Differential NPY-Y1 Receptor Density in the Motor Cortex of ALS Patients and Familial Model of ALS

Destabilization of faciliatory and inhibitory circuits is an important feature of corticomotor pathology in amyotrophic lateral sclerosis (ALS). While GABAergic inputs to upper motor neurons are reduced in models of the disease, less understood is the involvement of peptidergic inputs to upper motor neurons in ALS. The neuropeptide Y (NPY) system has been shown to confer neuroprotection against numerous pathogenic mechanisms implicated in ALS. However, little is known about how the NPY system functions in the motor system. Herein, we investigate post-synaptic NPY signaling on upper motor neurons in the rodent and human motor cortex, and on cortical neuron populations in vitro. Using immunohistochemistry, we show the increased density of NPY-Y1 receptors on the soma of SMI32-positive upper motor neurons in post-mortem ALS cases and SOD1G93A excitatory cortical neurons in vitro. Analysis of receptor density on Thy1-YFP-H-positive upper motor neurons in wild-type and SOD1G93A mouse tissue revealed that the distribution of NPY-Y1 receptors was changed on the apical processes at early-symptomatic and late-symptomatic disease stages. Together, our data demonstrate the differential density of NPY-Y1 receptors on upper motor neurons in a familial model of ALS and in ALS cases, indicating a novel pathway that may be targeted to modulate upper motor neuron activity.

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Partial Reconstruction of Muscle Activity From a Pruned Network of Diverse Motor Cortex Neurons

Journal of Neurophysiology ◽

10.1152/jn.00544.2006 ◽

2007 ◽

Vol 97 (1) ◽

pp. 70-82 ◽

Cited By ~ 29

Author(s):

Marc H. Schieber ◽

Gil Rivlis

Keyword(s):

Motor Cortex ◽

Motor Neurons ◽

Primary Motor Cortex ◽

Activity Patterns ◽

Neuron Activity ◽

Emg Activity ◽

Weighted Sum ◽

Partial Reconstruction ◽

Average Similarity ◽

Upper Motor Neurons

Primary motor cortex (M1) neurons traditionally have been viewed as “upper motor neurons” that directly drive spinal motoneuron pools, particularly during finger movements. We used spike-triggered averages (SpikeTAs) of electromyographic (EMG) activity to select M1 neurons whose spikes signaled the arrival of input in motoneuron pools, and examined the degree of similarity between the activity patterns of these M1 neurons and their target muscles during 12 individuated finger and wrist movements. Neuron–EMG similarity generally was low. Similarity was unrelated to the strength of the SpikeTA effect, to whether the effect was pure versus synchrony, or to the number of muscles influenced by the neuron. Nevertheless, the sum of M1 neuron activity patterns, each weighted by the sign and strength of its SpikeTA effect, could be more similar to the EMG than the average similarity of individual neurons. Significant correlations between the weighted sum of M1 neuron activity patterns and EMG were obtained in six of 17 muscles, but showed R2 values ranging from only 0.26 to 0.42. These observations suggest that additional factors—including inputs from sources other than M1 and nonlinear summation of inputs to motoneuron pools—also contributed substantially to EMG activity patterns. Furthermore, although each of these M1 neurons produced SpikeTA effects with a significant peak or trough 6–16 ms after the triggering spike, shifting the weighted sum of neuron activity to lead the EMG by 40–60 ms increased their similarity, suggesting that the influence of M1 neurons that produce SpikeTA effects includes substantial synaptic integration that in part may reach the motoneuron pools over less-direct pathways.

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Mutations and Protein Interaction Landscape Reveal Key Cellular Events Perturbed in Upper Motor Neurons with HSP and PLS

Brain Sciences ◽

10.3390/brainsci11050578 ◽

2021 ◽

Vol 11 (5) ◽

pp. 578

Author(s):

Oge Gozutok ◽

Benjamin Ryan Helmold ◽

P. Hande Ozdinler

Keyword(s):

