Presynaptic alpha-7 nicotinic acetylcholine receptors modulate excitatory synaptic transmission in hippocampal neurons.
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 dihydro-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.
Liu
Zhen-Wei
ZW
Beijing Institute of Pharmacology and Toxicology, Beijing 100850. zhenwei_Liu@yahoo.com
Yang
Sheng
S
Zhang
Yong-Xiang
YX
Liu
Chuan-Hui
CH
D000818:Animals; D002038:Bungarotoxins / Q000502:physiology; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology; D018722:Nicotinic Agonists / Q000494:pharmacology; D010138:Pacemaker, Artificial; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000502:physiology*; D017661:Receptors, Presynaptic / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission; D064569:alpha7 Nicotinic Acetylcholine Receptor
D002038:Bungarotoxins; C579165:Chrna7 protein, rat; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D017661:Receptors, Presynaptic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D018698:Glutamic Acid; D004246:Dimethylphenylpiperazinium Iodide