Anticholinesterase-induced epileptiform activity in immature rat piriform cortex slices, in vitro.

Aitchison, E., Weston, S.E., Constanti, A. and Whalley, B.J. (2010) Anticholinesterase-induced epileptiform activity in immature rat piriform cortex slices, in vitro. Neuroscience Letters, 473 (4). pp. 252-256. 10.1016/j.neulet.2010.02.060 .

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DOI: 10.1016/j.neulet.2010.02.060

Abstract

Purpose: Acute in vitro brain slice models are commonly used to study epileptiform seizure generation and to test anti-epileptic drug action. Seizure-like activity can be readily induced by manipulating external ionic concentrations or by adding convulsant agents to the bathing medium. We previously showed that epileptiform bursting was induced in slices of immature (P14–28) rat piriform cortex (PC) by applying oxotremorine-M, a potent muscarinic receptor agonist. Here, we examined whether raising levels of endogenous acetylcholine (ACh) by exposure to anticholinesterases, could also induce epileptiform events in immature (P12–14) or early postnatal (P7–9) rat PC brain slices. Methods: The effects of anticholinesterases were investigated in rat PC neurons using both extracellular MEA (P7–9 slices) and intracellular (P12–14 slices) recording methods. Results: In P7–9 slices, eserine (20 μM) or neostigmine (20 μM) induced low amplitude, low frequency bursting activity in all three PC cell layers (I–III), particularly layer III, where neuronal muscarinic responsiveness is known to predominate. In P12–14 neurons, neostigmine produced a slow depolarization together with an increase in input resistance and evoked cell firing. Depolarizing postsynaptic potentials evoked by intrinsic fibre stimulation were selectively depressed although spontaneous bursting was not observed. Neostigmine effects were blocked by atropine (1 μM), confirming their muscarinic nature. We conclude that elevation of endogenous ACh by anticholinesterases can induce bursting in early postnatal PC brain slices, further highlighting the epileptogenic capacity of this brain region. However, this tendency declines with further development, possibly as local inhibitory circuit mechanisms become more dominant.

Item Type:Article
Additional Information:Full text available electronically from the School of Pharmacy Library.
Uncontrolled Keywords:Piriform cortex (PC); Anticholinesterase; Acetylcholine (ACh); Epileptiform activity
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:1670
Journal or Publication Title:Neuroscience Letters
Deposited By:Library Staff
Deposited On:14 Jul 2010 15:35
Last Modified:25 Nov 2011 10:35

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