GABAergic disinhibition and impaired KCC2 cotransporter activity underlie tumor‐associated epilepsy. Issue 1 (26th July 2014)

• Record Type: Journal Article
• Authors: Campbell, Susan L.; Robel, Stefanie; Cuddapah, Vishnu A.; Robert, Stephanie; Buckingham, Susan C.; Kahle, Kristopher T.; Sontheimer, Harald
• Is Part Of: Glia. Volume 63:Issue 1(2015:Jan.)
• Page Start: 23
• Page End: 36
• Publication Date: 2014-07-26
• Subjects: Neuroglia -- Periodicals; Neurology -- Periodicals; 611.0188
• DOI: 10.1002/glia.22730
• Languages: English
• ISSNs: 0894-1491

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Seizures frequently accompany gliomas and often escalate to peritumoral epilepsy. Previous work revealed the importance of tumor‐derived excitatory glutamate (Glu) release mediated by the cystine‐glutamate transporter (SXC) in epileptogenesis. We now show a novel contribution of GABAergic disinhibition to disease pathophysiology. In a validated mouse glioma model, we found that peritumoral parvalbumin‐positive GABAergic inhibitory interneurons are significantly reduced, corresponding with deficits in spontaneous and evoked inhibitory neurotransmission. Most remaining peritumoral neurons exhibit elevated intracellular Cl⁻ concentration ([Cl⁻]_i) and consequently depolarizing, excitatory gamma‐aminobutyric acid (GABA) responses. In these neurons, the plasmalemmal expression of KCC2, which establishes the low [Cl⁻]_i required for GABA_AR‐mediated inhibition, is significantly decreased. Interestingly, reductions in inhibition are independent of Glu release, but the presence of both decreased inhibition and decreased SXC expression is required for epileptogenesis. We suggest GABAergic disinhibition renders peritumoral neuronal networks hyper‐excitable and susceptible to seizures triggered by excitatory stimuli, and propose KCC2 as a therapeutic target. GLIA 2015;63:23–36</p> </abstract>