIPK3 and MLKL. Activation of this pathway was indicated by the phosphorylation of RIPK3 and MLKL and the formation of protein oligomers characteristic of necrosomes. In contrast, caspase-8 dependent apoptotic signaling was decreased. Upregulation of necroptotic signaling occurred predominantly in macroneurons in cortical layers II–III, with little expression in other cell types. The presence of activated necroptotic proteins in neurons was increased in MS cases with prominent meningeal inflammation, with a 30-fold increase in phosphoMLKL+ neurons in layers I–III. The density of phosphoMLKL+ neurons correlated inversely with age at death, age at progression and disease duration. In vivo induction of chronically elevated TNF and INFγ levels in the CSF in a rat model via lentiviral transduction in the meninges, triggered inflammation and neurodegeneration in the underlying cortical grey matter that was associated with increased neuronal expression of TNFR1 and activated necroptotic signaling proteins. Exposure of cultured primary rat cortical neurons to TNF induced necroptosis when apoptosis was inhibited. Our data suggest that neurons in the MS cortex are dying via TNF/TNFR1 stimulated necroptosis rather than apoptosis, possibly initiated in part by chronic meningeal inflammation. Neuronal necroptosis represents a pathogenetic mechanism that is amenable to therapeutic intervention at several points in the signaling pathway.

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Kir6.2-containing ATP-sensitive potassium channels protect cortical neurons from ischemic/anoxic injury in vitro and in vivo

Neuroscience ◽

10.1016/j.neuroscience.2006.10.043 ◽

2007 ◽

Vol 144 (4) ◽

pp. 1509-1515 ◽

Cited By ~ 31

Author(s):

H.-S. Sun ◽

Z.-P. Feng ◽

P.A. Barber ◽

A.M. Buchan ◽

R.J. French

Keyword(s):

Potassium Channels ◽

Cortical Neurons ◽

Anoxic Injury

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Intracellular injection of Lucifer yellow into cortical neurons in lightly fixed sections and its application to human autopsy material

Journal of Neuroscience Methods ◽

10.1016/0165-0270(88)90157-4 ◽

1988 ◽

Vol 26 (2) ◽

pp. 95-103 ◽

Cited By ~ 42

Author(s):

Gillian Einstein

Keyword(s):

Cortical Neurons ◽

Lucifer Yellow ◽

Autopsy Material ◽

Intracellular Injection ◽

Human Autopsy Material ◽

Human Autopsy

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Correlative In Vivo 2 Photon and Focused Ion Beam Scanning Electron Microscopy of Cortical Neurons

PLoS ONE ◽

10.1371/journal.pone.0057405 ◽

2013 ◽

Vol 8 (2) ◽

pp. e57405 ◽

Cited By ~ 58

Author(s):

Bohumil Maco ◽

Anthony Holtmaat ◽

Marco Cantoni ◽

Anna Kreshuk ◽

Christoph N. Straehle ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Cortical Neurons ◽

Focused Ion Beam ◽

Ion Beam ◽

Beam Scanning ◽

Scanning Electron

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Synaptic Interactions Between Thalamic and Cortical Inputs Onto Cortical Neurons In Vivo

Journal of Neurophysiology ◽

10.1152/jn.01105.2003 ◽

2004 ◽

Vol 91 (5) ◽

pp. 1990-1998 ◽

Cited By ~ 22

Author(s):

Pablo Fuentealba ◽

Sylvain Crochet ◽

Igor Timofeev ◽

Mircea Steriade

Keyword(s):

Cortical Neurons ◽

Time Course ◽

Input Resistance ◽

Maximal Effect ◽

Time Intervals ◽

Neocortical Neurons ◽

Synaptic Interactions ◽

Cortical Responses ◽

Cortical Inputs

To study the interactions between thalamic and cortical inputs onto neocortical neurons, we used paired-pulse stimulation (PPS) of thalamic and cortical inputs as well as PPS of two cortical or two thalamic inputs that converged, at different time intervals, onto intracellularly recorded cortical and thalamocortical neurons in anesthetized cats. PPS of homosynaptic cortico-cortical pathways produced facilitation, depression, or no significant effects in cortical pathways, whereas cortical responses to thalamocortical inputs were mostly facilitated at both short and long intervals. By contrast, heterosynaptic interactions between either cortical and thalamic, or thalamic and cortical, inputs generally produced decreases in the peak amplitudes and depolarization area of evoked excitatory postsynaptic potentials (EPSPs), with maximal effect at ∼10 ms and lasting from 60 to 100 ms. All neurons tested with thalamic followed by cortical stimuli showed a decrease in the apparent input resistance ( Rin), the time course of which paralleled that of decreased responses, suggesting that shunting is the factor accounting for EPSP's decrease. Only half of neurons tested with cortical followed by thalamic stimuli displayed changes in Rin. Spike shunting in the thalamus may account for those cases in which decreased synaptic responsiveness of cortical neurons was not associated with decreased Rin because thalamocortical neurons showed decreased firing probability during cortical stimulation. These results suggest a short-lasting but strong shunting between thalamocortical and cortical inputs onto cortical neurons.

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