Wang GH, Chuang AY, Lai YC, Chen HI, Hsueh SW, Yang YC. Pre- and post-synaptic A-type K
+ channels regulate glutamatergic transmission and switch of the network into epileptiform oscillations.
Br J Pharmacol 2022;
179:3754-3777. [PMID:
35170022 DOI:
10.1111/bph.15818]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/28/2021] [Accepted: 02/02/2022] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE
Anticonvulsants targeting K+ channels have not been clinically available, although neuronal hyperexcitability in seizures could be suppressed by activation of K+ channels. Voltage-gated A-type K+ channel (A-channel) inhibitors may be prescribed for diseases of neuromuscular junction but could cause seizures. Consistently, genetic loss of function of A-channels may also cause seizures. It is unclear why inhibition of A-channels, if compared with the other types of K+ channels, is particularly prone to seizure induction. This hinders the development of relevant therapeutic interventions.
EXPERIMENTAL APPROACH
The epileptogenic mechanisms of A-channel inhibition and antiepileptic actions of A-channel activation were investigated in electrophysiological and behavioral seizures with pharmacological and optogenetic maneuvers.
KEY RESULTS
Presynaptic Kv1.4 and postsynaptic Kv4.3 A-channels act synergistically to gate glutamatergic transmission and control rhythmogenesis in the amygdala. The interconnected neurons set into the oscillatory mode by A-channel inhibition would reverberate with regular paces and the same top frequency, demonstrating a spatiotemporally well-orchestrated system with built-in oscillatory rhythms normally curbed by A-channels. Accordingly, selective over-excitation of glutamatergic neurons or inhibition of A-channels suffices to induce behavioral seizures, which are effectively ameliorated by A-channel activators such as NS-5806 or AMPA receptor antagonists such as perampanel.
CONCLUSION AND IMPLICATIONS
Transsynaptic voltage-dependent A-channels serve as a biophysical-biochemical transducer responsible for a novel form of synaptic plasticity. Such a network-level switch into and out of the oscillatory mode may underlie a wide-scope of telencephalic information processing, or to its extreme, epileptic seizures. A-channels thus constitute a potential target of antiepileptic therapy.
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