Striatal seeding of protofibrillar alpha-synuclein causes cortical hyperreactivity in behaving mice

SummaryAlpha-synucleinopathies are characterized by self-aggregation of the protein alpha-synuclein (a-syn), causing alterations on the molecular and cellular level. To unravel the impact of transneuronal spreading and templated misfolding of a-syn on the microcircuitry of remotely connected brain areas, we investigated cortical neuron function in awake mice 9 months after a single intrastriatal injection of a-syn preformed fibrils (PFFs), using in vivo two-photon calcium imaging. We found altered function of layer 2/3 cortical neurons in somatosensory cortex (S1) of PFF-inoculated mice, as witnessed by an enhanced response to whisking and increased synchrony, accompanied by a decrease in baseline Ca2+ levels. Stereological analyses revealed a reduction in GAD67-positive inhibitory cells in S1 in PFF-injected brains. These findings point to a disturbed excitation/inhibition balance as an important pathomechanism in alpha-synucleinopathies and demonstrate a clear association between the spread of toxic proteins and the initiation of altered neuronal function in remotely connected areas.

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Cortical Circuit Dysfunction in a Mouse Model of Alpha-synucleinopathy in Vivo

10.21203/rs.3.rs-112938/v1 ◽

2020 ◽

Author(s):

Sonja Blumenstock ◽

Fanfan Sun ◽

Petar Marinkovic ◽

Carmelo Sgobio ◽

Sabine Liebscher ◽

...

Keyword(s):

Cerebral Cortex ◽

Cortical Neurons ◽

Lewy Body Dementia ◽

Alpha Synuclein ◽

Cognitive Changes ◽

Two Photon ◽

Cortical Circuit ◽

Cortical Dysfunction ◽

Intrastriatal Injection

Abstract Considerable fluctuations in cognitive performance and eventual dementia are an important characteristic of alpha-synucleinopathies, such as Parkinson’s disease (PD) and Lewy Body dementia (LBD) and are linked to cortical dysfunction. The presence of misfolded and aggregated alpha-synuclein (a-syn) in the cerebral cortex of patients has been suggested to play a crucial role in this process. However, the consequences of a-syn accumulation on the function of cortical networks at cellular resolution in vivo are largely unknown. Here we used the striatal seeding model in wildtype mice in order to induce robust a-synuclein pathology in the cerebral cortex. 9 months after a single intrastriatal injection of a-syn preformed fibrils, we performed in vivo two-photon calcium imaging in awake mice. We observed profound alterations of the function of layer 2/3 cortical neurons in somatosensory cortex (S1), as witnessed by an enhanced response to whisking and increased synchrony, accompanied by a decrease in baseline Ca2+ levels. Stereological analyses revealed a reduction in GAD67-positive inhibitory cells in S1 in PFF-injected brains. These findings point to a disturbed excitation/inhibition balance as an important driver of circuit dysfunction in alpha-synucleinopathies, which may underly cognitive changes in these diseases.

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Microglia motility depends on neuronal activity and promotes structural plasticity in the hippocampus

10.1101/515759 ◽

2019 ◽

Cited By ~ 1

Author(s):

Felix C. Nebeling ◽

Stefanie Poll ◽

Lena C. Schmid ◽

Manuel Mittag ◽

Julia Steffen ◽

...

Keyword(s):

Neuronal Activity ◽

Dendritic Spines ◽

Synapse Formation ◽

Brain Parenchyma ◽

Two Photon ◽

Contact Rates ◽

Health And Disease ◽

The Impact ◽

The Brain

AbstractMicroglia, the resident immune cells of the brain, play a complex role in health and disease. They actively survey the brain parenchyma by physically interacting with other cells and structurally shaping the brain. Yet, the mechanisms underlying microglia motility and their significance for synapse stability, especially during adulthood, remain widely unresolved. Here we investigated the impact of neuronal activity on microglia motility and its implication for synapse formation and survival. We used repetitive two-photon in vivo imaging in the hippocampus of awake mice to simultaneously study microglia motility and their interaction with synapses. We found that microglia process motility depended on neuronal activity. Simultaneously, more dendritic spines emerged in awake compared to anesthetized mice. Interestingly, microglia contact rates with individual dendritic spines were associated with their stability. These results suggest that microglia are not only sensing neuronal activity, but participate in synaptic rewiring of the hippocampus during adulthood, which has profound relevance for learning and memory processes.

