Effects of extracellular concentration of calcium and intensity of stimulation on short-term plasticity in single inhibitory synapses between cultured hippocampal neurons |
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Authors: | N A Kravchenko A A Moskalyuk S A Fedulova N S Veselovskii |
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Institution: | (1) Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine;(2) International Center for Molecular Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine |
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Abstract: | We studied the characteristics of short-term plasticity in inhibitory synapses of cultured neurons of the rat hippocampus.
In our experiments, we used techniques of voltage clamp in the whole-cell configuration and of local electrical stimulation
(pairs of stimuli were applied to a single synaptic terminal of the GABA-ergic neuron under conditions of the blockade of
spreading excitation). We demonstrated that an increase or a decrease in the extracellular concentration of calcium ions (Ca2+]o) results in modifications of the pattern of this plasticity. Depression of the second postsynaptic response under conditions
of normal Ca2+]o was characterized by a paired-pulse ratio (PPR) equal, on average, to 0.78 ± 0.04 (n = 5). With a decrease in the Ca2+]o to 0.5 mM, depression was changed to facilitation (PPR = 1.17 ± 0.08, n = 5), while with a rise in the Ca2+]o to 5.0 mM, depression became more clearly pronounced (PPR = 0.48 ± 0.03, n = 5). Alterations of responses, which were determined by a decrease or an increase in the Ca2+]o, differed significantly from those related to a decrease or an increase in the amplitude of presynaptic stimulation. Analysis
of the parameters of the pairs of evoked inhibitory postsynaptic currents under conditions of various Ca2+]o and different intensities of stimulation of the presynaptic terminal allows us to conclude that in these terminals calcium-dependent
(and, probably, also voltage-dependent) mechanisms underlying control of short-term synaptic plasticity are present.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 2, pp. 103–112, March–April, 2006. |
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Keywords: | paired-pulse depression and facilitation single synapse inhibitory postsynaptic current culture of rat hippocampal neurons |
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