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ISSN 2522-9028 (Print)
ISSN 2522-9036 (Online)
DOI: https://doi.org/10.15407/fz

Fiziologichnyi Zhurnal

is a scientific journal issued by the

Bogomoletz Institute of Physiology
National Academy of Sciences of Ukraine

Editor-in-chief: V.F. Sagach

The journal was founded in 1955 as
1955 – 1977 "Fiziolohichnyi zhurnal" (ISSN 0015 – 3311)
1978 – 1993 "Fiziologicheskii zhurnal" (ISSN 0201 – 8489)
1994 – 2016 "Fiziolohichnyi zhurnal" (ISSN 0201 – 8489)
2017 – "Fiziolohichnyi zhurnal" (ISSN 2522-9028)

Fiziol. Zh. 2016; 62(6): 19-24


Modulation of the hippocampal propensity to nonsynaptic epileptiform synchronization in low-calcium model of epilepsy

O.S. Zapukhliak, O.V. Netsyk, O.S. Rasulova, D.S. Isaev

    O.O.Bogomoletz Institute of Physiology of National Academy of Science of Ukraine, Kyiv
DOI: https://doi.org/10.15407/fz62.06.019

Abstract

The CA3 and CA1 regions are the main stages of the “three-synaptic pathway”, which plays a role in the generation of hyper-synchronous events in the hippocampus. Under certain experimental conditions, this brain structure might support pathological epileptiform synchronization that is independent of active chemical synaptic transmission. In present work, we estimated the conditions that would facilitate nonsynaptic synchronization of the hippocampus. Non-synaptic epileptiform activity was induced in hippocampal slices by the omission calcium ions from the extracellular milieu. The propensity of hippocampal regions to nonsynaptic interactions was estimated by measuring the delay time needed for the development of lowCa2+ discharges in the CA3 and CA1. Next, an increase of neuronal excitability was induced by the preincubation of hippocampal slices in 4-aminopyridine (4-AP) and by the reduction of extracellular osmolarity. Pre-incubation of hippocampal slices with 4-AP under normal osmotic conditions resulted in decreased latency for non-synaptic discharges in the CA3, but not in the CA1. However, hypo-osmotic conditions caused increased excitability of the CA3 region, which resulted in decreased delay time for nonsynaptic discharges and this level of cellular excitability was not further enhanced by the pre-incubation with 4-AP.

Keywords: low-Ca2+ seizure-like activity; 4-aminopyridine; hypo-osmolarity; hippocampus.

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