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Essential Roles in Development and Pigmentation for the Drosophila Copper Transporter DmATP7

Molecular Biology of the Cell ◽

10.1091/mbc.e05-06-0492 ◽

2006 ◽

Vol 17 (1) ◽

pp. 475-484 ◽

Cited By ~ 53

Author(s):

Melanie Norgate ◽

Esther Lee ◽

Adam Southon ◽

Ashley Farlow ◽

Philip Batterham ◽

...

Keyword(s):

Copper Homeostasis ◽

Cellular Level ◽

Loss Of Function ◽

Neuronal Function ◽

Copper Transporter ◽

Disease Phenotypes ◽

In Vivo Analysis ◽

Cellular Copper ◽

P Type

Defects in the mammalian Menkes and Wilson copper transporting P-type ATPases cause severe copper homeostasis disease phenotypes in humans. Here, we find that DmATP7, the sole Drosophila orthologue of the Menkes and Wilson genes, is vital for uptake of copper in vivo. Analysis of a DmATP7 loss-of-function allele shows that DmATP7 is essential in embryogenesis, early larval development, and adult pigmentation and is probably required for copper uptake from the diet. These phenotypes are analogous to those caused by mutation in the mouse and human Menkes genes, suggesting that like Menkes, DmATP7 plays at least two roles at the cellular level: delivering copper to cuproenzymes required for pigmentation and neuronal function and removing excess cellular copper via facilitated efflux. DmATP7 displays a dynamic and unexpected expression pattern in the developing embryo, implying novel functions for this copper pump and the lethality observed in DmATP7 mutant flies is the earliest seen for any copper homeostasis gene.

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In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

Journal of Visualized Experiments ◽

10.3791/50148 ◽

2013 ◽

Cited By ~ 4

Author(s):

Vania Y. Cao ◽

Yizhou Ye ◽

Surjeet S. Mastwal ◽

David M. Lovinger ◽

Rui M. Costa ◽

...

Keyword(s):

Cortical Neurons ◽

Molecular Changes ◽

Two Photon ◽

Photon Imaging ◽

Two Photon Imaging

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Temporally precise control of single-neuron spiking by juxtacellular nanostimulation

Journal of Neurophysiology ◽

10.1152/jn.00479.2016 ◽

2017 ◽

Vol 117 (3) ◽

pp. 1363-1378 ◽

Cited By ~ 4

Author(s):

Maik C. Stüttgen ◽

Lourens J. P. Nonkes ◽

H. Rüdiger A. P. Geis ◽

Paul H. Tiesinga ◽

Arthur R. Houweling

Keyword(s):

Short Duration ◽

Cortical Neurons ◽

Action Potentials ◽

Neural Coding ◽

Spike Trains ◽

Precise Control ◽

Neuronal Spike Trains ◽

The Impact ◽

Activity Dependent

Temporal patterns of action potentials influence a variety of activity-dependent intra- and intercellular processes and play an important role in theories of neural coding. Elucidating the mechanisms underlying these phenomena requires imposing spike trains with precisely defined patterns, but this has been challenging due to the limitations of existing stimulation techniques. Here we present a new nanostimulation method providing control over the action potential output of individual cortical neurons. Spikes are elicited through the juxtacellular application of short-duration fluctuating currents (“kurzpulses”), allowing for the sub-millisecond precise and reproducible induction of arbitrary patterns of action potentials at all physiologically relevant firing frequencies (<120 Hz), including minute-long spike trains recorded in freely moving animals. We systematically compared our method to whole cell current injection, as well as optogenetic stimulation, and show that nanostimulation performance compares favorably with these techniques. This new nanostimulation approach is easily applied, can be readily performed in awake behaving animals, and thus promises to be a powerful tool for systematic investigations into the temporal elements of neural codes, as well as the mechanisms underlying a wide variety of activity-dependent cellular processes. NEW & NOTEWORTHY Assessing the impact of temporal features of neuronal spike trains requires imposing arbitrary patterns of spiking on individual neurons during behavior, but this has been difficult to achieve due to limitations of existing stimulation methods. We present a technique that overcomes these limitations by using carefully designed short-duration fluctuating juxtacellular current injections, which allow for the precise and reliable evocation of arbitrary patterns of neuronal spikes in single neurons in vivo.

