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Long‐lasting facilitation of excitatory postsynaptic potentials in the rat hippocampus by acetylcholine.
Author(s) -
Markram H,
Segal M
Publication year - 1990
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1990.sp018177
Subject(s) - excitatory postsynaptic potential , neuroscience , postsynaptic current , nmda receptor , acetylcholine , kainate receptor , hyperpolarization (physics) , postsynaptic potential , inhibitory postsynaptic potential , chemistry , glutamate receptor , voltage clamp , biophysics , biology , electrophysiology , ampa receptor , endocrinology , receptor , biochemistry , organic chemistry , nuclear magnetic resonance spectroscopy
1. The effects of acetylcholine (ACh) on excitatory postsynaptic potentials (EPSPs) evoked by stimulating Schaffer‐commissural afferents and on ionophoretically applied L‐glutamate ligands, were investigated in CA1 neurones of hippocampal slices using current‐ and voltage‐clamp techniques. 2. ACh produced a transient suppression followed by a long‐lasting facilitation of EPSPs. The facilitation was also seen in Cs(+)‐filled cells under voltage‐clamp conditions. Both suppressing and facilitating effects were blocked by atropine. 3. All components of the EPSP were reduced in the initial phase of ACh action, while only the slow component was enhanced during the later phase. The facilitation was blocked by an N‐methyl‐D‐aspartate (NMDA) receptor antagonist, d‐2‐amino‐5‐phosphonovalerate (2‐APV) and by hyperpolarization. 4. ACh also facilitated responses to ionophoretically applied NMDA in voltage‐clamped, Cs(+)‐filled cells in Ba2(+)‐treated slices. ACh facilitated responses to L‐glutamate which was blocked by 2‐APV. ACh failed to affect responses to kainate or quisqualate. 5. We conclude that ACh, acting on muscarinic receptors, exerts a primary effect in the hippocampus to specifically amplify NMDA receptor‐mediated synaptic responses and thereby facilitate EPSPs.