Motor Neurons ◽

Protein Interaction ◽

Protein Interactions ◽

Cortical Neurons ◽

Therapeutic Interventions ◽

Functional Identification ◽

Protein Protein Interaction ◽

Cellular Events ◽

Interaction Domains ◽

Upper Motor Neurons

Hereditary spastic paraplegia (HSP) and primary lateral sclerosis (PLS) are rare motor neuron diseases, which affect mostly the upper motor neurons (UMNs) in patients. The UMNs display early vulnerability and progressive degeneration, while other cortical neurons mostly remain functional. Identification of numerous mutations either directly linked or associated with HSP and PLS begins to reveal the genetic component of UMN diseases. Since each of these mutations are identified on genes that code for a protein, and because cellular functions mostly depend on protein-protein interactions, we hypothesized that the mutations detected in patients and the alterations in protein interaction domains would hold the key to unravel the underlying causes of their vulnerability. In an effort to bring a mechanistic insight, we utilized computational analyses to identify interaction partners of proteins and developed the protein-protein interaction landscape with respect to HSP and PLS. Protein-protein interaction domains, upstream regulators and canonical pathways begin to highlight key cellular events. Here we report that proteins involved in maintaining lipid homeostasis and cytoarchitectural dynamics and their interactions are of great importance for UMN health and stability. Their perturbation may result in neuronal vulnerability, and thus maintaining their balance could offer therapeutic interventions.

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MCP1-CCR2 and neuroinflammation in the ALS motor cortex with TDP-43 pathology

Journal of Neuroinflammation ◽

10.1186/s12974-019-1589-y ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 6

Author(s):

Javier H. Jara ◽

Mukesh Gautam ◽

Nuran Kocak ◽

Edward F. Xie ◽

Qinwen Mao ◽

...

Keyword(s):

Motor Cortex ◽

Motor Neuron ◽

Motor Neurons ◽

Neuronal Cells ◽

Treatment Strategies ◽

Brain Parenchyma ◽

Neuroinflammatory Response ◽

Upper Motor Neurons ◽

Als Patients ◽

Betz Cells

Abstract Background The involvement of non-neuronal cells and the cells of innate immunity has been attributed to the initiation and progression of ALS. TDP-43 pathology is observed in a broad spectrum of ALS cases and is one of the most commonly shared pathologies. The potential involvement of the neuroimmune axis in the motor cortex of ALS patients with TDP-43 pathology needs to be revealed. This information is vital for building effective treatment strategies. Methods We investigated the presence of astrogliosis and microgliosis in the motor cortex of ALS patients with TDP-43 pathology. prpTDP-43A315T-UeGFP mice, corticospinal motor neuron (CSMN) reporter line with TDP-43 pathology, are utilized to reveal the timing and extent of neuroimmune interactions and the involvement of non-neuronal cells to neurodegeneration. Electron microscopy and immunolabeling techniques are used to mark and monitor cells of interest. Results We detected both activated astrocytes and microglia, especially rod-like microglia, in the motor cortex of patients and TDP-43 mouse model. Besides, CCR2+ TMEM119- infiltrating monocytes were detected as they penetrate the brain parenchyma. Interestingly, Betz cells, which normally do not express MCP1, were marked with high levels of MCP1 expression when diseased. Conclusions There is an early contribution of a neuroinflammatory response for upper motor neuron (UMN) degeneration with respect to TDP-43 pathology, and MCP1-CCR2 signaling is important for the recognition of diseased upper motor neurons by infiltrating monocytes. The findings are conserved among species and are observed in both ALS and ALS-FTLD patients.

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Cell-type specific in vitro gene expression profiling of stem-cell derived neural models

10.1101/2020.04.30.064709 ◽

2020 ◽

Author(s):

James A. Gregory ◽

Emily Hoelzli ◽

Rawan Abdelaal ◽

Catherine Braine ◽

Miguel Cuevas ◽

...

Keyword(s):

Stem Cell ◽

Motor Neurons ◽

Molecular Mechanisms ◽

Induced Pluripotent Stem Cell ◽

Underlying Disease ◽

Mouse Tissue ◽

Cell Type ◽

Primary Mouse ◽

Cell Type Specific

AbstractGenetic and genomic studies of brain disease increasingly demonstrate disease-associated interactions between the cell types of the brain. Increasingly complex and more physiologically relevant human induced pluripotent stem cell (hiPSC)-based models better explore the molecular mechanisms underlying disease, but also challenge our ability to resolve cell-type specific perturbations. Here we report an extension of the RiboTag system, first developed to achieve cell-type restricted expression of epitope-tagged ribosomal protein (RPL22) in mouse tissue, to a variety of in vitro applications, including immortalized cell lines, primary mouse astrocytes, and hiPSC-derived neurons. RiboTag expression enables efficient depletion of off-target RNA in mixed species primary co-cultures and in hiPSC-derived neural progenitor cells, motor neurons, and GABAergic neurons. Nonetheless, depletion efficiency varies across independent experimental replicates. The challenges and potential of implementing RiboTags in complex in vitro cultures are discussed.

