title: Alpha-7 and alpha-4 nicotinic receptor subunit immunoreactivity in genioglossus muscle motoneurons.
abstract: In the present study, immunohistochemistry combined with retrograde labeling techniques were used to determine if hypoglossal motoneurons (HMNs), retrogradely labeled after cholera toxin B subunit (CTB) injection to the genioglossus muscle in rats, show immunoreactivity for alpha-7 and alpha-4 subunits of nicotinic acetylcholine receptors (nAChRs). CTB-positive HMNs projecting to the genioglossus muscle were consistently labeled throughout the rostrocaudal extent of the hypoglossal nuclei with the greatest labeling at and caudal to area postrema. Alpha-7 subunit immunoreactivity was found in 39.44+/-5.10% of 870 CTB-labeled motoneurons and the alpha-4 subunit in 51.01+/-3.71% of 983 CTB-positive neurons. Rostrally, the number of genioglossal motoneurons demonstrating immunoreactivity for the alpha-7 subunit was 45.85+/-10.04% compared to 34.96+/-5.11% at and caudal to area postrema (P>0.1). The number of genioglossal motoneurons that showed immunoreactivity for the alpha-4 subunit was 55.03+/-4.83% at and caudal to area postrema compared to 42.98+/-3.90% in rostral areas (P=0.074). These results demonstrate that nAChR immunoreactivity is present in genioglossal motoneurons and suggest a role for alpha-7 and alpha-4 subunits containing nAChRs in the regulation of upper airway patency.
authors.affiliation: Department of Surgery, Howard University Hospital, 2041 Georgia Avenue, NW, Washington, DC 20060, USA. odehkordi@howard.edu
authors.forename: Ozra
authors.initials: O
authors.lastname: Dehkordi
authors.forename: Richard M
authors.initials: RM
authors.lastname: Millis
authors.forename: Gary C
authors.initials: GC
authors.lastname: Dennis
authors.forename: Bernell R
authors.initials: BR
authors.lastname: Coleman
authors.forename: Sheree M
authors.initials: SM
authors.lastname: Johnson
authors.forename: Loubat
authors.initials: L
authors.lastname: Changizi
authors.forename: C
authors.initials: C
authors.lastname: Ovid Trouth
mesh_terms: D000818:Animals; D002452:Cell Count / Q000379:methods; D002772:Cholera Toxin / Q000378:metabolism; D007002:Hypoglossal Nerve / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D008526:Medulla Oblongata / Q000166:cytology* / Q000378:metabolism; D009046:Motor Neurons / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000145:classification / Q000378:metabolism*; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: C579165:Chrna7 protein, rat; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D002772:Cholera Toxin