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Muscarinic Depolarization of Layer II Neurons of the Parasubiculum

Title:

Muscarinic Depolarization of Layer II Neurons of the Parasubiculum

Glasgow, Stephen D. and Chapman, C. Andrew (2013) Muscarinic Depolarization of Layer II Neurons of the Parasubiculum. PLoS ONE, 8 (3). e58901. ISSN 1932-6203

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Official URL: http://dx.doi.org/10.1371/journal.pone.0058901

Abstract

The parasubiculum (PaS) is a component of the hippocampal formation that sends its major output to layer II of the entorhinal cortex. The PaS receives strong cholinergic innervation from the basal forebrain that is likely to modulate neuronal excitability and contribute to theta-frequency network activity. The present study used whole cell current- and voltage-clamp recordings to determine the effects of cholinergic receptor activation on layer II PaS neurons. Bath application of carbachol (CCh; 10–50 µM) resulted in a dose-dependent depolarization of morphologically-identified layer II stellate and pyramidal cells that was not prevented by blockade of excitatory and inhibitory synaptic inputs. Bath application of the M1 receptor antagonist pirenzepine (1 µM), but not the M2-preferring antagonist methoctramine (1 µM), blocked the depolarization, suggesting that it is dependent on M1 receptors. Voltage-clamp experiments using ramped voltage commands showed that CCh resulted in the gradual development of an inward current that was partially blocked by concurrent application of the selective Kv7.2/3 channel antagonist XE-991, which inhibits the muscarine-dependent K+ current IM. The remaining inward current also reversed near EK and was inhibited by the K+ channel blocker Ba2+, suggesting that M1 receptor activation attenuates both IM as well as an additional K+ current. The additional K+ current showed rectification at depolarized voltages, similar to K+ conductances mediated by Kir 2.3 channels. The cholinergic depolarization of layer II PaS neurons therefore appears to occur through M1-mediated effects on IM as well as an additional K+ conductance.

Divisions:Concordia University > Faculty of Arts and Science > Psychology
Item Type:Article
Refereed:Yes
Authors:Glasgow, Stephen D. and Chapman, C. Andrew
Journal or Publication:PLoS ONE
Date:2013
Funders:
  • Concordia Open Access Author Fund
Digital Object Identifier (DOI):10.1371/journal.pone.0058901
ID Code:977448
Deposited By: C. ANDREW CHAPMAN
Deposited On:22 Jul 2013 14:44
Last Modified:18 Jan 2018 17:44
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