Document Detail

Nicotinic modulation of area postrema neuronal excitability in rat brain slices.
MedLine Citation:
PMID:  15261119     Owner:  NLM     Status:  MEDLINE    
We investigated the functions of nicotinic receptor activation on area postrema neurons by making whole-cell recordings in rat brainstem slices. Excitatory responses to nicotine application were found in approximately 78% (35/45) of all cells tested. Responsive cells included both the cells that display the hyperpolarization-activated cation current (I(h)) and cells that do not display I(h). An inhibitory effect of nicotine was never seen. Current-clamp recordings showed the nicotine-induced depolarization of a cell's membrane potential that could be sufficient to cause spontaneous firing. In voltage-clamp recordings, many cells showed nicotine-induced inward currents (18.3+/-3.2 pA, n=6) that persisted during pharmacological blockade of synaptic transmission (e.g., zero [Ca(2+)](out) and 5 mM [Mg(2+)](out), n=6/8). Other two cells, however, showed increases in the frequency of excitatory postsynaptic currents (EPSCs), which were blocked by CNQX (n=2/8). We analyzed miniature EPSCs (mEPSCs) recorded from cells that showed no inward currents but marked increases in the frequency of mEPSCs (0.8+/-0.2 to 4.8+/-1.7 Hz, n=4) during nicotine application. Nicotine augmented mEPSC amplitude (n=4); however, amplitude distribution was not significantly changed in two of four cells tested. We conclude that nicotinic receptors in the rat area postrema can excite cells via (1) a direct post- and/or extrasynaptic mechanism; and (2) an indirect enhancement of glutamate release.
Makoto Funahashi; Yoshihiro Mitoh; Ryuji Matsuo
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brain research     Volume:  1017     ISSN:  0006-8993     ISO Abbreviation:  Brain Res.     Publication Date:  2004 Aug 
Date Detail:
Created Date:  2004-07-20     Completed Date:  2004-10-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  227-33     Citation Subset:  IM    
Department of Oral Physiology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan.
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MeSH Terms
6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
Animals, Newborn
Area Postrema / cytology*
Dose-Response Relationship, Drug
Drug Interactions
Excitatory Amino Acid Antagonists / pharmacology
Neural Inhibition / drug effects
Neurons / drug effects*
Nicotine / pharmacology*
Nicotinic Agonists / pharmacology*
Patch-Clamp Techniques
Rats, Sprague-Dawley
Receptors, Nicotinic / physiology*
Tetrodotoxin / pharmacology
Reg. No./Substance:
0/Excitatory Amino Acid Antagonists; 0/Nicotinic Agonists; 0/Receptors, Nicotinic; 115066-14-3/6-Cyano-7-nitroquinoxaline-2,3-dione; 4368-28-9/Tetrodotoxin; 54-11-5/Nicotine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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