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Abstracts

A Novel Anti-seizure Medication Targeting G Protein-gated Inwardly Rectifying Potassium (GIRK) Channels

Abstract number : 1.269
Submission category : 7. Anti-seizure Medications / 7A. Animal Studies
Year : 2023
Submission ID : 30
Source : www.aesnet.org
Presentation date : 12/2/2023 12:00:00 AM
Published date :

Authors :
Presenting Author: Robert Rifkin, MD, PhD – Columbia University

Brianna Pereira, BS – Columbia University; Xiaoping Wu, MD – Columbia University; Edward Merricks, PhD – Columbia University; Brian Gill, MD – Columbia University; Paul Slesinger, PhD – Icahn School of Medicine at Mount Sinai; Peter Canoll, MD, PhD – Columbia University; Catherine Schevon, MD, PhD – Columbia University

Rationale:
G protein-gated inwardly rectifying potassium (GIRK) channels regulate neuronal excitability and may contribute to epilepsy if disregulated. However, there is currently no anti-seizure medication targeting GIRKs. Recently, a highly selective GIRK1/2 agonist, G protein-independent GIRK Activator 1 (GiGA1), has been developed (1).
Methods:
We utilized an established mouse model of tumor-associated epilepsy (TAE) in which mouse glioma cells are injected into the frontal cortex of adult wild-type (WT) mice, or mice expressing the calcium sensor GCaMP in excitatory neurons (Thy1-GCaMP mice) (2,3). Mice were sacrificed 28-35 days after injection and 400 µm coronal slices were recorded on a 96-electrode Utah array and using wide-field calcium imaging.

We utilized two experimental paradigms: a prevention paradigm in which slices were exposed to artificial cerebrospinal fluid containing zero-Mg2+ (ZMG-ACSF) containing either vehicle (DMSO) or drug (100 µM GiGA1) for 30 minutes; and a treatment paradigm in which slices received ZMG-ACSF containing vehicle for 20 minutes, then ZMG-ACSF with 100 µM GiGA1 for 20 minutes.

Wilcoxon rank-sum test or Wilcoxon signed-rank test were used for unpaired or paired analyses respectively.
Results:
First, we tested GiGA1 in the prevention paradigm using slices from WT mice without tumors. GiGA1 reduced Local Field Potential (LFP) cumulative line-length (p = 0.0172; n = 10 slices; 6 mice), peak amplitude (p = 0.0035, n = 11 slices) and peak frequency (p = 0.0006).

Second, in the treatment paradigm using slices from WT mice injected with glioma (Figure 1), GiGA1 reduced LFP line-length (p = 1.6874 x 10-18, n = 106 channels, 5 slices), peak amplitude (p = 2.7498 x 10-22, n = 129 channels) and peak frequency (p = 3.2934 x 10-10; n = 141 channels).

Third, in the treatment paradigm in slices from Thy1-GCaMP mice injected with glioma (Figure 2), GiGA1 decreased LFP line-length (p = 4.0882 x 10-17, n = 121 channels, 8 slices), peak amplitude (p = 3.2023 x 10-14, n = 110 channels) and peak frequency (p = 0.0014; n = 129 channels). Similarly, in calcium recordings, GiGA1 decreased calcium peak amplitude (p = 4.113 x 10-30, n = 517 ROIs), frequency (p = 6.0131 x 10-93, n = 561 ROIs), and the correlation between adjacent regions of interest as measured by Pearson correlation (p = 5.2459 x 10-84, n = 612 ROIs).

Conclusions:
These findings suggest that GIRK channels are a potential new target for anti-seizure medications, and that dysregulation of GIRK channels  may play a role in the pathogenesis of focal neocortical seizures.

1. Zhao, Y. et al. Identification of a G-Protein-Independent Activator of GIRK Channels. Cell Rep 31, 107770 (2020).

2. Gill, B. J. A. et al. Single unit analysis and wide-field imaging reveal alterations in excitatory and inhibitory neurons in glioma. Brain awac168 (2022) doi:10.1093/brain/awac168.

3. Gill, B. J. A. et al. Ex vivo multi-electrode analysis reveals spatiotemporal dynamics of ictal behavior at the infiltrated margin of glioma. Neurobiology of Disease 134, 104676 (2020).

 



Funding: NINDS R25 Grant (R25 NS070697)
New York Presbyterian Rhodes Center for Glioblastoma

Anti-seizure Medications