Mecamylamine inhibits seizure-like activity in CA1-CA3 hippocampus through antagonism to nicotinic receptors

PLoS One. 2021 Mar 12;16(3):e0240074. doi: 10.1371/journal.pone.0240074. eCollection 2021.

Abstract

Cholinergic modulation of hippocampal network function is implicated in multiple behavioral and cognitive states. Activation of nicotinic and muscarinic acetylcholine receptors affects neuronal excitability, synaptic transmission and rhythmic oscillations in the hippocampus. In this work, we studied the ability of the cholinergic system to sustain hippocampal epileptiform activity independently from glutamate and GABA transmission. Simultaneous CA3 and CA1 field potential recordings were obtained during the perfusion of hippocampal slices with the aCSF containing AMPA, NMDA and GABA receptor antagonists. Under these conditions, spontaneous epileptiform discharges synchronous between CA3 and CA1 were recorded. Epileptiform discharges were blocked by addition of the calcium-channel blocker Cd2+ and disappeared in CA1 after a surgical cut between CA3 and CA1. Cholinergic antagonist mecamylamine abolished CA3-CA1 synchronous epileptiform discharges, while antagonists of α7 and α4β2 nAChRs, MLA and DhβE, had no effect. Our results suggest that activation of nicotinic acetylcholine receptors can sustain CA3-CA1 synchronous epileptiform activity independently from AMPA, NMDA and GABA transmission. In addition, mecamylamine, but not α7 and α4β2 nAChRs antagonists, reduced bicuculline-induced seizure-like activity. The ability of mecamylamine to decrease hippocampal network synchronization might be associated with its therapeutic effects in a wide variety of CNS disorders including addiction, depression and anxiety.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bicuculline / pharmacology
  • CA1 Region, Hippocampal / drug effects*
  • CA1 Region, Hippocampal / physiology
  • CA3 Region, Hippocampal / drug effects*
  • CA3 Region, Hippocampal / physiology
  • Excitatory Amino Acid Antagonists / pharmacology
  • GABA Antagonists / pharmacology
  • In Vitro Techniques
  • Mecamylamine / pharmacology*
  • Mecamylamine / therapeutic use
  • Nicotinic Antagonists / pharmacology*
  • Nicotinic Antagonists / therapeutic use
  • Patch-Clamp Techniques
  • Rats
  • Rats, Wistar
  • Receptors, Nicotinic / chemistry
  • Receptors, Nicotinic / metabolism*
  • Seizures / prevention & control
  • Seizures / veterinary
  • Synaptic Transmission / drug effects

Substances

  • Excitatory Amino Acid Antagonists
  • GABA Antagonists
  • Nicotinic Antagonists
  • Receptors, Nicotinic
  • Mecamylamine
  • Bicuculline

Grants and funding

This work was supported by the NIH Grants NS108765 and NS108296 (GLH), National Research Foundation of Ukraine Grant 2201/0266. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.