Adenosine A₁ receptor–mediated suppression of carbamazepine‐resistant seizure‐like events in human neocortical slices

Abstract

Zin Juan Klaft is a last year medical student and former member of the Heinemann lab. SUMMARYObjective: The need for alternative pharmacologic strategies in treatment of epilepsies is pressing for about 30% of patients with epilepsy who do not experience satisfactory seizure control with present treatments. In temporal lobe epilepsy (TLE) even up to 80% of patients are pharmacoresistant, and surgical resection of the ictogenic tissue is only possible for a minority of TLE patients. In this study we investigate purinergic modulation of drug-resistant seizure-like events (SLEs) in human temporal cortex slices. Methods: Layer V/VI field potentials from a total of 77 neocortical slices from 17 pharmacoresistant patients were recorded to monitor SLEs induced by application of 8 mM [K + ] and 50 lM bicuculline. Results: Activating A 1 receptors with a specific agonist completely suppressed SLEs in 73% of human temporal cortex slices. In the remaining slices, incidence of SLEs was markedly reduced. Because a subportion of slices can be pharmacosensitive, we tested effects of an A 1 agonist, in slices insensitive to a high dose of carbamazepine (50 lM). Also in these cases the A 1 agonist was equally efficient. Moreover, ATP and adenosine blocked or modulated SLEs, an effect mediated not by P2 receptors but rather by adenosine A 1 receptors. Significance: Selective activation of A 1 receptors mediates a strong anticonvulsant action in human neocortical slices from pharmacoresistant patients. We propose that our human slice model of seizure-like activity is a feasible option for future studies investigating new antiepileptic drug (AED) candidates.

Astrocytic glutamine synthetase is expressed in the neuronal somatic layers and down‐regulated proportionally to neuronal loss in the human epileptic hippocampus

“…Subsequently, the tissue was transported from the operation room to the laboratory, where it was cut into slices of 500 mm using a vibratome (Campden Instruments Ltd, Leicester, UK). Part of the sections was used for electrophysiological measurements (Antonio et al, 2016;Klaft et al, 2016;Sandow et al, 2015). A subset of slices was fixed in 4% w/v paraformaldehyde and cut at 30 mm sections using a cryostat (CM1850, Leica Microsystems GmbH, Nussloch,…”

Contribution of Intrinsic Lactate to Maintenance of Seizure Activity in Neocortical Slices from Patients with Temporal Lobe Epilepsy and in Rat Entorhinal Cortex

“…With respect to chronic epileptic tissue the relevance of A 1 receptor modulation might be even larger as the enzyme adenosine kinase, which contributes to the termination of adenosine effects, is upregulated in astrocytes [ 54 , 55 ]. Indeed, application of a non-metabolisable A 1 agonist could reverse recurrent epileptiform activity even in otherwise pharmacoresistant tissue [ 56 ].…”

“…All experiments were approved by the Ethics Committee of Charité-Universitätsmedizin Berlin on 01.11.2014 (EA2/111/14) and were in agreement with the Declaration of Helsinki. Transport, slicing and maintenance of the human tissue samples was carried out as described previously [ 30 , 56 ]. Immediately after surgery, the resected tissue was transferred to cold carbogenated transport solution (95% O 2 , 5% CO 2 ) composed of (in mM) KCl 3, NaH 2 PO 4 1.25, glucose 10, sucrose 200, MgSO 4 2, MgCl 2 1.6, CaCl 2 1.6, and α-tocopherol 0.1 (pH 7.4, osmolality, 304 mOsmol/kg).…”

In vitro Models for Seizure-Liability Testing Using Induced Pluripotent Stem Cells

“…Although the focus of this review is on models for drug-induced seizures, research using resected human tissue from patients with drug-resistant epilepsy should be considered. The possibilities for human tissue range from histopathological analyses, to modulation of SLE in drug-resistant tissue and the testing of novel anti-convulsant compounds and electrophysiological investigation ( Gabriel et al, 2004 ; Hsiao et al, 2015 ; Jones et al, 2016 ; Klaft et al, 2016 ). Furthermore, a number of methods are now available that increase the longevity of the resected tissue, enabling increased throughput of investigations ( Schwarz et al, 2017 ; Wickham et al, 2018 ).…”