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All-optical interrogation of neural circuits in behaving mice

10.1101/2021.06.29.450430 ◽

2021 ◽

Author(s):

Lloyd E. Russell ◽

Henry W.P. Dalgleish ◽

Rebecca Nutbrown ◽

Oliver Gauld ◽

Dustin Herrmann ◽

...

Keyword(s):

Neural Circuits ◽

Neural Circuit ◽

Barrel Cortex ◽

Brain Area ◽

Imaging Data ◽

Temporal Precision ◽

Two Photon ◽

All Optical ◽

The Impact

Recent advances combining two-photon calcium imaging and two-photon optogenetics with digital holography now allow us to read and write neural activity in vivo at cellular resolution with millisecond temporal precision. Such 'all-optical' techniques enable experimenters to probe the impact of functionally defined neurons on neural circuit function and behavioural output with new levels of precision. This protocol describes the experimental strategy and workflow for successful completion of typical all-optical interrogation experiments in awake, behaving head-fixed mice. We describe modular procedures for the setup and calibration of an all-optical system, the preparation of an indicator and opsin-expressing and task-performing animal, the characterization of functional and photostimulation responses and the design and implementation of an all-optical experiment. We discuss optimizations for efficiently selecting and targeting neuronal ensembles for photostimulation sequences, as well as generating photostimulation response maps from the imaging data that can be used to examine the impact of photostimulation on the local circuit. We demonstrate the utility of this strategy using all-optical experiments in three different brain areas - barrel cortex, visual cortex and hippocampus - using different experimental setups. This approach can in principle be adapted to any brain area for all-optical interrogation experiments to probe functional connectivity in neural circuits and for investigating the relationship between neural circuit activity and behaviour.

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Unraveling the Spatiotemporal Distribution of VPS13A in the Mouse Brain

International Journal of Molecular Sciences ◽

10.3390/ijms222313018 ◽

2021 ◽

Vol 22 (23) ◽

pp. 13018

Author(s):

Esther García-García ◽

Nerea Chaparro-Cabanillas ◽

Albert Coll-Manzano ◽

Maria Carreras-Caballé ◽

Albert Giralt ◽

...

Keyword(s):

Mouse Brain ◽

Cortical Neurons ◽

Expression Profiles ◽

Cholinergic Neurons ◽

Relevant Information ◽

Cellular Level ◽

Spatiotemporal Distribution ◽

Loss Of Function ◽

Vacuolar Protein

Loss-of-function mutations in the human vacuolar protein sorting the 13 homolog A (VPS13A) gene cause Chorea-acanthocytosis (ChAc), with selective degeneration of the striatum as the main neuropathologic feature. Very little is known about the VPS13A expression in the brain. The main objective of this work was to assess, for the first time, the spatiotemporal distribution of VPS13A in the mouse brain. We found VPS13A expression present in neurons already in the embryonic stage, with stable levels until adulthood. VPS13A mRNA and protein distributions were similar in the adult mouse brain. We found a widespread VPS13A distribution, with the strongest expression profiles in the pons, hippocampus, and cerebellum. Interestingly, expression was weak in the basal ganglia. VPS13A staining was positive in glutamatergic, GABAergic, and cholinergic neurons, but rarely in glial cells. At the cellular level, VPS13A was mainly located in the soma and neurites, co-localizing with both the endoplasmic reticulum and mitochondria. However, it was not enriched in dendritic spines or the synaptosomal fraction of cortical neurons. In vivo pharmacological modulation of the glutamatergic, dopaminergic or cholinergic systems did not modulate VPS13A concentration in the hippocampus, cerebral cortex, or striatum. These results indicate that VPS13A has remarkable stability in neuronal cells. Understanding the distinct expression pattern of VPS13A can provide relevant information to unravel pathophysiological hallmarks of ChAc.