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Cell Type-Specific In Vitro Gene Expression Profiling of Stem Cell-Derived Neural Models

Cells ◽

10.3390/cells9061406 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1406

Author(s):

James A. Gregory ◽

Emily Hoelzli ◽

Rawan Abdelaal ◽

Catherine Braine ◽

Miguel Cuevas ◽

...

Keyword(s):

Stem Cell ◽

Motor Neurons ◽

Molecular Mechanisms ◽

Induced Pluripotent Stem Cell ◽

Underlying Disease ◽

Mouse Tissue ◽

Cell Type ◽

Primary Mouse ◽

Cell Type Specific

Genetic and genomic studies of brain disease increasingly demonstrate disease-associated interactions between the cell types of the brain. Increasingly complex and more physiologically relevant human-induced pluripotent stem cell (hiPSC)-based models better explore the molecular mechanisms underlying disease but also challenge our ability to resolve cell type-specific perturbations. Here, we report an extension of the RiboTag system, first developed to achieve cell type-restricted expression of epitope-tagged ribosomal protein (RPL22) in mouse tissue, to a variety of in vitro applications, including immortalized cell lines, primary mouse astrocytes, and hiPSC-derived neurons. RiboTag expression enables depletion of up to 87 percent of off-target RNA in mixed species co-cultures. Nonetheless, depletion efficiency varies across independent experimental replicates, particularly for hiPSC-derived motor neurons. The challenges and potential of implementing RiboTags in complex in vitro cultures are discussed.

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Local Application of Dopamine Inhibits Pyramidal Tract Neuron Activity in the Rodent Motor Cortex

Journal of Neurophysiology ◽

10.1152/jn.00078.2002 ◽

2002 ◽

Vol 88 (6) ◽

pp. 3439-3451 ◽

Cited By ~ 30

Author(s):

Patrick W. Awenowicz ◽

Linda L. Porter

Keyword(s):

Motor Cortex ◽

Dopamine Receptors ◽

Spontaneous Activity ◽

Cortical Neurons ◽

Pyramidal Tract ◽

D2 Receptor ◽

Simultaneous Recording ◽

Neuron Activity ◽

Receptor Subtypes ◽

Baseline Levels

Cortical neurons respond in a variety of ways to locally applied dopamine, perhaps because of the activation of different receptors within or among subpopulations of cells. This study was conducted to assess the effects of dopamine and the receptor subtypes that mediate the responses of a specific population of neurons, the pyramidal tract neurons (PTNs) in the rodent motor cortex. The specific subfamilies of dopamine receptors expressed by PTNs also were determined. PTNs were identified by antidromic stimulation in intact animals. Extracellular recordings of their spontaneous activity and glutamate-induced excitation were performed with multi-barrel pipettes to allow simultaneous recording and iontophoresis of several drugs. Prolonged (30 s) application of dopamine caused a progressive, nonlinear decrease in spontaneous firing rates for nearly all PTNs, with significant reductions from baseline spontaneous activity (71% of baseline levels) occurring between 20 and 30 s of iontophoresis. The D1 selective (SCH23390) and the D2 selective (eticlopride) antagonists were both effective in blocking dopamine-induced inhibition in nearly all PTNs. Mean firing levels were maintained within 3% of baseline levels during co-application of the D1 antagonist with dopamine and within 11% of baseline levels during co-application of the D2 antagonist and dopamine. SCH23390 was ineffective however, in 2 of 16 PTNs, and eticlopride was ineffective in 3 PTNs. The dopamine blockade by both antagonists in most neurons, along with the selective blockade by one, but not the other antagonist in a few neurons indicate that the overall population of PTNs exhibits a heterogeneous expression of dopamine receptors. The firing rate of PTNs was significantly enhanced by iontophoresis of glutamate (mean = 141% of baseline levels). These increases were attenuated significantly (mean= 98% of baseline) by co-application with dopamine in all PTNs, indicating dopaminergic interactions with glutamate transmission. The expression of dopamine receptors was studied with dual-labeling techniques. PTNs were identified by retrograde labeling with fast blue and the D1a, D2, or D5 receptor proteins were stained immunohistochemically. Some, but not all PTNs, showed labeling for D1a, D2, or D5 receptors. The D1a and D2 receptor immunoreactivity was observed primarily in the somata of PTNs, whereas D5 immunoreactivity extended well into the apical dendrites of PTNs. In accordance with findings of D1 and D2 receptor antagonism of dopamine's actions, the identification of three DA receptor subtypes on PTNs suggests that dopamine can directly modulate PTN activity through one or more receptor subtypes.

