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Presynaptic alpha-7 nicotinic acetylcholine receptors modulate excitatory synaptic transmission in hippocampal neurons

Liu Zhenwei, Yang Sheng, Zhang Yongxiang, Liu Chuanhui

Beijing Institute of Pharmacology and Toxicology.Beijing 100850

Abstract

The effects of presynaptic nicotinic acetylcholine receptors (nAChRs) on excitatory synaptic transmission in CA1 pyramidal neurons of the rat hippocampus were examined by blind whole-cell patch clamp recording from hippocampal slice preparations. Local application of the nAChRs agonist dimethylphenyl-piperazinium iodide (DMPP) did not induce a postsynaptic current response in CA1 pyramidal cells. However, DMPP enhanced the frequency and amplitude of spontaneous excitatory postsynaptic current (sEPSC) in these cells in a dose-dependent manner. This enhancement was blocked by the selective nicotinic #alpha#-7 receptor antagonist #alpha#-bungarotoxin, but not by the antagonist mecamylamine, hexamethonium or dihyhro-#beta#-erythroidine. The frequency of miniature excitatory postsynaptic current (mEPSC) in CA1 pyramidal neurons was also increased by application of DMPP, indicating a presynaptic site of action of the agonist. Taken together, these results suggest that activation of presynaptic nAChRs in CA1 pyramidal neurons, which contain #alpha#-7 subunits, potentiates presynaptic glutamate release and consequently modulate excitatory synaptic transmission in the hippocampus.

Key words: Nicotinic;Acetylcholine receptors （ nAChRs）;Hippocampal slice synaptic transmission;Glutamate （ Glu）;Dimethylphenyl-piperazinium iodide （DMPP）

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Citing This Article：

Liu Zhenwei, Yang Sheng, Zhang Yongxiang, Liu Chuanhui. Presynaptic alpha-7 nicotinic acetylcholine receptors modulate excitatory synaptic transmission in hippocampal neurons. Acta Physiol Sin 2003; 55 (6): (in Chinese with English abstract).