Evidence of a functional α7-neuronal nicotinic receptor subtype located on motoneurons of the dorsal motor nucleus of the vagus

Manuel Ferreira, Steven N. Ebert, David C. Perry, Robert P. Yasuda, Chandra M. Baker, Martha I. Dávila-GarcíA, Kenneth J. Kellar, Richard A. Gillis

Research output: Contribution to journalArticlepeer-review

Abstract

In vitro autoradiography using 125I-α-bungarotoxin (αBGTx) and anti-α7 immunohistochemistry were performed on the dorsal motor nucleus of the vagus (DMV) of sham and chronically vagotomized rats to determine whether the α7-nicotinic acetylcholine receptor (nAChR) is located postsynaptically on DMV neurons whose axons contribute to the vagus nerve. Intense bilateral 125I-α-BGTx binding and anti-α7 immunostaining were observed in coronal brain sections containing the DMV of sham-vagotomized animals. Unilateral cervical vagotomy resulted in ipsilateral losses of 125I-α-BGTx binding and anti-α7 immunostaining from the DMV. Simultaneous staining of rat brainstem sections with anti-α7 and anti-choline acetyltransferase (ChAT) antibodies (to identify cholinergic DMV neurons that project into the vagus nerve) revealed that every DMV neuron that was stained for ChAT showed α7-staining as well. In vagotomized animals, no ChAT-positive neurons expressing α7-nAChRs remained in the ipsilateral DMV. We conclude that the α7-nAChR subtype is located postsynaptically on DMV neurons. To test whether the α7-nAChR is similar to the α7-homomeric nAChR, experiments were performed in anesthetized rats, and compounds were microinjected into the DMV while monitoring intragastric pressure (IGP). α-BGTx and strychnine antagonized nicotine-induced increases in IGP; no antagonism was observed with methyllycaconitine, a compound known to block the homomeric α7-nAChR subtype. Recovery from α-BGTx-induced antagonism of the nicotine response was observed. We conclude that there is a nAChR containing the α7-subunit in the DMV that is different from the homomeric α7-nAChR subtype.

Original languageEnglish (US)
Pages (from-to)260-269
Number of pages10
JournalJournal of Pharmacology and Experimental Therapeutics
Volume296
Issue number2
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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