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Intravital imaging of cerebral microinfarct reveals an astrocyte reaction led to glial scar

10.1101/2021.09.29.462492 ◽

2021 ◽

Author(s):

Jingu Lee ◽

Joon-Goon Kim ◽

Sujung Hong ◽

Young Seo Kim ◽

Soyeon Ahn ◽

...

Keyword(s):

Monoamine Oxidase ◽

Brain Tissue ◽

Neuronal Death ◽

Cellular Level ◽

Intravital Imaging ◽

Monoamine Oxidase B ◽

Infarct Area ◽

The Impact ◽

The Brain

AbstractCerebral microinfarct increases the risk of dementia. But how microscopic cerebrovascular disruption affects the brain tissue in cellular-level are mostly unknown. Herein, with a longitudinal intravital imaging, we serially visualized in vivo dynamic cellular-level changes in astrocyte, pericyte and neuron as well as microvascular integrity after the induction of cerebral microinfarction for 1 month in mice. At day 2-3, it revealed a localized edema with acute astrocyte loss, neuronal death, impaired pericyte-vessel coverage and extravascular leakage indicating blood-brain barrier (BBB) dysfunction. At day 5, edema disappeared with recovery of pericyte-vessel coverage and BBB integrity. But brain tissue continued to shrink with persisted loss of astrocyte and neuron in microinfarct until 30 days, resulting in a collagen-rich fibrous scar surrounding the microinfarct. Notably, reactive astrocytes appeared at the peri-infarct area early at day 2 and thereafter accumulated in the peri-infarct. Oral administration of a reversible monoamine oxidase B inhibitor significantly decreased the astrocyte reactivity and fibrous scar formation. Our result suggests that astrocyte reactivity may be a key target to alleviate the impact of microinfarction.

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Alpha-Synuclein Aggregation Induced by Brief Ischemia Negatively Impacts Neuronal Survival in vivo: A Study in [A30P]alpha-Synuclein Transgenic Mouse

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2010.170 ◽

2010 ◽

Vol 31 (3) ◽

pp. 913-923 ◽

Cited By ~ 24

Author(s):

Isin Unal-Cevik ◽

Yasemin Gursoy-Ozdemir ◽

Muge Yemisci ◽

Sevda Lule ◽

Gunfer Gurer ◽

...

Keyword(s):

Transgenic Mice ◽

Neuronal Survival ◽

Alpha Synuclein ◽

In Vivo Model ◽

Neuronal Necrosis ◽

Mca Occlusion ◽

Nitrative Stress ◽

The Impact

Alpha-synuclein oligomerization and aggregation are considered to have a role in the pathogenesis of neurodegenerative diseases. However, despite numerous in vitro studies, the impact of aggregates in the intact brain is unclear. In vitro, oxidative/nitrative stress and acidity induce α-synuclein oligomerization. These conditions favoring α-synuclein fibrillization are present in the ischemic brain, which may serve as an in vivo model to study α-synuclein aggregation. In this study, we show that 30-minute proximal middle cerebral artery (MCA) occlusion and 72 hours reperfusion induce oligomerization of wild-type α-synuclein in the ischemic mouse brain. The nonamyloidogenic isoform β-synuclein did not form oligomers. Alpha-synuclein aggregates were confined to neurons and colocalized with ubiquitin immunoreactivity. We also found that 30 minutes proximal MCA occlusion and 24 hours reperfusion induced larger infarcts in C57BL/6(Thy1)-h[A30P]alphaSYN transgenic mice, which have an increased tendency to form synuclein fibrils. Trangenics also developed more selective neuronal necrosis when subjected to 20 minutes distal MCA occlusion and 72 hours reperfusion. Enhanced 3-nitrotyrosine immunoreactivity in transgenic mice suggests that oxidative/nitrative stress may be one of the mechanisms mediating aggregate toxicity. Thus, the increased vulnerability of transgenic mice to ischemia suggests that α-synuclein aggregates not only form during ischemia but also negatively impact neuronal survival, supporting the idea that α-synuclein misfolding may be neurotoxic.

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