Neocortical in vivo focal and spreading potassium responses and the influence of astrocytic gap junctional coupling

EbrahimAmini, Azin; Bazzigaluppi, Paolo; Aquilino, Mark S.; Stefanović, Bojana; Carlen, Peter L.

doi:10.1016/j.nbd.2020.105160

Cited by 10 publications

(21 citation statements)

References 51 publications

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“…Abnormally high levels of [K]o are associated with neurological conditions such as neurotrauma, migraine, stroke, and epilepsy [10,11]. Astrocytes are known to be one of the major factors in regulating [K]o. Astrocytes have a hyperpolarized resting membrane potential and a high permeability to K [12].…”

Section: Discussionmentioning

confidence: 99%

“…The decay time and amplitude of the K response were affected more than the lag time of the spreading responses following optical stimulation. This observation could imply that the astrocytic membrane potential presumably plays a more significant role in regulating the resident/local [K]o and adjusting the concentration of the existing K in the local extracellular space rather than the global distribution of K, whereas astrocytic gap junctional coupling has a more prominent role in speeding up the spread of the spreading K response [11].…”

Section: Discussionmentioning

confidence: 99%

“…The electrodes were pulled borosilicate capillaries (tip diameter~1 µm, World Precision Instruments, Sarasota, FL, USA). In the case of the K-sensitive electrode, the interior wall of the capillary was silanized with dimethyldichlorosilane vapor and dried at 120 • C for 2 h [11]. K-sensitive electrodes were filled with K + ionophore I-cocktail B (Sigma-Aldrich, Oakville, ON, Canada) at the tip and back-filled with 0.2 M KCl solution [11].…”

Section: Electrophysiology: K-sensitive Recording Electrodementioning

confidence: 99%

“…In the case of the K-sensitive electrode, the interior wall of the capillary was silanized with dimethyldichlorosilane vapor and dried at 120 • C for 2 h [11]. K-sensitive electrodes were filled with K + ionophore I-cocktail B (Sigma-Aldrich, Oakville, ON, Canada) at the tip and back-filled with 0.2 M KCl solution [11]. The Ksensitive recording electrodes were then calibrated using different concentrations (0, 2.5, 4.5, 6.5 and 22.5 mM) of KCl solutions.…”

Section: Electrophysiology: K-sensitive Recording Electrodementioning

confidence: 99%

“…A K-sensitive electrode (KE) was coupled with a double-barreled LFP recording electrode, creating a KE-LFP recording electrode. The double-barreled electrode was filled with saline and cemented to the K-sensitive electrode such that the distance between the tips of the electrodes was approximately 50 µm apart [11]. First, the K-sensitive electrode was mounted to a head stage of an Axopatch 200B amplifier.…”

Section: Electrophysiology: 2(ke-lfp) Electrode and Kclmentioning

confidence: 99%

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In Vivo Neocortical [K]o Modulation by Targeted Stimulation of Astrocytes

EbrahimAmini

Mylvaganam

Bazzigaluppi

et al. 2021

IJMS

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A normally functioning nervous system requires normal extracellular potassium ion concentration ([K]o). Throughout the nervous system, several processes, including those of an astrocytic nature, are involved in [K]o regulation. In this study we investigated the effect of astrocytic photostimulation on [K]o. We hypothesized that in vivo photostimulation of eNpHR-expressing astrocytes leads to a decreased [K]o. Using optogenetic and electrophysiological techniques we showed that stimulation of eNpHR-expressing astrocytes resulted in a significantly decreased resting [K]o and evoked K responses. The amplitude of the concomitant spreading depolarization-like events also decreased. Our results imply that astrocytic membrane potential modification could be a potential tool for adjusting the [K]o.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Electrophysiology: K-sensitive Recording Electrodementioning

confidence: 99%

Section: Electrophysiology: K-sensitive Recording Electrodementioning

confidence: 99%

Section: Electrophysiology: 2(ke-lfp) Electrode and Kclmentioning

confidence: 99%

See 3 more Smart Citations

In Vivo Neocortical [K]o Modulation by Targeted Stimulation of Astrocytes

EbrahimAmini

Mylvaganam

Bazzigaluppi

et al. 2021

IJMS

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Overview Article Astrocytes as Initiators of Epilepsy

et al. 2022

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Astrocytes play a dual role in the brain. On the one hand, they are active signaling partners of neurons and can for instance control synaptic transmission and its plasticity. On the other hand, they fulfill various homeostatic functions such as clearance of glutamate and K+ released from neurons. The latter is for instance important for limiting neuronal excitability. Therefore, an impairment or failure of glutamate and K+ clearance will lead to increased neuronal excitability, which could trigger or aggravate brain diseases such as epilepsy, in which neuronal hyperexcitability plays a role. Experimental data indicate that astrocytes could have such a causal role in epilepsy, but the role of astrocytes as initiators of epilepsy and the relevant mechanisms are under debate. In this overview, we will discuss the potential mechanisms with focus on K+ clearance, glutamate uptake and homoeostasis and related mechanisms, and the evidence for their causative role in epilepsy.

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The Role of Astrocytes in Migraine with Cortical Spreading Depression: Protagonists or Bystanders? A Narrative Review

Yang,

Ren,

Pan

et al. 2024

Pain Ther

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Cortical spreading depression (CSD) is a slow wave of cortical depolarization closely associated with migraines with an aura. Previously, it was thought that CSD depolarization was mainly driven by neurons, with characteristic changes in neuronal swelling and increased extracellular potassium (K + ) and glutamate. However, the role of astrocytes, a member of the neurovascular unit, in migraine with CSD has recently received increasing attention. In the early stages of CSD, astrocytes provide neurons with energy support and clear K + and glutamate from synaptic gaps. However, in the late stages of CSD, astrocytes release large amounts of lactic acid to exacerbate hypoxia when the energy demand exceeds the astrocytes’ compensatory capacity. Astrocyte endfoot swelling is a characteristic of CSD, and neurons are not similarly altered. It is primarily due to K + influx and abnormally active calcium (Ca 2+ ) signaling. Aquaporin 4 (AQP-4) only mediates K + influx and has little role as an aquaporin. Astrocytes endfoot swelling causes perivascular space closure, slowing the glymphatic system flow and exacerbating neuroinflammation, leading to persistent CSD. Astrocytes are double-edged swords in migraine with CSD and may be potential targets for CSD interventions.

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Neocortical in vivo focal and spreading potassium responses and the influence of astrocytic gap junctional coupling

Cited by 10 publications

References 51 publications

In Vivo Neocortical [K]o Modulation by Targeted Stimulation of Astrocytes

In Vivo Neocortical [K]o Modulation by Targeted Stimulation of Astrocytes

Overview Article Astrocytes as Initiators of Epilepsy

The Role of Astrocytes in Migraine with Cortical Spreading Depression: Protagonists or Bystanders? A Narrative Review

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