Nicotinic modulation of area postrema neuronal excitability in rat brain slices

Makoto Funahashi, Yoshihiro Mitoh, Ryuji Matsuo

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

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 (Ih) and cells that do not display Ih. 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 [Ca2+]out and 5 mM [Mg2+]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.

Original languageEnglish
Pages (from-to)227-233
Number of pages7
JournalBrain Research
Volume1017
Issue number1-2
DOIs
Publication statusPublished - Aug 13 2004

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Keywords

  • Acetylcholine receptors: nicotinic
  • Area postrema
  • Neurotransmitters, modulators, transporters, and receptors
  • Nicotinic ACh receptor
  • Rat
  • Slice
  • Whole-cell patch-clamp

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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