PT  - JOURNAL ARTICLE
AU  - Manuel Ferreira
AU  - Steven N. Ebert
AU  - David C. Perry
AU  - Robert P. Yasuda
AU  - Chandra M. Baker
AU  - Martha I. Dávila-García
AU  - Kenneth J. Kellar
AU  - Richard A. Gillis
TI  - Evidence of a Functional α7-Neuronal Nicotinic Receptor Subtype Located on Motoneurons of the Dorsal Motor Nucleus of the Vagus
DP  - 2001 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 260--269
VI  - 296
IP  - 2
4099  - http://jpet.aspetjournals.org/content/296/2/260.short
4100  - http://jpet.aspetjournals.org/content/296/2/260.full
SO  - J Pharmacol Exp Ther2001 Feb 01; 296
AB  - In vitro autoradiography using 125I-α-bungarotoxin (α-BGTx) 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 bilateral125I-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.