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Hindbrain V2a neurons impose rhythmic activity on motor neurons in anin vitroreticulospinal circuit

10.1101/620674 ◽

2019 ◽

Author(s):

Adele V Bubnys ◽

Hagar Kandel ◽

Lee-Ming Kow ◽

Donald W Pfaff ◽

Inna Tabansky

Keyword(s):

Spinal Cord ◽

Motor Neurons ◽

Complex Mixture ◽

Cell Types ◽

Neuron Activity ◽

Neuronal Cultures ◽

Cell Type ◽

Medullary Reticular Formation ◽

Spinal Motor

AbstractThe reticulospinal system is an evolutionarily conserved pathway among vertebrates that relays locomotor control signals from the hindbrain to the spinal cord. Recent studies have identified specific hindbrain cell types that participate in this circuit, including Chx10+neurons of the medullary reticular formation, which project to the spinal cord and are active during periods of locomotion. To create a system in which reticulospinal neurons communicate with spinal motor effectors, we have constructed anin vitromodel using two purified excitatory neuronal subtypes: HB9+spinal motor neurons and Chx10+hindbrain neurons. Cultured separately, these neurons exhibit cell type-specific patterns of activity; the Chx10+cultures developed regular, synchronized bursts of activity that recruited neurons across the entire culture, whereas motor neuron activity consisted of an irregular pattern. A combination of the two subtypes produced cultures in which Chx10+neurons recruited the motor neurons into synchronized network bursts, which were dependent on AMPA receptors. In addition to demonstrating that the activity ofin vitronetworks can depend on the developmental identity of their constituent neurons, we provide a new model with genetically specified nerve cell types to study the activity of a reticulospinal circuit.Significance statementModels of the brain that use cultured neurons are usually comprised of a complex mixture of different kinds of cells, making it hard to determine how each cell type contributes to the overall pattern of activity. We made a simplified culture containing two cell types known to form a reticulospinal circuitin vivo. While in isolated cultures, each cell type had a distinct pattern of activity, in coculture the activity of one cell type came to dominate, indicating that the patterns observed in complex neuronal cultures arise in part from the distinctive properties of the constituent neurons.

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Excitability of human motor cortex during hyperventilation and hypercapnia

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y94-128 ◽

1994 ◽

Vol 72 (8) ◽

pp. 909-913 ◽

Cited By ~ 5

Author(s):

K. Kong ◽

C. Ukachoke ◽

P. Ashby ◽

K. R. Chapman

Keyword(s):

Motor Cortex ◽

Cortical Neurons ◽

Healthy Subjects ◽

Magnetic Stimulation ◽

Motor Units ◽

Spinal Motoneurons ◽

Human Motor Cortex ◽

Corticospinal Pathway ◽

Human Motor ◽

End Tidal

We tested the hypothesis that the excitability of corticospinal neurons was altered by changes in [Formula: see text]. Magnetic stimulation was used to excite the neurons in the human motor cortex that give rise to the fast-conducting corticospinal pathway. The characteristics of the composite excitatory postsynaptic potentials (EPSPs) produced in individual spinal motoneurons by cortical stimulation were derived from changes in the firing probability of voluntarily activated motor units. The amplitudes of these composite EPSPs in response to a constant cortical stimulus were assumed to reflect the excitability of cortical neurons. In 10 healthy subjects, we found no statistically significant changes in the excitability of the cortical neurons during normocapnic conditions (mean end-tidal [Formula: see text] 5.1 kPa), during hyperventilation-induced hypocapnia (mean end-tidal [Formula: see text] 2.9 kPa), and during hyperoxic hypercapnia induced by a rebreathing technique (mean end-tidal [Formula: see text] 6.9 kPa). We conclude that the excitability of corticospinal neurons activated by magnetic stimulation is not significantly affected by changes in [Formula: see text].Key words: corticospinal neurons, [Formula: see text], magnetic stimulation.

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