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Some pharmacological differences between hippocampal excitatory and inhibitory synapses in transmitter release: An in vitro study
Author(s) -
Kamiya Haruyuki
Publication year - 1991
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890080309
Subject(s) - excitatory postsynaptic potential , inhibitory postsynaptic potential , bicuculline , postsynaptic current , glutamatergic , adenosine , neuroscience , chemistry , postsynaptic potential , neurotransmission , glutamate receptor , carbachol , biology , gabaa receptor , biochemistry , receptor , stimulation
The effects of adenosine, carbachol, and baclofen on synaptic transmission between neurons in cultured rat hippocampal explants were studied using the tight‐seal whole cell clamp technique. In the culture, stimulations of neurites cause postsynaptic currents (PSCs) in nearby neurons under voltage‐clamp condition. In the presence of 20 μM bicuculline, most PSCs were considered as glutamatergic excitatory postsynaptic currents (EPSCs), because they were blocked by glutamate antagonist, kynurenate at 1 mM. In the presence of 1 mM kynurenate, PSCs seemed to be inhibitory postsynaptic currents mediated by γ‐aminobutyric acid (GABA), because they were blocked by GABA antagonist, bicuculline at 20 μM. Adenosine at 100 μM and carbachol at 10 μM suppressed these EPSCs to about 35% of control. However, adenosine and carbachol at the same concentration did not suppress the IPSCs. Baclofen at 10 μM suppressed both EPSCs and IPSCs significantly (EPSCs: to about 40% of control, IPSCs: to about 30% of control). In contrast, membrane currents elicited by ionophoretically applied glutamate and GABA were not suppressed by 100 μM adenosine, 10 μM carbachol, and 10 μM baclofen. From these results, it is suggested that the pharmacological sensitivities of transmitter release from presynaptic terminals are different between glutamatergic excitatory synapses and GABAergic inhibitory synapses in hippocampal cultures.