Ballistic labeling and dynamic imaging of astrocytes in organotypic hippocampal slice cultures

Benediktsson, Adrienne M.; Schachtele, Scott J.; Green, Steven H.; Dailey, Michael E.

doi:10.1016/j.jneumeth.2004.05.013

Cited by 166 publications

(165 citation statements)

References 112 publications

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“…Astrocytes can contact up to 100,000 synapses [55], and while they may work as a syncytium propagating calcium waves over long distances [7,56], it has been proposed that they might be able to differentiate between individual inputs [57]. Our experiments using single-synapse photoactivation show that the regulation of PAP motility and synapse stability is synapse specific, consistent with the notion that Ca 2+ transients can occur in defined microdomains of astrocytic processes [15,16,29,58]. Through these spatially restricted mechanisms, astrocytes can participate in controlling the function and stability of individual synapses and thereby contribute to the specificity of learning-related structural rearrangements [26].…”

Section: Discussionsupporting

confidence: 86%

Activity-Dependent Structural Plasticity of Perisynaptic Astrocytic Domains Promotes Excitatory Synapse Stability

et al. 2014

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SummaryBackground: Excitatory synapses in the CNS are highly dynamic structures that can show activity-dependent remodeling and stabilization in response to learning and memory. Synapses are enveloped with intricate processes of astrocytes known as perisynaptic astrocytic processes (PAPs). PAPs are motile structures displaying rapid actin-dependent movements and are characterized by Ca 2+ elevations in response to neuronal activity. Despite a debated implication in synaptic plasticity, the role of both Ca 2+ events in astrocytes and PAP morphological dynamics remain unclear. Results: In the hippocampus, we found that PAPs show extensive structural plasticity that is regulated by synaptic activity through astrocytic metabotropic glutamate receptors and intracellular calcium signaling. Synaptic activation that induces long-term potentiation caused a transient PAP motility increase leading to an enhanced astrocytic coverage of the synapse. Selective activation of calcium signals in individual PAPs using exogenous metabotropic receptor expression and two-photon uncaging reproduced these effects and enhanced spine stability. In vivo imaging in the somatosensory cortex of adult mice revealed that increased neuronal activity through whisker stimulation similarly elevates PAP movement. This in vivo PAP motility correlated with spine coverage and was predictive of spine stability. Conclusions: This study identifies a novel bidirectional interaction between synapses and astrocytes, in which synaptic activity and synaptic potentiation regulate PAP structural plasticity, which in turn determines the fate of the synapse. This mechanism may represent an important contribution of astrocytes to learning and memory processes.

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Section: Discussionsupporting

confidence: 86%

Activity-Dependent Structural Plasticity of Perisynaptic Astrocytic Domains Promotes Excitatory Synapse Stability

et al. 2014

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“…In acute brain slices some mobile astrocytic processes can be detected (Hirrlinger et al, 2004; Nishida and Okabe, 2007; Nixdorf‐Bergweiler et al, 1994). Very fine, and apparently highly mobile, astrocytic processes have been reported in organotypic brain slices using a membrane‐bound GFP (Benediktsson et al, 2005). Furthermore, co‐labeling of dendritic spines and PAPs in hippocampal (Halassa et al, 2007a; Perez‐Alvarez et al, 2014; Verbich et al, 2012) and cerebellar slices (Lippman Bell et al, 2010; Lippman et al, 2008) as well as in vivo (Bernardinelli et al, 2014b; Perez‐Alvarez et al, 2014) suggested that PAPs are highly dynamic structures that engage and disengage with dendritic spines, also responding to the induction of synaptic plasticity (Bernardinelli et al, 2014b; Perez‐Alvarez et al, 2014).…”

Section: Current Methods To Monitor Fine Astrocyte Morphology: Promismentioning

confidence: 99%

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Heller

Rusakov

2015

Glia

135

137

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Memory formation in the brain is thought to rely on the remodeling of synaptic connections which eventually results in neural network rewiring. This remodeling is likely to involve ultrathin astroglial protrusions which often occur in the immediate vicinity of excitatory synapses. The phenomenology, cellular mechanisms, and causal relationships of such astroglial restructuring remain, however, poorly understood. This is in large part because monitoring and probing of the underpinning molecular machinery on the scale of nanoscopic astroglial compartments remains a challenge. Here we briefly summarize the current knowledge regarding the cellular organisation of astroglia in the synaptic microenvironment and discuss molecular mechanisms potentially involved in use‐dependent astroglial morphogenesis. We also discuss recent observations concerning morphological astroglial plasticity, the respective monitoring methods, and some of the newly emerging techniques that might help with conceptual advances in the area. GLIA 2015;63:2133–2151

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“…Preparations of the DiOlistic bullets were based on the method of Gan et al (2000) and Benediktsson et al (2005). Briefly, 2-4 mg of DiI (D282; Invitrogen) or DiD (D307; Invitrogen) was dissolved in 200 l of methylene chloride (Sigma-Aldrich) and added to 0.05 g of gold or tungsten, dried, then dissolved in 3 ml of double-distilled H 2 O.…”

Section: Diolistic Labelingmentioning

confidence: 99%

“…1 A, B,E-G). Lipophilic dyes are incorporated throughout the plasma membrane, revealing the full structure of the cell, including fine laminate processes that are GFAP negative (Benediktsson et al, 2005). Because the majority of astrocytes in the adult mouse cortex express low levels of GFAP, we initially diolistically labeled astrocytes in transgenic mice expressing eGFP under the astrocyte-specific promoter hGFAP (supplemental Fig.…”

Section: Cortical Astrocytes Are Organized In Nonoverlapping Domainsmentioning

confidence: 99%

Loss of Astrocytic Domain Organization in the Epileptic Brain

et al. 2008

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Gliosis is a pathological hallmark of posttraumatic epileptic foci, but little is known about these reactive astrocytes beyond their high glial fibrillary acidic protein (GFAP) expression. Using diolistic labeling, we show that cortical astrocytes lost their nonoverlapping domain organization in three mouse models of epilepsy: posttraumatic injury, genetic susceptibility, and systemic kainate exposure. Neighboring astrocytes in epileptic mice showed a 10-fold increase in overlap of processes. Concurrently, spine density was increased on dendrites of excitatory neurons. Suppression of seizures by the common antiepileptic, valproate, reduced the overlap of astrocytic processes. Astrocytic domain organization was also preserved in APP transgenic mice expressing a mutant variant of human amyloid precursor protein despite a marked upregulation of GFAP. Our data suggest that loss of astrocytic domains was not universally associated with gliosis, but restricted to seizure pathologies. Reorganization of astrocytes may, in concert with dendritic sprouting and new synapse formation, form the structural basis for recurrent excitation in the epileptic brain.

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Ballistic labeling and dynamic imaging of astrocytes in organotypic hippocampal slice cultures

Cited by 166 publications

References 112 publications

Activity-Dependent Structural Plasticity of Perisynaptic Astrocytic Domains Promotes Excitatory Synapse Stability

Activity-Dependent Structural Plasticity of Perisynaptic Astrocytic Domains Promotes Excitatory Synapse Stability

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Loss of Astrocytic Domain Organization in the Epileptic Brain

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